Crop Residue Helps, but There's More to It for Controlling Soil Erosion

This series of five photos taken June 20, 2014 demonstrate the effectiveness of conservation measures, up to a certain point, for controlling loss of soil from crop fields.

Leaving crop residue on the soil's surface is a conservation practice that helps hold soil in place when rain drops strike the soil surface and residue also helps protect soil against erosion by wind and water erosion.

In these images, even with a little residue, there is water erosion. At some point the soil, slope length and slope steepness are too much for certain levels of residue to control erosion.

Photo 5 shows little signs of water erosion when the ground is covered by approximately 30 percent residue even though the slopes are 8 percent and 150 feet long.

Photos 3 and 4 show the same field and residue amounts but on a slightly steeper slope (about 10 percent and 150 feet long). Ephemeral gullies have started to form showing that 30 percent residue is not enough to control the water erosion. Alternative conservation practices should be considered and would include increasing the amount of surface residue, using a no-till farming system, contour farming, terraces or other conservation practices.

Photos 1and 2 in the same field show deposition. Here, contour farming was used in addition to the 30 percent residue. However, the adjacent slope was much steeper (18 percent at 100 feet long). Sheet erosion transported valuable top soil from the slope and deposited it at the base creating sediment about 4-6 inches deep. A full set of conservation practices should be considered including no-till, nterraces, contour farming and a conservation crop rotation that includes high residue crops and perennial crops such as alfalfa.

Consider using a combination of conservation practices to provide better protection for cropland fields against wind and water erosion while maintaining or improving productivity.

To learn more, contact your local USDA Natural Resources Conservation Service (NRCS), or visit the Soil Health Information Center at the NRCS web site: www.nrcs.usda.gov/wps/portal/nrcs/main/national/soils/hea....

Photos by Mark Washechek, Resource Conservationist, Natural Resources Conservation Service, Brookings, SD.