Never leave soil bare. Once you have harvested your crop, sow a green manure. Mustard, phacelia, clover, etc. Mustard disinfects, clover fixes nitrogen. Dig them in before they get too big.
Great idea. Farmers use this technique to get nitrogen, etc back into the soil and to keep the weeds down. A great natural way to boost your soil. This is a great topic to do a whole page on - thanks for the idea Fran - Leah