Final Report for LS94-058
Project Information
[Note to online version: The report for this project includes tables that could not be included here. The regional SARE office will mail a hard copy of the entire report at your request. Just contact Southern SARE at (770) 412-4787 or sare@griffin.uga.edu]
The majority of contracts on 1.2 million acres of CRP lands in Oklahoma will expire in 1996, 1997, and 1998. A general lack of integrated management guidelines exists on how highly erodible lands (HEL) should be used for grazing livestock production or how to revert to annual cropping while meeting conservation compliance. Under USDA-ARS coordination, a collaborative project was conducted on two CRP fields under contract since 1987 and 1989. The project objectives were to assess, on the field-scale, environmentally sound grazing-crop options for highly erodible CRP lands. One study site is near Forgan, OK in a 450-mm precipitation zone of NW Oklahoma. The other is near Duke, OK in a 750-mm precipitation zone in the SW. Both sites were seeded to Old World bluestem (Bothriochlora ischaemum L.). Field-scale comparisons of management systems for OWB, conservation- and no-tillage wheat (Triticum aestivum L.), and conservation-tillage cotton (Gossypium hirsutum L.) production systems were made to evaluate the productivity and the optimal management of HEL after the CRP. Each of the project year, we implemented the grass and wheat recrop options in a new area of the CRP field and re-established the Year 1 (first established in 1994) and Year 2 (first established in 1995) treatments. This approach allowed us to assess the options' performance for the first time out of CRP grass and producing second and third-year crops under weather conditions of each year during the 1994-1997 period. Small-plot experiments were also conducted to evaluate herbicides and fertilizer requirements for killing the sod and preparing the fields for reverting CRP lands to crop production. Rainfall simulations were conducted to measure runoff and soil erosion characteristics the first year following conversion of CRP to winter wheat production during 1996. During the project, we found that:
1. CRP lands planted to OWB require improvements before they are used in hay or grazing livestock production. Greatest limitations are inadequate N, P, stand density, and forage quality. After the initial removal of the old growth, baseline unfertilized OWB production in 1994 averaged 3,200 and 3,600 kg/ha at Forgan and Duke, respectively. In 1995, an application of 67 kg N/ha resulted in no significant increase in forage production at Forgan. In contrast, the application of urea-N tripled OWB dry matter production over the unfertilized plots at Duke, equaling 81% of the biomass accumulated over the seven years that the field was enrolled in the CRP. In 1996, applications of 67 kg N and 22 kg P/ha resulted in an average 1.7-fold increase in OWB forage production at both locations. In 1997, OWB forage production tripled and quadrupled by improved management and fertilizers at Forgan and Duke, respectively. Therefore, management actions are needed at the end of the contract period to convert CRP fields into productive grasslands. Overall, minimal management action such as removing the dead grass litter in early spring stimulated forage production. Fertilizers enhanced production and forage quality for both stands. However, optimal use of OWB still depended upon a delicate balance between forage yield and peak nutritive value of the forage.
2. Our results showed the need to move back the time line that CRP landowner or operator would be permitted to work on the grass cover, if provisions for soil erosion control are in place. Timing of suppression of a warm-season grass is critical for conserving stored soil water that is vital to the success of producing a wheat crop in the year a CRP contract expires. Otherwise a year of production would be lost. In nutrient-depleted CRP fields, fertilization was necessary to achieve agronomic yields; unfertilized plots yielded only 34 and 60% of plots receiving 112 kg N/ha at Forgan and Duke, respectively. The amount of old dry matter removed and new regrowth is critical to how well we can perform reduced tillage, kill the growing cover, and establish a uniform crop stand. In 1994, dryland wheat yields averaged 890 and 1,660 kg/ha at Forgan and Duke, respectively. NT wheat yields were equal to or 21% higher than CT wheat at both CRP sites, because of higher soil water storage attained with surface residues and the absence of tillage. Without prior removal of old growth, MT and burial of the sod had highest wheat yields, followed by DT, and NT at both locations, due to uniform stand, higher plant density in the clean tilled surface. In 1995, wheat yields ranged from 190 to 880 kg/ha due to the extremely dry weather. NT was significantly better during the drought of 1995 when the crop was produced mainly from stored water and no significant rains fell between October 1995 and June 1996. In the third year, herbicide application and tillage (sweep and disk tillage) effectively control OWB. Early chemical suppression of OWB promoted early emergence and growth of wheat during 1996 and early 1997. However, night temperatures on April 12 and 13, 1997 dipped below -6 and -8 °C at Forgan and -4.5 and -6.8 °C at Duke, OK. Freeze damage was extensive for the Duke wheat crop that was in the grain-fill stage of development and had a yield potential in the 2800-3000 kg/ha range. The Forgan wheat crop was not as far along in development, in the early booting stage. That wheat crop partially recovered as excellent growing conditions existed following the cold spell. Final yields averaged 715 and 1045 kg/ha at Forgan and 580 and 910 kg/ha at Duke for conservation-till and no-till treatments, respectively. Overall, NT practices were more effective at conserving and utilizing stored soil water for crop production on former CRP fields and wheat yields were significantly higher than CT yields at both locations between 1994 and 1997.
3. Conversion to dryland cotton was not as successful as yields averaged 100 kg/ha due poor weather conditions that existed at planting and during boll setting stage in 1995. A 1996 crop was not planted due to the extremely dry conditions that prevailed at the site and throughout the region. In summary, climatic variability served as a constant reminder of the precarious environment and the high risk of agricultural production in the Great Plains while considering the conversion of CRP lands back to intensive cultivation of either summer- or winter-season crops.
4. No difference in cumulative runoff was found between grass and wheat treatments under simulated rainfall at an intensity of 65 mm/hour. Significant differences in surface cover existed between undisturbed CRP, grass regrowth after burning, conservation disk-tilled, and no-till wheat treatments at Duke, OK on June 13-18, 1996. Surface coverage values ranged from 42, 71, 79, and 100% on disk-tilled, no-till, and OWB regrowth, and undisturbed OWB treatments, respectively. The data suggested that conversion of this CRP site to winter wheat production using no-till and disk-till management practices did not enhance runoff or reduce water infiltration. However, soil loss in disk-tilled plots was 3 to 4 times greater than no-till wheat and OWB plots, averaging 210 kg/ha, compared to 58 kg/ha for no-till and OWB treatments. Although differences in soil erodibility existed, conversion to wheat production would not result in excessive erosion during the first year of production using the disk-tillage practices to destroy the sod.
5. Using regional custom rates, the total variable costs for the first year following conversion were 122 and 131 dollars per acre for conservation-till (CT) and no-till (NT) wheat production, respectively. Wheat breakeven price to cover these variable costs would be $2.50 and $2.76/bu at a yield goal of 35 bu/A for CT and NT, respectively. Potential income for grazing the wheat forage was not included and would reduce the total variable costs.
6. Outreach activities in 1995-1997 included field days at the study sites, producer metings, and technical conferences. The Duke tour was held on April 4, 1996 and the Forgan tour on April 11, 1996 to highlight crop growth under drought conditions and last year's research results. Field days were held at Duke, OK on April 11 and at Forgan, OK on April 17, 1997. These were the final tours to be organized at the study sites and attracted nearly 100 attendees from Oklahoma and Texas. The study results were focused on Old World bluestem grass management and wheat production options. The CRP study results were also presented at SARE Sustainable Agriculture Field Day at Tyrone, OK on August 20, 1997. The event attracted 250 producers and agricultural industry and agency personnel. A team of extension specialists from Colorado, Kansas, New Mexico, Oklahoma, and Texas conducted a series of day-long producer meetings to update CRP contract holders on proposed regulations and future land uses based on economic decisions from Sep 30 to October 10, 1996. A national technical CRP conference was organized in Amarillo, TX to elaborate on research results and post-contract management options on October 22-23, 1996. The program targeted the message to NRCS and ES personnel in the Central and Southern Great Plains. In the final year of the project, a major effort was focused on the technology transfer and extension of the R&D results to producers, action agency personnel, and the general public. Two major conferences were organized and held in conjunction with the All Oklahoma Chapter of the Soil and Water Conservation Society. The conferences titled "The Future of CRP in Oklahoma-Alternatives and Planning Options" were held in Altus and Woodward, OK on February 10-11, 1997. Over 200 producers, agency personnel, bankers, and businessmen attended.
Other outreach efforts were made to prepare publications and news articles for the local and regional farm press. Information from our studies was a major component of a 4-page insert in the Conservation Technology Information Center Partners newsletter. The insert "CRP: Converting to Cropland" offered practical assistance to growers who were planning to farm their CRP land in various region of the country. Two Production Technology information sheets also were prepared on the conversion of CRP to winter wheat production and livestock production on former CRP lands.
The objectives of the study were to:
1. Develop best management practices to prepare post-CRP grasslands for livestock grazing or haying.
2. Determine the productivity and economics of land management systems to revert successfully and environmentally soundly to winter wheat and cotton production on highly erodible lands.
Congress mandated the set-aside of approximately 36.5 million acres of erosion-prone croplands for 10 years to protect the soil resource base and the environment across the nation. The program was established in Title XII of the Food Security Act of 1985. Soon after its inception, the very nature of its merit, the program's implementation strategies, benefits and deficiencies, and its future have been extensively debated (Grazinglands Forum, 1988). While benefits of the CRP are many and include erosion control, enhanced wildlife, reduction in surplus commodities, and farm income support (Dicks, 1994), most often the program has been credited with substantial reduction in sediment discharges and airborne dust in many parts of the country (Margheim, 1994).
Results of surveys of CRP landowners' attitudes showed that a large portion of the 36.5 million acres enrolled in the program may revert to crop production (Novak et al., 1991). Contract holders will have to re-qualify under more restrictive environmental benefit indices of the CRP II or choose a future use for their CRP lands. Across the Great Plains, 39% of the enrolled acres may not meet the minimum erosion index or environmental benefit requirements of the proposed program. After the first signup under the re-authorized program, 1.019 million acres did not re-qualify in Texas or a net loss of 26% of re-bided lands. In Oklahoma, 427,370 acres of 838,382 acres submitted were accepted in signup No. 15, a 51% acceptance rate (Sanders, 1997).
For landowners who could not reenroll in the new CRP, they will decide whether to use or lease CRP grasslands for livestock production or revert to annual crop production. It is likely that land managers of the 400+ thousand acres this year will have to choose between maintaining the grass cover and use or lease the land for raising livestock or destroying the grass sod to revert to production and protect their wheat base. They will have to choose to remove or not remove the accumulated litter, plow under the sod, or no-till the first crop into killed grass. The effects of integrated residue management technologies for HEL on the long-term productivity of the land resource and their impact on water quality are not fully understood, particularly at the field or watershed level.
A lack of integrated management information exists on how best to farm HEL while meeting conservation compliance. The deficiency must be addressed to prevent resource degradation that is likely to recur once these HEL are returned to crop or forage production. Oklahoma has 1.2 million acres enrolled in the CRP. Forty percent of this acreage is in the panhandle and another 48% are in western counties along the Texas-Oklahoma border. Before CRP, much of this land was cropped annually to winter wheat. Cotton production is also important in SW Oklahoma. Sediments, airborne dust, and particulate-associated nutrient discharges are significant problems in the production of both crops. Residue management practices are effective in controlling soil erosion. In dry and semiarid regions, an advantage of residue management methods is the conservation of soil water for agronomic production (Unger and Wiese, 1979; Deibert et al., 1986; Wilhelm et al., 1989; Dao and Nguyen, 1989). Further research and development and field-scale demonstration of these alternative crop-livestock production systems are needed to document their sustainability and environmental impact. From 1994 to 1997, a collaborative multi-agency project was developed and implemented on two actual CRP fields under contract to evaluate environmentally sound livestock-crop production options for using highly erodible CRP lands in the post-contract period. The effects of integrated management technologies for highly erodible lands were evaluated to determine the optimal production capacity, soil erosion risks, and economics of specific land use options for the two study sites.
Research
State and federal researchers, USDA action agency personnel, and local producers in NW and SW Oklahoma have been working together for the past three years to develop sustainable post-contract options for CRP lands in NW and SW Oklahoma.
1. Field-scale evaluation of grazing and farming options for post-contract CRP lands.
Field studies were conducted on two CRP fields under contract since 1987 and 1989. One experimental site is in Beaver Co. near the town of Forgan, OK in a 450-mm precipitation zone of NW Oklahoma. The major soil is Dalhart fine sandy loam on a 1 to 3% slope (Table 1). The field was planted to OWB in 1989. In May 1994, controlled burning was used to remove the old grass growth on 10 hectares (25 A) to establish various land management treatments. In 1995, an additional 10-ha block was burned to re establish a similar set of treatments. In 1996 another 10- ha block was swathed and the hay baled because of a statewide "burning ban". Field plots measuring 50 m by 100 m were established to study the following land management options:
1. OWB, minimum management (no fertilizer following controlled burning)
2. OWB, optimum management (added fertilizer following controlled burning)
3. Conversion to wheat1: CT (sweep tillage), wheat forage and grain production
4. Conversion to wheat2: no-till, wheat forage and grain production
In March of 1994, 1995, and 1996, the OWB plots were mowed to remove last year's growth due to low dry matter production during the previous year. Half the grass plots were not fertilized and left to produce without any further management input. On the other half of grass plots, we applied 67 kg N/ha. Forage production and quality characteristics were determined by periodic sampling. Total dry matter accumulation was measured from replicated sampling in September.
Conservation tillage was performed by undercutting the existing sod with a 36-in wide V-blade in July 1994. The sweep cut and lifted approximately a 10-cm layer of sod and soil to dry and kill the OWB sod. No other tillage was subsequently performed during the summer.
In 1995, sweep tillage was performed in July, August and again in September, prior to planting because of significant regrowth of the sod and weeds. The OWB sod in the NT plots was sprayed with a mixture of glyphosate, ammonium sulfate and surfactant at the rate of 1.12 kg ai/ha of glyphosate in August (1994), and in June (1995) and a second time in September of both years before drilling wheat. In 1995, the first-year CT and NT plots were also re established after grain harvest. CT plots were sweep-tilled in July and in September. The OWB regrowth in NT plots were treated with 1.12 kg/ha of glyphosate in July and September and plots were planted back to wheat. A no-till drill was used to direct-seed the ST plots on Oct. 13, using “AgSeco 7805” wheat at the rate of 67 kg/ha. “Tomahawk” wheat was planted in these NT plots using a NT drill set at a 20-cm row spacing at the rate of 78 kg/ha. One hundred-twelve kg/ha of 18 46 0 fertilizer was placed in the seed row. Sixty-seven kg/ha of urea N was topdressed to all plots in March. Spring weed control and fertilization (67 kg urea-N/ha) were performed in March. Wheat forage yields were measured in replicated sampling of the plots. Grain yields were measured using a plot harvester and combine in June 1995 and 1996.
In May of 1996, a 10-ha block of undisturbed CRP grass was swathed and the hay baled to initiate Year3 grass and cropped treatments for the first time at Forgan, OK. Half the grass plots were not fertilized and left to produce without any further management input. On the other half of grass plots, we applied 67 kg N/ha. Previous years OWB plots (Year 1 and Year 2 ) were re-established and mowed to remove last year's growth in March. Total dry matter accumulation and crude protein concentration of the forage was measured from replicated sampling in July 1997. Conservation tillage was performed by undercutting the existing sod with a 36-in wide V-blade in July 1996. Sweep tillage was performed in August and again in September, prior to planting. The OWB sod in the NT plots was sprayed with a mixture of glyphosate, ammonium sulfate and surfactant at the rate of 1.12 kg ai/ha of glyphosate in June 1996 and a second time in September before drilling wheat. The first-year CT and NT plots and the second-year plots were also re established after grain harvest. CT plots were sweep-tilled in July and in September. Wheat stubbles in NT plots were treated with 1.12 kg/ha of glyphosate in July and September and plots were planted back to wheat. A no-till drill was used to direct-seed the ST and NT plots in October, using “Tomahawk” wheat at the rate of 78 kg/ha. A starter fertilizer (18 20 0 NPK) at the rate of 112 kg/ha was placed in the seed row. Sixty-seven kg/ha of urea N was topdressed to all plots in March. Spring weed control and fertilization (67 kg urea-N/ha) were performed in March. Wheat forage yields were measured in replicated sampling of the plots. Grain yields were measured using a plot harvester and combine in June 1997. Larry Hodges, a local producer-cooperator helped combine the remainder of the plots.
The second CRP site was in the subhumid SW near Duke, OK in a 750-mm precipitation zone. The major soil at the site is La Casa clay loam (Table 1). The field was under contract since 1987. After swathing the old growth, field plots (60 by 300 m and 30 m by 60 m) were established to evaluate:
1. OWB, minimum management (no added fertilizer)
2. OWB, optimum management (added fertilizer)
3. Conversion to wheat1: CT (disk tillage), wheat forage and grain production
4. Conversion to wheat2: no-till, wheat forage and grain production
5. Conversion to cotton: row (strip) tillage in killed wheat at Duke, OK.
The OWB old growth was swathed in early June 1994 because of the delay in the granting of contract exemption and land release by the FSA. The grass stand was regrowing actively and was too green for a controlled burning of the old litter. The Altus NRCS field office arranged for local producers/cooperators to help us in swathing and baling of the OWB hay, collecting about 197 large round bales from an area of 400 by 400 m. In 1995, controlled burning was conducted on OWB plots to remove last year's growth on April 5. Half the grass plots either were not fertilized and left to produce without any further management input or had 67 kg/ha of urea-N applied a week later. Biomass production and forage quality were determined by periodic sampling. Total dry matter accumulation was measured from replicated sampling in October. Thirty acres of the OWB old growth was swathed in early May 1996. New grass plots were measured in this cleared area of the CRP field. Half the grass plots either were not fertilized and left to produce without any further management input or had 67 kg/ha of urea-N applied a week later. Biomass production and forage quality were determined from replicated sampling in August.
In cropped plots, disking was performed to kill and partially incorporate the sod. Two to three trips were required to uproot the grass cover and partially smooth the soil surface. Dead clumps of OWB were still visible from the soil surface. The OWB regrowth in NT plots was sprayed with a mixture of glyphosate, ammonium sulfate, and surfactant at the rate of 1.12 kg ai/ha in June. 1994. Another application of the herbicide mixture was made on October before wheat planting. "Pioneer 2180" wheat was planted in the DT and NT plots using a NT drill set for 20-cm row spacing at the rate of 78 kg/ha. A starter fertilizer was applied in the seed row at the rate of 45 kg/ha of 18-46-0. Additional fertilizer was surface broadcasted before wheat planting to have a total of 100 kg N and 40 kg P2O5. In March, an application of chlorsulfuron (69 g/ha or 1/6 oz/acre) was made to control broadleaf weeds. Chlorpyrifos was applied by air to control greenbugs. Wheat forage and grain yields were measured in replicated subsampling of the plots during March. Grain yields were measured using a plot harvester and combine on June 14, 1995. In 1996, disk tillage (DT) was performed to kill and partially incorporate the sod. The OWB regrowth in NT plots was sprayed with a mixture of glyphosate, ammonium sulfate, and surfactant at the rate of 1.12 kg ai/ha in June 1996. Another disking or application of the herbicide mixture was made on October before wheat planting. “Pioneer 2180” wheat was planted in the DT and NT plots using a NT drill set for 20-cm row spacing at the rate of 78 kg/ha. A starter fertilizer was applied in the seed row at the rate of 45 kg/ha of 18-20-0. Additional fertilizer was surface broadcasted before wheat planting to have a total of 100 kg N and 40 kg P2O5. In March, an application of chlorsulfuron (69 g/ha or 1/6 oz/acre) was made to control broadleaf weeds. Chlorpyrifos was applied by air to control greenbugs. Wheat forage and grain yields were measured in replicated subsampling of the plots during March. Grain yields were measured using a plot harvester and combine in June 1997. Doug Lamford, a local producer helped combine the remainder of the plots.
2. Fertilizer requirements of winter wheat in re-cropping CRP fields.
Small field plots (6 by 8 m) were established at Forgan and Duke to evaluate the effects of nitrogen and phosphorus fertilizers and sources for winter wheat production in re-cropped CRP lands and the decomposition of the grass residues. An application of 1.12 kg/ha of glyphosate was made in mid June. Primary tillage treatments were MT, DT, and NT. Liquid fertilizer treatments were sprayed on the OWB biomass before tillage and included (I) 0 kg N/ha, (ii) 112 kg N/ha as 28% UAN, (iii) 112 kg N/ha and 56 kg P2O5/ha, and (iv) 112 kg N/ha as 34-0-0. The plots were seeded with "Tomahawk" wheat at the rate of 84 kg/ha. Visual ratings of wheat vigor and stand density were made periodically during the growing season. Grain yields were determined with a plot combine.
3. Runoff and Soil erodibility in OWB and wheat-cropped treatments
Duplicate rainfall simulation plots of 12 ft by 35 ft were established in four CRP treatments (undisturbed OWB, managed OWB, DT wheat, and NT wheat). A large format rainfall simulator was used to apply rainfall at the intensity of 6.5 mm/hour. A one-hour rainfall simulation was conducted at soil water contents found during June 13-18, 1996. A second one-hour application of simulated rain was conducted approximately 24 hour later to determine erosion characteristics under saturated soil conditions. Water discharges were determined using an HS flume and a water level recorder. Runoff samples were collected at 5-minute intervals for determining sediment concentrations from OWB treatments and CRP lands re-cropped to winter wheat.
4. Outreach activities
Active involvement of the state and federal action agency field offices in conducting the field research, and local agro-businesses and producers in carrying out selected field operations were actively sought to facilitate the technology transfer by diffusion during such interactions. Outreach efforts included field days at each location in the past three year. Technical conference and producers’ meetings were also conducted during the year to deliver project recommendations to producers, local, state and federal action agency personnel, soil and water industry professionals, regulators, and the general public. Outreach efforts also included publications and news articles for the local and national press.
1. OWB and crop productivity
The study showed that management actions are needed on CRP fields at the end of the contract period to convert these fields into productive grasslands. Greatest limitations are low nutrient levels, particularly nitrogen and phosphorus, forage quality, and concealed sparse stand. The overgrowth smothered and impeded development of new tillers. It prevented new seedlings from establishing in bare soil between existing crowns. In addition, the large accumulation of old dry matter lowered forage quality by diluting crude protein concentrations of new growth. Plant nutrient applications and weed control must be made to improve density and quality of the stand and optimize forage production. In 1995, an application of 67 kg N and 22 kg P/ha resulted in no significant increase in forage production at Forgan and a 2.9-fold increase at Duke. In 1996, OWB forage production increased an average 1.7-fold by improved management and fertilizers at both locations. In 1997, OWB forage production tripled and quadrupled by improved management and fertilizers at Forgan and Duke, respectively. At Forgan, unfertilized and fertilized OWB yielded 1686 (±161) and 4770 (±462) kg/ha, respectively. At Duke these OWB treatments yielded 3623 (±358) and 13781 (±735) kg/ha, respectively (Figure 2). Overall, minimal management action such as removing the dead grass litter in early spring stimulated forage production. Fertilizers enhanced production and forage quality for both stands. However, optimal use of OWB still depended upon a delicate balance between forage yield and peak nutritive value of the forage.
Our results showed the need to move back the time line that CRP landowner or operator would be permitted to work on the grass cover, if provisions for soil erosion control are in place. Early spring suppression of the grass will conserve stored water that is vital to the production of a cool-season crop in the Great Plains and save a year of production. NT wheat yields were significantly higher than CT yields at both locations as the management practice more effectively stored and conserved stored water for crop production. At Forgan, late tillage and suppression of OWB depleted stored soil water of CT plots in 1994. Higher profile moisture in NT plots resulted in a better stand, forage accumulation, and grain yield than in CT plots. At Duke, early chemical suppression of OWB helped emergence and growth of wheat. The crop grew better under the high residue NT system. CT and NT wheat yields averaged 24.1 and 26.3 bu/A, respectively. In an extremely dry 1995, crop yields were low, regardless of soil management methods at both locations. Wheat yields ranged from 3 to 14 bu/A. NT wheat was significantly better during the drought of 1995. The crop was produced mainly from stored water as no significant rains fell between October 1995 and June 1996. Applications of herbicides and tillage (sweep and disk tillage) effectively control OWB in 1997. Early OWB suppression with herbicides helped in rapid emergence and growth of wheat. However, night temperatures on April 12 and 13, 1997 dipped below -6 and -8 °C at Forgan and -4.5 and -6.8 °C at Duke, OK. Freeze damage was extensive for the Duke wheat crop that was in the grain-fill stage of development and had a yield potential in the 2800-3000 kg/ha range. The Forgan wheat crop was not as far along in development, in the early booting stage. That wheat crop partially recovered as excellent growing conditions existed following the cold spell. Final yields averaged 715 and 1045 kg/ha at Forgan and 580 and 910 kg/ha at Duke for conservation-till and no-till treatments, respectively (Table 2). NT wheat yields were significantly higher than CT yields, i.e. 46 to 57% higher at Forgan and Duke, respectively. Again, climatic factors clearly influenced the production capacity of these soils. Crop performance was severely affected by last year’s drought. A late spring freeze kept crop yields from being optimal this year.
Conversion to cotton was not as successful as dryland yields averaged 100 kg/ha in 1995. Poor weather conditions existed at planting and during boll setting stage. A 1996 crop was not planted due to the extremely dry conditions that prevailed at the site and throughout the region. Variability in weather conditions served as a constant reminder of the precarious environment and the high risk of agricultural production in the Great Plains for both warm- and cool-season crops.
Amendments of nitrogen and phosphorus fertilizers were essential for producing acceptable agronomic yields, regardless of tillage methods. In nutrient-depleted CRP fields, unfertilized plots yielded about 34% and 60% of fertilized plots in Forgan and Duke, respectively. Where the old grass growth was not removed before tillage, herbicide application, and planting, highest dryland wheat yields were attained with MT, averaging 1,320 and 1,871 kg/ha at Forgan and Duke, respectively. No significant difference in grain yield was observed between fertilizer sources.
2. Management and Soil susceptibility to erosion
No significant difference in cumulative runoff was found between grassed and wheat treatments (Table 3). The data suggested that conversion of this CRP site to winter wheat production using no-till and disk-till management practices did not enhance runoff or reduce water infiltration. Soil loss in disk-tilled plots was 3 to 4 times greater than no-till wheat and OWB plots, averaging 210 kg/ha, compared to 58 kg/ha for no-till and OWB treatments. Although differences in soil susceptibility to erosion were present, the conversion of CRP lands to wheat production would not result in excessive erosion during the first year of production in this region. Increasing relative risks were in the order of OWB = NT wheat production and highest with DT wheat production.
Educational & Outreach Activities
Participation Summary:
Dao, T.H., W.A. Berg, J.H. Stiegler, T.F. Peeper, J.C. Banks, M.E. Hodges, F. Schmedt, and K. Vaughn. 1995. Post-CRP land use options for Oklahoma HEL. p. 14-15 in Converting CRP lands to cropland and grazing: Conservation technologies for the transition. Soil Water Conserv. Soc., June 6-8, 1995 Lincoln, NE.
Medlin, C.R., T.F. Peeper, J.H. Stiegler, T.H. Dao, M.E. Hodges, J.B. Solie, and J.C. Banks.
Oklahoma post-CRP land management and sustainable production alternatives research and extension project. Proc. Southern Weed Sci. Soc. Vol. 48:248-249.
Stiegler, J.H., T.F. Peeper, and T.H. Dao. 1995. Post-CRP Land Management and sustainable Production Alternatives for Highly Erodible Lands. p. 97-99. In: Conservation Farming: A focus on water quality. Proc. Southern Conserv. Tillage Conf. For Sustainable Agric. , Jackson, MS, June 26-28, 1995
Dao, T.H., J.H. Stiegler, T.F. Peeper, J.C. Banks, and M.E. Hodges. 1995. Converting CRP
lands to cropping: Effects on selected soil properties. Agron. Abstracts p. 290.
Dao, T.H., W.A. Berg, J.H. Stiegler, T.F. Peeper, J.C. Banks, M.E. Hodges, F. Schmedt, and K. Vaughn. 1995. Post-CRP land use options for Oklahoma HEL. p. 14-15 in Converting CRP lands to cropland and grazing: Conservation technologies for the transition. Soil Water Conserv. Soc., June 6-8, 1995 Lincoln, NE.
Pigg, C. 1996. For grazing, crops B CRP land may require major renovations. SW Farm Press. February 15, 1996 issue.
Crummett, D. 1996. Look before you leap. . . out of CRP. Oklahoma Farmer-Stockman. February 1996 issue.
Stiegler, J., T.H. Dao, T.F. Peeper, J.C. Banks and M. Hodges. 1996. Winter wheat production on former crp lands in the Southern Great Plains. In: T.H. Dao (ed). Proc. Conf. Preparing for future CRP Land Use in the Central and Southern Great Plains. Oct.
22-23, 1996, Amarillo, TX.
Dao, T.H., J.H. Stiegler, T.F. Peeper, J.C. Banks, and F. Schmedt. 1996. Post CRP production Alternatives for Highly Erodible Lands in the Southern Great Plains. p. 130-138. In: T.H. Dao (ed). Proc. Conf. Preparing for future CRP Land Use in the Central and Southern Great Plains. Oct. 22-23, 1996, Amarillo, TX.
Schmedt, F. 1996. Economics of Post CRP wheat and sorghum production. p.186-191 In: T.H. Dao (ed). Proc. Conf. Preparing for future CRP Land Use in the Central and Southern Great Plains. Oct. 22-23, 1996, Amarillo, TX.
Gilley, J.E., J.W. Doran, and T.H. Dao. 1997. Runoff, erosion, and soil quality characteristics of a former CRP site in SW Oklahoma. Applied Engineering in Agric. 13(5) 617-622.
Stiegler, J.H., and T.H. Dao. 1997. Converting CRP lands to crop production: winter wheat. Oklahoma State University Production Technology 97-21. Vol 9 No 21:1-5.
Redmon, L, and J.H. Stiegler. 1997. Livestock production on land formerly enrolled in the CRP program. Oklahoma State University Production Technology 97-23. Vol 9 No 23:1-5.
As most CRP contracts will expire during the next three years beginning in 1996 landowners and operators must decide the future use of their lands. The educational component of the first year of the project was focused on informing producers, action agency personnel, and the public about the project area, and the studies being conducted at the two experimental sites.
A large field sign (5 by 6 ft) was erected at each location to draw attention to the project site (Picture 2). They also serve as an announcement to the public about the project and the involvement of many organizations including USDA-ARS, OSU, Noble Foundation, USDA-NRCS, and USDA-FSA. Field plans and preliminary data sheets were placed in a mail box erected next to the sign for use by anyone interested in the project. Hundreds of the copies have been removed.
Outreach activities included field days at both study sites, private talks with producers, land owners and operators, and extension workshops, and a national technical conference. In 1995-96, the Duke tour was held on April 4, 1996 and the Forgan tour on April 11, 1996 to highlight crop growth under drought conditions and 1996 research results. From Sep 30 to October 10, a team of extension specialists from Colorado, Kansas, New Mexico, Oklahoma, and Texas conducted a series of day-long producers’ meetings to update CRP contract holders on proposed regulations.
A technical conference entitled “Preparing for Future CRP Land Use in the Central and Southern Great Plains” was organized by the Project Coordinator in Amarillo, TX. The CRP conference provided a forum for the exchange of information and discussion of post-contract management options and the results from recent CRP research and demonstration projects conducted in the five-state area of the Central and Southern Great Plains. The conference was jointly sponsored by USDA-ARS, Texas Agricultural Extension Service, Texas A & M Agriculture Experiment Station, Soil & Water Conservation Society Golden Spread Chapter, Noble Foundation, USDA-Natural Resource Conservation Service, USDA-Farm Service Agency, and three professional societies (Society for Range Management, the Soil & Water Conservation Society, and the Soil Science Society of America). Twenty-eight speakers from Colorado, Kansas, Nebraska, New Mexico, Oklahoma, and Texas addressed concepts and practices for the optimal management of the grass cover for livestock production, the conversion to croplands, and the economic aspects of CRP extension and the alternative land uses. The Conference message was targeted to NRCS and ES personnel in the Central and Southern Great Plains. The participants came from a wide range of institutional organizations from six states and Washington, DC. Of the 150 attendees, there were farmers (11%), representatives from chemical and fertilizer industries (7%), Parks and Wildlife departments (7%), University (9%), private research foundations (2%), USDA-FSA (5%), USDA-NRCS (45%), and USDA-ARS (15%).
In the final year of the project, a major effort was focused on the technology transfer and extension of the R&D results to producers, action agency personnel, and the general public. Field days were held at Duke, OK on April 11 and at Forgan, OK on April 17. These were the final tours to be organized at the study sites and attracted nearly 100 attendees from Oklahoma and Texas. The study results were focused on Old World bluestem grass management and wheat production options. In 1997, field tours were organized at Duke, OK and Forgan OK on April 10 and April 17, 1997, respectively. Speakers addressed OWB grass management options, and recropping CRP lands. The OK State Conservation Board attended the Forgan activities along with about sixty Extension Service and USDA-NRCS field agents and producers. About forty attended the Duke event. Handouts were distributed for their use. The CRP study results were also presented at SARE Sustainable Agriculture Field Day at Tyrone, OK on August 20, 1997. The event attracted 250 producers and agricultural industry and agency personnel. Two conferences were organized and held in conjunction with the All Oklahoma Chapter of the Soil and Water Conservation Society. The conferences titled "The Future of CRP in Oklahoma-Alternatives and Planning Options" were held in Altus and Woodward, OK on February 10-11, 1997. Over 200 producers, agency personnel, bankers, and businessmen attended.
Technical publications and popular news articles were featured for regional and national farm press during the project. Information from our studies was a major component of a 4-page insert in the Conservation Technology Information Center Partners newsletter. The insert "CRP Converting to Cropland" offered practical assistance to growers who were planning to farm their CRP land. It has extensive nationwide distribution. Two Production Technology information sheets also were prepared. PT97-21 deals with conversion of CRP to winter wheat production. PT97-23 deals with livestock production on land formerly in CRP. Both were extensively distributed through Oklahoma county extension offices.
Project Outcomes
The CRP curtailed the degradation of 1.2 million acres of former OK croplands and the 4.5 million acres in adjoining Texas, as well as the 36.5 million acres of marginal lands across the US. Our research results showed that management action is needed at the end of the CRP contract to convert CRP grasslands into productive lands, regardless of future land use. Landowners or operators should be advised of the risks of the neglected conditions and nutrient depletion that currently exist on CRP lands. The results also showed that early spring suppression of the grass conserves stored water that is vital to the production of a cool-season crop in the Great Plains in the year the contract expires. That saves a full year of production for the owner or land operator.
The study also demonstrated that integrated conservation production practices will allow reverting to wheat production and would not result in excessive erosion of the soil resource the first year following conversion of highly-erodible CRP lands to row crop production. Management guidelines for HEL were suggested for developing conservation policy and regulation by land resource managers, regulators, and legislators.
Economic Analysis
The economics of post-CRP crop production were drawn for the Oklahoma panhandle, SW Kansas, and SW Oklahoma. Using custom rates, the total variable costs for the first year following conversion were 122 and 131 dollars per acre for conservation-till (CT) and no-till (NT) wheat production, respectively. Wheat breakeven price to cover these variable costs would be $3.50/bu and $3.86/bu at a yield goal of 25 bu/A for CT and NT, respectively. The breakeven price decreased to 2.50 and 2.76/bu at a yield goal of 35 bu/A for CT and NT, respectively. Potential income for grazing the wheat forage was not included and may reduce the total variable costs. A greater accumulation of wheat forage was produced with NT management than CT management and would narrow the gap between the total variable cost between the two management options.
Farmer Adoption
The project has generated further cooperation with the following entities:
1. USDA-ARS, Stillwater, OK. Study of the dynamics and movement of ground beetles from CRP grassland to re-cropped CRP fields. Research is in partial fulfillment of requirements of a PhD dissertation for F. Wade.
2. OSU-Agronomy, Stillwater, OK. Post-CRP land management and sustainable production alternatives. The research project will be in partial fulfillment of requirements of a M.S. thesis for C.R. Medlin.
3. OSU-Agronomy, Stillwater, OK. Study of changes in physical and chemical properties of CRP soils and re-cropped-CRP lands. The research project will be in partial fulfillment of requirements of a M.S. thesis for C. Modisaotsile.
4. Monsanto Company, Wichita, KS and Stillwater, OK. Study of the susceptibility of OWB to herbicide; effectiveness of time and doses of glyphosate in burn, mowed and intact stand of OWB.
5. USDA-ARS, Lincoln, NE. A study of the erodibility of CRP grassland and fields re-cropped to winter wheat was initiated during 1997. The research project resulted in a publication entitled A runoff, erosion, and soil quality characteristics of a former CRP site in SW Oklahoma”.
Areas needing additional study
Dao, T.H. 1993. Tillage and winter wheat residue management effects on soil water infiltration and storage. Soil Sci. Soc. Amer. J. 57:1586-1595.
Dao, T.H. 1996. Effects of tillage system and crop residues on surface compaction of a Paleustoll. Agron. J. 88:141-148.
Dao, T.H. 1996. Effects of tillage system and crop residues on CO2 evolution and carbon storage in a Paleustoll. Soil Sci. Soc. Am. J. 62(1)
Dao. T.H. and H.T. Nguyen. 1989. Growth response of cultivars to conservation tillage in a continuous wheat cropping system. Agron. J. 81:923-929.
Dick, M.R. 1994. Costs and benefits of the CRP. When the CRP contracts expire: The policy options. Conf. Proc. p. 39-45. Soil Water Conserv. Soc., Ankeny, IA.
Diebert, E.J., E. French, and B. Hoag. 1986. Water storage and use by spring wheat under conservation tillage and no-till in continuous and alternate crop-fallow systems in the northern Great Plains. J. Soil Water Conserv. 41:53-58.
Grazing lands Forum. 1988. Grazing Lands and the Conservation Reserve Program. Third Forum, October 11-13, 1988, Harpers Ferry, WV.
Knapp, A.K. and T.R. Seastedt. 1986. Detritus accumulation limits productivity of tallgrass prairie. Bioscience 36:662-668.
Margheim, G.A. 1994. Soil erosion and sediment control. When the CRP contracts expire: The policy options. Conf. Proc. p. 15-18. Soil Water Conserv. Soc., Ankeny, IA.
Novak, P.J., M. Schnepf, and R. Barnes. 1991. When the CRP contracts expire: A national survey of farm owners and operators who have enrolled in the Conservation Reserve. 80 p. Soil Water Conserv. Soc., Ankeny, IA.
Sanders, L.D. 1997. New CRP signup results suggest shift in focus. Agric. Policy Econ. Issues. Oklahoma State Univ. Vol. 13 (5) :1-4.
Schertz, D.L. 1995. Concerns for converting CRP to production. Post-CRP land use: information needed by action agencies. p. 2-3 in Converting CRP lands to cropland and grazing: Conservation technologies for the transition. Soil Water Cons. Soc., June 6-8, 1995 Lincoln, NE.
Unger, P.W. and A.F. Wiese. 1979. Managing irrigated winter wheat residues for water storage and subsequent dryland sorghum production. Soil Sci. Soc. Amer. J. 43:582-588.
Wilhelm, W.W. and H. Bouzerzour, and J.F. Power. 1989. Soil disturbance-residue management effect on winter wheat growth and yield. Agron. J. 81:581-588.
Information Products
- Economics of PostCRP Wheat and Sorghum Production (Conference/Presentation Material)
- Livestock Production On Land Formerly Enrolled In The CRP Program (Fact Sheet)
- PostCRP Land Management and Sustainable Production Alternatives for Highly Erodible Lands (Conference/Presentation Material)
- Runoff Erosion And Soil Quality Characteristics of a Former Conservation Reserve Program Site In Southwestern Oklahoma (Article/Newsletter/Blog)
- The Oklahoma CRP Project PostCRP Production Alternatives for Highly Erodible Lands in the Southern Great Plains (Conference Proceeding)
- Winter Wheat Production on Former CRP Lands in the Southern Great Plains (Conference Proceeding)
- Coverting CRP Land To Crop Production Winter Wheat (Fact Sheet)
- PostCRP landuse options for Oklahomas HEL (Conference/Presentation Material)