Chapter 6

Cover Crops for Organic Farms

(book excerpts)

Proper choice and management of cover crops are important in maximizing the benefits and reducing potential problems. To select a species or mix, the organic grower should first identify the purpose and objectives for its use. Subsequent factors to consider include seed availability, moisture requirements, crop rotation, and equipment for seeding and planting. Cover crop choice is important because different species provide different benefits. For example, small grains such as barley, oat, rye, triticale and winter wheat may provide biomass for building soil organic matter and weed suppression. Some crops may also have allelopathic effects, where chemicals produced by the cover crop inhibit growth of weeds. This can be beneficial for weed control, but may be detrimental to small seeded vegetable crops that are direct sown within two weeks after cover crop kill. Legumes such as crimson clover, ladino white clover, red clover, hairy vetch and winter pea do not generally produce as much biomass as small grains, but are able to fix nitrogen that may be available for the following cash crop. A mixture of two or more cover crop species—usually a grain and a legume—can optimize the benefits of both crop types.

Click on the following topics for more information on cover crops for organic farms.

Topics Within This Chapter:

  • Introduction to Cover Crops for Organic Farms
  • National Organic Program Standards for Cover Crops
  • Section 205.203 Soil Fertility and Crop Nutrient Management Practice Standard
  • Section 205.204 Seeds and Planting Stock Practice Standard
  • Section 205.205 Crop Rotation Practice Standard
  • Benefits and Drawbacks fo Cover Crops
  • Benefits of Cover Crops
  • Erosion Control
  • Increase in Organic Matter
  • Soil Structure Improvement
  • Nitrogen Fixation
  • Recycling or Scavenging Unused Nutrients
  • Pest Control
  • Weed Suppression
  • Soil Microbial Activity
  • Soil Water Management
  • Soil Temperature
  • Drawbacks of Cover Crops
  • Deplete Available Water Supply
  • Additional Costs
  • Rates of Mineralization of Nutrients for the Subsequent Crop
  • Pest Problems
  • Interference with Primary Crop
  • Risk of Frost Damage
  • Life Cycle of Cover Crops
  • Annual Cover Crops
  • Perennial Cover Crops
  • Biennial Cover Crops
  • Types of Cover Crops
  • Legumes
  • Carbon:Nitrogen Ratio
  • Cool Season and Warm Season Legumes
  • Life Cycles of Common Legumes
  • Grasses
  • Carbon:Nitrogen Ratio
  • Cool Season and Warm Season Grasses
  • Life Cycles of Common Grasses
  • Brassicas
  • Buckwheat
  • Cover Cropping Systems
  • Monocultures
  • Mixtures
  • Insectary Mixes
  • Resident Vegetation
  • Nitrogen Fixation by Legumes
  • Seed Inoculation
  • Nitrogen Fixing Capacity
  • Nitrogen Availability
  • Green Manures
  • Green Manures Species Selection
  • Nitrogen Management with Green Manures
  • Carbon:Nitrogen Ratio of Green Manures
  • Potential Nitrogen Losses
  • Organic Matter Management with Green Manures
  • Undersowing with Green Manures
  • Mowing Green Manure Crops
  • Terminating Green Manure Crops
  • Catch Crops
  • Effectiveness of Catch Crops
  • Managing Pests with Cover Crops
  • Cover Crops for Managing Insects
  • Managing Cover Crops to Encourage Beneficial Insects
  • Cover Crops for Managing Diseases
  • Cover Crops for Managing Weeds
  • Choose the Right Cover Crop for the Climate and Season
  • Managing Cover Crops to Help Suppress Weeds
  • Cover Crop Residues
  • Allelopathy
  • Cover Crops for Managing Nematodes
  • Cover Crop Strategies with Crop Rotations
  • Replacing Fallow with Cover Crops
  • Year-long Fallow with Cover Crops
  • Summer Fallow with Cover Crops
  • Winter Cover Crops
  • Smother Crops
  • Relay Seeding
  • Cover Crops Interseeded into Vegetables
  • Cover Crops Interseeded into Corn and Soybeans
  • Strip Cropping
  • Selecting Cover Crop Species
  • Nitrogen Contribution
  • Carbon Nitrogen Ratio
  • Improve Nutrient Availability in the Soil
  • Scavenge Nutrients
  • Soil Erosion Considerations
  • Improve Soil Structure
  • Improve Drainage and Alleviate Soil Compaction
  • Conserve Soil Moisture
  • Winter Factors
  • Summer Factors
  • Relative Vigor of Cover Crops
  • Growth Habit
  • Insect and Disease Suppression
  • Weed Management Objectives
  • Seed Availability and Cost of Planting
  • Cover Crops for Specific Purposes
  • Buliding Complimentary Cover Crop Mixtures
  • Complementary Growth Periods
  • Complementary Growth Forms
  • Complementary Nitrogen Acquisition Strategies
  • Complimentary Weed Management Strategies
  • Complementary Insectary Mixture Strategies
  • Cover Crops in Perennial Systems
  • Cover Cropping Farming Systems
  • Annually Tilled and Seeded
  • Non-tillage Floor Management with Annual Cover Crop Species
  • Non-tillage Floor Management with Perennial Species
  • Tilled and No-till Farming Systems
  • Self-reseeding Cover Crops
  • Challenges in Growing Cover Crops In Perennial Systems
  • Water Use
  • Risk of Frost
  • Tree and Vine Vigor
  • Shade Tolerance
  • Establishment of Cover Crops
  • Cover Crop Seed Selection and Quality
  • National Organic Program (NOP)
  • Seed Quality
  • Seed Bed Preparation
  • Conventional Seeding
  • No-till Seeding
  • Planting Times
  • Pre- or Post-season Seeding
  • Frost Seeding
  • Dormant Seeding
  • Interseeding
  • Seeding Depth
  • Seed Drill Configurations
  • Seeding Methods
  • Broadcast Seeding
  • Seed Drilling
  • No-Till Drilling
  • Harrow Seeding
  • Aerial Inter-Crop Seeding
  • Fertilization
  • Termination of Cover Crops
  • Termination Time for Cover Crops
  • Winter-Killing Cover Crops
  • Cover Crop Termination with Tillage
  • Rolling-Crimping
  • Mowing
  • Rotary Mowers
  • Sickle Bar Mowers
  • Flail Mowers
  • Undercutting
  • Termination Methods by Cover Crop Species
  • References