Cover Cropping for Organic Agriculture

• Cover cropping is a key organic agriculture practice that must provide value, particularly in challenging economic conditions, by improving yield, reducing production costs, or maintaining soil.

Goals of Cover Cropping

• Leguminous cover crops supply nitrogen by fixing it from the atmosphere.
• Dense cover crops suppress weeds by outcompeting them.
• Cover crops improve soil structure, organic matter, and water infiltration.

Management Decisions

• Single-species cover crops are simpler to manage
• Multi-species mixes provide a wider range of benefits.
• Drilling ensures good seed-to-soil contact.
• Broadcasting is less precise but quicker.
• Early seeding maximizes growth.
• Late seeding is sometimes necessary after certain crops.
• Manure boosts cover crop growth.
• Harvesting or grazing can provide additional income.
• Termination includes tillage, herbicides (not in organic), or natural methods like frost.

Cover Cropping Practices

• Proven & Consistent practices provide tangible benefits in nitrogen supply, weed suppression, and soil maintenance.
• Proven practices work consistently under local soil and climate conditions.
• Proven practices do not compromise the following crop's productivity.
• fit cover crops into new parts of the crop rotation.
• Intermediate practices maximize cover crop growth
• Intermediate practices can result in greater overwinter soil cover.
• Emerging & Innovative practices may offset traditional weed control methods.
• Emerging & Innovative practices can accelerate soil improvement.
• Emerging & Innovative practices may generate added revenue.

Proven: Frost-Seeded Red Clover

• Used in clay loam soils.
• Single-cut red clover used at 8 lbs/acre, early April.
• Compost applied in fall before tillage.
• Terminated in fall by disk ripper.
• Provides nitrogen to corn.
• Improves soil tilth.
• Spring termination attempts with high-speed disk + cultivator were unsuccessful due to excessive residue.

Proven: Straight Oats After Wheat

• Used in clay loam soils.
• After straw harvest, beef manure is spread.
• Broadcast at 70 lbs/acre and cultivate + pack.
• Grazed by cattle or left to grow.
• Terminated in fall by plow.
• Followed by soybeans.
• Provides weed suppression (better than red clover).
• Allows additional grazing.
• Improves soil tilth ("like chocolate cake").
• Terminate oats before heading.
• Plowing is preferred over disking

Proven: 7-Way, Oat-Based Mix After Wheat

• Used in silt loam and clay loam soils.
• Wheat stubble disk-ripped; cover crop broadcast and incorporated with crumbler.
• Manure applied after cover well established.
• Terminated in fall by additional disk-ripping or plowing.
• Provides stand consistency.
• Allows for manure nutrient carryover.
• Improves soil tilth.
• More consistent stand compared to red clover
• Leaves minority of acres untilled until spring.

Manure and Cover Crops Together

• Manure feeds cover crops, resulting in greater growth.
• Manure applied to non-legume cover crops often gives earlier and greater nitrogen release.
• Manure aids reduce nitrogen tie-up.
• Applying manure before emergence or after cover crop is well established is often best
• Delaying cover crop seeding will reduce growth
• Select cover crop species/mixes more likely to use manure nutrients, hold onto them, and carry them forward to following crop

Intermediate: Inter-Seeded Cover Crop Into Corn

• Used in clay soils.
• Interseeder built with 3 rows between 30-in row spacing.
• Radish (0.5-1 lb/ac) and double-cut red clover (5 lbs/ac).
• Corn yield range: 130-200 bu/ac (175 bu/ac average).
• Improves soil tilth.
• Eliminates mud at harvest.
• Annual ryegrass grew successfully but was a challenge to terminate.
• Less growth shown with taller corn.
• Timeliness is a challenge.

Intermediate: Late-Season Seeding After Corn

• Seed a winter cereal after corn harvest by drill, broadcast, broadcast + incorporation, or aerially.
• Protects from erosion via roots and no fall tillage.
• Suppresses weeds (winter annuals).
• Only appropriate for land where primary tillage is suitable in spring.
• Timely termination is critical and can be difficult in a wet spring on certain soil types.

Intermediate: Roller Crimping Cereal Rye for No-Till Soybeans

• Used on coarse-textured soil.
• 5,000 gallons/ac hog manure applied before rye seeding.
• Drilled Aroostook rye seeded at 125 lbs/ac on Sept. 7.
• Soybeans custom planted at 300K/ac on June 3-4 with Kinze planter (hydraulic downforce) –2x to achieve 15-in. rows.
• Roller crimped June 2 and June 8.
• Achieved soybean yield of 45 bu/ac (2023).
• Suppresses weeds without tillage.
• Reduces labor and fuel.
• Improves soil organic matter and structure.
• Dry start, but above-average rainfall in 2023 growing season.
• Plowed after soy harvest; planted grain corn following year – yield of 150 bu/ac.

Emerging & Innovative: Winterkilled Cover Crops for Organic No-Till Wheat

• Winterkilled cover crops grown ahead of spring or winter wheat.
• Mulch used for weed control; crimping ahead of winter wheat seeding.
• Improves soil health.
• Shifts tillage timing to summer.

Emerging & Innovative: Min. Till Soybeans After Rye for Forage

• Common cereal rye drilled in September.
• Rye harvested for green feed –mid May.
• Stubble tilled 2x with high-speed disk.
• Solid-seeded @ 325K/ac+ with no-till drill.
• Tine weeding performed.
• Provides additional forage.
• Higher soybean yields (50-75 bu/ac).
• Suppresses weeds without scuffling.
• No-till drill has given best results.
• Be aware of rye re-growth and seed set.

Drawbacks of Cover Cropping Practices

• Proven practices address only the post-small grain window in rotation.
• Proven practices rely on more aggressive tillage and leave soil vulnerable to erosion.
• Intermediate practices are less consistent.
• Intermediate practices increase short-term costs without immediate payback.
• Intermediate practices may require specialized equipment and success may be weather-dependent.
• Emerging & Innovative practices are unproven across a broad acreage.
• Emerging & Innovative practices require adjustments to common cropping sequences.
• Emerging & Innovative practices have a higher level of risk.

Erosion

• Water erosion risk calculation relies on crop type, soil, topography, and tillage.
• Cover crop + spring mulch-till before corn protects soil.
• Match cover crop management to set goals.
• Consider if any new practice will improve productivity, reduce costs, or play a key soil maintenance role.
• Research, access local knowledge, and start small with one new practice each season.