By Sjoerd Willem Duiker
Cover crops are an essential component of soil management. Cover crops provide diversity in the landscape, protect soil from erosion, reduce runoff, increase infiltration, recycle nutrients, fix atmospheric nitrogen, assist with weed control and improve soil organic matter content as well as provide emergency forage. At this time, you have many cover crop species options (Table 1).
You can still plant legumes that fix nitrogen, such as: hairy vetch, crimson clover, and Austrian peas. You can also plant brassicas, such as: radishes, rapeseed, and turnips that can fight compaction with their taproots and recycle large quantities of nutrients. Finally, you have a repertoire of grass-type cover crops, such as oats, annual ryegrass, barley, wheat, or rye.
These will quickly cover soil, help improve soil structure, fight weeds, and add large quantities of organic matter. Some species will winterkill (oats, radish) which is ideal prior to spring planted alfalfa, grass, or oats without need to apply herbicide at that time.Winter hardy species are recommended to plant prior to summer crops such as corn or soybeans.
Source : psu.edu