How can farmers use cover crops to improve soil fertility?

Cover crops increase soil organic matter and improve soil fertility by capturing excess nutrients after harvest. They also increase soil moisture retention capacity, help prevent soil erosion, limit nutrient runoff, reduce soil compaction, and may even help to suppress some pests.

Farmers

can support these principles by using cover crops, which are conservation plantations for fast-growing annual plants, such as rye, clovers, peas and radishes. Cover crops protect and improve soil when a commercial crop isn't growing.

For summer staple crops, such as corn and soybeans, cover crops can keep the ground covered in fall, winter and early spring. They facilitate the use of direct tillage or other conservation tillage methods that alter the soil less and help control weeds. Plant diversity is useful for soil organisms because it provides them with a greater variety of food sources, and cover crops are an easy way to diversify crop rotation that would otherwise only grow one or two crops in a field. Adding cover crops to a rotation can greatly increase the part of the year in which there are living roots for soil organisms to feed on.

Cover crops can increase nutrient efficiency by reducing soil erosion (less soil organic matter and losses of soil nutrients in the upper soil layer). Cover crops remove residual nitrogen (N) and convert N into proteins (enzymes, hormones, amino acids). Nitrogen uptake depends on soil N, climate, cover crop species, seeding rate, and date of sowing and death. Crops that cover winter grass (cereal, rye, annual ryegrass) accumulate N in autumn and winter due to rapid root growth.

After the starting stage, there is not much additional N uptake in grasses. Legumes accumulate N for a longer time in spring, but with a high N content in the soil, the N fixation of legumes decreases. Use grasses or brassica species to absorb and recycle N if excess N comes from manure or fertilizer. Use legumes to supplement N for the next harvest if more N is needed for fertilization.

By keeping roots in the ground, cover crops break up the soil and prevent it from compacting. Roots hold the soil in place and help create an underground space that allows the soil to better absorb and store water, which is useful during both floods and droughts. Many commodity producers in the Corn Belt are adding a third cash crop to their rotation, usually a small grain, such as wheat, and then using the previous wheat crop to grow a more diverse mix of crops for several months. Cover crop residues, such as rye, can protect the soil while commercial crops are established and prevent it from getting too hot.

We also work with major food brands, foundations and farmer groups to promote the use of cover crops to improve soil health and reduce water runoff. While cover crops feed directly to bacteria and fungi, many other soil organisms feed on fungi and bacteria, including earthworms and arthropods (insects and small crustaceans, such as the “roly poly”). However, one alternative that can reduce the need for expensive fertilizers is to plant one of the cover crops, such as shaggy peas, clovers or peas, which are especially good at extracting nitrogen from the air and carrying it to the ground, to nourish the next round. Research has shown that cover crops (with the help of earthworms) help loosen compacted soil even more effectively than subsoil equipment, which consumes a lot of diesel fuel.

We work with families and children, farmers and business owners, community leaders and elected officials to build better lives, better businesses and better communities to make Ohio great. The slower release of N occurs more in dry climates than in humid years, due to the decrease in microbial activity needed to break down waste, and it has been suggested that the release of N volatilizes in cover crops that remain on the soil surface, but only small losses of NH3 have been demonstrated with zero tillage. In addition to improving soil health and cash crop yields, cover crops can add financial value to a farm, especially one with livestock. For more information on cover crops, visit the Midwest Cover Crops Council website or the OMAFRA Cover Crops website.

Only a small percentage of farmers actually plant cover crops because most farmers believe that the disadvantages outweigh the advantages. A pound of soil organic matter has the capacity to absorb 18 to 20 pounds of water, which is beneficial in a dry year. Overtillage destroys soil structure, while cover crops and the soil organisms they feed on create the glue (glomalin) that binds soil particles together, allowing better soil aggregation and a solid soil structure. In many fields that have some slope, half of the top layer of soil has already been lost since the days when they were first cultivated.

By reducing wind speed at ground level and slowing water velocity in runoff, cover crops greatly reduce wind and water erosion. .