Come spring, several weeks before I plan to plant each area, I’ll cut or mow or pull the grain and legume combination down, depending on which pair I used and where they’re located, then turn under the remains. It’s like composting in place, with the foliage and underlying root system decomposing to improve soil texture and fertility.
Cover crops can serve other purposes: Some specialized ones, like various Brassicas, can also provide not just biomass but other benefits including pest and disease control (more on that from Cornell). The subject is much wider than this simple explanation, but stated most simply:
Grasses (like rye, sorghum-sudangrass crosses, and wheat) add organic matter to the soil very effectively. Note that I don’t list buckwheat here, another great, fast-growing cover crop that bees love, too. That rhubarb and sorrel relative is not technically a grass or grain, though we think of it as such because of how we use it food-wise. Legumes (clovers, cow and field peas, vetch) with their inherent Nitrogen-fixing capability, provide Nitrogen effectively. Plus: you can even eat the leafy tips and blooms and young pods of field peas along the way, if you choose that one. Brassicas and Mustards (rapeseed or canola; radish; mustard) have proven effective against various Read more on awaytogarden.com