Cover Crop
Also called: green manure
A cover crop is a plant grown primarily to protect and improve soil rather than for harvest. Common cover crops include winter rye, crimson clover, hairy vetch, and daikon radish. They reduce erosion, suppress weeds, add organic matter, fix nitrogen (if legume), and break pest cycles — typically planted in the off-season between cash crops.
How Cover Crop Works
Cover crops perform six agronomic functions: (1) erosion control by keeping roots in soil year-round, (2) nitrogen fixation when legume species like clover or vetch are used, (3) nutrient scavenging — deep-rooted species like rye or radish pull subsoil nutrients up into the topsoil, (4) weed suppression through competitive canopy, (5) organic matter addition as the residue decomposes, and (6) pest-cycle interruption by breaking crop-family continuity.
Three common patterns: (a) winter cover — rye or vetch planted in autumn after cash crop harvest, terminated before spring planting; (b) summer cover — buckwheat or sorghum-sudangrass for 60-90 days between spring and fall cash crops; (c) living mulch — low-growing species like white clover planted between rows of the cash crop.
Cover crops typically add €30–100/ha in direct costs (seed, planting, termination) but deliver €100–300/ha in benefits over 2–3 years: reduced fertilizer (nitrogen-fixing covers), reduced herbicide (weed suppression), higher cash-crop yields (improved soil structure), and erosion-prevention value. USDA NRCS funds a large share of cover-crop costs through EQIP and similar programs. Recent US adoption has risen from 3% of cropland in 2012 to 8% in 2022, reflecting strong ROI and policy support.
Sources
- USDA Census of Agriculture (2022). Cover crop adoption trends.
- SARE (2020). Cover Crops for Sustainable Crop Rotations.