Soil Conservation: Soil compaction
Steven Graber, Resource Soil Scientist
Soil compaction occurs on nearly every farm in the United States, with the results of compaction evident in crop growth. Recent research has shown that organic matter on the surface and within the soil is an important factor in reducing soil compaction. Low soil organic matter levels have been shown to make the soil more susceptible to soil compaction.
Organic residues on the soil surface are able to cushion the effects of soil compaction. Organic matter is able to be compressed, but retain its shape and structure even after the traffic has passed over it. This is unlike mineral soil aggregates, which tend to compress under the pressure of traffic.
Excessive traffic or tillage will break up organic matter and accelerate its decomposition. Organic residues in the soil profile may be even more important than residues on the surface. This is because organic matter attaches to soil particles and helps to keep the particles from compacting, maintaining soil tilth.
Soil compaction has a biological component, and research has shown that a root cause of soil compaction is a lack of actively growing plants and active roots in the soil. Plant roots create voids and macro pores in the soil for air and water movement. Plant roots also provide the food source for soil microbes and fauna. Finally, organic matter is lighter and less dense, and when mixed with mineral soil material, it helps to reduce the density of the mineral soil material.
Compacted soil is not easy to alleviate. Although subsoiling or chiseling can alleviate compaction immediately, the second pass by a single vehicle or implement may nullify the effort. The use of different strategies will be the best solution in solving the problem. Reducing tillage, controlling traffic, planting deep rooted cover crops, and increasing organic matter will all benefit the soil, improve soil quality, and increase crop production.
For assistance, please contact your local NRCS office or conservation district office located at your local county U.S. Department of Agriculture (USDA) Service Center, listed in the telephone book under “United States Government” or online at offices.usda.gov. More information is also available on the Kansas website at www.ks.nrcs.usda.gov. Follow us on Twitter @NRCS_Kansas.