Date of this Version
Cooperative Extension Service Institute of Agriculture and Natural Resources, University of Nebraska, 1985.
The Importance of Conservation Tillage
Conservation tillage has been practiced for many years and is becoming increasingly popular with Nebraska farmers. Recent surveys show, about 8 of 19 million cropland acres in Nebraska were farmed with conservation tillage systems. Conservation tillage includes a variety of tillage and planting systems that leave at least 30 percent of the previous crop's residue on the soil surface after planting.
Knowing how to measure or estimate residue cover is an important facet of conservation tillage. A minimum requirement of cover on the soil surface is often specified for U.S. Department of Agriculture programs and some natural resources district's conservation tillage cost-sharing programs. Residue cover can also be an important component of a farm's overall soil and water conservation plan.
Research in Nebraska and other states shows that on fields with a 20 - 30 percent residue cover, soil erosion caused by water will be at least 50 percent less than comparable cleanly tilled fields. The greater the residue cover, the greater the erosion reduction will be. No-till systems, leaving the largest amount of residue cover, often reduce soil erosion by 90 to 95 percent. In comparison to conventional tillage methods, conservation tillage reduces erosion, saves fuel, labor, and soil moisture.
The percentage of soil surface covered with residue is important in determining how much erosion will occur from rainfall runoff. Rainfall, while essential for crop growth, dislodges soil particles from the surface, allowing them to be washed away. Crop residue shields the soil surface from raindrop impact, reducing soil particle detachment. Residue also creates "small dams" which slows the rate of runoff, allowing more time for water to infiltrate the soil. Slowing the runoff reduces the potential for soil erosion as the water flows over the surface.