Using Conservation Tillage to Control Erosion
Fortunately, a key method of reducing soil erosion on cropland—conservation tillage—is generally well suited to southeastern Minnesota. If properly managed, conservation tillage can reduce average soil erosion by up to two-thirds. It often lets a farm maintain or enhance profitability through production cost savings. When combined with other common conservation practices—such as grassed waterways, buffers and contour planting—it can help to retard erosion even on the region’s steeper, longer slopes where erosion of unprotected cropland is severe. Generally, the conservation tillage benchmark of 30 percent surface residue after planting provides significant erosion control. This is easy to achieve following corn production, but can be a difficult target to attain for crops planted in soybean stubble. Somewhat less surface residue still gives substantial erosion control. Therefore, fields meet crop residue targets if they have greater than 30 percent residue following corn, and at least 15 percent residue cover following soybeans.
Reduced tillage risks and benefits
Many farmers are reluctant to farm with greater amounts of crop residues on their fields. They fear yield loss and don’t like the appearance of a crop growing in heavy residue. Their perception is influenced by several factors: 1) upsetting the landlord, business partner or a family member; 2) ridicule from neighbors; 3) lack of crop man-agement skills to adopt conservation tillage; 4) recent purchase of equipment for aggressive tillage; and 5) on-farm research results. Overcoming the aesthetics of crop emergence in a field covered with residue takes patience, time and an understanding of the system. Farmers who have used conservation tillage learn to appreciate the “look” of a crop growing in higher levels of residue and the lower cost of production.
When evaluating potential yield loss that may result from adopting a very high-residue system such as no-till, it is important that farmers compare differences in production costs as well as expected differences in yield to arrive at a sound business management decision. The following example is intended only for illustration. Each farm will have its own production costs and risks based on equipment, management skills, crop rotation and other farm-specific factors.
The risk associated with reduced tillage is most pronounced for no-till production of continuous corn. In the Karst region, over 40 site-years of field research with continuous corn show that the yield difference is only 2 to 6 percent lower for no-till compared to chisel plowing. Following is a brief comparison of average tillage costs for no-till and chisel-plow systems, which can be used as a guide to determine how much of the potential yield penalty from no-till may be offset by cost savings from reduced tillage trips.
All costs above include labor, fuel, maintenance and depreciation. Estimated costs based on William Lazarus, Minnesota Farm Machinery Economic Cost Estimates for 2000, University of Minnesota Extension Service, St. Paul.
The tillage cost difference in the example is $13.56/A in favor of no-till. Weed control costs and the remaining costs through harvest would be similar for both methods. Assuming a 170 bu/A corn yield at $2.00/bu, the farmer would gross $340.00/A. If yields were 4 percent lower for the no-till system, there would be no difference in dollars returned for the two systems; however, the no-till farmer would need less labor, have a reduced line of equipment to maintain and cause less soil erosion and compaction. This example demonstrates that unless the average yield penalty associated with no-till exceeds about seven bushels of corn per acre, no-till production may be more profitable than a chisel-plow system.