Final report for LNC15-375

Summary:

This project addresses two problems. First, science-based information on the potential return on investment at the farm-level associated with the use of cover crops by Cornbelt farmers is very limited. We provide the first set of partial budgets to evaluate the private economic returns to cover crops in Midwest row crop farming. Second, row crop farming in the Midwest has been increasingly singled out as a major non-point source of nitrate pollution in waterways. We provide an evaluation of the potential impacts of cover crop adoption in nitrate leaching and soil erosion, and the cost saving potential for local water treatment plants. If aggregate cost savings in drinking water treatment plants stemming from reduced nitrate levels and soil erosion are greater than the sum of potential net losses across cover crop adopters, then economic theory suggests that a reallocation of resources from water treatment plants to cover crop users might improve social welfare.

Contrary to our expectations, we found that cover crops typically induce negative net returns in Midwest row crop systems. Using the cover crop biomass for grazing livestock or harvesting it for forage is the most likely source of additional revenue (or cost savings in a crop/livestock system) that would result in positive net returns to cover crops.
Our long term agronomic simulations suggest that using cover crops every year in a corn/soybean rotation for two decades would result in higher average soybean yields, similar corn yields, and lower nitrate leaching and soil erosion than in a comparable crop system without cover crops.

However, the potential of cover crops to save costs to water treatment plants in the Midwest is limited by the relatively small annual operating costs for removing nitrates from untreated water sources. Therefore, and contrary to our expectations, the societal benefits defined in this very narrow way would be insufficient to offset the negative returns to Midwest farmers associated with large scale adoption of cover crops.

Introduction:

Row crop farming in the Midwest has been increasingly singled out as a major non-point source of nitrate pollution in waterways, putting pressure on farmers to adopt conservation practices. One of the promising conservation practices is the use of cover crops, which is known to promote many aspects of soil and water sustainability (Kaspar & Singer, 2011; Chatterjee, 2013). For instance, preliminary results from simulations based on a long-term cover crop study in Iowa suggest that nitrate concentration in tile drainage can be reduced by 54% when a winter rye cover crop is added to corn-soybean acres (Miguez, Basche, and Archontoulis, 2013). Moreover, the Iowa Nutrient Reduction Strategy (2014), Illinois Nutrient Loss Reduction Strategy (2015) and Minnesota Nutrient Reduction Strategy (2014) all list cover crops as one of the practices with the greatest potential for nitrate-N reduction. However, despite the considerable benefits the cropping systems can accrue, adoption of cover crops is very low in the Midwest. Singer, Nusser, and Alf (2007) found that in 2006, only 11% of farmers surveyed in Illinois, Iowa, Minnesota and Indiana had grown a cover crop within the previous five years. An analysis by the National Wildlife Federation of seed dealer data calculated that in 2011, less than 2% of the total cropland acreage in the Mississippi River Basin was planted to cover crops (Bryant, Stockwell, and White, 2013). Rundquist and Carlson (2017), using satellite imagery, report that in 2015 cover crops were incorporated into corn and soybean rotations in 2.3% of Illinois cropland, 7.1% of Indiana cropland and 2.65% of Iowa cropland.

It has long been recognized that lack of familiarity with novel approaches in agriculture can inhibit adoption of conservation practices (Nassauer, et al. 2011). The top cover crop challenges farmers reported across four annual cover crop surveys (Watts and Myers 2013, 2014, 2015, and 2016) were establishment, time or labor required and increased management, and species selection. Farmers’ perceptions that cover crops are costly is also found to be a major barrier to their adoption: 74% of the respondents to the Iowa farm and Rural Life Poll (Arbuckle, 2015) report that potential economic impacts have moderate to very strong influence on changes in their management practices, and 57% agree with the statement that “pressure to make profit margins makes it difficult to invest in conservation practices”. During the 2014 National Conference on Cover Crops and Soil Health, participants highlighted the need for economic analyses to document short- and long-term impacts of cover crops (Sustainable Agriculture Research and Education 2014). Roesch-McNally, et al. (2017) found that despite having successfully planted cover crops, farmers tended to believe that greater economic incentives would be needed to spur more widespread adoption of the practice. The U.S Department of Agriculture Natural Resource Conservation Service (2017) estimated that Iowa farmers planted more than 353,000 acres of cover crops with financial assistance from the Iowa Department of Agriculture and Land Stewardship (through the Iowa Water Quality Initiative, state cost-share, and local watershed project) and federal conservation programs (through the Environmental Quality Incentives Program (EQIP), Conservation Stewardship Program (CSP), and Regional Conservation Partnership Program (RCPP)) in the fall of 2016 – nearly 18 percent more than the previous year.

Science-based information on the potential return on investment at the farm-level associated with the use of cover crops by Midwest farmers is very limited. A handful of papers evaluate the economic impact of cover crops on different cash crops including Reddy (2009) with soybeans in Mississippi; Mahama, et al. (2016) with corn in Kansas; and Roberts, et al. (1998) with no-till corn in Tennessee. However, those studies are based on field experiments set up to evaluate agronomic factors, and the resulting estimates of economic returns might not apply to real farms where management practices do not follow an experimental design. Roberts and Swinton (1995) use actual data from 15 farms growing corn in Michigan in 1994 to explore the relationship between operating costs and crop diversity, and they concluded that cover crops reduce non-point source pollution without significantly reducing net returns. However, the small sample size limits the robustness of the results. Snapp, et al. (2005) provided a summary of the potential benefits and costs from the cover crops, both external and internal to the farm, and report qualitative findings from focus group discussions with eight Michigan potato farmers.

There is a gap in the literature on the actual changes in economic costs and revenues faced by farmers who choose to use cover crops in their corn-soybean rotations in the Midwest. This project addressed the limited availability of science-based economic evaluations of cover crops in Midwest row crop systems by engaging farmers in developing and promoting the use of partial budgets for cover crops. Partial budgets capture the net annual private economic benefit or loss associated with the use of cover crops by identifying and monetizing the differences in management practices across production systems with and without cover crops. We provide a suite of partial budgets for cover crops in Midwest row crop production systems (by cover crop species, location, planting and termination method, tillage practices, cash crop rotation, and years of experience with cover crops) that serve both as benchmarks to current and potential cover crop users, and ground-truthing for agricultural and environmental policy design.

Cover crops may provide soil conservation benefits in the reduction of on-site erosion. Soil erosion represents a cost to land owners, farmers and society as a whole. Duffy (2012) estimated the value of soil erosion to landowners in Iowa at approximately 4.8% of the adjusted 2011 land values.

USDA/NRCS (2009, 2010) studies reported that each ton of soil eroded contained the equivalent of 2.32 pounds of nitrogen and 1 pound of phosphorous. The estimated costs per pound of nitrogen and phosphorous for Iowan farmers in 2015 were $0.47 and $0.48, respectively (Plastina, 2015). One way to value soil loss from the farmer’s perspective is in terms of the value of lost fertilizer, and that results in $1.57 per ton of soil loss. This approach is fraught with shortcomings, and more farm-specific economic valuations for farmers (as the one discussed in this proposal) are needed.

The USDA/NRCS (2009, 2010) studies also estimated a per-ton benefit of $4.93 per acre for improved water quality benefits. Summing the values of soil loss saved for the farmer ($1.57 per ton of soil saved) and water quality benefits ($4.93 per ton of soil saved), participation in the Environmental Quality Incentives Program (EQIP) creates benefits for farmers and society at large, valued at $6.50 per ton of soil. Using the estimated 8.6 tons per acre reduction in soil erosion for land in EQIP, enrollment in EQIP saves soil valued at $55.90 per acre.

Hansen and Ribaudo (2008) estimate the total annual water-related benefits from soil erosion abatement in the Corn Belt at $2.77 per ton of soil saved; and the reduction of municipal water treatment costs due to reduced turbidity at $0.18 per ton of soil saved. These estimates focus on the benefits stemming from reduced sediments in waterways, but exclude the benefits stemming from reduced nitrogen load on tile drainage.

Des Moines Water Works (DMWW), a regional water utility providing drinking water to approximately 500,000 Iowans, reported having incurred approximately $900,000 in treatment costs and lost revenues when nitrate levels in the Raccoon and Des Moines Rivers were record high in 2013; and another $540,000 in operations and additional expenses between December 2014 and March 2015. DMWW (2015) claimed that “record high nitrate concentrations will require future capital investments of $76-183 million to remove the pollutant and provide safe drinking water to a growing central Iowa.” On March 10, 2015, DMWW filed a lawsuit against the Boards of Supervisors of three Iowa counties for the discharge of nitrate pollutants into the Raccoon River, and requested that they be recognized and held accountable as a point source polluter. This lawsuit is currently inactive (Center for Agricultural Law and Taxation, 2017), but served as a starting point for our investigation into the operating costs incurred by water treatment plants in Iowa, Illinois, and Minnesota to remove nitrates and reduce turbidity stemming from agricultural land. If aggregate cost savings in drinking water treatment plants stemming from reduced nitrate levels and soil erosion were greater than the sum of potential net losses across cover crop adopters, then economic theory would suggest that a reallocation of resources from water treatment plants to cover crop adopters might improve social welfare.

Our societal economic evaluation was based on the analysis of existing long-term field trial data collected by Practical Farmers of Iowa and simulations of farm-specific yield and soil erosion estimates using the Agricultural Production System Simulator (APSIM), along with the operating costs incurred by water treatment plants to treat nitrates and turbidity. Due to the costs associated with generating data from numerous field research sites, simulations are used to develop best estimates of the impact of cover crops on nitrate leaching and soil erosion. This method provides much better estimates than off-the-shelf values from the literature alone, and allowed us to avoid large-scale experimentation which is costly and impractical. By providing a science-based report on the potential reduction in soil erosion and nutrient loading stemming from cover crops use, we expect to heighten awareness about the benefits of this practice in sustaining and improving the environmental quality and natural resource base for agriculture.

As expected, our findings indicate that cover crops generate clear environmental benefits (although with regional differences), but contrary to our expectations, individual, regional, and state-wide partial budgets suggest that farmers who use cover crops tend to incur in annual net losses when the operation cannot benefit from livestock feed savings through grazing or harvesting the cover crop biomass for forage. These findings are robust across cover crop species, location, planting and termination method, tillage practices, cash crop rotation, and years of experience with cover crops; and take into account cost-share payments.

The societal economic evaluation, given the annual negative net returns to cover crops and the minor costs (if any) to operate equipment to remove nitrates in water treatment plants, and the small potential influence of cover crops use in reducing water turbidity, suggests that additional cost-share funding for cover crop expansion cannot be justified based solely on water treatment plant savings. However, it must be noted that our approach excludes other environmental benefits (Tang et al. 2018) from the calculation that if included could provide a solid rationale for a more extensive support to cost-share programs.

References

Arbuckle Jr., J.G. (2012). Attitudes towards Cover Crops in Iowa: Benefits and Barriers. Iowa Farm and Rural Life Poll, Iowa State University Extension and Outreach, PMR 1010, March.

Bryant, L., R. Stockwell, and T. White. (2013). Counting Cover Crops. National Wildlife Federation. Available at: https://www.nwf.org/~/media/PDFs/Media%20Center%20-%20Press%20Releases/10-1-13_CountingCoverCrops-FINALlowres.ashx

Carlson, S. and R. Stockwell. (2013). Research priorities for advancing adoption of cover crops in agriculture-intensive regions. Journal of Agriculture, Food Systems and Community Development. Advance online publication. http://dx.doi.org/10.5304/jafscd.2013.034.017

Center for Agricultural Law and Taxation. 2017. Des Moines Water Works Litigation Resources. Available at: https://www.calt.iastate.edu/article/des-moines-water-works-litigation-resources Last accessed Feb 2, 2018.

Chatterjee, A. (2013). North-Central US: Introducing cover crops in the rotation. Crops and Soils, 46(1): 14-15.

Des Moines Water Works (DMWW). (2015). Board of Water Works Trustees Votes to Pursue Lawsuit Against Drainage Districts. Available at: http://www.dmww.com/about-us/announcements/board-of-water-works-trustees-votes-to-pursue-lawsuit-against-drainage-districts.aspx

Duffy, M. (2012). Value of Soil Erosion to the Land Owner. Ag Decision Maker File A1-75. Available at: www.extension.iastate.edu/agdm/crops/html/a1-75.html

Hansen, L. and M. Ribaudo. (2008). “Economic Measures of Soil Conservation Benefits, Regional Values for Policy Assessment,” USDA/ERS, Technical Bulletin 1922.

Kaspar, T., and J. Singer. (2011). The Use of Cover Crops to Manage Soil. In Soil Management: Building a Stable Base for Agriculture. Ed. J.L. Hatfield and T.J. Sauer. Madison: American Society of Agronomy and Soil Science Society of America.

Miguez, F., A. Basche and S. Archontoulis. (2013). Predicting long-term cover crop impacts on soil quality using a cropping systems model. Leopold Center for Sustainable Agriculture. Available at: http://www.leopold.iastate.edu/grants/e2013-19

Nassauer, J., J. Dowdell, Z. Wang, D. McKahn, B. Chilcott, C.Kling and S. Secchi. (2011). Iowa Farmers’ responses to transformative scenarios for Corn Belt agriculture. Journal of Soil and Water Conservation, 66(1): 18A-24A.

Natural Resource Conservation Service (NRCS) of Iowa. (2012). Practices Improving Soil Health Also Reduce Erosion. Available at: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/ia/home/?cid=STELPRDB1097491

Plastina, A. (2015). Estimated Costs of Crop Production in Iowa. Ag Decision Maker File A1-20. Available at: www.extension.iastate.edu/agdm/crops/html/a1-20.html

SARE. (2013). 2012-2013 Cover Crop Survey: June 2013 Survey Analysis. North Central SARE and Conservation Technology Information Center: https://northcentral.sare.org/Educational-Resources/From-the-Field/Cover-Crops-Survey-Analysis

SARE. (2014). “Preliminary draft report from the National Conference on Cover Crops and Soil Health,” Omaha, NE, Feb 17-19.

Singer, J., S. Nusser, and C.Alf. (2007). Are cover crops being used in the US corn belt? Journal of Soil and Water Conservation, 62(5): 353–358.

Tang, C., G.E. Lade, D.A. Keiser, C.L. Kling, Y. Ji, and Y-H. Shr. “Economic Benefits of Nitrogen Reductions in Iowa.” Iowa State University, Center for Agricultural and Rural Development. February 2018. Available at https://www.card.iastate.edu/products/publications/texts/water-quality-report.pdf. Last accessed Feb 27, 2018.

SDA/NRCS. (2009). Summary Report: 2007 National Resources Inventory, Natural Resources Conservation Service, Washington, DC, and Center for Survey Statistics and Methodology, Iowa State University, Ames, Iowa. 123 pages.

USDA/NRCS. (2010). Final Benefit-Cost Analysis for the Environmental Quality Incentives Program (EQIP), Natural Resources Conservation Service, Washington, DC, May 10.

Project Objectives:

This project had two objectives: to address the limited availability of science-based economic evaluations of cover crops in Midwest row crop systems through partial budgets; and to evaluate the long-term impacts of cover crop adoption in nitrate leaching and soil erosion (and the resulting cost saving potential for local water treatment plants) through long-term agronomic simulations.

An entire suite of partial budgets for cover crops in Midwest row crop production (by cover crop species, location, planting and termination method, tillage practices, cash crop rotation, and years of experience with cover crops) was developed based on: farmer focus groups conducted in Iowa, Illinois, and Minnesota; online survey responses from 11 states; hard-copy survey responses from Iowa; and analyses of existing data from multi-year field trials from Practical Farmer of Iowa.

The Agricultural Production System Simulator (APSIM) model was used to simulate the long-term effects of cover crop adoption on soil erosion and nitrate leaching for a variety of locations, soil types, and alternative management practices. The APSIM model follows the Natural Resource Conservation Services’ Revised Universal Soil Loss Equation (RUSLE2).

Estimating the private and social cost of soil erosion is extremely difficult and subject to a variety of assumptions. We focused on estimating only a portion of all possible social costs of soil erosion, namely those related to increased costs of drinking water treatment due to increased turbidity and/or nitrogen load. We interviewed water treatment plant managers in Iowa, Illinois, and Minnesota, to learn about the technology available to reduce nitrates and turbidity in drinking water caused by cropland soil erosion.

Click linked name(s) to expand/collapse or show everyone's info

Sarah Carlson
sarah@practicalfarmers.org
Midwest Cover Crop Research Coordinator
Practical Farmers of Iowa
500 6th St Suite 100
Ames, IA 50010
(515) 232-5661 (office)
Fangge Liu
fangge@iastate.edu
PhD Student
Iowa State University
83 Heady Hall
Department of Economics
Ames, IA 50011
(515) 294-6846 (office)
Dr. Fernando Miguez
femiguez@iastate.edu
Assistant Professor
Iowa State University
1206 Agronomy Hall
Department of Agronomy
Ames, IA 50011
(515) 294-5980 (office)
Dr. Bhavna Sharma
bhavna@iastate.edu
Postdoctorate
Iowa State University
1203 Agronomy Hall
Department of Agronomy
Ames, IA 50011
(515) 294-6868 (office)
Wendiam Sawadgo
Research Assistant
Department of Economics, Iowa State University (1862 Land Grant)
478 Heady Hall
Ames, IA 50011
Guillermo Marcillo
Research Assistant
Department of Agronomy, Iowa State University (1862 Land Grant)
1203 Agronomy Hall
Ames, IA 50011
Alisha Bower
alisha@practicalfarmers.org
Midwest Cover Crop Associate
Practical Farmers of Iowa (Nonprofit / non-governmental organization)

Hypothesis:

Hypothesis 1: the net returns to cover crops in Midwest row crop production are positive.

Hypothesis 2: large scale adoption of cover crops in the Midwest has the potential to generate sufficient cost savings to water treatment plants to justify expanding incentives to farmers to adopt cover crops.

Materials and methods:

Hypothesis 1: To test the first hypothesis, we use partial budgets.

Partial budgets capture the net annual private economic benefit or loss associated with the use of cover crops by identifying and monetizing the differences in management practices across production systems with and without cover crops.

In 2016, we developed a methodological framework and an accompanying survey questionnaire to create partial budgets for cover crops for different soil types, cover crop mixes, and farm management practices; as well as to implement socio-economic and agronomic impact analyses.

The development of the methodological framework and the survey questionnaire required extensive interaction between team members, farmers, and researchers. Three focus group with experienced cover crops farmers were conducted in Iowa, Minnesota, and Illinois to discuss reasons for adoption, required changes in practices, and resulting changes in costs and revenues. They served as the basis to identify relevant production practices and variables that influence cover crop use. Based on that information and a comprehensive literature review, a first draft of the survey questionnaire was developed. Focus group participants were asked to provide feedback on the survey questionnaire. Farmers were duly compensated for their time and effort.

In January 2017, electronic invitations to participate in the online survey were sent to more than 20,000 farmers, including members of PFI, the Midwest Cover Crops Council, National Wildlife Federations’ Cover Crops Champions Program, and the American Society of Agronomy among other regional associations.

In February 2017, a hard copy version of the same survey questionnaire was implemented in Iowa through the Upper Midwest Office of the National Agricultural Statistical Service (NASS) of the U.S. Department of Agriculture. The stratified random sample selected by NASS consisted of about 1,250 farm operators who reported planting 10 or more acres of cover crops on the 2012 Census of Agriculture, had 50 or more acres of cropland, and reported harvesting one or more field crops. The sample was stratified by small, medium, and large size operations, based on cropland.

Hypothesis 2: to test the second hypothesis, we use a combination of long-term agronomic simulations and interviews with water treatment plant managers.

We used the Agricultural Production Systems Simulator (APSIM) model to understand the effects of cover crops on a number of variables of interest, by simulating the behavior of production and environmental components on cropping systems without cover crops (baseline), and on cropping systems with cover crops (treatment). APSIM is a powerful cropping systems model which can generate estimates on crop growth and soil-water dynamics on a daily basis and can take into account variables at the individual field level. Since our focuses are corn yield and nitrogen loss, we replicated the simulations for 4 nitrogen application rates, 3 soil series, and 13 locations across the Midwest from 1980 to 2014, which include variations in the corresponding weather data.

The simulated variables include corn yield, corn biomass, soil loss, surface runoff, subsurface drainage, and Nitrogen loss through drainage. We calculated nitrate leaching as the concentration of nitrate (No₃) loss through drainage in mg/L as nitrate load divided by subsurface drainage times 100.

In an attempt to understand the costs incurred by water treatment plants due to high nitrate concentrations and turbidity in raw water, we conducted three in-person interviews with water treatment plant managers in Des Moines (Iowa), Cedar Rapids (Iowa), and Fairmont (Minnesota), and exchanged emails with water treatment plant managers in Bloomington (Illinois) and the City of Decatur (Illinois). During the in-person interviews, we first presented a summary of our findings from the APSIM model, and then followed a structured questionnaire to guide the discussion and help us discern variable operational costs associated with nitrate removal and turbidity from fixed costs (depreciation of equipment in use) and sunk costs (planned replacement of equipment in use, building of new facilities).

Research results and discussion:

Hypothesis 1:

Results from regional online survey:

More than 300 responses were received from farmers in 11 states, but only 79 responses were used in the calculation of partial budgets, after excluding responses from: (1) farmers who were interested in cover crops but had no hands-on experience; (2) farmers that did not plant cover crops in 2015; (3) farmers that planted cover crops in 2015 on all their acres; (4) farmers that in 2016 planted a different cash crop on acres following cover crops than on acres left fallow during winter; and (5) incomplete responses. This selection process reduces the sample size, but improves the validity of the results by focusing on the changes in costs and revenues associated with cover crop use controlling for the farm manager effect and the macroeconomic conditions prevalent in 2015-2016.

More than two-thirds of the respondents operated farms in Minnesota, Iowa, or Illinois, and nearly 80 percent of the farms were larger than 500 acres in size (Table 1). The single most frequently used cover crop species among survey respondents was cereal rye, but nearly half of the respondents used cover crop mixes composed of three or more cover crop seeds. The most commonly used planting method was drilling, followed by aerial seeding.

The average number of farmers’ years of experience with cover crops was 3.94 years, and the range of responses went from 0.2 to 15 years, with a median of 4 years (Table 2). The average cumulative cover crop acreage per farmer was 1,483 acres, but the median was 540 acres, indicating that while a few large farms are captured in the data, most farms tend to be much smaller than the average.

The mean changes in revenues, costs and profits per acre across partial budgets suggests that cover crops induce net losses in the absence of cost-share programs (Table 3); and only cover crops winterkilled, or terminated with herbicides before planting soybeans tend to break even when cost-share payments are present (Tables 4-7). There is substantial variability in the net returns to cover crops, driven by the difference in yields obtained in fields with and without cover crops, planting costs, and cost-share program payments. For most farmers, cost-share payments are insufficient to cover all private costs associated with cover crop use, but are a critical incentive to support this practice. This study suffers from several limitations related to the self-selection bias of survey respondents, the potential unrepresentativeness of the sample, and the limited number of responses included in the partial budgets. However, it is the first study to attempt to generate partial budgets using field data (instead of experimental plots) from farmers that manage row crop production on acres with cover crops and on acres with no cover crops.

Table 1. Farm characteristics.

Factors	Factor levels	Count of farms	Percent in sample
Cover crop mix	Cereal rye	34	43.04
	Annual Ryegrass	4	5.06
	Cereal Rye + Oats	2	2.53
	Annual ryegrass + crimson clover + oilseed radish	5	6.33
	Annual ryegrass + crimson clover + oilseed radish + rapeseed	2	2.53
	Oats + oilseed radish + buckwheat	1	1.27
	Crimson clover + oilseed radish	3	3.80
	Oats + oilseed radish + turnip	1	1.27
	Other	27	34.18
	Subtotal	79	100
Size of farms (acres)	50-99	1	1.27
	100-199	5	6.33
	200-499	11	13.92
	500-999	19	24.05
	1000-1999	20	25.32
	2000+	23	29.11
	Subtotal	79	100
Farm location	Illinois	12	15.19
	Iowa	21	26.58
	Minnesota	24	30.38
	Other states^	22	27.84
	Subtotal	79	100
Planting method	Drilling	50	56.82
	Aerial	20	22.73
	Broadcast	5	5.68
	Other	13	14.77
	Subtotal	88	100

^Other states: North Dakota (11 farms), Indiana (3 farms), Nebraska (2 farms), Ohio (2 farms), Michigan (1 farm), Missouri (1 farm), South Dakota (1 farm), and Wisconsin (1 farm)

Table 2. Farmers’ experience with cover crops

Variable	Mean	Standard deviation	Median	Min	Max
Number of years planting cover crops	3.94	2.64	4	1	15
Cumulative cover crop acreage	1483	3783	540	5	30000

Table 3. Summary of Results: Mean changes in revenues, costs and profits by calculated partial budget.

Sources of changes in net profits	Cover crops terminated with herbicides followed by corn for grain ($/acre)	Cover crops terminated with herbicides followed by soybeans ($/acre)	Cover crops terminated with herbicides in corn-soybean rotation ($/acre)	Cover crops winterkilled followed by corn or soybeans($/acre)
A. Changes in revenue:
1. Cash Crop Yield	-9.18	31.74	-1.80	-8.25
2. Cost-share program	25.33	28.07	31.14	43.83
Subtotal	16.16	59.81	29.34	35.58
B. Changes in costs:
1. Cover crop planting	31.84	31.14	33.60	32.06
2. Herbicide expenses	4.05	3.82	6.94	-0.33
3. Other Costs	1.02	-0.27	0.57	-2.57
Subtotal	36.91	34.69	41.12	29.16
Net change in profit (A-B):	-20.76	25.13	-11.78	6.43
Net change in profit without Cost-Share	-46.09	-2.95	-42.92	-37.41

Table 4. Partial budget for cover crops terminated with herbicides followed by corn for grain:

Sources of changes in net profits	Mean ($/acre)	1^st Quartile ($/acre)	Median ($/acre)	3rd Quartile ($/acre)	N
A. Changes in revenue:
3. Corn Yield (valued @ $3.35/bushel)	-9.18	-33.50	0.00	18.36	21
4. Cost-share program	25.33	17.00	25.00	25.00	6
Subtotal	16.16	-16.50	25.00	43.36
B. Changes in costs:
4. Cover crop planting	31.84	39.86	29.88	23.05
a. Seeds	16.33	21.00	14.00	12.00	21
b. Planting (excluding seeds) (weighted average of i-ii)	15.51	18.86	15.88	11.05
i. Custom work	17.50	19.00	16.00	15.00	8
ii. Non-Custom	14.44	18.78	15.82	8.95	15
5. Herbicide expenses (weighted average of a-b)	4.05	7.38	0.72	0.72
a. For farmers that did not apply herbicides before planting corn in baseline	15.06	15.06	15.06	15.06	1
i. Herbicide cost to terminate cover crops	9.00	9.00	9.00	9.00	1
ii. Application (Non-custom )	6.06	6.06	6.06	6.06	1
b. For farmers that applied herbicides before planting corn in baseline	3.50	7.00	0.00	0.00	20
i. Additional herbicide costs on top of regular weed control program*	3.50	7.00	0.00	0.00	20
ii. Labor costs to apply herbicides on top of regular weed control program*					0
6. Other Costs (sum of a-k)	1.02	1.41	0.30	0.00
a. Corn seed costs	0.00	0.00	0.00	0.00	21
b. Corn planting costs (excluding seeds)	0.71	0.00	0.00	0.00	21
c. Nitrogen costs	0.26	0.00	0.00	0.00	21
d. P & K costs	0.00	0.00	0.00	0.00	21
e. Manure costs	0.00	0.00	0.00	0.00	21
f. Insecticide costs	0.90	0.00	0.00	0.00	21
g. Fungicide costs	0.00	0.00	0.00	0.00	21
h. Soil testing costs	0.00	0.00	0.00	0.00	21
i. Management ($15 per hour)	1.24	1.41	0.30	0.00	15
j. Cash rent	-1.43	0.00	0.00	0.00	14
k. Soil erosion repairs	-0.67	0.00	0.00	0.00	21
Subtotal	36.91	48.65	30.90	23.77
Net change in profit (A-B):	-20.76	-65.15	-5.90	19.59
Net change in profit without Cost-Share	-46.09	-82.15	-30.90	-5.41

N = number of responses per row; *values for farmers who used herbicide on both cover crop and non-cover acres

Table 5. Partial budget for cover crops terminated with herbicides followed by soybeans:

Sources of changes in net profits	Mean ($/acre)	1^st Quartile ($/acre)	Median ($/acre)	3rd Quartile ($/acre)	N
A. Changes in revenue:
1. Soybean Yield (valued @ $9.95/bushel)	31.74	0.00	4.78	57.30	34
2. Cost-share program	28.07	20.00	25.00	30.00	14
Subtotal	59.81	20.00	29.78	87.30
B. Changes in costs:
1. Cover crop planting	31.14	35.95	29.77	24.82
a. Seeds	15.11	17.00	13.50	11.00	34
b. Planting (excluding seeds) (weighted average of i-ii)	16.02	18.95	16.27	13.82
i. Custom work	13.61	15.00	14.50	11.50	14
ii. Non-Custom	17.44	21.25	17.31	15.17	24
2. Herbicide expenses (weighted average of a-b)	3.82	5.50	4.05	2.33
a. For farmers that did not apply herbicides before planting soybeans in baseline	16.85	23.38	17.23	9.91	8
i. Herbicide cost to terminate cover crops	11.25	16.50	11.00	6.00	8
ii. Application (weighted average a-b)	5.60	6.88	6.23	3.91	8
(a) Custom work	6.17	7.00	6.50	5.00	3
(b) Non-Custom	5.26	6.81	6.06	3.25	5
b. For farmers that applied herbicides before planting soybeans in baseline	-0.19	0.00	0.00	0.00	26
i. Additional herbicide costs on top of regular weed control program*	-0.19	0.00	0.00	0.00	26
ii. Labor costs to apply herbicides on top of regular weed control program*					0
3. Other Costs (sum of a-k)	-0.27	1.41	0.27	0.00
a. Soybean seed costs	0.21	0.00	0.00	0.00	34
b. Soybean planting costs (excluding seeds)	1.18	0.00	0.00	0.00	34
c. Nitrogen costs	0.00	0.00	0.00	0.00	34
d. P & K costs	0.00	0.00	0.00	0.00	34
e. Manure costs	0.53	0.00	0.00	0.00	34
f. Insecticide costs	-0.21	0.00	0.00	0.00	34
g. Fungicide costs	-0.38	0.00	0.00	0.00	34
h. Soil testing costs	0.00	0.00	0.00	0.00	34
i. Management ($15 per hour)	0.97	1.41	0.27	0.00	24
j. Cash rent	-2.50	0.00	0.00	0.00	20
k. Soil erosion repairs	-0.06	0.00	0.00	0.00	34
Subtotal	34.69	42.86	34.09	27.15
Net change in profit (A-B):	25.13	-22.86	-4.31	60.15
Net change in profit without Cost-Share	-2.95	-42.86	-29.31	30.15

N = number of responses; *values for farmers who used herbicide on both cover crop and non-cover acres

Table 6. Annual average partial budget for cover crops terminated with herbicides in corn-soybean rotation:

Sources of changes in net profits	Mean ($/acre)	1^st Quartile ($/acre)	Median ($/acre)	3rd Quartile ($/acre)	N
A. Changes in revenue:
1. Cash crop yield (corn @ $3.35/bu; soy @ $9.95/bu)	-1.80	-26.19	0.81	24.06	55
2. Cost-share program	31.14	21.31	29.76	31.55	55
Subtotal	29.34	-4.88	30.57	55.61
B. Changes in costs:
1. Cover crop planting	33.60	40.79	31.72	25.31
a. Seeds	16.81	20.63	14.63	12.31	55
b. Planting (excluding seeds) (weighted average of i-ii)	16.80	20.16	17.09	13.01
i. Custom work	17.38	18.96	16.70	14.83	22
ii. Non-Custom	16.47	20.84	17.31	11.98	39
2. Herbicide expenses (weighted average of a-b)	6.94	9.04	5.36	4.96
a. For farmers that did not apply herbicides before planting cash crop in baseline	32.58	34.65	32.78	30.31	9
i. Herbicide cost to terminate cover crops	23.41	24.89	23.34	21.94	9
ii. Application (weighted average a-b)	9.17	9.76	9.44	8.38	8
(a) Custom work	6.17	7.00	6.50	5.00	3
(b) Non-Custom	10.67	11.13	10.91	10.07	6
b. For farmers that applied herbicides before planting cash crop in baseline	1.93	4.03	0.00	0.00	46
i. Additional herbicide costs on top of regular weed control program*	1.93	4.03	0.00	0.00	46
ii. Labor costs to apply herbicides on top of regular weed control program*					0
3. Other Costs (sum of a-k)	0.57	1.49	0.30	0.00
a. Cash crop seed costs	0.08	0.00	0.00	0.00	55
b. Cash crop planting costs (excluding seeds)	0.94	0.00	0.00	0.00	55
c. Nitrogen costs	0.17	0.00	0.00	0.00	55
d. P & K costs	0.00	0.00	0.00	0.00	55
e. Manure costs	0.21	0.00	0.00	0.00	55
f. Insecticide costs	0.51	0.00	0.00	0.00	55
g. Fungicide costs	-0.15	0.00	0.00	0.00	55
h. Soil testing costs	0.00	0.00	0.00	0.00	55
i. Management ($15 per hour)	1.20	1.49	0.30	0.00	39
j. Cash rent	-1.93	0.00	0.00	0.00	34
k. Soil erosion repairs	-0.46	0.00	0.00	0.00	55
Subtotal	41.12	51.31	37.38	30.27
Net change in profit (A-B):	-11.78	-56.19	-6.81	25.33
Net change in profit without Cost-Share	-42.92	-77.50	-36.58	-6.22

N = number of responses; *values for farmers who used herbicide on both cover crop and non-cover acres

Table 7. Partial budget for cover crops winterkilled followed by corn or soybeans:

Sources of changes in net profits	Mean ($/acre)	1^st Quartile ($/acre)	Median ($/acre)	3rd Quartile ($/acre)	N
A. Changes in revenue:
1. Cash crop yield (corn @ $3.35/bu; soy @ $9.95/bu)	-8.25	-18.00	0.00	0.00	24
2. Cost-share program	43.83	40.00	46.50	48.00	6
Subtotal	35.58	22.00	46.50	48.00
B. Changes in costs:
1. Cover crop planting	32.06	42.43	29.15	19.69
a. Seeds	18.23	23.50	15.50	10.00	24
b. Planting (excluding seeds) (weighted average of i-ii)	13.83	18.93	13.65	9.69
i. Custom work	9.50	11.50	10.00	7.50	8
ii. Non-Custom	16.31	23.17	15.73	10.94	14
2. Herbicide expenses	-0.33	0.00	0.00	0.00
a. Additional herbicide costs on top of regular weed control program*	-0.33	0.00	0.00	0.00	24
b. Labor costs to apply herbicides on top of regular weed control program*					0
3. Other Costs (sum of a-k)	-2.57	0.97	0.30	0.00
a. Cash crop seed costs	-0.63	0.00	0.00	0.00	24
b. Cash crop planting costs (excluding seeds)	0.00	0.00	0.00	0.00	24
c. Nitrogen costs	-2.54	0.00	0.00	0.00	24
d. P & K costs	-0.25	0.00	0.00	0.00	24
e. Manure costs	1.25	0.00	0.00	0.00	24
f. Insecticide costs	0.00	0.00	0.00	0.00	24
g. Fungicide costs	0.00	0.00	0.00	0.00	24
h. Soil testing costs	0.00	0.00	0.00	0.00	24
i. Management ($15 per hour)	0.70	0.97	0.30	0.00	21
j. Cash rent	-1.11	0.00	0.00	0.00	9
k. Soil erosion repairs	0.00	0.00	0.00	0.00	24
Subtotal	29.16	43.39	29.45	19.69
Net change in profit (A-B):	6.43	-21.39	17.05	28.31
Net change in profit without Cost-Share	-37.41	-61.39	-29.45	-19.69

N = number of responses; *values for farmers who used herbicide on both cover crop and non-cover acres; responses from 11 farms that planted corn, and 13 farms that planted soybean in 2016.

Results from hard copy survey in Iowa:

A total of 674 responses were received, of which 440 reported planting cover crops in 2015. After filtering out all responses according to the criteria 1-5 described in the previous paragraph, partial budgets were developed for different combinations of: cover crop mix and following cash crop, crop reporting district (location), cover crop planting and termination method, tillage method, and years of experience with cover crops.

The average area planted to cover crops in 2015 by our survey respondents amounted to 268 acres (Table 8). Respondents had, on average, 7.9 years of experience with cover crops. However, half (two-thirds) of them had 5 (8) years of experience or less. The cumulative number of cover crop acres planted through all the years of experience averaged 870 acres per operator.

Eighty-three percent of the respondents operated farms between 200 and 2,000 acres in size, and the median farm size was 500-999 acres (Table 9). The most frequently planted cover crop among our survey respondents was cereal rye (typically by itself, and to a lesser extent mixed with oats), followed in a distant second place by annual ryegrass. The most extensively used planting method was drilling (76%), followed by aerial and broadcast (4%) seeding (19% and 4%, respectively). Two-thirds of the respondents used herbicides to terminate cover crops, and the other third chose tillage, mowing, or winter kill as termination method. Three in 5 respondents planted corn for grain or seed following cover crops, while the other cover croppers typically planted soybeans in 2016.

The average calculated changes in net returns stemming from the use of cover crops terminated with herbicides, across all cover crops, all planting methods, and all tillage methods were positive: $8.59 per acre for cover crops followed by corn (Table 10) and $14.25 per acre for cover crops followed by soybeans (Table 11). However, those averages include in their calculations the cost savings in livestock feed from farmers that use cover crops for grazing or forage: an average of $35 per acre for cover crops followed by corn across 9 farms, and $32.54 per acre for cover crops followed by soybeans across 13 farms. When those cost savings in livestock feed are excluded from the calculations, the resulting changes in net returns average losses of $26.41 for cover crops followed by corn, and $18.29 for cover crops followed by soybeans. Furthermore, the net returns to cover crops in the absence of both savings on livestock feed and cost-share payments average net losses of $48.82 for cover crops followed by corn, and $38.42 for cover crops followed by soybeans. Finally, the average reduction in yields following cover crops (comparing yields across a field with cover crops and another similar field without cover crops operated by the same farmer) was 2 bushels for corn, and 0.1 bushel for soybeans. Although the median yield differences were null in Tables 3 and 4, the same qualitative results are derived when analyzing median changes instead of average changes in net returns due to cover crops use.

The major cost drivers in Tables 10 and 11 are planting costs, which add up to $33 per acre, composed in nearly equal parts by seed costs and planting costs (excluding seeds). It is interesting to note that the reported rates paid to hire custom planting of cover crop seeds come very close, on average, to the calculated costs of using farmers’ own planting machinery based on Cartwright and Kirwan (2014).

Termination costs depend on whether the operator sprays all his or her acres with herbicides as part of the pre-plant treatment. About 80% of the farms in Tables 10 and 11 applied a pre-plant burn down across all their acres, and their extra herbicide costs (on top of the typical pre-plan burn down) to terminate cover crops averaged less than $1 per acre. The reported extra termination costs for these farmers were related to higher concentrations of active ingredients, or in some cases an extra field pass when the first herbicide application was not effective to fully terminate the cover crop. However, note that the median extra termination costs for this group of farmers are null in Tables 3 and 4.

For the minority of farmers that do not apply herbicides as part of their pre-plant program, termination of cover crops with herbicides represent a major additional expense: $16.82 for cover crops followed by corn, and $18.54 for cover crops followed by soybeans, on average. Furthermore, for the subset of farmers that custom hire the termination of cover crops with herbicides, the average custom rate paid is nearly twice higher than the cost of using their own sprayers.

Finally, while farmers who planted cover crops followed by corn experienced, on average, small savings in nitrogen, manure, insecticide, fungicide, soil testing, soil repair costs, and cash rents due to cover crops use, some farmers experienced large cost savings and others experienced increases in those categories (see the ranges in Tables 10). However, the median change in cost in each and all “other costs” category was null. Similarly, the average changes in other costs for operators who planted cover crops followed by soybeans were small, and the median changes were null (Table 11).

In order to explore the relationship between years of experience with cover crops and net returns, we developed partial budgets across all cover crop species terminated with herbicides and followed by corn production, across all planting methods, and all tillage methods for operators with: (a) up to 3 years of experience (Table 12); (b) 4 to 9 years of experience (Table 13); and (c) 10 or more years of experience (Table 14). While the average yield drag on corn production due to cover crops was smaller for farmers in (b) than for farmers in (a) (-0.1 bushels versus -5 bushels); and farmers in (c) experienced an average 0.5 yield increase due to cover crops, the net returns to cover crops excluding savings in livestock feed due to grazing or forage were negative for all experience levels. The average changes in net returns due to cover crops use followed by corn for operators in (a), (b), and (c) amounted, respectively, to -$37.12 (Table 12), -$18.59 (Table 13), and -$14.97 (Table 14).

A comparable analysis for cover crops followed by soybeans resulted in similar qualitative and quantitative results. The average changes in net returns due to cover crops use followed by soybeans excluding savings in livestock feed due to grazing or forage for operators with up to 3 years of experience, with 4 to 9 years of experience, and with 10 or more years of experience amounted, respectively, to -$24.36 (Table 15), -$11.70 (Table 16), and -$21.04 (Table 17). An important difference between Tables 8-10 and Tables 5-7 from the agronomic (although not from the economic) standpoint is that while the average corn yield drag from cover crops declined with experience, the opposite trend was observed in the average soybean yield drag from cover crops. The average change in soybean yields due to cover crops use was 0.43 bushels for farmers with up to 3 years of experience, 0.25 bushels for farmers with 4 to 9 years of experience, and -0.09 bushels for farmers with 10 or more years of experience.

In order to explore the relationship between tillage practices and net returns to cover crops use, we developed partial budgets for cereal rye terminated with herbicides and followed by corn, across all planting methods, for no-till (Table 18), reduced-till (Table 19), and conventional- or vertical-till (Table 20) operations. The number of respondents using no-till practices is almost twice the number of respondents using reduced-till, conventional- or vertical-till.

While the three partial budgets have similar average planting costs for cereal rye, they differ in the average costs to terminate cereal rye. Those differences are driven by the extra labor hours required to terminate cereal rye with herbicides among farmers that apply a pre-plant burn down in all acres; and the custom rate paid by farmers that hire custom sprayers to terminate the cereal rye. The median (which is less affected by extreme values than the average) change in total costs in the no-till budget is similar to the change in total costs in the reduced-till budget ($34.83 and $33.85, respectively), but lower than in the conventional-till budget ($46.26). Furthermore, the median cost-share payments received by reduced-till farmers ($27.00) were higher than the corresponding payments received by no-till, and conventional-till farmers ($20.00 and $17.50, respectively). Consequently, the net losses from cereal rye use (excluding savings in livestock feed from grazing or forage) were the smallest for reduced-till operations (-$6.80), followed by no-till operations (-$14.83), and conventional-till operations (-$28.76).

The net returns for alternative planting methods (drilling and aerial seeding) for cover crops were calculated across all cover crop species for no-till operations. The average changes in costs due to cover crops use followed by corn were similar across planting methods: $40.55 for operations using drills (Table 21), and $42.59 for operations using aerial seeding (Table 22). In both partial budgets, the average change in yields due to cover crop use was negative (around 3 bushels per acre), and nearly one third of the operators received cost-share payments. The average net losses due to cover crops use followed by corn (excluding savings in livestock feed from grazing or forage) was slightly lower in operations drilling cover crop seeds (-$26.99) than in operations using aerial seeding (-$34.53).

The average changes in costs due to cover crops use followed by soybeans were similar across planting methods: $37.45 for operations using drills (Table 23), and $39.12 for operations using aerial seeding (Table 24). Contrary to the changes in corn yields observed in Tables 14 and 15, average changes in soybean yields are positive for both panting methods: 0.28 extra bushels in fields where cover crops were planted with drills (Table 23), and 0.50 extra bushels in fields aerial seeded (Table 24). A larger proportion of farmers using aerial seeding received cost-share payments than of farmers using drills (65% versus 38%), but the average payments were similar: $18.55 (Table 24) and $16.70 (Table 23). The average net losses due to cover crops use followed by soybeans (excluding savings in livestock feed from grazing or forage) were slightly lower in operations using aerial seeding (-$15.58, Table 24) than in operations using drills (-$17.95, Table 23). Note that the calculated net losses from cover crops followed by soybeans are, on average, smaller than the net losses from cover crops followed by corn.

The net returns for alternative termination methods (herbicide application and tillage) for cover crops planted using drills and followed by corn were calculated across all cover crop species for operations using conventional- or vertical-till. In order to avoid large biases in the average measures caused by extreme values among few observations, the following discussion focuses only on median (instead of average) values. The median cost of planting cover crops using drill planters is slightly higher for operations that used herbicide termination than for operations that used tillage to terminate cover crops: $33.50 (Table 25) and $28.51 (Table 26), respectively. While the median extra cost to terminate cover crops was null for those farmers that applied the termination method to all their acreage (with and without cover crops) as part of the spring pre-plant soil conditioning, it amounted to $15.54 for farmers that only applied herbicides in spring to their acres with cover crops (Table 25). The resulting net losses due to cover crops (excluding savings in livestock feed from grazing or forage) were slightly lower for operations using tillage than for operations using herbicides as the selected termination method: -$13.01 (Table 26) and -$20.61 (Table 25).

This study suffers from several limitations related to the self-selection bias of survey respondents and the potential unrepresentativeness of the sample. However, it provides a variety of partial budgets based on field data (instead of experimental plots) from farmers that manage row crop production on acres with cover crops and on acres with no cover crops, that can be used as benchmarks for current and potential cover croppers, as well as ground-truth references for agricultural and conservation policy design.

Table 8. Characteristics of operators surveyed

Variable	Mean	Median	Range	#Obs.
Acres of cover crops planted in fall 2015	268	80	[5, 7500]	227
Total number of acres planted to cover crops since starting using cover crops	870	360	[4, 10000]	230
Number of years of experience with cover crops	7.9	6	[1, 45]	233

Table 9. Survey responses by farm size, cover crop species, planting method, termination method, and following cash crop

Farm Characteristic	#Obs.	Percent
Farm Size
1 to 49 acres	1	0.43
50-99 acres	1	0.43
100-199 acres	14	6.03
200-499 acres	54	23.28
500-999 acres	76	32.76
1000-1999 acres	63	27.16
2000 acres or more	23	9.91
Total	232	100
Cover crop species
Cereal Rye	164	71.00
Cereal Rye + Oats	11	4.76
Annual Ryegrass	12	5.19
Annual ryegrass + crimson clover + oilseed radish	3	1.30
Annual ryegrass + crimson clover + oilseed radish + rapeseed	2	0.87
Oats + oilseed radish + buckwheat	1	0.43
Oats + oilseed radish + turnip	4	1.73
Other	34	14.72
Total	231	100
Planting method
Aerial Seeding	40	18.87
Broadcast Seeding	9	4.25
Drilling	161	75.94
Other	2	0.94
Total	212	100
Termination method
Herbicide	154	66.38
Tillage	36	15.52
Mowing	21	9.05
Winter kill	18	7.76
Other	3	1.29
Total	232	100
Following cash crop
Corn for grain or seed	135	58.70
Soybeans	87	37.83
Oats for grain	1	0.43
Other	7	3.04
Total	230	100
Hired custom planting of cover crops
Yes for all	69	30
Yes for some	24	10.43
No	137	59.57
Total	230	100

Table 10. Overall changes in net returns due to cover crop use followed by corn, for all cover crop species, all planting methods, terminated with herbicides.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	22.41	20.00	[5; 80]	39
2. Value of change in following corn yield*	-8.06	0.00	[-108; 80]	69
3. Savings or extra revenue from grazing or harvesting cover crop for forage	35.00	22.00	[3; 100]	9
Subtotal A. Changes in Revenue	49.35	42.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	17.70	16.00	[5; 47]	76
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	14.82	16.15
i. Custom work	14.39	15.00	[4; 30]	41
ii. Non-Custom	15.14	16.99	[2.42; 25.33]	56
Subtotal B.1	32.52	32.15
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	8.07	0.00		68
i. Extra herbicide cost on top of regular weed control program	0.56	0.00	[0; 17]	68
ii. Extra labor costs to apply herbicides on top of regular weed control program^	5.54	0.00	[0; 130]	68
iii. Other termination expenses	1.97	0.00	[0; 40]	68
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	16.82	15.54		16
i. Herbicide cost to terminate cover crops	9.50	8.00	[4; 24]	16
ii. Herbicide application cost. Weighted average of custom and non-custom work.	7.32	7.54	[3.06; 15.4]
1. Custom Work	14.20	14.00	[6; 30]	5
2. Non-Custom	5.02	5.38	[2.08; 10.53]	15
Subtotal B.2 (weighted average of B.2.a and B.2.b)	9.74	2.96
3. Changes in other costs~
a. Nitrogen Costs	-0.18	0.00	[-20; 5]	83
b. Manure Costs	-0.09	0.00	[-10; 2.5]	83
c. Insecticide Costs	-0.11	0.00	[-12; 3]	83
d. Fungicide Costs	-0.13	0.00	[-14; 3.5]	83
e. Soil Testing Costs	-0.14	0.00	[-16; 4]	83
f. Costs to Repair Soil Erosion	-0.16	0.00	[-18; 4.5]	83
g. Change in Cash Rent due to Cover Crops Use	-0.68	0.00	[-20; 0]	44
Subtotal B.3	-1.50	0.00
Subtotal B. Changes in Costs	40.76	35.11
C. Net Change in Profits (C=A-B)	8.59	6.89
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-26.41	-15.11

* Reported changes in corn yields following cover crops due to cover crops use ranged from -27 to 20 bushels per acre, with an average loss of 2 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 10 hours, and averaged 0.43 hours. The median farmer reported no extra labor to terminate cover crops .

~ No respondent indicated changes in cash crop seed costs, cash crop planting costs (excluding seeds), P and K costs, or management time due to cover crops use.

Table 11. Overall changes in net returns due to cover crop use followed by soybeans, for all cover crop species, all planting methods, terminated with herbicides.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	20.13	15.00	[7; 46]	23
2. Value of change in following soybean yield*	-1.07	0.00	[-100; 50]	56
3. Savings or extra revenue from grazing or harvesting cover crop for forage	32.54	20.00	[2; 150]	13
Subtotal A. Changes in Revenue	51.60	35.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	16.34	15.00	[2; 50]	50
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	16.47	16.95
i. Custom work	16.52	16.00	[6; 32]	21
ii. Non-Custom	16.45	17.47	[3.59; 24.17]	38
Subtotal B.1	32.81	31.95
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)^	2.63	0.00		49
i. Extra herbicide cost on top of regular weed control program	0.29	0.00	[-11; 12]	49
ii. Extra labor costs to apply herbicides on top of regular weed control program	1.33	0.00	[0; 39]	49
iii. Other termination expenses	1.02	0.00	[0; 20]	49
b. Extra expenses for farmers that did not apply herbicides before planting soybean in acres without cover crops.	18.54	14.55		9
i. Herbicide cost to terminate cover crops	11.56	10.00	[2; 30]	9
ii. Herbicide application cost. Weighted average of custom and non-custom work.	6.99	4.55	[4.16; 13.53]
1. Custom Work	13.67	8.00	[8; 25]	3
2. Non-Custom	4.48	3.25	[2.72; 9.23]	8
Subtotal B.2 (weighted average of B.2.a and B.2.b)	5.10	2.26
3. Changes in other costs~
a. Cash crop seed costs	-0.18	0.00	[-11; 0]	61
b. Costs to Repair Soil Erosion	-0.02	0.00	[-1; 0]	61
c. Change in Cash Rent due to Cover Crops Use	-0.37	0.00	[-10; 0]	27
Subtotal B.3	-0.57	0.00
Subtotal B. Changes in Costs	37.34	34.21
C. Net Change in Profits (C=A-B)	14.25	0.79
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-18.29	-19.21

* Reported changes in soybean yields following cover crops due to cover crops use ranged from -10 to 5 bushels per acre, with an average loss of 0.11 bushels. The median farmer reported no change in soybean yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 3 hours, and averaged 0.10 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in soybean planting costs (excluding seeds); N, P or K costs; manure, insecticide, fungicide, or soil testing costs; or management time due to cover crops use.

Table 12. Changes in net returns due to cover crop use followed by corn, for all cover crop species, all planting methods, terminated with herbicides. Farmers with up to 3 years of experience with cover crops.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	20.83	20.00	[15; 30]	6
2. Value of change in following corn yield*	-20.00	-20.00	[-60; 0]	9
3. Savings or extra revenue from grazing or harvesting cover crop for forage	80.00	80.00	[80; 80]	1
Subtotal A. Changes in Revenue	80.83	80.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	15.60	15.00	[8; 30]	10
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	15.09	14.20
i. Custom work	18.50	15.50	[13; 30]	4
ii. Non-Custom	13.14	13.46	[9.79; 15.82]	7
Subtotal B.1	30.69	29.20
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	5.00	0.00		7
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	7
ii. Extra labor costs to apply herbicides on top of regular weed control program	0.00	0.00	[0; 0]	7
iii. Other termination expenses	5.00	0.00	[0; 20]	7
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	15.17	15.54		2
i. Herbicide cost to terminate cover crops	8.00	8.00	[8; 8]	2
ii. Herbicide application cost. Weighted average of custom and non-custom work.	7.17	7.54	[5.06; 8.91]
1. Custom Work	14.00	14.00	[14; 14]	1
2. Non-Custom	4.89	5.38	[2.08; 7.21]	3
Subtotal B.2 (weighted average of B.2.a and B.2.b)	7.26	3.45
3. Changes in other costs~
a. Nitrogen Costs	0.00	0.00	[0; 0]	11
b. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	4
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	37.95	32.65
C. Net Change in Profits (C=A-B)	42.88	47.35
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-37.12	-32.65

* Reported changes in corn yields following cover crops due to cover crops use ranged from -15 to 0 bushels per acre, with an average and median loss of 5 bushels.

~ No respondent indicated changes in corn planting costs; N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time due to cover crops use.

Table 13. Changes in net returns due to cover crop use followed by corn, for all cover crop species, all planting methods, terminated with herbicides. Farmers with 4 to 9 years of experience with cover crops.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	24.60	20.00	[7; 80]	20
2. Value of change in following corn yield*	-0.41	0.00	[-32; 28]	29
3. Savings or extra revenue from grazing or harvesting cover crop for forage	35.00	20.00	[10; 100]	5
Subtotal A. Changes in Revenue	59.19	40.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	16.85	16.00	[9; 25]	41
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	14.56	16.11
i. Custom work	13.92	15.00	[5; 25]	24
ii. Non-Custom	15.07	16.99	[2.42; 25.33]	30
Subtotal B.1	31.41	32.11
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	10.79	0.00		34
i. Extra herbicide cost on top of regular weed control program	0.97	0.00	[0; 17]	34
ii. Extra labor costs to apply herbicides on top of regular weed control program^	7.65	0.00	[0; 130]	34
iii. Other termination expenses	2.18	0.00	[0; 40]	34
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	17.42	14.82		11
i. Herbicide cost to terminate cover crops	9.27	8.00	[4; 24]	11
ii. Herbicide application cost. Weighted average of custom and non-custom work.	8.15	6.82	[3.79; 15.4]
1. Custom Work	17.00	14.00	[7; 30]	3
2. Non-Custom	5.20	4.42	[2.72; 10.53]	9
Subtotal B.2 (weighted average of B.2.a and B.2.b)	12.41	3.62
3. Changes in other costs~
a. Nitrogen Costs	0.11	0.00	[0; 5]	47
b. Change in Cash Rent due to Cover Crops Use	-1.15	0.00	[-20; 0]	26
Subtotal B.3	-1.05	0.00
Subtotal B. Changes in Costs	42.78	35.73
C. Net Change in Profits (C=A-B)	16.41	4.27
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-18.59	-15.73

* Reported changes in corn yields following cover crops due to cover crops use ranged from -8 to 7 bushels per acre, with an average loss of 0.1 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 10 hours, and averaged 0.59 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs; P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time due to cover crops use.

Table 14. Changes in net returns due to cover crop use followed by corn, for all cover crop species, all planting methods, terminated with herbicides. Farmers with 10 or more years of experience with cover crops.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	17.00	16.00	[10; 25]	3
2. Value of change in following corn yield*	2.00	0.00	[0; 16]	8
3. Savings or extra revenue from grazing or harvesting cover crop for forage	28.50	28.50	[22; 35]	2
Subtotal A. Changes in Revenue	47.50	44.50
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	16.75	15.50	[10; 28]	8
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	15.12	17.21
i. Custom work	13.33	15.00	[10; 15]	3
ii. Non-Custom	15.71	17.95	[3.59; 19.29]	9
Subtotal B.1	31.87	32.71
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	1.55	0.00		11
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	11
ii. Extra labor costs to apply herbicides on top of regular weed control program^	1.18	0.00	[0; 13]	11
iii. Other termination expenses	0.36	0.00	[0; 4]	11
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	8.25	8.25		1
i. Herbicide cost to terminate cover crops	4.00	4.00	[4; 4]	1
ii. Herbicide application cost. Weighted average of custom and non-custom work.	4.25	4.25	[3.12; 5.38]
1. Custom Work	0.00	0.00	[0; 0]	0
2. Non-Custom	4.25	4.25	[3.12; 5.38]	2
Subtotal B.2 (weighted average of B.2.a and B.2.b)	2.10	0.69
3. Changes in other costs~
a. Nitrogen Costs	0.00	0.00	[0; 0]	13
b. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	4
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	33.97	33.40
C. Net Change in Profits (C=A-B)	13.53	11.10
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-14.97	-17.40

* Reported changes in corn yields following cover crops due to cover crops use ranged from 0 to 4 bushels per acre, with an average increase of 0.5 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hour, and averaged 0.09 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs; N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 15. Changes in net returns due to cover crop use followed by soybeans, for all cover crop species, all planting methods, terminated with herbicides. Farmers with up to 3 years of experience with cover crops.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	15.00	15.00	[15; 15]	4
2. Value of change in following soybean yield*	4.29	0.00	[-40; 50]	7
3. Savings or extra revenue from grazing or harvesting cover crop for forage	31.00	31.00	[31; 31]	1
Subtotal A. Changes in Revenue	50.29	46.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	14.17	15.00	[10; 17]	6
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	15.99	15.74
i. Custom work	15.33	15.00	[15; 16]	3
ii. Non-Custom	17.95	17.95	[17.95; 17.95]	1
Subtotal B.1	30.16	30.74
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)^	6.60	0.00		5
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	5
ii. Extra labor costs to apply herbicides on top of regular weed control program	2.60	0.00	[0; 13]	5
iii. Other termination expenses	4.00	0.00	[0; 20]	5
b. Extra expenses for farmers that did not apply herbicides before planting soybean in acres without cover crops.	24.96	25.63		3
i. Herbicide cost to terminate cover crops	19.33	20.00	[8; 30]	3
ii. Herbicide application cost. Weighted average of custom and non-custom work.	5.63	5.63	[5.63; 5.63]
1. Custom Work	8.00	8.00	[8; 8]	2
2. Non-Custom	3.25	3.25	[3.25; 3.25]	2
Subtotal B.2 (weighted average of B.2.a and B.2.b)	13.48	9.61
3. Changes in other costs~
a. Cash crop seed costs	0.00	0.00	[0; 0]	8
b. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	3
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	43.64	40.35
C. Net Change in Profits (C=A-B)	6.64	5.65
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-24.36	-25.35

* Reported changes in soybean yields following cover crops due to cover crops use ranged from -5 to 4 bushels per acre, with an average increase of 0.43 bushels. The median farmer reported no change in soybean yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.20 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs; N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 16. Changes in net returns due to cover crop use followed by soybeans, for all cover crop species, all planting methods, terminated with herbicides. Farmers with 4 to 9 years of experience with cover crops.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	22.63	15.00	[10; 46]	8
2. Value of change in following soybean yield*	2.50	0.00	[-70; 40]	20
3. Savings or extra revenue from grazing or harvesting cover crop for forage	30.71	20.00	[5; 83]	7
Subtotal A. Changes in Revenue	55.84	35.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	18.00	14.00	[8; 50]	23
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	18.04	16.76
i. Custom work	17.50	16.00	[6; 32]	10
ii. Non-Custom	19.84	19.29	[17.95; 22.29]	3
Subtotal B.1	36.04	30.76
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)^	0.95	0.00		22
i. Extra herbicide cost on top of regular weed control program	0.41	0.00	[-11; 12]	22
ii. Extra labor costs to apply herbicides on top of regular weed control program	0.00	0.00	[0; 0]	22
iii. Other termination expenses	0.55	0.00	[0; 12]	22
b. Extra expenses for farmers that did not apply herbicides before planting soybean in acres without cover crops.	14.00	14.06		2
i. Herbicide cost to terminate cover crops	8.00	8.00	[6; 10]	2
ii. Herbicide application cost. Weighted average of custom and non-custom work.	6.00	6.06	[2.72; 9.23]
1. Custom Work	0.00	0.00	[0; 0]	0
2. Non-Custom	6.00	6.06	[2.72; 9.23]	3
Subtotal B.2 (weighted average of B.2.a and B.2.b)	2.04	1.17
3. Changes in other costs~
a. Cash crop seed costs	-0.42	0.00	[-11; 0]	26
b. Change in Cash Rent due to Cover Crops Use	-0.83	0.00	[-10; 0]	12
Subtotal B.3	-1.26	0.00
Subtotal B. Changes in Costs	36.83	31.93
C. Net Change in Profits (C=A-B)	19.01	3.07
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-11.70	-16.93

* Reported changes in soybean yields following cover crops due to cover crops use ranged from -5 to 4 bushels per acre, with an average increase of 0.43 bushels. The median farmer reported no change in soybean yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.20 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs; N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 17. Changes in net returns due to cover crop use followed by soybeans, for all cover crop species, all planting methods, terminated with herbicides. Farmers with 10 or more years of experience with cover crops.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	15.75	15.00	[8; 25]	4
2. Value of change in following soybean yield*	-0.91	0.00	[-50; 40]	11
3. Savings or extra revenue from grazing or harvesting cover crop for forage	43.75	10.00	[5; 150]	4
Subtotal A. Changes in Revenue	58.59	25.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	16.33	14.50	[10; 30]	12
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	16.22	16.12
i. Custom work	17.67	15.00	[10; 28]	3
ii. Non-Custom	15.86	16.41	[7.91; 21.93]	12
Subtotal B.1	32.55	30.62
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)^	2.17	0.00		12
i. Extra herbicide cost on top of regular weed control program	0.25	0.00	[0; 3]	12
ii. Extra labor costs to apply herbicides on top of regular weed control program	1.08	0.00	[0; 13]	12
iii. Other termination expenses	0.83	0.00	[0; 10]	12
b. Extra expenses for farmers that did not apply herbicides before planting soybean in acres without cover crops.	10.32	10.32		2
i. Herbicide cost to terminate cover crops	6.00	6.00	[2; 10]	2
ii. Herbicide application cost. Weighted average of custom and non-custom work.	4.32	4.32	[3.25; 5.38]
1. Custom Work	0.00	0.00	[0; 0]	0
2. Non-Custom	4.32	4.32	[3.25; 5.38]	2
Subtotal B.2 (weighted average of B.2.a and B.2.b)	3.33	1.47
3. Changes in other costs~
a. Cash crop seed costs	0.00	0.00	[0; 0]	14
b. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	5
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	35.88	32.09
C. Net Change in Profits (C=A-B)	22.71	-7.09
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-21.04	-17.09

* Reported changes in soybean yields following cover crops due to cover crops use ranged from -5 to 4 bushels per acre, with an average loss of -0.09 bushels. The median farmer reported no change in soybean yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.08 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs; N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 18. Changes in net returns due to cereal rye use followed by corn, for all planting methods, terminated with herbicides. Operations in rotational or continuous no-till only.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	24.69	20.00	[10; 80]	13
2. Value of change in following corn yield*	-14.17	0.00	[-108; 28]	35
3. Savings or extra revenue from grazing or harvesting cover crop for forage	17.33	20.00	[10; 22]	3
Subtotal A. Changes in Revenue	27.85	40.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	17.03	15.00	[8; 30]	32
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	15.12	16.07
i. Custom work	15.16	15.00	[5; 30]	19
ii. Non-Custom	15.08	16.99	[2.42; 25.33]	22
Subtotal B.1	32.15	31.07
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	5.31	0.00		26
i. Extra herbicide cost on top of regular weed control program	0.69	0.00	[0; 17]	26
ii. Extra labor costs to apply herbicides on top of regular weed control program^	1.50	0.00	[0; 13]	26
iii. Other termination expenses	3.12	0.00	[0; 40]	26
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	17.59	15.98		8
i. Herbicide cost to terminate cover crops	8.63	6.50	[4; 24]	8
ii. Herbicide application cost. Weighted average of custom and non-custom work.	8.97	9.48	[7.27; 11.01]
1. Custom Work	30.00	30.00	[30; 30]	1
2. Non-Custom	4.76	5.38	[2.72; 7.21]	5
Subtotal B.2 (weighted average of B.2.a and B.2.b)	8.20	3.76
3. Changes in other costs~
a. Nitrogen Costs	0.00	0.00	[0; 0]	35
b. Change in Cash Rent due to Cover Crops Use	-1.11	0.00	[-20; 0]	18
Subtotal B.3	-1.11	0.00
Subtotal B. Changes in Costs	39.24	34.83
C. Net Change in Profits (C=A-B)	-11.38	5.17
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-28.72	-14.83

* Reported changes in corn yields following cover crops due to cover crops use ranged from -28 to 7 bushels per acre, with an average loss of 3.54 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.12 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs (including seeds); N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time due to cover crops use.

Table 19. Changes in net returns due to cereal rye use followed by corn, for all planting methods, terminated with herbicides. Operations in reduced-till only.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	29.00	27.00	[15; 45]	3
2. Value of change in following corn yield*	4.57	0.00	[-8; 40]	7
3. Savings or extra revenue from grazing or harvesting cover crop for forage	0.00	0.00	[0; 0]	0
Subtotal A. Changes in Revenue	33.57	27.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	18.17	19.00	[9; 25]	6
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	12.94	13.38
i. Custom work	11.33	12.00	[10; 12]	3
ii. Non-Custom	14.15	14.42	[9.79; 17.95]	4
Subtotal B.1	31.11	32.38
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	2.80	0.00		5
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	5
ii. Extra labor costs to apply herbicides on top of regular weed control program^	2.60	0.00	[0; 13]	5
iii. Other termination expenses	0.20	0.00	[0; 1]	5
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	8.84	8.84		1
i. Herbicide cost to terminate cover crops	4.00	4.00	[4; 4]	1
ii. Herbicide application cost. Weighted average of custom and non-custom work.	4.84	4.84	[4.29; 5.38]
1. Custom Work	0.00	0.00	[0; 0]	0
2. Non-Custom	4.84	4.84	[4.29; 5.38]	2
Subtotal B.2 (weighted average of B.2.a and B.2.b)	3.81	1.47
3. Changes in other costs~
a. Nitrogen Costs	0.00	0.00	[0; 0]	7
b. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	3
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	34.91	33.85
C. Net Change in Profits (C=A-B)	-1.34	-6.85
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-1.34	-6.85

* Reported changes in corn yields following cover crops due to cover crops use ranged from -2 to 10 bushels per acre, with an average loss of 1.14 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.20 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in corn planting costs (including seeds); N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time due to cover crops use.

Table 20. Changes in net returns due to cereal rye use followed by corn, for all planting methods, terminated with herbicides. Operations in conventional- or vertical-tillage only.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	19.00	17.50	[7; 35]	6
2. Value of change in following corn yield*	-7.20	0.00	[-40; 0]	10
3. Savings or extra revenue from grazing or harvesting cover crop for forage	70.00	80.00	[30; 100]	3
Subtotal A. Changes in Revenue	81.80	97.50
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	15.88	17.00	[10; 21]	8
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	14.04	14.10
i. Custom work	14.20	15.00	[8; 20]	5
ii. Non-Custom	13.93	13.46	[7.55; 19.38]	7
Subtotal B.1	29.92	31.10
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	44.50	14.50		6
i. Extra herbicide cost on top of regular weed control program	2.50	0.00	[0; 10]	6
ii. Extra labor costs to apply herbicides on top of regular weed control program^	36.83	13.00	[0; 130]	6
iii. Other termination expenses	5.17	1.50	[0; 20]	6
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	17.40	16.16		4
i. Herbicide cost to terminate cover crops	10.25	10.00	[6; 15]	4
ii. Herbicide application cost. Weighted average of custom and non-custom work.	7.15	6.16	[5.06; 11.52]
1. Custom Work	10.50	10.50	[7; 14]	2
2. Non-Custom	5.81	4.42	[4.29; 10.53]	5
Subtotal B.2 (weighted average of B.2.a and B.2.b)	33.66	15.16
3. Changes in other costs~
a. Nitrogen Costs	0.45	0.00	[0; 5]	11
b. Change in Cash Rent due to Cover Crops Use	-2.00	0.00	[-10; 0]	5
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	34.91	33.85
C. Net Change in Profits (C=A-B)	-1.34	-6.85
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-1.34	-6.85

* Reported changes in corn yields following cover crops due to cover crops use ranged from -10 to 0 bushels per acre, with an average loss of 1.80 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 10 hours, and averaged 2.83 hours. The median farmer reported 1 extra labor hour to terminate cover crops.

~ No respondent indicated changes in corn planting costs (including seeds); P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time due to cover crops use.

Table 21. Changes in net returns due to cover crops use followed by corn, for all cover crop species, terminated with herbicides, in no-till systems. Planting method: drilling.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	27.10	20.50	[15; 80]	10
2. Value of change in following corn yield*	-13.55	0.00	[-108; 28]	31
3. Savings or extra revenue from grazing or harvesting cover crop for forage	13.33	10.00	[10; 20]	3
Subtotal A. Changes in Revenue	26.88	30.50
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	18.03	17.00	[5; 35]	35
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	15.94	16.28
i. Custom work	16.00	15.00	[5; 30]	16
ii. Non-Custom	15.90	16.99	[7.86; 25.33]	29
Subtotal B.1	33.97	33.28
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	4.90	0.00		29
i. Extra herbicide cost on top of regular weed control program	0.79	0.00	[0; 17]	29
ii. Extra labor costs to apply herbicides on top of regular weed control program^	0.90	0.00	[0; 13]	29
iii. Other termination expenses	3.21	0.00	[0; 40]	29
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	20.54	18.27		8
i. Herbicide cost to terminate cover crops	11.25	9.00	[5; 24]	8
ii. Herbicide application cost. Weighted average of custom and non-custom work.	9.29	9.27	[3.81; 14.81]
1. Custom Work	18.00	18.00	[6; 30]	2
2. Non-Custom	4.93	4.90	[2.72; 7.21]	4
Subtotal B.2 (weighted average of B.2.a and B.2.b)	8.28	3.95
3. Changes in other costs~
a. Nitrogen Costs	-0.54	0.00	[-20; 0]	37
b. Costs to Repair Soil Erosion	-0.11	0.00	[-4; 0]	37
c. Change in Cash Rent due to Cover Crops Use	-1.05	0.00	[-20; 0]	19
Subtotal B.3	-1.70	0.00
Subtotal B. Changes in Costs	40.55	37.23
C. Net Change in Profits (C=A-B)	-13.66	-6.73
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-26.99	-16.73

* Reported changes in corn yields following cover crops due to cover crops use ranged from -27 to 7 bushels per acre, with an average loss of 3.39 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.07 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in cash crop planting costs (including seeds); P, K, manure, insecticide, fungicide, or soil testing costs; or changes in management time due to cover crops use.

Table 22. Changes in net returns due to cover crops use followed by corn, for all cover crop species, terminated with herbicides, in no-till systems. Planting method: aerial.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	19.20	16.00	[5; 45]	5
2. Value of change in following corn yield*	-11.14	0.00	[-100; 4]	14
3. Savings or extra revenue from grazing or harvesting cover crop for forage	15.00	20.00	[3; 22]	3
Subtotal A. Changes in Revenue	23.06	36.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	19.31	20.00	[10; 26]	13
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	16.00	15.61
i. Custom work	16.33	15.00	[10; 25]	15
ii. Non-Custom	15.01	17.44	[3.59; 25.33]	5
Subtotal B.1	35.31	35.61
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	5.45	0.00		11
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	11
ii. Extra labor costs to apply herbicides on top of regular weed control program^	2.36	0.00	[0; 13]	11
iii. Other termination expenses	3.09	0.00	[0; 15]	11
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	13.97	14.42		3
i. Herbicide cost to terminate cover crops	9.67	10.00	[4; 15]	3
ii. Herbicide application cost. Weighted average of custom and non-custom work.	4.31	4.42	[3.12; 5.38]
1. Custom Work	0.00	0.00	[0; 0]	0
2. Non-Custom	4.31	4.42	[3.12; 5.38]	3
Subtotal B.2 (weighted average of B.2.a and B.2.b)	7.28	3.09
3. Changes in other costs~
a. Nitrogen Costs	0.00	0.00	[0; 0]	15
b. Costs to Repair Soil Erosion	0.00	0.00	[0; 0]	15
c. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	6
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	42.59	38.70
C. Net Change in Profits (C=A-B)	-19.53	-2.70
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-34.53	-22.70

* Reported changes in corn yields following cover crops due to cover crops use ranged from -25 to 1 bushels per acre, with an average loss of 2.79 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.18 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in cash crop planting costs (including seeds); N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 23. Changes in net returns due to cover crop use followed by soybeans, for all cover crop species, terminated with herbicides, in no-till systems. Planting method: drilling.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	16.70	15.00	[7; 38]	10
2. Value of change in following soybean yield*	2.80	0.00	[-20; 40]	25
3. Savings or extra revenue from grazing or harvesting cover crop for forage	15.00	17.00	[2; 31]	7
Subtotal A. Changes in Revenue	34.50	32.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	16.67	13.50	[6; 32]	24
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	17.82	18.53
i. Custom work	21.50	22.00	[10; 32]	4
ii. Non-Custom	17.21	17.95	[8.34; 24.17]	24
Subtotal B.1	34.49	32.03
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)^	2.43	0.00		23
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[-11; 8]	23
ii. Extra labor costs to apply herbicides on top of regular weed control program	1.13	0.00	[0; 13]	23
iii. Other termination expenses	1.30	0.00	[0; 20]	23
b. Extra expenses for farmers that did not apply herbicides before planting soybean in acres without cover crops.	13.99	14.66		3
i. Herbicide cost to terminate cover crops	9.33	10.00	[8; 10]	3
ii. Herbicide application cost. Weighted average of custom and non-custom work.	4.66	4.66	[4.48; 4.83]
1. Custom Work	8.00	8.00	[8; 8]	1
2. Non-Custom	2.99	2.99	[2.72; 3.25]	2
Subtotal B.2 (weighted average of B.2.a and B.2.b)	3.77	1.69
3. Changes in other costs~
a. Costs to Repair Soil Erosion	-0.04	0.00	[-1; 0]	26
b. Change in Cash Rent due to Cover Crops Use	-0.77	0.00	[-10; 0]	13
Subtotal B.3	-0.81	0.00
Subtotal B. Changes in Costs	37.45	33.72
C. Net Change in Profits (C=A-B)	-2.95	-1.72
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-17.95	-18.72

* Reported changes in soybean yields following cover crops due to cover crops use ranged from -2 to 4 bushels per acre, with an average increase of 0.28 bushels. The median farmer reported no change in soybean yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.09 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in soybean planting costs (including seeds); N, P or K costs; manure, insecticide, fungicide, or soil testing costs; or management time due to cover crops use.

Table 24. Changes in net returns due to cover crop use followed by soybeans, for all cover crop species, terminated with herbicides, in no-till systems. Planting method: aerial.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	18.55	15.00	[10; 35]	11
2. Value of change in following soybean yield*	5.00	0.00	[-60; 40]	14
3. Savings or extra revenue from grazing or harvesting cover crop for forage	15.00	10.00	[5; 30]	3
Subtotal A. Changes in Revenue	38.55	25.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	18.06	15.00	[10; 32]	16
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	18.18	15.73
i. Custom work	19.46	16.00	[12; 35]	13
ii. Non-Custom	14.00	14.86	[8.34; 17.95]	4
Subtotal B.1	36.24	30.73
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)^	1.53	0.00		15
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	15
ii. Extra labor costs to apply herbicides on top of regular weed control program	0.87	0.00	[0; 13]	15
iii. Other termination expenses	0.67	0.00	[0; 10]	15
b. Extra expenses for farmers that did not apply herbicides before planting soybean in acres without cover crops.	12.99	12.99		2
i. Herbicide cost to terminate cover crops	10.00	10.00	[10; 10]	2
ii. Herbicide application cost. Weighted average of custom and non-custom work.	2.99	2.99	[2.72; 3.25]
1. Custom Work	0.00	0.00	[0; 0]	0
2. Non-Custom	2.99	2.99	[2.72; 3.25]	2
Subtotal B.2 (weighted average of B.2.a and B.2.b)	2.88	1.53
3. Changes in other costs~
a. Costs to Repair Soil Erosion	0.00	0.00	[0; 0]	17
b. Change in Cash Rent due to Cover Crops Use	0.00	0.00	[0; 0]	8
Subtotal B.3	0.00	0.00
Subtotal B. Changes in Costs	39.12	32.26
C. Net Change in Profits (C=A-B)	-0.58	-7.26
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-15.58	-17.26

* Reported changes in soybean yields following cover crops due to cover crops use ranged from -6 to 4 bushels per acre, with an average increase of 0.50 bushels. The median farmer reported no change in soybean yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.07 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in soybean planting costs (including seeds); N, P or K costs; manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 25. Changes in net returns due to cover crops use followed by corn, for all cover crop species, planted with drills in conventional or vertical tillage systems. Termination method: herbicides.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	16.75	16.00	[7; 28]	4
2. Value of change in following corn yield*	-8.00	0.00	[-40; 0]	5
3. Savings or extra revenue from grazing or harvesting cover crop for forage	80.00	80.00	[80; 80]	1
Subtotal A. Changes in Revenue	88.75	96.00
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	17.40	19.00	[10; 21]	5
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	14.50	14.50
i. Custom work	14.33	15.00	[13; 15]	3
ii. Non-Custom	14.57	14.28	[9.79; 19.38]	7
Subtotal B.1	31.90	33.50
2. Cover Crop Termination
a. Extra expenses for farmers that applied herbicides to all acres (with and without cover crops)	13.25	0.00		4
i. Extra herbicide cost on top of regular weed control program	0.00	0.00	[0; 0]	4
ii. Extra labor costs to apply herbicides on top of regular weed control program^	3.25	0.00	[0; 13]	4
iii. Other termination expenses	10.00	0.00	[0; 20]	4
b. Extra expenses for farmers that did not apply herbicides before planting corn in acres without cover crops.	15.26	15.54		1
i. Herbicide cost to terminate cover crops	8.00	8.00	[8; 8]	1
ii. Herbicide application cost. Weighted average of custom and non-custom work.	7.26	7.54	[6.72; 7.54]
1. Custom Work	14.00	14.00	[14; 14]	1
2. Non-Custom	5.02	5.38	[4.29; 5.38]	3
Subtotal B.2 (weighted average of B.2.a and B.2.b)	13.65	3.11
3. Changes in other costs~
Subtotal B.3	0.00	0.00	[0; 0]	8
Subtotal B. Changes in Costs	45.55	36.61
C. Net Change in Profits (C=A-B)	43.20	59.39
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-36.80	-20.61

* Reported changes in corn yields following cover crops due to cover crops use ranged from -10 to 0 bushels per acre, with an average loss of 2.00 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.25 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in cash crop planting costs (including seeds); N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in management time or cash rent paid due to cover crops use.

Table 26. Changes in net returns due to cover crops use followed by corn, for all cover crop species, terminated with herbicides, in conventional or vertical tillage systems. Termination method: tillage.

Sources of changes in net profits	Mean	Median	Range	#Obs.
Sources of changes in net profits	$/acre			#Obs.
A) Changes in Revenues
1. Cost-share program	15.50	15.50	[11; 20]	2
2. Value of change in following corn yield*	9.00	0.00	[0; 52]	8
3. Savings or extra revenue from grazing or harvesting cover crop for forage	41.00	20.00	[15; 88]	3
Subtotal A. Changes in Revenue	65.50	35.50
B) Changes in Costs
1. Cover Crop Planting
a. Seeds	20.20	16.50	[5; 45]	10
b. Planting (excluding seeds). Weighted average of custom and non-custom work.	13.54	12.01
i. Custom work	27.00	27.00	[27; 27]	1
ii. Non-Custom	12.04	10.34	[7.59; 18.61]	9
Subtotal B.1	33.74	28.51
2. Cover Crop Termination
a. Extra expenses for farmers that used conventional till in all acres (with and without cover crops)	4.90	0.00		10
i. Extra labor costs to till cover crop acres on top of regular costs to till no cover crop acres^	3.90	0.00	[0; 13]	10
ii. Other termination expenses	1.00	0.00	[0; 5]	10
Subtotal B.2	4.90	0.00
3. Changes in other costs~
a. Opportunity cost of management time~	0.30	0.00	[0; 30]	10
Subtotal B.3	0.30	0.00
Subtotal B. Changes in Costs	38.34	28.51
C. Net Change in Profits (C=A-B)	26.56	6.99
C.1. Net Change in Profits excluding grazing/forage (C.1 = C - A.3)	-14.44	-13.01

* Reported changes in corn yields following cover crops due to cover crops use ranged from 0 to 13 bushels per acre, with an average gain of 2.25 bushels. The median farmer reported no change in corn yields.

^ Reported changes in labor hours per acre to terminate cover crops with herbicides ranged from 0 to 1 hours, and averaged 0.30 hours. The median farmer reported no extra labor to terminate cover crops.

~ No respondent indicated changes in cash crop planting costs (including seeds); N, P, K, manure, insecticide, fungicide, or soil testing costs; or changes in costs to repair soil erosion; or changes in cash rent paid due to cover crops use. Only one operator reported 2 extra management hours required per acre per year to manage cover crops.

Hypotheses 2: results from agronomic simulations.

Table 27 reports the marginal effects of cover crop use, soil type, nitrogen rate, and location on corn yields, corn biomass, soil loss, runoff, nitrate load, subsurface drainage, and nitrate leaching. The baseline scenario is a crop system with Tama soil, in region CC in Iowa, with Nitrogen application rate of 150 kg/ha, and without cover crop. The average annual marginal effects of cover crop use (after accounting for soil type, nitrogen rate, and location) over the 20-year simulation periods are to:

increase corn yields by 1.1 bushels per acre
increase corn biomass by 83 kg/ha
reduce soil loss by a quarter of a ton per hectare
reduce water runoff by 1.6 mm
reduce nitrate load by 37% (6 kg/ha)
reduce nitrate leaching by 27% (0.025 mg/L).

In order to explore the temporal pattern of the reduction in nitrate leaching due to cover crops use, the daily average concentration of nitrate leaching was evaluated across the 20 simulation years. Cover crop reduces nitrate concentration significantly in the spring when nitrate concentration is typically high. Although cover crop use results in slightly higher concentrations over the winter, the baseline concentration level is lower than the typical peak period without cover crops (Figure 1). Between day-of-the-year (doy) 180 and 300, the difference between the two systems with cover crops and without cover crops is negligible, since both nitrate load and drainage are low when a cash crop (typically corn or soybeans) is in the ground.

During our interviews with water treatment plant managers, we learned that water treatment plants are more concerned with peak levels of nitrate concentration than with overall average levels. We calculated the average number of days in a year (over 20 simulated years) when the nitrate concentration levels exceeded the 10.4 mg/L effective safety limit of drinking water set by the EPA are relevant (Figure 2). On average, the use of cover crops reduces the number of peak days by 3 over the year, and such reduction is significant at the 5% significance level.

A summary of results from complementary tests conducted on agronomic simulations including 4 nitrogen application rates (100, 150, 200, and 250 kg/ha), 3 soil types (Canisteo, Webster, and Tama), and 4 states (Iowa, Illinois, Indiana, and Minnesota) and their agricultural districts, indicates that:

mean corn yields are higher (+1 bu/acre) with cover crops than without cover crops for all observations across all locations, nitrogen rates, and soil types (5% significance level);
mean corn yields are higher (+2 bu/acre) with cover crops than without cover crops for a nitrogen rate application of 100 kg/ha, across all locations and soil types (5% significance level);
mean corn yields in Iowa are higher (+2 bu/acre) with cover crops than without cover crops, across all nitrogen rate applications and soil types (5% significance level);
mean nitrate leaching (concentration) is lower (-0.239 x 100ppm) with cover crops than without cover crops, for all observations across all locations, nitrogen rates, and soil types (5% significance level);
mean nitrate leaching (concentration) is lower with cover crops than without cover crops in Iowa, Indiana, and Illinois (10% significance level), but the mean difference is not significant at the 10% level for Minnesota.
the simulations for the following agricultural districts indicated that mean nitrate leaching (concentration) is lower with cover crops than without cover crops in Central-East, Central-Central, Central-West, South-Central, South-East, and South-West regions in Iowa; North-East region in Iowa (5% significance level). No significant differences (at 10% level of significance) were found for North-West and North-Central and regions in Iowa; or South-East and South-West regions in Minnesota.
mean nitrate leaching (concentration) is lower with cover crops than without cover crops in Tama, Canisteo and Webster soils (5% significance level).
mean soil loss is lower (-0.284 kg/ha) with cover crops than without cover crops, for all nitrogen application rates across all locations (5% significance level).
mean soil loss is lower with cover crops than without cover crops in Iowa, Illinois, and Minnesota (5% significance level), but no significant difference (at 10% significance level) was found in Indiana.
the simulations for the following agricultural districts indicated that mean soil loss is lower with cover crops than without cover crops in South-West, Central-East, Central-Central, Central-West and South-Central (5% significance level); North-West and North-Central (10% significance level) regions in Iowa; South-East, and South-West (10% significance level) regions in Minnesota. No difference for North-East and South-East regions in Iowa (10% significance level).
mean soil loss is lower with cover crops than without cover crops, for Tama, Canisteo and Webster soils (5% significance level).

Using linear regression techniques on simulations from the APSIM model, the following sets of marginal effects of cover crops were calculated:

Marginal effects on soil loss using no cover, Nitrogen application rate 150 kg/ha, Tama soil in Iowa as baseline:

Average soil loss in Baseline=1.53 kg/ha (1% significance level)
Cover crops reduce soil loss by 0.26 kg/ha (1% significance level) after accounting for all regional differences
Soil loss in Minnesota is 0.732 kg/ha lower than in Baseline (1% significance level)
Soil loss in Illinois is 0.182 kg/ha higher than in Baseline (5% significance level)
No significant difference in soil loss across different Nitrogen application levels.
No significant difference in soil loss across Tama, Canisteo, or Webster soils.
No significant difference in soil loss between Indiana and Baseline.

Marginal effects on corn yields using no cover, Nitrogen application rate 150 kg/ha, Tama soil in Iowa as baseline:

Mean corn yield in Baseline=165.6 bushels per acre (1% significance level)
Cover crops increase corn yields by 1.117 bushels (1% significance level) after accounting for all regional differences
Nitrogen application levels affect yields in baseline as expected (1% significance level)
Mean corn yield in Webster soils is 1.20 bushels higher than in Baseline (5% significance level).
No significant yield difference between Canisteo soils and Baseline.
Corn yields 6.01 bushels higher in Minnesota than in Baseline (1% significance level)
Corn yields 4.06 bushels lower in Illinois than in Baseline (1% significance level)
No significant yield difference between Indiana and Baseline.

Marginal effects on nitrate leaching using no cover, Nitrogen application rate 150 kg/ha, Tama soil in Iowa as baseline:

Mean leaching in Baseline=0.085 mg/L (1% significance level)
Cover crops reduce leaching by 0.025 mg/L (1% significance level) after accounting for all regional differences.
N levels have the expected effects on leaching (1% significance level)
Mean leaching in Webster soils is 0.047 higher than in Baseline (1% significance level)
No leaching difference between Canisteo soils and Baseline.
Mean leaching in Minnesota is 0.006 mg/L lower than in Baseline (5% significance level)
Mean leaching in Indiana is 0.012 mg/L lower than in Baseline (1% significance level).
No significant difference in mean leaching between Illinois and Baseline.

A similar analysis was conducted focusing on soybean yields in a corn/soybean rotations, but only for Canisteo soils and a Nitrogen application rate of 150 kg/ha. Our findings suggest that:

mean soybean yields are higher (+1.66 bu/acre) with cover crops than without cover crops for all observations across all locations (5% significance level);
mean soybean yields in Iowa are higher (+1.71 bu/acre) with cover crops than without cover crops (5% significance level);
no significant mean soybean yield differences exists between systems with cover crops and without cover crops for Illinois, Indiana, or Minnesota, or within agricultural districts in Iowa or Minnesota.

An analysis of the marginal effects of cover crops on soybean yields in Canisteo soils in Central Iowa, using a Nitrogen application rate of 150 kg/ha as the baseline, suggest that:

Mean soybean yield in Baseline=56.80 bushels (1% significance level)
Cover crops increase soybean yields by 1.85 bushels (5% significance level) after accounting for all regional differences.
Mean soybean yields are 3.88 bushels lower in South-East Minnesota than in Baseline (5% significance level)
Mean soybean yields are 11.12 bushels lower in South-West Minnesota than in Baseline (1% significance level)
Mean soybean yields are 5.24 bushels lower in Indiana than in Baseline (5% significance level)
Mean soybean yields are 9.95 bushels lower in Illinois than in Baseline (5% significance level)
Mean soybean yields are lower in southern Iowa regions and in Central-East and Central West Iowa regions than in Baseline.
No significant yield difference exists between northern Iowa regions and Baseline.

Table 27. Marginal effects of cover crop use, soil type, nitrogen rate, and location on corn yields, corn biomass, soil loss, runoff, nitrate load, subsurface drainage, and nitrate leaching

	Yield	Biomass	Soil loss	Runoff	Nitrate load	Subs. Drain	Nitrate Leaching (Concentration)
	bu/acre	kg/ha	ton/ha	mm	kg/ha	mm	mg/L
(Intercept)	165.6***	19478**	1.237***	44.79***	15.97***	136.9***	0.093***
	(0.891)	(77.5)	(0.080)	(1.395)	(0.912)	(5.477)	(0.004)
Cover crop	1.112***	83.27**	-0.257***	-1.655**	-5.998***	-5.794**	-0.025***
Cover crop	(0.417)	(36.3)	(0.037)	(0.653)	(0.427)	(2.565)	(0.002)
Nrate=100 kg/ha	-9.726***	-903***	0.076	0.8917	-5.95***	0.622	-0.028***
	(0.593)	(51.6)	(0.053)	(0.929)	(0.608)	(3.648)	(0.003)
Nrate=200 kg/ha	3.231***	302***	-0.018	-0.1687	6.293***	-2.162	0.03***
	(0.586)	(51.0)	(0.052)	(0.918)	(0.600)	(3.604)	(0.003)
Nrate=250 kg/ha	4.295***	405***	-0.039	-0.3675	13.31***	-2.028	0.063***
	(0.586)	(51.0)	(0.052)	(0.918)	(0.6010)	(3.606)	(0.003)
Canisteo	-0.843*	-77.2*	0.030	-1.1454	-10.27***	-114.3***	0.003
	(0.510)	(44.4))	(0.046)	(0.798)	(0.522)	(3.135)	(0.002)
Webster	1.223**	105**	0.024	-0.3746	37.62***	279.5***	0.047***
	(0.510)	(44.4)	(0.046)	(0.798)	(0.522)	(3.136)	(0.002)
IA-CE	-1.422	-98.03	0.088	-3.182*	-3.547***	-34.24***	0.005
	(1.066)	(92.7)	(0.095)	(1.667)	(1.0910)	(6.548)	(0.005)
IA-CW	-1.422	-98.03	0.08765	-3.182*	-3.547***	-34.24***	0.005
	(1.065)	(92.7)	(0.095)	(1.667)	(1.0910)	(6.548)	(0.005)
IA-NC	11.62***	1294***	-0.349***	-9.412***	-3.491***	-7.216	-0.02***
	(1.047)	(91.1)	(0.094)	(1.640)	(1.072)	(6.439)	(0.005)
IA-NE	7.388***	989***	0.104	2.762*	-3.613***	17.5***	-0.023***
	(1.036)	(90.2)	(0.093)	(1.623)	(1.061)	(6.373)	(0.005)
IA-NW	4.549***	829***	-0.359***	-11.96***	-7.679***	-61.23***	-0.01**
	(1.074)	(93.5)	(0.096)	(1.682)	(1.10)	(6.604)	(0.005)
IA-SC	-5.041***	-478***	1.173***	16.93***	-1.584	13.08**	-0.016***
	(1.049)	(91.3)	(0.094)	(1.642)	(1.074)	(6.449)	(0.005)
IA-SE	-7.615***	-766***	0.828***	9.815***	-0.944	19.8***	-0.015***
	(1.039)	(90.5)	(0.093)	(1.628)	(1.065)	(6.393)	(0.005)
IA-SW	-7.860***	-891***	0.975***	16.337***	-1.336	-8.339	0.001
	(1.037)	(90.3)	(0.093)	(1.624)	(1.062)	(6.377)	(0.005)
IL	-4.091***	-414***	0.477***	2.1883	0.430	35.73***	-0.01**
	(1.051)	(91.5)	(0.094)	(1.646)	(1.077)	(6.466)	(0.005)
IN	0.764	104.97	0.303***	-2.5861	2.43**	66.09***	-0.021***
	(1.032)	(89.8)	(0.092)	(1.616)	(1.057)	(6.345)	(0.005)
MN-SE	4.868***	961***	-0.187**	-1.9514	-3.429***	21.27***	-0.022***
	(1.055)	(91.8)	(0.094)	(1.652)	(1.081)	(6.488)	(0.005)
MN-SW	7.263***	1290***	-0.698***	-16.64***	-7.941***	-55.47***	-0.007
	(1.065)	(92.7)	(0.095)	(1.668)	(1.091)	(6.552)	(0.005)
Adjusted
R-squared	0.134	0.203	0.080	0.080	0.524	0.640	0.168

Significant codes: ***0.01, **0.05, *0.1

Figure 1. Nitrate concentration, load, and drainage averaged across locations and years for soil series Webster. For reference, doy 100 is April 10th, doy 180 is June 29th, and doy 300 is Oct 17th.

Figure 2. Number of days when nitrate concentrations exceed 10.4 mg/L, by nitrogen application rate and cover crop adoption status.

Hypotheses 2: results from interviews with water treatment plant managers.

Different water treatment plants use different methods to maintain nitrates below the federally mandated level of 10 mg/L. While all interviewed water treatment plants use blending of water from different sources as the most cost-effective way to provide safe drinking water, some plants solely rely on this method. Most interviewed plants have access to alternative ground water systems, while some rely mostly on surface water. Usually, large ground water systems (deep wells) are well maintained, fill up with naturally filtered water (through rocks, sand, etc.), and seldom observe spikes in nitrate concentration near or above the safety threshold level. When that occurs, water treatment plants blend such water with water from other wells with lower nitrate concentration to dilute nitrate levels per liter back to safe levels. For these plants, the costs associated with treating nitrates and turbidity stemming from agricultural production tend to be negligible, since blending decisions are made on a daily basis to maintain about three dozen parameters within drinking water standards and nitrate concentration and turbidity tend to be of secondary relevance (because most blending decisions are made based on other safety indicators).

For water treatment plants that rely on surface water (rivers or lakes), nitrate concentration and turbidity tend to carry more relevance for choosing treatment methods than for plants that rely on ground water. Blending remains the top choice whenever at least one source of raw water has low concentration levels. However, when blending is not an option, and nitrate removal specific equipment (ion-exchange or reverse osmosis) is available, a portion of the untreated water goes through such equipment and the output is blended with untreated water to produce a minimum cost blend of nitrate compliant raw water. Then, this blend continues the treatment process to achieve the remaining drinking water safety standards.

Des Moines Water Works (DMWW) in Iowa operates a reverse osmosis system in one location and an ion-exchange system in another location. Since reverse osmosis is not nitrate-specific, and the decision to use this equipment is never driven by nitrate levels or turbidity, we found no reason to impute the operational costs of this equipment solely to nitrate removal or turbidity. Only the ion-exchange system is nitrate-specific and is only turned on when blending and reverse osmosis are insufficient. Therefore, all operational costs of the ion-exchange are attributed to nitrate removal efforts: $644,896 in 2013; $325,912 in 2014; $1,401,308 in 2015; and $633,335 in 2016. DMWW serves about half a million customers, so a quick calculation assuming an annual cost of nitrate removal of $1.5 million would results in a monthly cost per customer of $0.25 per month. The cost to replace the existing equipment or expand the treatment facilities were not included in our calculations because we consider that those decisions are more related to the size of the customer base and normal depreciation of productive assets than to observed nitrate levels. The City of Decatur (Illinois) operates an ion-exchange system, but we were not able to have access to operational costs.

Combining the information from our interviews with water treatment plants and the partial budget results, we can approximate the additional acres that could be planted to cover crops if a sum equivalent to the highest observed annual costs to remove nitrates ($1.5 million) could be added to the existing pool of cost-share programs and new cover croppers would be willing to receive a $20 payment per acre to plant cover crops (despite the fact that on average farmers will see their net returns decline by around $15-$20 if cover crops are not used for grazing livestock or forage): $1.5 million / $20 per acre = 75,000 acres. Although 75,000 additional acres would result in a double-digit growth rate in cover crop acres for Iowa, they only represent 1.17% of all acres in the Raccoon River Watershed (6.4 million acres). In conclusion, and contrary to our expectations, potential savings in water treatment plants would be insufficient to scale up cover crop use even within a limited watershed. The focus of our analysis is very narrow by design, and many other environmental benefits from cover crops are not considered that could justify a heightened effort to expand the use of cover crops. Finally, it must be noted that results from our interviews with large water treatment plants do not apply to small communities facing high nitrate concentrations in small wells, and no alternative sources of water to blend.

Research conclusions:

There is substantial variability in the net returns to cover crops, driven by the difference in yields obtained in fields with and without cover crops, planting and termination costs, and cost-share program payments.
General agronomic and economic recommendations for all types of cover crops in Midwestern row crop production systems should be avoided, and instead recommendations should be issued for a specific region and a specific cover crop mix.
For most farmers, cost-share payments are insufficient to cover all private costs associated with cover crop use, but are a critical incentive to support this practice.
Grazing cover crops or harvesting them for forage is likely to generate sufficient additional revenue (or cost savings in an integrated crop/livestock production system) to result in overall positive returns to cover crops.
Although partial budgets based on survey data suffer from several limitations related to the self-selection bias of survey respondents and the potential unrepresentativeness of the sample, they provide valuable information for farmers and policy makers. The calculated returns are based on field data (instead of experimental plots) from farmers that manage row crop production on acres with cover crops and on acres with no cover crops, and can be used as benchmarks for current and potential cover croppers, as well as ground-truth references for agricultural and conservation policy design.
Agronomic simulations suggest that sustained cover crop use is likely to result in soybean yield increases, and generates positive environmental externalities: reduced nitrate leaching and soil erosion.
However, additional economic incentives to scale up cover crop adoption cannot be currently justified by the potential cost savings to water treatment plants.
The results of the present study (particularly those comparing net returns across different levels of experience with cover crops), in conjunction with a lack of market valuations for actual soil health, suggest that the necessary conditions to substantially scale up the use of cover crops are currently missing.
Potential measures to improve the economic viability of cover crops without increasing government transfers to cover croppers include (1) the development of a more competitive market for cover crop seeds (offering high quality seed adapted to local conditions, at low cost); (2) promoting the use of cover crops for livestock grazing or forage; and (3) developing and promoting location-specific guidelines to facilitate the decision-making process for farmers, seed companies, and implement dealers, but particularly to minimize the yield drag on corn and soybeans, while containing planting and termination costs. An obvious but likely unsustainable alternative (due to federal and state budget constraints) to reduce the net losses derived from cover crop use is to increase the flow of public monies to adopters of the practice through cost-share payments, subsidized seed bags, discounted crop insurance premiums, tax credits, or similar incentives.
It is critical for cover crop advocates to understand that cover crops cannot be scaled up to mainstream agriculture if the practice does not at least break-even in the short term. Given the potential short term losses if cover crop management is poor, cover crop advocates should not expect farmers to massively adopt cover crops solely based on their long-term effects on soil and water quality.

Participation Summary

990 Farmers participating in research

Educational approach:

The findings of our project were communicated to farmers as stand-alone presentations or integrated into broader presentations during field days, workshops, and conferences.
Stand-alone presentations to academic audiences were conducted through selected posters and selected posters at professional conferences.
A stand-alone presentation of our results to undergraduate students of Advanced Farm Management (ECON330) in the Department of Economics at Iowa State University was conducted in Fall 2017.

Farmers interviews

study-circle-focus-group

Proposed Farmers/Ranchers:

20

Actual Farmers/Ranchers:

16

Proposed Ag Educators:

3

Actual Ag Educators:

3

Proposed Completion Date:

December 31, 2015

Actual Completion Date:

December 31, 2015

Accomplishments:

In particular, we were interested in learning about the changes observed by farmers in their crop rotation systems since they first started using cover crops; and whether the motivations to use cover crops for the first time differed from the motivations to use cover crops in successive years.

To cover a wide range of different management practices and soil and weather conditions, Practical Farmers of Iowa recruited 16 farmers from Iowa, Minnesota and Illinois based on their years of experience with cover crops, species used, crop rotations used, interest in better understanding cover crops return on investment, and availability. The focus group discussions were held in Ames (Iowa), Urbana (Illinois), and Albert Lea (Minnesota) during December 2015.

Following Morgan, et al. (1998), we used the same procedures in all three discussions. A research team member who has extensive knowledge about cover crops and interacts with farmers on a regular basis moderated the discussions. We started with a ten-minute presentation about the project, and then opened a two-hour discussion revolving around 10 structured questions. The first two questions asked the participants to introduce themselves and to describe their farms (i.e., location, soil types, rotations), and indicate when was the first time they planted cover crops. The next two questions asked about what prompted the use of cover crops for the first time and what motivated the continued use of cover crops. After that, the moderator asked the participants to reflect on the differences in practices between rotations with and without cover crops for two minutes, and to write down their thoughts before taking turns to share them with the group. The same procedures were followed to discuss the differences in revenues and costs for rotations with and without cover crops.

The discussions were recorded with farmers’ written consent, and later transcribed by a professional transcriber. During the discussions, another team member annotated the main points on table top pads, and the main points were reviewed and summarized at the end of the meeting.

Reasons for using cover crops

Most farmers first started using cover crops because of their potential benefits, such as soil health improvement and soil erosion abatement, and due to the availability of outside resources, e.g. education events, conferences, and cost-share programs. Two farmers also mentioned the family tradition of “leaving the farm better than the way you found it”. Farmers had expectations that cover crops would lead to fertilizer savings from nutrient recycling and herbicide savings from weed control. One Minnesota farmer, who faced increasing competition from neighboring farmers attempting to outbid him for the farmland he had been leasing for several years, was the first one in the area to use cover crops on rented land as a way to differentiate himself from his neighbors and deter competition based solely on cash rents. One farmer from Minnesota mentioned improvement of water quality as one of the reasons.

The most common reason for continued cover crop use was the perceived reduction in soil erosion. Six out of the eight farmers who had planted cover crops for more than seven years stated having seen considerably less soil erosion over the years, especially during excessive rainfall. Farmers also emphasized soil health improvement as an important factor: higher organic matter leading to higher water holding capacity, increased biodiversity on the field, and better soil quality in general. These improvements have the potential of translating into higher cash crop yields in the future. One farmer in Iowa described cover cropping as a risk management tool to protect their main asset, land, from extreme weather events. Another farmer from Illinois perceived cover crops as a legal risk management tool, in the sense that a history of documented conservation practices may considerably reduce the risk of being involved in an environmental lawsuit. The discussion took place while the lawsuit filed by Des Moines Water Works against ten Iowa drainage districts was open. A farmer from Iowa also expressed concerns over environmental lawsuits, but citing the algae bloom in Lake Erie, Ohio: “I do not understand why there was not a massive lawsuit involved in that. …. a friend … said it’s just a matter of time until the massive lawsuits start…. They’ll take a watershed and they will check every farmer in there and if you’ve got good documentation on what your practice is, you may avoid being placed in the lawsuit. They may just go down the road to the next one.”

Cost savings was also among the reasons for continued use of cover crops. Three farmers from Illinois expressed a hope of lowering fertilizer costs from nutrient recycling through cover crops. Two of them also reported seeing the effect of cover crops as a weed control mechanism, lowering their herbicide costs. Another reported source of cost savings for a farmer in Iowa producing on hilly ground came from the ability of cereal rye to hold the hog manure in the soil during rain events in the fall. The focus group conducted in Minnesota was not able to discuss the reasons for continued cover crop use because of time constrains.

Changes in crop management practices

Incorporating a new plant species into the rotation system entails new decisions. First, the choice of cover crop species, the approaches for planting and termination depend on the existing rotations, field conditions, weather, and costs. Farmers across the three states switched to earlier varieties of soybeans or shorter season corn in order to plant cover crops earlier; and some moved the soybean planting date to an earlier date to accommodate an earlier harvest and therefore an earlier planting date for cover crops.

Farmers from Iowa reported experimenting with different varieties of cereal rye before selecting one with higher growth potential during the winter and a higher cost per bag than the typical bag of cereal rye available in the market. Farmers from Illinois described switching varieties of annual ryegrass after experiencing a failure to winter kill one variety, and the challenge to plant the following cash crop into growing ryegrass in a wet spring. Illinois farmers reported having tried more species and mixes than farmers from the other two states, probably due to the slightly warmer fall and winter temperatures in their area. Farmers in Minnesota have a shorter planting window, and they generally aerial seed cover crops into soybeans and cornstalks. When asked whether they would plant cover crops on all their hectares, a farmer said “…if the opportunity presents itself. It’s always weather”.

Cover crop adoption also heightened competition for resources such as farm labor and custom hired services. For example, some farmers custom hire the planting and harvesting of the cash crop so that they can focus on planting and terminating the cover crops themselves. Four out of five farmers from Minnesota mentioned the difficulty of hiring aerial seeding in the early fall, especially when the demand for insecticide application was high; and, as a result, some of them had been moving cover crop planting a few days earlier every year.

Several farmers reported experiencing changes in costs related to cover crop use. Changes in cash crop seed expenses were associated with changes in planting populations: one farmer in Iowa decreased the cash crop seeding rate with the expectation that the extra nutrients made available through cover cropping would more than offset the negative effect of a lower seeding rate on cash crop yields; another farmer in Iowa increased the cash crop seeding rate because of the potential for slow soil warming in the presence of substantial biomass; and another farmer in Minnesota increased the seeding rate to compensate for a relatively late planting time.

One Iowa farmer had to buy new attachments for the soybean planter because of cover crop residue; other farmers bought tractors or drills for cover crop planting.

Some farmers experienced lower weed pressure and were able to lower their herbicide use. Conversely, one farmer increased the spraying rate and added an extra pass upon hearing rumors about voluntary cereal rye growing after termination.

One Iowa and two Minnesota farmers experienced an outbreak of armyworms in their fields, resulting in higher demand for scouting and insecticide use.

Various changes in fertilizer use, in terms of application time, method and amount were reported. Changes in fertilizer use had different effects on costs across farmers. For example, three farmers from Minnesota lowered fertilizer costs because of the nitrogen credit, while some Iowa farmers applied extra nitrogen for corn at planting because they believed nitrogen would be tied up in the cover crop residue, or increased the amount of phosphorous and potassium. Some farmers moved the anhydrous ammonia application from fall to spring; others applied less in the spring, holding the total amount unchanged.

A major added cost to the operation stemmed from the opportunity cost of time associated with extra management of the cropping system. Farmers reportedly needed to pay constant attention to the cover crops to prevent unexpected situations, or pay more attention to weather around planting and termination times.

Other reported changes in costs were less straightforward. A few farmers started to review their nitrogen programs and conduct soil testing to gather more information about nitrogen usage because of the potential of cover crops to sequester nitrogen. One farmer said: “it's not a direct result of the cover crops but … it was the cover crops that instigated the investigation of the soil health and the soil mechanisms.” Some farmers extended practices that they found to be more efficient into hectares without cover crops as an “adaptation to cover crops”. For example, based on his investigation into soil health that started with cover crops, one farmer stopped using hog manure and started using soil samples to determine nutrient needs later delivered through side-dressing applications. These findings suggest that cover crops are associated with more research and experimentation towards integrated management and soil health improvement.

Cover crops also had implications for the tillage system. Four farmers from Minnesota and Illinois stated that they switched from conventional to no-till farming when they adopted cover crops, resulting in considerable savings in cost. Farmers agreed that the adoption of cover crops and the move towards no-till were both part of the same effort to conserve soil: “It could be because of the cover crop. Or it could be that no-till and cover crops go together.” All participants from Iowa were long time no-till farmers before starting to use cover crops. The improvement in soil condition led to other cost savings: three farmers eliminated the need to repair soil erosion, while the farmer from Minnesota that faced a competitive farmland rental market successfully used cover crops to negotiate an extension of their farm leasing contract maintaining the rental rate unchanged. Another farmer from Minnesota stated that they were able to renew their farmland leasing agreement because of promises to use cover crops to take better care of the soil, even though the benefit is hard to quantify.

Several farmers reported experiencing changes in revenues associated with cover crop use. The only source of reduced revenue mentioned by farmers was yield losses in corn and soybeans. All losses occurred following the first or the second time farmers planted cover crops, when they were least knowledgeable about this practice. However, some farmers reported higher yields in corn and soybeans after several years of using cover crops, stemming from planting different hybrids or varieties, or from improved soil conditions. One farmer from Illinois believed that they had more consistent stands in the field where they had been planting cover crops for years.

Other sources of increased revenues were cost-share payments received by farmers and savings in livestock feed costs because of grazing or harvesting cover crops for forage.

A farmer in Illinois who grew wheat as a lower income cash crop to improve soil health reported obtaining similar results in terms of soil health by replacing wheat with cover crops (cereal rye and other grasses) in some acres. Despite losing revenue from the wheat enterprise, he expected an improvement in corn and soybean yields in the fields where cover crops were planted. Farmers in Iowa and Illinois reported seeing improvements in soil health, organic matter content, and soil moisture stemming from cover crops use, and they believed that those effects would eventually translate into higher revenues.

Finally, a farmer in Iowa was able to expand his operation by outbidding other farmers competing for the same parcel of land after offering the landowner to plant cover crops on the rented ground as part of the leasing agreement.

Pilot Survey

study-circle-focus-group

Proposed Farmers/Ranchers:

20

Actual Farmers/Ranchers:

16

Proposed Completion Date:

June 1, 2016

Actual Completion Date:

June 1, 2016

Accomplishments:

An online survey questionnaire to collect information on the changes in costs and revenues associated with the use of cover crops in row crop agriculture was developed based on the focus group discussions. We sent a follow-up online survey to all farmers in the focus groups in order to construct a partial budget for each of them for 2014/15 crop year, and to serve as a pilot survey for a larger project involving a regional survey. Partial budgets capture the net annual economic benefit or loss associated with the use of cover crops by identifying and monetizing the differences in management practices across production systems with and without cover crops (Kay, Edwards, and Duffy, 1994). Partial budgets are designed to answer the question of how profits change when a modification is introduced to a baseline system of production. Since enterprise budgets are used to calculate the profitability of an enterprise, partial budgets capture, in essence, the differences between two enterprise budgets: one for a baseline enterprise (e.g. corn production), and one for another enterprise consisting of the baseline enterprise with some modification (e.g. corn production preceded by cover crops).

Instead of asking directly about changes in costs and revenues, the survey first asked farmers about revenues and expenses in their cropping system with cover crops, and second whether those values were different in their cropping system without cover crops. Finally, if a farmer indicated that a difference existed, the survey then asked for the typical values in their cropping system without cover crops. We designed the display of questions to be conditional upon previous answers to minimize the number of questions presented to farmers.

The first section of the survey collected basic information, such as number of years of experience with cover crops, total hectares of cover crops planted since starting using cover crops, and whether cover crops were used for grazing or as a forage. The survey instrument then asked which cover crop mix was most extensively planted in the fall of 2014 and the number of hectares planted (as opposed to farmers’ experience with all cover crops discussed in the focus groups). The next section focused on the added costs associated with seed and planting of the cover crop chosen, followed by a question concerning termination. The second part of the survey asked which cash crop was most extensively planted in the spring of 2015 following the cover crop, the number of hectares planted, and the observed differences in yield and other sources of revenues, compared to the typical values without cover crops. The questionnaire then focused on sources of changes in costs, such as planting, fertilizer use, herbicide use, and tillage. The last section asked about the cash crop harvested in 2014, preceding the reported cover crop mix.

Some of the questions regarding cash revenues and costs in the survey asked for dollar values, including those about cost-share payment received, seed costs, fertilizer costs, herbicide costs, or custom hired work. For non-cash costs, such as the costs of own machinery, the survey asked about the type of machinery used and the number of field passes. The associated costs were derived from a partial budget tool developed specifically for cover crop budgeting by the Natural Resource Conservation Service (Cartwright and Kirwan, 2014). The partial budget tool is an Excel® spreadsheet that asks the user to input information on farm management practices and calculates the net change in profit associated with the incorporation of cover crops into the user-defined cropping system. The partial budget tool includes costs for a list of machineries that served as the basis for our pilot survey.

Our pilot survey also asked for labor hours involved in the activity along with the machinery used. The opportunity cost of added management was calculated as the product of the number of additional management hours from cover crop use for the field under analysis and a $13.80 per hour wage rate, divided by the number of hectares managed. The wage rate used for management work is higher than the wage rate for non-management work ($12 per hour) used in Cartwright and Kirwan (2014) to reflect the higher opportunity cost of the former.

To calculate changes in revenue stemming from yield differences, 2015 marketing year average prices for corn ($138.58 per metric ton) and soybeans ($327.39 per metric ton) from the National Agricultural Statistics Service (2017) were used.

Survey results

After two rounds of reminders, 15 out of the 16 focus groups participants completed the survey. On average, respondents had had 9 years of experience with cover crops, and had planted 994 hectare to cover crops over the years by summer 2015. The average number of acres planted to cover crops per respondent in fall 2014 was 186 hectares, accounting for 19% of the average total area planted to cover crops over the years. This finding reflects the fact that participating farmers started using cover crops in small test plots and, as they developed adjustments to their crop management practices, the area planted to cover crops tended to increase. Eleven farmers planted cereal rye, and the rest planted annual ryegrass or mixes including radish. In 2015, two Iowa farmers and all Minnesota farmers planted corn following cover crops, while all Illinois farmers planted soybeans. During the focus group discussions, one farmer from Illinois mentioned that they had experienced yield losses in corn following annual ryegrass because the field was too muddy. Most farmers terminated their cover crops by herbicide applications; except for two Minnesota farmers who relied on tillage or winter kill.

We calculated the net change in profits associated with cover crops use for each respondent by manually entering the values from the online survey into the digital partial budget tool (Cartwright and Kirwan, 2014). The use of cover crops in 2014 entailed, on average, an economic loss of $53.72 per hectare. Calculated net changes in profits ranged from a reduction of $166.4 per hectare to an increase of $163.3, with a median net decrease in profits of $64.06 per hectare.

The main drivers of added costs were cover crop seed and planting expenses. The costs for cover crop termination were relatively low, on average. However, termination costs varied substantially across farms, depending on the termination method and the typical pre-plant spring management practices. Thirteen farmers used herbicides to terminate cover crops, but eleven of them typically apply a pre-plant burn down to all their fields irrespectively of the use of cover crops. Consequently, little to no additional herbicide costs were associated with cover crops for those eleven farmers. The other two farmers incurred termination costs ranging from $34.2 to $42.5 per hectare. The termination costs for farmers that relied on winter kill or used tillage to terminate cover crops were null. In the latter case, the farmer used rotational till on all his acres (with and without cover crops), and tillage was an expense that would have been incurred irrespectively of cover crops use.

Nitrogen use, herbicide use and tillage contribute to increased costs for some farms and reduced costs for some other farms, in line with the conclusions reached in focus group discussions. However, the median changes for those variables were zero.

Cost-share program payments and yield increases generated average increases in revenues of $28.99 and $22.14 per hectare, respectively. Only one farmer reported extra revenue from grazing cover crops, at a rate of $24.7 per hectare in 2015. However, the median changes in revenues due to yield increase or grazing across survey respondents were zero. No farmer reported decreases in revenue in 2015 due to cover crops.

The net returns to cover crop use were positive only for one farmer in Iowa and two farmers in Minnesota. They all reported yield increases and modest cover crop seed costs; two received cost-share payments; and one of them is the only farmer who reported added revenues from grazing. Eleven out of 15 farmers reported increases in management hours, although the calculated extra costs per hectare (calculated as extra management hours per year multiplied by a wage rate of $13.8/hour, and divided by the number of hectares planted to the following cash crop) were relatively low. Only three farmers reported saving costs from soil erosion repairs in 2015 due to cover crops use, with an average of $17.90 per hectare. Cost-share payments received by eight farmers averaged $54.40 per hectare. The four farmers with larger than average cover crop seed expenses ($50.41 per hectare) were the ones who experienced the largest reductions in profits per hectare due to cover crop use. However, no distinct cost patterns were observed across cover crop species or states due to the small sample size.

We attempted an analysis of net changes in profits for different configurations of costs and revenues. Interestingly, the net changes in profits for three out of the four farms that experienced cash crop yield increases in 2015 due to cover crop use were positive, and the average increase in profits across the four farms amounted to $35.20 per hectare. No other configuration of changes in costs and revenues resulted in average increases in profits for the farmers in the sample.

Discussion

All participants mentioned the fact that they knew of no available method to quantify the benefits from cover crops, and stressed the need to quantify those gains in order to properly weigh the short-term costs and the long-term benefits, which is especially relevant in the context of the land tenure. Each farmer received a copy of their own partial budget results, as well as a set of graphs summarizing the anonymized partial budgets results for all survey respondents. Only one farmer provided feedback on those results, and although they accepted that in any given year annual returns to cover crops can be negative, they felt that more research was needed to understand the long-term economic returns to cover crops: “Your study so far has focused on the short term agronomic benefits of cover crops as a standalone practice. Most of what we get in return from cover crop use is from growing soil under regenerative management and can’t be quantified separately as there is no way to determine if the plant residue we are converting to soil organic matter comes from the cash crops or cover crops. When selecting cover crop species to plant, balancing the carbon/ nitrogen ratio as close to 25/1 is a primary goal. As for the short term agronomic benefits of using cover crops we’ve had about an equal number of wins and losses. We have a lot of knowledge in regards to regenerative management, but little of it is quantified. We have tried many times to get funding and grants to do the quantifying, but were always turned down.”

Our findings highlight some common elements affecting the decisions to adopt cover crops in Iowa, Illinois, and Minnesota; but most importantly, they highlight that cover crop use might be associated with cost reductions in specific lines of the budget for farmers in one state and cost increases in the same line for farmers in another state. The corollary of this result is that general agronomic and economic recommendations for all types of cover crops in Midwestern row crop production systems should be avoided, and instead recommendations should be issued for a specific region and a specific cover crop mix.

Final Survey

other

Proposed Farmers/Ranchers:

500

Actual Farmers/Ranchers:

990

Proposed Completion Date:

December 31, 2016

Actual Completion Date:

March 15, 2017

Accomplishments:

The final survey questionnaire consisted of 192 questions, organized in seven sections: basic farm information, cover crop planting, cover crop termination, revenues and costs, tillage, previous rotation, and perceptions about cover crops.

The strategy to identify differences across production systems with and without cover crops was to ask respondents to characterize the production practices implemented in their production system with cover crops first, and then to ask them whether such characteristics also apply to their production system without cover crops. Such strategy is deemed better than the traditional way of asking farmers about the dollar values of their perceived changes in costs and revenues associated with cover crops, because (1) all respondents are exposed to the same exhaustive list of possible changes in practices (instead of just a few broad categories that can be interpreted by different respondents to include fewer or more concepts), and (2) their attention is directed toward both practices that generate changes in cash flows and opportunity costs (instead of only the former).

Two strategies were used to implement the final survey: maximum regional coverage was pursued through an online implementation of the questionnaire; and maximum local coverage was pursued through a hard-copy implementation of the same questionnaire in the state of Iowa.

Regional Online Survey

The survey was implemented online with Qualtrics®, and the display of questions was designed to be conditional upon previous answers where possible, minimizing the total number of questions asked. On average, respondents spent about half an hour to complete the online survey.

Electronic invitations to participate in the survey were sent to more than 20,000 farmers, including members of PFI, the Midwest Cover Crops Council, National Wildlife Federations’ Cover Crops Champions Program, and the American Society of Agronomy among other regional associations. More than 300 responses were received, but only 79 responses were used in the calculation of partial budgets, after excluding responses from: (1) farmers who were interested in cover crops but had no hands-on experience; (2) farmers that did not plant cover crops in 2015; (3) farmers that planted cover crops in 2015 on all their acres; (4) farmers that in 2016 planted a different cash crop on acres following cover crops than on acres left fallow during winter; and (5) incomplete responses. This selection process reduces the sample size, but improves the validity of the results by focusing on the changes in costs and revenues associated with cover crop use controlling for the farm manager effect and the macroeconomic conditions prevalent in 2015-2016.

Hard-copy Survey in Iowa

To mitigate our concerns about the limited sample size in the online survey and with additional funding from the Iowa State University Center for Agricultural and Rural Development (CARD), we were able to retain the services of the USDA National Agricultural Statistics Service (NASS) to implement a hard-copy version of the final survey in the state of Iowa.

A stratified random sample of 1,250 operators in the state of Iowa was identified by NASS based on the population of farmers that reported planting at least 10 acres of cover crops in rotation with row crops in farms of at least 50 cropland acres in size in the 2012 U.S. Census of Agriculture. Row crop farming rotations were defined for this study to include corn, soybean, and wheat (i.e., excluding fruits, vegetables, tree nuts, greenhouse, nursery and floriculture production, tobacco, cotton, etc.). The sampling strategy accounted for farm sizes (small, medium, and large), and geographical coverage across the state.

The survey questionnaire was mailed on February 1, 2017, and a second questionnaire mailing was sent to all non-respondents by mid-February. Finally, telephone follow-ups of non-respondents were conducted.

Despite its geographical coverage, and the detailed criteria followed in developing the random sample by NASS, the sampling framework (which excluded operators who adopted cover crop after 2012, and included operators who discontinued the use of cover crops or retired after 2012) does not allow us to make any inferences about population totals or averages. However, our results are the best estimates of net returns to cover crops available to date, both due to the partial budget approach used in the calculations and the sample size of non-experimental field data.

A total of 674 responses were received, amounting to a 54% response rate, of which 440 corresponded to operators who had planted cover crops, and 234 corresponded to operators with no cover crops experience. The data used to calculate partial budgets correspond to the subset of operators who planted cover crops in 2015 in some of their acres (but not all), and planted the same cash crop in 2016 both in acres following cover crops and in acres without cover crops. A total of 233 responses distributed across all nine agricultural districts were left after excluding responses from: (1) farmers with no cover crops experience; (2) farmers that did not plant cover crops in 2015; (3) farmers that planted cover crops in 2015 on all their acres; (4) farmers that in 2016 planted a different cash crop on acres following cover crops than on acres left fallow during winter; and (5) incomplete responses. This selection process reduces the sample size, but improves the validity of the results by focusing on the changes in costs and revenues associated with cover crop use controlling for the farm manager effect and the macroeconomic conditions prevalent in 2015-2016.

The results from both version of the final survey are available in the Research Section of this Final Report.

1 Curricula, factsheets or educational tools

4 Published press articles, newsletters

15 Webinars / talks / presentations

11 Workshop field days

6 Other educational activities: 3 Peer Reviewed Publications
3 Research Reports

Participation Summary:

553 Farmers participated

635 Ag professionals participated

Education/outreach description:

Field Days:

Cover Crop Field Day-Rock Creek. Osage. Sep-21, 2017. Attendance: 30
Cover Crop Field Day. Eagle Grove. Sep-22, 2017. Attendance: 35
Watershed Academy. Boone. Oct-25, 2017. Attendance: 40
Cover Crops for Risk Management. Corning. Nov-13, 2017. Attendance: 40
Cover Crops for Source Water Training. Ames. Nov-14, 2017. Attendance: 3
Cover Crops for Risk Management. Slater. Nov-21, 2017. Attendance: 55
Cover crops for Crop Insurance. regional. Nov-28, 2017. Attendance: 200
National Cover Crop Conference. Indianapolis. Dec-07, 2017. Attendance: 30
Iowa Learning Farms Cover Crop Workshop. Oakland. Dec-13, 2017. Attendance: 40
Cover Crops for Corn and Soybeans. Iowa Falls. Jan-02, 2018. Attendance: 40
Cover crops for corn and soybeans. Yankton, SD. Jan-05, 2018. Attendance: 40

Webinars:

“Cover Crop Economics: Thoughts and Data.” Cover Crop Working Group Webinar. August 1, 2017.http://www.practicalfarmers.org/farmer-knowledge/farminar-archive/cover-crop-economics-thoughts-data/ 97 archived views on PFI site; 222 views on Youtube (This presentation was not live, it was only recorded, so there were no live viewers and we have no survey feedback)
“Integrating Livestock and Cover Crops for Profit in Nebraska.” Farminar. December 19, 2017. http://www.practicalfarmers.org/farmer-knowledge/farminar-archive/integrating-livestock-cover-crops-profit-nebraska/ 19 live viewers; 56 archived views
“Integrating Livestock and Cover Crops for profit in Kansas.” Farminar. December 13, 2017. http://www.practicalfarmers.org/farmer-knowledge/farminar-archive/integrating-livestock-cover-crops-profit-kansas/ 24 live viewers; 53 archived views.

Presentations to Agricultural Professionals:

Carlson, S. "Cover crops for corn and soybeans." NRCS field staff training. Des Moines, IA. Feb 15, 2018. 120 attendees.
Carlson, S. “Keep Your Farmer Customers Happy With Better Cover Crop Recommendations.” Ag Industry & Crop Management Conference, Agribusiness Association of Iowa. Des Moines, IA. Feb 13, 2018. 45 attendees.
Plastina, A., Miguez, F., Liu, F., Sawadgo, W., Carlson, S., and G. Marcillo. “How do cover crops affect whole farm profitability?” Practical Farmers of Iowa Annual Conference. Ames, IA. Jan 18, 2018. 80 attendees.
Carlson, S. "Economics of Cover Crops." Pisces Foundation Water Quality Funders Meeting. Washington, DC. Jan-11, 2018. 12 attendees.
Plastina, A., Miguez, F., Liu, F., Sawadgo, W., Carlson, S., and G. Marcillo. “How do cover crops affect whole farm profitability?” Integrated Crop Management Conference, Iowa State University Extension and Outreach. Ames, IA. Nov 29, 2017. 268 attendees.
Gailans, S. “Soil fertility and nitrogen dynamics with a rye cover crop.” Crop Advantage Series, Iowa State University. Iowa City, IA. Jan 25, 2017. 50 attendees.
Gailans, S. “Results from on-farm cover crop research projects and ideas for maximizing cover crop benefits.” Iowa Learning Farms Cover Crop Workshop. Oakland, IA. Dec 13, 2017. 40 attendees.
Plastina, A. “Economic Evaluation of Cover Crops in Midwest Row Crop Farming.” USDA/NASS Upper Midwest Office. Des Moines, IA. Feb 27, 2017. 20 attendees.

Presentations at Professional Meetings (* indicates presenter):

Marcillo, G. (*), and F. Miguez. 2017. "Towards sustainability in maize systems: A modeling evaluation of cover crops on US maize production." Selected Paper for XXII Latin American Maize Conference (XXII Reunión Latinoamericana de Maíz). Quevedo, Ecuador. September 27-29.
Plastina, A. (*), Liu, F., Sawadgo, W., Miguez, F., and S. Carlson. 2017. "Partial budgets for cover crops in Midwest row crop farming." Conservation Infrastructure (CI) - Cover Crops Working Group. Iowa Farm Bureau Federation - West Des Moines. August 4. Available at: https://www.card.iastate.edu/products/presentations/files/cover_crop_economics_-_plastina.pdf
Plastina, A. and F. Liu (*). 2016. “Comprehensive Partial Budgets for Cover crops in Midwest Row Crop Agriculture.” Selected Poster, Agricultural and Applied Economics Association and West & Western Agricultural Economics Association Joint Annual Meeting. Boston, MA. July 30 - Aug 2.
Plastina, A., Miguez (*), F., Carlson, S., and F. Liu. 2016. “Economic Evaluation of Cover Crops in Midwest Row Crop Farming.” Invited Presentation, SARE Advisory Committee. Ames, IA. June 24.

Educational Tools:

Edwards, W., and A. Plastina. Economics of Cover Crops: Projected Costs and Returns without Grazing. Decision Tool to be published in Ag Decision Maker Website and linked from Practical Farmers of Iowa's website.

Press articles:

Plastina, A. “Figuring cost vs. return for cover crops.” Wallaces Farmer, Timely Tips Section. Feb 27, 2018. http://www.wallacesfarmer.com/management/figuring-cost-vs-return-cover-crops
Alisha Bower. “Cover Crop Economics Survey: Participate Today!” Practical Farmers Blog. February 14, 2017. http://practicalfarmers.org/blog/2017/02/14/participate-today-cover-crop-economics-survey/
Alisha Bower. “Making cover crop mixes pay off.” Wallaces Farmer. Mar 20, 2017. http://www.wallacesfarmer.com/cover-crops/making-cover-crop-mixes-pay
Alisha Bower. “Weed suppression and cover crops finding the facts.” Wallaces Farmer. Feb 16, 2017. http://www.wallacesfarmer.com/cover-crops/weed-suppression-and-cover-crops-finding-facts

Peer Reviewed Publications:

Plastina, A., Liu, F., Miguez, F., and S. Carlson. 2018. “Partial budgets for cover crops in Midwest row crop farming.” Journal of the American Society of Farm Managers and Rural Appraisers (in press).
Plastina, A., Liu, F., Miguez, F., and S. Carlson. “Cover Crops Use in Midwestern U.S. Agriculture: Net Returns versus Perceived Benefits.” Renewable Agriculture and Food Systems. Under review.
Plastina, A., Liu, F., Sawadgo, W., Carlson, S., Miguez, F., and G. Marcillo. “Annual Net Returns to Cover Crops in Iowa” Journal of Applied Farm Economics. Under review.

Research Reports (Practical Farmers of Iowa conducted economic analyses in each of the following on-farm trials solely because of the results of the regional survey):

“RESEARCH REPORT: N Fertilizer Strategies for Corn Following Cover Crop.” Practical Farmers Blog. Stefan Gailans. November 20, 2017. http://www.practicalfarmers.org/blog/2017/11/20/research-report-n-fertilizer-strategies-corn-following-cover-crop/
“Winter Cereal Rye Cover Crop Effect on Cash Crop Yield, Year 9.” Practical Farmers Blog. Stefan Gailans. November 30, 2017. http://www.practicalfarmers.org/blog/2017/11/30/winter-cereal-rye-cover-crop-effect-cash-crop-yield-year-9/
“RESEARCH REPORT: Roll-Crimping Cover Crops and Soybean Seeding Date.” Practical Farmers Blog. Stefan Gailans. December 4, 2017. http://www.practicalfarmers.org/blog/2017/12/04/research-report-roll-crimping-cover-crops-soybean-seeding-date/

133 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Key areas taught:

economic evaluation of cover crops
cover crop/livestock integration
enterprise diversification

Key practices changed:

2 Grants applied for that built upon this project

2 Grants received that built upon this project

Success stories:

Follow up evaluation surveys were conducted among viewers of our two farminars:

87.5% reported a moderate to large change in knowledge.
37.5% reported they will make a change in production practices (62.5% reported N/A, 0% said "no").
Comments included "Will add some diversity to my fall seeded cover crops that I use for grazing and will plant as early as I can;" and " I'll add oats as late summer cover crop."

2. The Conservation Infrastructure Initiative recommended to the Iowa Department of Agriculture and Land Stewardship an evaluation of the funding for conservation practices, in particular an evaluation of cover crop adoption and cost share practices.

Economic Evaluation of Cover Crops in Midwest Row Crop Farming

Project Information

Introduction:

Cooperators

Research

Education

Project Activities

Educational & Outreach Activities

Participation Summary:

Learning Outcomes

Project Outcomes