Compaction is caused by traveling on wet soil or by heavy equipment. In this century, pesticides and chemical fertilizers have revolutionized U.S. agriculture. In addition to their desired effects, they can harm non-target organisms and pollute water and air if they are mismanaged. Nutrients from organic sources also can become pollutants when misapplied or over-applied. Keeping the ground covered Bare soil is susceptible to wind and water erosion, and to drying and crusting.
Farmers often leave crop residue on the surface to cover the ground between growing seasons.
Living cover crops create new organic matter and help feed soil organisms. Groundcover must be managed to prevent problems with delayed soil warming in spring, diseases, and excessive build-up of phosphorus at the surface. Diversity is beneficial for several reasons. Each crop contributes a unique root structure and type of residue to the soil. A diversity of soil organisms helps control pest populations, and a diversity of cultural practices reduces weed and disease pressures.