When we learned about organic farming in the 1980’s, the term “cover crop” was brand new in the language of farming here in Canada. Pioneered by organic farmers the use of cover crops is now catching on with conventional agriculture as a means to enrich the soil and prevent erosion. Cover crops are plantings that are intended primarily for soil improvement. Usually they are incorporated into the soil while the crop is green and growing. The tilling in of lush, green vegetation feeds the soil biology. Just like the livestock in our barns thrive on good feed, the livestock below the surface (earthworms, insects, microbes, etc) multiply and accelerate in their fertility building work when supplied with sufficient food. We used to plant just one or two species; oilseed radish or buckwheat or peas and oats, but the latest wisdom is that planting a wide variety of species together yields a greater benefit. This is no surprise as one of the basic rules of ecology is the principle of diversity. Nature abhors monoculture!
This planting (pic) includes buckwheat ( a traditional remedy for impoverished soil), tillage radish (aggressive tap root for breaking through compaction) forage peas (legume which pulls nitrogen from the air and fixes it in the soil), sorghum (corn-like but no cob - explosive growth) and forage oats. Weeds plant themselves and add to the salad. All this will be turned back into the soil in a few weeks, setting up ideal conditions for the next harvested crop.