Thursday, June 10, 2010
Converting Conservation Reserve Program (CRP) land to cropland
Thousands of CRP contracted acres will be expiring soon. Idaho growers will have to decide on the best course of action to take before converting CRP acres back into production. Conservationists with USDA’s Natural Resources Conservation Service (NRCS) provide the following options for growers to consider.
Primary issues when converting CRP land to cropland are how to effectively kill existing cover, conserve soil moisture, and maintain soil quality. Proper planning is essential and should consider:
• Maintain grass cover in critical erosion areas
• Continue with CRP buffer practices
• Remove existing cover effectively
• Crop rotation
• Tillage and planting systems
• Soil conditions limiting crop growth
• Nutrient management
• Conservation Compliance requirements on Highly Erodible Land
• Environmental quality impacts
To kill existing cover use a systemic herbicide, such as glyphosate along with other herbicides like Dicamba or 2-4-D. Maximize herbicide uptake by timing application to coincide with carbohydrate transfer to the root system. Haying, grazing or shredding to stimulate new shoot growth prior to applying the herbicide will improve effectiveness.
Consider soil moisture conditions when choosing to plant a fall or spring crop and when applying herbicides. Drought stressed plants will not absorb or translocate the herbicide effectively.
When deciding what crop to plant on converted CRP land, consider profitability, protecting or enhancing soil quality, controlling soil erosion, managing pests and effectively using available soil water.
Tillage System Selection
When converting grassland to cropland, no-till systems maintain the soil quality improvements gained from years in CRP. Along with diverse crop rotation and minimal fallow periods, no-till systems effectively improve or maintain soil organic matter, aggregate stability, soil infiltration and available water holding capacity creating soil that is in better condition to grow plants over the long-term. Conventional tillage systems can destroy soil quality improvements gained under CRP in just the first year.
Soils in long-term CRP cover can be different than regularly cropped soils. Complete soil tests to determine fertility before returning fields to production, allowing time to schedule and apply fertilizer. If soil test phosphorus levels are low, apply starter fertilizer at planting. With heavy residue, soil micro-organisms may temporarily tie up nitrogen; increase nitrogen by 10% over recommended rates to compensate. Think about a legume cover or forage crop to improve the transition to the first cash crop. Legumes fix atmospheric nitrogen and have a low C:N ratio which helps decompose remaining sod residue and provides nitrogen, creating an easier transition to the following crop.
Soil Erosion and Highly Erodible Land
Depending on the cropping system, soil erosion rates can increase significantly when Highly Erodible Land (HEL) is cropped compared to land maintained in sod. The Conservation Compliance (HEL) provisions of the Food Security Act require USDA program participants who produce annual agricultural commodities on HEL fields to apply an approved conservation system on those fields. The conservation system applied must control wind, water and gully erosion and prevent off-site damages to be considered acceptable. Contact your local NRCS office for erosion estimates and alternatives for different cropping/tillage systems.
Impacts on Environmental Quality
Land enrolled in CRP benefits soil erosion, soil quality, water quality, air quality and wildlife habitat through establishing grasses, legumes, trees and shrubs. Consider the impacts to these resources as you decide whether and how to transition CRP acres back to crop production.
For additional information contact: Marlon Winger, State Agronomist for NRCS Idaho, 208-378-5730
Deb Nace, District Conservationist, Idaho Falls, 208-522-6250, ext. 108