Chapter 6

Cover Crops for Organic Farms

(book excerpts)

Cover crops are an integral part of organic and sustainable production systems. Today’s organic farmer relies on the use of traditional cover crops (e.g., small grains, clovers, vetches) to reduce erosion, control weeds, and provide organic matter and nutrients to improve soil quality. Organic farmers are also finding new benefits from non-traditional cover crops (e.g., forage radish, phacelia, black oats) to break up compacted soils, eliminate problem pests, and increase habitat for beneficial insects and pollinators. The purpose of cover cropping in organic farm systems do not differ from those in conventionally managed systems. However, the role of cover crops takes on greater importance in organic farm systems because the use of synthetic chemical fertilizers and pesticides are generally not allowed. Because of the important role of cover crops in providing these benefits, the use of cover crops in organic farming systems must meet National Organic Program (NOP) requirements. Cover crops are often referred to as “green manures,” “catch crops,” or “living mulches.”

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

Topics Within This Chapter:

  • Benefits and Limitations fo Cover Crops
  • Benefits of Cover Crops
  • Erosion Control
  • Organic Matter and Soil Structure
  • Nitrogen Fixation
  • Recycling or Scavenging Unused Nutrients
  • Pest Control
  • Weed Suppression
  • Soil Microbial Activity
  • Soil Water Management
  • Soil Temperature
  • Limitations 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
  • Nitrogen Fixing Capacity
  • Nitrogen Availability
  • Seed Inoculation
  • 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
  • Allelopathic Compounds
  • 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
  • Annual Ryegrass
  • Interseeding
  • Cover Crops Interseeded into Vegetables
  • Cover Crops Interseeded into Corn and Soybeans
  • Smother Crops
  • Strip Cropping
  • Selecting Cover Crop Species
  • Nitrogen Contribution
  • Improve Nutrient Availability in the Soil
  • Scavenge Nutrients
  • Carbon Nitrogen Ratio
  • 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
  • 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
  • Overseeding
  • Fertilization
  • Termination of Cover Crops
  • Termination Time for Cover Crops
  • Winter-Killing Cover Crops
  • Mowing
  • Rotary Mowers
  • Sickle Bar Mowers
  • Flail Mowers
  • Cover Crop Termination with Tillage
  • Rolling-Crimping
  • Undercutting
  • Termination Methods by Cover Crop Species
  • References