Cover crops are plants grown primarily to benefit the soil rather than to harvest. Common cover crops include legumes (clover, vetch — add nitrogen), grasses (rye, oats — prevent erosion, add biomass), and brassicas (radish, mustard — break up compacted soil). Farmers plant them between cash crops or alongside them.
Cover cropping is central to regenerative and organic agriculture — the practice builds soil organic matter, reduces fertilizer needs, and protects against erosion. Industrial row-crop agriculture historically under-adopted cover cropping; it's a growing practice across scale.