Winter cover crops such as black oats and winter legumes or a late summer second crop such as sorghum or pearl millet have secured the germination of spring planted crops such as soybeans and maize by providing adequate residue cover in the spring to protect the soil from the crusting impact of heavy rain. Soil compaction can be a severe limiting factor on soils high in low-activity clays. In areas with reasonable rainfall, such as Maringa, Brazil, a deep rooted winter cover crop such as black oats has made no-till soybeans and maize possible on these soils. In the U.S. cool wet springs have impacted germination and growth of no-till corn on poorly drained soils. The surface residue keeps the soil cool longer.
Many farmers continue to no-till soybeans but have returned to tillage for corn.
However, other persistent farmers have found a solution to this problem. They strip till and apply fertilizer in the fall and plant the corn into these narrow strips in the spring. The soil in these narrow strips warms up faster in the spring ensuring even germination and growth. Producers are also concerned about disease and weed management in no-till and this has been a major barrier to adoption in traditional wheat monoculture. The 1996 Farm Bill now allows freedom of crop choice.