This project was first conducted in Kansas (Kansas State Univ.) from 2011 to 2012, and then it was transferred to Nebraska (Univ. of Nebraska) in late December 2012 where it continued from 2013 to 2014. Our project goal was similar in both States. The project assessed the positive and negative impacts of crop residue removal on soil quality and crop production. The experiments in Kansas focused on wheat rotations, while those in Nebraska focused on continuous corn. In western Kansas, we selected six representative on-farm research sites under no-till management in summer 2011. At the six sites, we removed wheat straw at five different levels (0, 25, 50, 75, or 100%) in a randomized complete block design with four replications at each site. All research plots were 30 ft by 30 ft in size for a total of 120 plots (6 sites × 5 treatments × 4 replications). Soil samples were collected from each plot in fall 2011, spring 2012 and fall 2012 to assess soil properties and soil C and N. In this project, we focused more on wind erosion risks due to the prolonged drought conditions during the study period. Crop residue removal at >75% reduced soil dry aggregate size and aggregate stability, indicating that excessive residue removal increased the soil’s susceptibility to wind erosion. Due to the drought, crop yield was very low in 2012. Residue removal did not affect any other soil property. Among three crops (wheat, corn, and sorghum), wheat seemed to be the least affected by residue removal. Both sorghum and corn yield decreased with residue removal rates above 75%.
In Nebraska, we used three experiments of corn stover removal under no-till continuous corn. The first site (irrigated) was at Brule (west central Nebraska) established in 2009, while the second site (irrigated) was at Clay Center (south central Nebraska) established in 2010. We established a third site (rainfed) near Lincoln, Nebraska (Rogers Memorial Farm) in fall 2013 with five different levels of corn stover removal (0, 25, 50, 75, and 100%). The latter experiment was specifically designed to establish permissible levels of stover removal in the long term similar to the experiments in Kansas. We measured grain and biomass yields, soil organic C pools (total C, organic C, and particulate organic matter), and soil hydrologic, compaction, structural, and fertility parameters. In addition to the above soil and crop parameters, greenhouse gas (CO2, CH4, and N2O) fluxes were measured using the LICOR system. Results from the sites at Clay Center and Brule showed that corn stover removal at high rates (>60%) after 4 and 5 yr, respectively, increased wind erosion potential and altered the soil structural properties near the surface. At the Clay Center site, stover removal (>60%) reduced soil water holding capacity and reduced plant available water, indicating that high rates of corn stover removal can reduce water storage and availability for crops. Other soil properties were not affected. Grain yield and greenhouse gas fluxes were not affected by corn stover removal at any site. Our results in Nebraska indicate that corn stover removal at high rates (>60%) can adversely impact soil properties after 4 or 5 yr but not in the first few years.
Overall, the main finding from both studies in Kansas and Nebraska is that crop residue removal at high rates (>60%) increases risks of soil erosion but it may not negatively affect crop yields.
Crop residues are considered as a potential feedstock for cellulosic ethanol production by the energy industry to meet the 30×30 goal (30% replacement of fossil fuels by biofuel by the year 2030). Production of cellulosic ethanol from renewable energy sources is a plausible goal. However, the potential adverse effects of residue removal on crop production and soil and water resources have not been adequately scrutinized in the NCR and Kansas and Nebraska in particular. Indiscriminate removal of crop residues may reduce soil organic matter and nutrient pools, jeopardize the soil quality, and increase risks of non-point source pollution of waters. Most of all, it may reduce future crop yields. By increasing soil erosion, residue removal may accelerate losses of nutrients, thereby further reducing crop yields and jeopardizing sustainable use of soil and water resources.
In some ecosystems, it may be feasible to remove a portion of crop residues for ethanol production without adversely impacting the soil organic matter pools and soil quality, but, at this point, site-specific information on maximum permissible residue removal rates is not available in the NCR. Indeed, no information is available on the effects of removal of residue from irrigated and non-irrigated crop production systems in Kansas and Nebraska. Depending on the soil, removal of a fraction of total residue produced may be beneficial to improve seed germination, facilitate planting, and reduce pest infestations. Thus, this project assessed not only the negative but also the positive aspects of crop residue removal.
This regional project conducted across Kansas and Nebraska was timely because no study had previously assessed the impacts of a partial removal of residues nor attempted to study established permissible levels of residue removal for corn, wheat, and sorghum on a regional basis in the NCR and in Kansas and Nebraska in particular. This project was also unique because it was conducted under on-farm conditions in Kansas in addition to large-scale research plots in Nebraska. Our project’s approach for assessing crop residue removal impacts under both farmers’ fields and research plots provided a superior way to achieve our objectives over other studies because it integrated results from research plots with those from on-farm sites. This information is important to better discern the impacts that residue removal may have if residues are harvested.
The outcomes can directly benefit farmers, rural communities, extension personnel, soil conservationists, land managers, policy makers, and biofuel industry groups because the project generated timely information needed to develop decision support systems. Information collected can be particularly useful to energy entrepreneurs involved in the emerging cellulosic ethanol industry. This project addressed a relevant topic in a time when there is an intensified national interest in using crop residues for producing cellulosic ethanol as well as livestock production.
Short-term Outcomes (1-2 years)
- Gain knowledge of the rapid positive or negative impacts of crop residue removal on soil and crop production. Specifically, farmers and other end users (extension personnel and biofuel industry groups) would learn/understand whether or not crop residue removal: 1) reduces grain and biomass yields, deteriorates soil quality, and reduces soil organic matter, and nutrient pools.
- Determine the preliminary threshold levels of crop residue removal based on the short-term data on residue removal impacts.
- Develop reports (e.g., journal and extension articles and conference papers) based on the short-term data and hold field days for impact evaluations.
Medium-term Outcomes (3 years)
- Determine the soil and crop response to crop residue removal by generating 3-yr data on soil hydrologic, compaction, structural, and fertility parameters as well as crop yields (grain and biomass). These data can provide a better understanding of crop residue removal impacts compared with the short-term (
- Establish the threshold levels of crop residue removal.
- Share the threshold levels of crop residue removal with farmers, extension personnel, biofuel industry groups, scientific community, and others through field days, conferences, project reports, and extension and journal articles.
- Influence the decision making process of the farmers about crop residue management through field days and publications.
As indicated earlier, this project was first conducted in Kansas and then in Nebraska. The initial and revised project proposals described in detail the Methods and Materials, so here we provide only a brief description of Methods used in both States.
Site Descriptions in Kansas
The project in Kansas was conducted simultaneously on 6 on-farm sites. The 6 on-farm sites were established in western Kansas in summer 2011 (Fig. 1). The treatments consisted of removing crop residues after harvest at five different levels (0, 25, 50, 75, and 100% of residue produced). Three crops (wheat, sorghum, and corn), which are main candidates as biofuel, were studied. The cropping systems included wheat-wheat-sorghum, wheat-corn-fallow, wheat-corn-wheat, wheat-sorghum, and wheat-sorghum-sorghum managed under no-till. Cropping systems that are common to each study site distributed in western Kansas were selected. The treatments were arranged in a completely randomized block design experiment with four replicates. A total of 20 plots (5 residue levels × 4 replicates) with dimensions of 30 ft by 30 ft were laid out. Six no-till farmers with a strong interest in the goals of this project were identified for each study site. Within each farmer’s field, 20 plots (30 ft by 30 ft) were laid out. Each farmer used the typical farming operations in the whole field. After harvest, the standing stalks or stubble in each plot were cut using a forage harvester at the five levels (0, 25, 50, 75, and 100% of residue height). All the six sites were planted to wheat before we started the experiment. Wheat was harvested at each site in June, 2011 prior to the initiation of the experiment. Details of management history for each site were reported in the Annual Report for 2011 and 2012.
Site Descriptions in Nebraska
The corn stover removal project was conducted simultaneously on 3 sites in Nebraska comprising 2 existing field-scale experiments and 1 (new) plot-scale experiment (Fig. 2) under dryland and irrigated conditions. The two field-scale experiments were established at Brule in 2009 and Clay Center in 2010, while the plot-scale experiment was established in fall 2013. All the three research sites are managed by the University of Nebraska-Lincoln (UNL).
First Large-Scale Experiment
A corn stover removal study located at UNL’s South Central Agricultural Field near Clay Center, Nebraska and established in 2010 was used (Fig. 2). The experimental field is about 12 acres (1060 ft by 510 ft). The treatments include two levels of corn stover removal, irrigation, and N fertilization, and three levels of organic C input and are laid out in a completely randomized split-split-split block with four replications. The main plots are 100% ET irrigation and 60% ET irrigation. The first split includes three treatments: winter cover crop, manure application, and control (no manure/cover crop). The second split involves stover removal at 85% and no stover removal. The third split consists of N fertilizer levels: 125 and 200 kg N ha-1. This is a no-till continuous corn experiment managed under irrigated conditions. No detailed data on soils had been collected from this experiment prior to our project.
Second Large-Scale Experiment
A corn stover removal experiment established near Brule, Nebraska in 2009 was used (Fig. 2). This experiment belongs to the UNL’s West Central Research and Extension Center at North Platte. This is another large-scale experiment and reflects the conditions of farmer’s fields. The experimental field is 126 ac of no-till continuous corn managed under full center pivot. The treatments are 1) no stover removal, 2) light grazing, 3) heavy grazing, and 4) stover removal by baling and are replicated twice. No detailed data on soils had been collected from this experiment prior to our project.
New Plot-Scale Experiment
The new experiment of corn stover removal was established at the UNL’s Rogers Memorial Farm near Lincoln in eastern NE (Fig. 2). This experiment was established in fall 2013 and consisted of removing corn stover after harvest at five different levels (0, 25, 50, 75, and 100%) after each harvest from dryland continuous corn under no-till. The treatments were arranged in a completely randomized block design experiment with four replicates. A total of 20 plots (5 stover levels × 4 replicates) with dimensions of 30 ft by 30 ft were laid out for this study. This experiment with five rates of stover removal is unique because it was designed to determine the amount of stover that can be safely removed without affecting soil and crop yields in major corn production areas in the western Corn Belt.
Assessment of Crop Production: Kansas and Nebraska
Grain and biomass yields were harvested and measured for each site and plot. Residue produced was baled at Brule and Clay Center sites after harvest. Residue produced at the Roger Memorial Farm site was distributed in each plot manually at corresponding levels (0, 25, 50, 75, and 100%) after harvest.
Assessment of Soil Quality: Kansas and Nebraska
Soil Properties: Impacts of the different scenarios of crop residue management on soil properties were assessed by monitoring changes in soil quality indicators including physical and chemical parameters for all sites. At each site, soil structural and compaction were monitored using standard methods. Soil water retention capacity and plant available water as a difference between water contents at field capacity and wilting point were determined on soil cores for the upper 0 to 8 inch depth. Soil aggregate stability was determined. Soil chemical properties such as pH, electrical conductivity, available phosphorus, and exchangeable potassium, calcium and magnesium, and micronutrients were measured.
Wind Erosion Potential: Soil samples were collected in 2011 and 2012 in Kansas and in spring 2013 and 2014 in Nebraska. Surface soil (0- to 2-inch) was collected from each plot for aggregate size distribution test by rotary sieve. Shovel was used to collect the surface soil. No less than 5 lb undisturbed sample was collected from each plot. All soil samples were dried at 56? for at least 72 hours. After passing through the rotary sieve, soil aggregates were classified into 7 groups (<0.42, 0.42-0.8, 0.84-2, 2-6.35, 6.35-14.05, 14.05-44.4, and >44.45 mm). Wind-erodible fraction (EF) was computed as:
EF= (Ma/Mt) x 100
where EF is the erodible fraction (%), Ma is the weight (g) of aggregates with diameter less than 0.84 mm, and Mt is the initial weight (g) of total sample.
Thirty aggregates from each plot were used for aggregate strength test by crushing method. Aggregates were pre-sieved at the time of field sampling. Then, aggregates were air dried for about 1 week in the greenhouse before the test. Pin meter was used to determine soil surface roughness. One digital picture was taken from center of each research plot. Pictures were analyzed using SigmaScan Pro 5 to assess soil roughness.
Soil Organic Matter Pools and Greenhouse Gas Emissions: The crop removal-induced changes in soil organic matter pools and its dynamics were assessed by measuring the concentrations of total soil organic C and stable and labile organic C fractions. The total C and total N concentrations of the soil samples were determined by the dry combustion method using a CN analyzer at all sites. Particulate organic matter was also determined for the experiments in Nebraska. Fluxes of CO2, CH4, and N2O were measured at two experimental sites (UNL’s Rogers Memorial Farm and Water Resources Lab near Brule). Fluxes of CO2 were measured using the automated CO2 flux system (LI-8100A-S2). Funding was provided by SARE to purchase this automated LICOR system. This equipment allowed the collection of more accurate data than the traditional or chamber method. Soil gas samples (about 50 ml) of the chamber headspace of the LICOR system were withdrawn during the CO2 measurements for the determination of fluxes of CH4 and N2O. Fluxes of CH4 and N2O were measured using a gas chromatograph. Soil water content, soil temperature, air-filled porosity, and other soil parameters were measured at the time of gas sampling with a TDR soil moisture meter and a digital thermometer.
KANSAS STATE UNIVERSITY
Figure 3 shows the results of the wind erodible fraction under different crop residue removal levels in fall 2011 and spring 2012 at each site. To observe the effects of freeze-thaw cycles, data from both fall 2011 and spring 2012 are shown in Fig. 3. In general, wind erodible fraction increased with increasing crop residue removal levels in spring 2012. Residue removal at rates above 75% increased wind erodible fraction. In fall 2011, two out of the six sites showed significant differences in wind erodible fraction. However, in 2012 spring, five out of the six sites showed significant differences, indicating that residue removal effects were greater in spring 2012 due to longer duration of the experiments (Fig. 3).
The freeze-thaw period during the winter may have also accelerated the soil’ susceptibility to wind erosion in spring time. In the study region, wind erosion is high during winter and early spring when winds are strong and there is limited soil surface cover. In fall 2011 (four months after experiment establishment), soil aggregate stability did not differ among residue removal treatments at any site, but in spring 2012 (eight months after experiment establishment), aggregate stability showed a decreasing trend with increasing residue removal rates at five sites. Removal rates above 75% appeared to have the largest adverse effects on dry aggregate stability. The greater the soil aggregate stability, the less susceptible the soil is to wind erosion. Aggregates with low stability tend to rapidly break into smaller aggregates. Plots with little or no residue cover develop crusts, which may temporarily reduce wind erosion. However, crusts can reduce seed germination and reduce plant growth. High rates of residue removal tended to reduce soil roughness, which can make soil susceptible to erosion.
Total C and N Concentration
Soil samples for total C and N were collected in spring 2012. The effect of residue removal on total C and N was not significant in five out of the six sites. The total C content, however, decreased significantly at the site near Rush Center with 100% residue removal. There were no significant differences in total N concentration among treatments at any site. Results show that effects of residue removal on soil C and N may not be measurable in the short term.
In 2012, two sites (La Crosse and Rush Center) were planted to wheat (Fig. 4). At these two sites, there were no significant differences in wheat yield among residue removal treatments. Similarly, two sites (La Crosse and Scott City) were planted to sorghum in 2012. The site at La Crosse was double cropped. Due to the extreme dry weather in 2012, there was no grain production at both sites. However, sorghum residue production decreased with an increase in residue removal rate, particularly at the Scott City site (Fig. 4). The biomass yield under 100% removal plots at Scott City was practically zero. Corn was planted at the sites near Colby and Norcatur in 2012. The biomass and grain yield are shown in Fig. 4. At Colby, both grain yield and biomass decreased with increasing residue removal rates. Residue removal rates above 75% had significant negative impacts on corn yield. At the site near Norcatur, residue removal effects were also significant. The effect of residue removal on crop yield depended on cropping system. Residue removal appeared to affect sorghum and corn more than it did wheat.
UNIVERSITY OF NEBRASKA
Assessment of Soil Physical Quality
In spring 2013 and 2014, soil samples were collected from the three experiments (Fig. 2). At each site, soil samples were collected to assess structural, compaction, and hydraulic parameters using standard methods. Laboratory determinations included soil bulk density, wet aggregate stability, and water retention capacity. Plant available water as a difference between field capacity and wilting point were computed.
At Brule, residue baling and grazing tended to reduce soil water storage (Fig. 5A). In 2013, baling and grazing also tended to reduce soil aggregate stability (Fig. 5B) and increase amount of wind erodible fraction (aggregates less than 0.84 mm in diameter) as discussed earlier in the annual report for 2013. The differences in soil aggregate stability and wind erodible fraction between baled and non-baled plots were not statistically significant in 2013. The large variability in data on aggregate stability and wind erodible fraction warranted a more intensive monitoring to discern spatial and temporal effects of residue baling and grazing at Brule.
In 2013, at Clay Center, data showed that residue removal (63% averaged across three years) reduced soil aggregate size and stability expressed as mean weight diameter of aggregates (Fig. 6). These results also showed that effects of removal were only significant in the 0 to 1 inch soil depth (Fig. 6A). Results thus indicate that residue removal at high rates may degrade soil structural properties near the soil surface (Fig. 6A) but not at deeper depths (Fig. 6B). Reduced aggregate size and stability near the soil surface may increase risks of water and wind erosion. Results in Fig. 6 also indicate that use of cover crop and manure may reduce the negative effects of residue removal on soil properties near the soil surface.
In 2014, at Brule, residue baling and grazing significantly increased wind erodible fraction (60%) should be avoided to reduce wind erosion potential.
Stover removal at Clay Center had significant and negative effects on soil water retention and plant available water (Table 1). It reduced water retention and plant available water in the 0 to 4 inch depth (Table 1). These results indicate that removing stover can reduce the ability of the soil to retain precipitation or irrigation water. Water retention is especially critical in this region with limited precipitation. Our findings suggest that stover removal at high rates (>60%) can have adverse effects on soil water storage and conservation. Soil bulk density and soil porosity were not, however, affected by stover removal at any of the sites.
Soil Organic C, Nutrients, and Greenhouse Gas Fluxes
We also determined soil organic C and nutrient concentrations for all sites for the near-surface layers (Figs. 8 and 9). In 2013, at Clay Center, residue removal reduced slightly soil organic C concentration near the soil surface, but addition of cover and manure offset the small residue removal effects (Fig. 8A). At Brule, residue baling and grazing had no effects on soil organic C, while baling tended to reduce soil organic C (Fig. 8B).
In 2014, at Clay Center, residue removal also reduced soil organic C concentration near the soil surface (0-2 inch; Table 2) similar to 2013. At Brule, residue baling and grazing had no effects on soil organic C and total N in 2014 similar to 2013 (Fig. 9). At Rogers Memorial Farm in Lincoln, there were no significant effects of stover removal on soil C and nutrients when stover was removed at 0, 25, 50, 75, and 100% after one year of stover removal.
We also measured greenhouse gas fluxes (CO2, CH4, and N2O) fluxes using the LICOR system at Brule and Rogers Memorial Farm (Lincoln; Table 2). Results showed that corn stover removal did not affect CO2, CH4, and N2O fluxes. Table 2 shows the CO2 and N2O fluxes by month and cumulative fluxes for 2014. These results suggest that stover removal may not increase or reduce CO2, CH4, and N2O fluxes under the conditions of this study. Nutrient concentrations did not differ among treatments, indicating that stover removal may not rapidly reduce soil essential nutrients in the short term. It is important to note, however, that significant amount of nutrients can be removed with crop residues, which deserves further consideration.
Corn grain and biomass yields were not affected by stover removal at any of the sites in Nebraska. Even after 3 and 4 years of stover removal Clay Center and Brule sites, respectively, stover removal did not reduce corn yields. Similarly, at Rogers Memorial Farm, the five stover removal rates (0, 25, 50, 75, and 100%) did not affect corn yields in the short term.
Establishment of Threshold Levels of Residue Removal
Data collected from this project can be used to suggest the maximum allowable levels of residue removal for Kansas and Nebraska by determining the rate of removal above which there are declines in crop yields, soil organic matter pools, and soil quality. Our results showed some negative effects of residue removal on crop yields in Kansas when residue was removed completely (100%). In Nebraska,we did not observe any reductions in corn yields after stover removal after 1, 4, and 5 years of stover removal. However, wind erosion potential was increased by high rates (>60%) of residue removal in both Kansas and Nebraska. Also, wet aggregate stability and soil organic C concentration was reduced near the surface layers at one of the sites in Nebraska after 60% stover removal. Based on these findings, we suggest that residue removal should not exceed 50% of residue produced if control of wind erosion and maintenance of soil organic C is important. In the short term, however, crop yields appear not to be affected even when 100% of residue is removed. Further monitoring of residue removal effects is needed to conclusively recommend and establish maximum allowable levels in this region.
- Residue removal and wind erosion
- Crop residue removal and crop yields in Kansas
- Residue baling and soil properties in Nebraska
- Residue removal and wet aggregate stability in Nebraska
- Residue removal and wind erosion in Nebraska
- Residue removal and soil carbon
- Residue removal and soil carbon and nitrogen
- Stover removal and soil properties measured in 2014 at the Clay Center site in Nebraska.
- Stover removal and greenhouse gas fluxes
This project funded by SARE had a high impact on farmers and livestock producers because we received very positive feedback during field days and through surveys conducted following the field days. Farmers and livestock producers in the region were very eager to learn more about uses of crop residues, particularly for livestock production. Our field days provided an opportunity to showcase our research data and practical application. The on-farm projects in Kansas and ongoing and large-scale experiments in Nebraska were fit to see firsthand the effects of crop residue removal on soil properties under real world conditions. The farmers and livestock producers who participated in field days and read our publications learned that excessive (>60%) crop residue removal can increase wind erosion. They participated and asked questions during field days, which showed their interest in the project outcomes. We shared with farmers and livestock producers that partial removal of residue (<50%) may be sustainable in the short or medium term
TALKS GIVEN TO FARMERS:
- Blanco, H., Annual West Central Crops & Water Field Day, UNL West Central Research Center, Brule, NE, “Corn Residue Baling and Grazing” (August 21, 2014). Attendees: 60 people (Farmers and livestock producers).
- Blanco, H., Sustainable use of corn residue by grazing cattle workshop, Brule, NE, “Crop residues and soil properties” (February 28, 2014). Attendees: 70 people (Farmers and livestock producers).
- Blanco, H., Sustainable use of corn residue by grazing cattle workshop, Elwood, NE “Corn residues and soil properties. (February 27, 2014). Attendees: 55 people (Farmers and livestock producers).
- Blanco, H., Research Symposium, Grand Island, NE “Crop residue removal and soil physical properties” (November 11, 2014). Attendees: 60 people (Farmers, livestock producers, soil conservationists, and crop consultants).
- Blanco, H., Extension presentation “Crop residue management” Mid Plains Beef Session. Mead, NE (December 16, 2013). Attendees: 40 people (Farmers and livestock producers).
- Blanco, H., Soils School. Title of presentation: “Crop residue removal and soil physical properties Grand Island, NE. (March 5, 2013). Attendees: 60 people (Farmers and livestock producers).
- Blanco, H., Field Day, Hays, KS. “Wheat and sorghum residue removal and effects on soil erosion” (August 11, 2011). Attendees: 90 people (Farmers and livestock producers).
TALKS GIVEN TO SOIL CONSERVATIONISTS, CROP CONSULTANTS, AND RESEARCHERS:
- He, Y., Blanco, H., Tatarko, J., Presley, D. R., 2014 ASA, CSSA, and SSSA Annual Meetings, Long Beach, CA, “Using sweep to simulate soil wind erosion under different crop residue removal levels”, (November 1, 2014). Attendees: 50 people (Soil conservationists, crop consultants, and researchers).
- He, Y., Blanco, H., Tatarko, J., Presley, D., 2013 ASA, CSSA, and SSSA Annual Meetings, ASA, CSSA, and SSSA, Tampa, FL, “Two-year on-farm study of crop residue removal on soil erodibility”, (November 4, 2013). Attendees: 45 people (Soil conservationists and researchers).
- Shaver, T., Stalker, L., van Donk, S., Blanco, H., ASA-CSSA-SSSA Annual Meetings, Tampa, FL, “Corn Residue Grazing and Baling Effects on Soil Compaction”, (November 4, 2013). Attendees: 50 people (Soil conservationists and researchers).
- Blanco, H., Shaver, T., van Donk, S., Stalker, L., Soil and Water Conservation Society, 68th International Annual Conference, Reno, NV, “Assessment of Soil Response to Corn Residue Baling and Grazing” (July 23, 2013 Attendees: 30 people (Soil conservationists, crop consultants, and researchers).
- Blanco, H., NC-1178 Meeting (Crop Residue Removal and Biofuels), Madison, WI, “Crop Residue Management in Nebraska” (June 4, 2013). Attendees: 20 people (Soil conservationists and researchers).
- Blanco, R.B. Ferguson, V.L. Jin, M.R. Schmer, and B. J. Wienhold. Using cover crops and animal manure to maintain or improve soil properties after corn stover removal. In 2013 ASA, CSSA, and SSSA Annual Meetings, Tampa, FL. Attendees: 40 people (Soil conservationists, crop consultants, and researchers).
- He, Yuxin, Humberto Blanco-Canqui, John Tatarko, Scott Staggenborg, and DeAnn Presley. 2012. Estimating crop residue removal effects on wind erosion using single-event wind erosion evaluation program (SWEEP). In: 2012 ASA, CSSA, and SSSA Annual Meetings, Cincinnati, OH. Attendees: 30 people (Soil conservationists and researchers).
- He, Yuxin, Humberto Blanco-Canqui, John Tatarko, Scott Staggenborg, and DeAnn Presley. 2012. On-farm assessment of crop residue removal impacts on soil wind erodibility parameters in the central Great Plains. In: 2012 ASA, CSSA, and SSSA Annual Meetings, Cincinnati, OH. Attendees: 25 people (Soil conservationists, crop consultants, and researchers).
Farmers and livestock producers who attended field days indicated that our project provided useful information. They showed interest in the presentations, asked questions, and gained information and knowledge about the implications of excessive crop residue removal. Farmers and livestock producers were particularly interested in learning more about excessive residue removal effects on soil water content and corn yields. Our data showed that crop residue removal at rates above 60% increased risks of wind erosion and reduced soil water content, but data also showed that crop yields were unaffected by crop residue removal. Our project provided database for decision-making processes.
While we do not have quantitative measures, farmers and livestock producers are more likely to adopt practices that reduce excessive residue removal (>60%) based on the information we shared during field days, handouts, and publications. Farmers and livestock producers are well aware of the need to conserve soil and water, but needed further knowledge and field research data to better understand the effects that crop residue removal may have on soil quality and crop production in the region. This project is also expected to have a broader impact not only on farmers but also on researchers and others through our published research articles and upcoming articles from this work.
Educational & Outreach Activities
- On-farm assessment of crop residue removal impacts on soil wind erodibility parameters in the central Great Plains (under preparation).
- Corn residue grazing and baling: Effects on soil compaction, wind erosion potential, and nitrogen cycling. Soil Science Society of America Journal (under review).
- Can cover crop and manure maintain soil properties after stover removal from irrigated no-till corn? 2013. Soil Science Society of America Journal. 78:1368-1377.
- Crop residue removal for bioenergy reduces soil C pools: How can we offset C losses? 2013. Bioenergy Research 6:358-371.
Yuxin He, a M.Sc. student, worked on the project in Kansas. His graduate assistantship was partially funded through this project. The title of this M.Sc. thesis was “On-farm assessment of crop residue removal impacts on soil properties and crop yields in the central Great Plains”
Areas needing additional study
There were some limitations and challenges with this project. First, short-term data (4 years to establish definitive threshold levels of residue removal. Changes in soil properties can be slow particularly in water-limited regions such as in Nebraska. Second, the unexpected and extended drought in 2012 possibly affected the treatment effects. In Kansas, crop yield in some sites was significantly reduced due to the drought in all treatments.
These limitations were considered during the interpretation of data, dissemination of results, and development of publications. Third, because of the PI move to Nebraska for job situations, we conducted this project first in Kansas for two years (2011-2012), and then in Nebraska for two years (2013-2014). This induced some discontinuity of measurements after 2012 for the experiments in Kansas. However, Yuxin He (graduate student at Kansas State Univ.) continued to monitor changes in soil properties and crop yields for the experiments in Kansas in order to complete his M.Sc. thesis.
We also believe that the PI move to Nebraska was beneficial to the overall project because it allowed to study crop residue removal effects for different regions in the central Great Plains. For example, the use of existing and new experiments in Nebraska allowed us to understand how corn stover removal affects soil and crop production and compare results with those obtained in Kansas. We learned a lot from this crop residue removal project in both States. The main finding was that excessive (>60%) residue removal in Kansas and Nebraska can affect particularly increase risks of wind erosion but may not affect crop yields for the duration of this project.
We extend our sincere thanks to NC-SARE for giving us this opportunity to assess how crop residue removal affects soils and crop production in Kansas and Nebraska. Thanks to this funding, we better understand the implications that crop residue removal may have on soils and crop production. The funding not only was essential to collect research data but also to share this information with farmers and livestock producers.