Cover Crops

The educational materials listed on this page are about Cover Crops.

What is a cover crop? A common definition of a cover crop is a plant that is used as part of a crop rotation to improve the soil, scavenge or add nutrients, smother weeds and as a tool for erosion control. Cover crops are not harvested, but are left in place in no-till farming or turned under, especially in organic farming. Another term for cover crops is green manures, especially when the crop residue is incorporated into the soil.

Cover crops can improve soil fertility by adding organic matter, and they help in nutrient management planning by adding nitrogen to soil or by taking up nutrients in soil after cash crop harvest. Winter cover crops are most common in corn and soybean grain production systems, while spring cover crops or summer cover crops can fit many vegetable production systems. Cover crops improve soil moisture, especially over time as soil organic matter and soil tilth are improved.

Cover crop cocktails are used by many farmers as a way to improve soil health. Cocktails or cover crop mixes usually include a grass cover crop such as cereal rye or annual ryegrass, a legume cover crop like crimson clover or hairy vetch, and sometimes a brassica cover crop like forage radish, sometimes called “tillage radish.” Cover crop benefits from cocktails are often greater than seeding a single cover crop species. Cover crop mixes contribute to pest control by attracting beneficial insects and they may increase weed control by providing more ground cover and leaving more crop residue on the soil surface. Some cover crops can mitigate plant disease by suppression soil pathogens. Cover crop cocktails also attract pollinators, including native pollinators.

Cover crop seed is increasingly available from seed companies. They may also be able to help you with information about cover crop selection as well as best timing and methods of planting cover crops.

Some SARE books will help you decide how and when to grow cover crops. Managing Cover Crops ProfitablyCrop Rotation on Organic Farms, and Building Soils for Better Crops are comprehensive guides or manuals. Another useful resource is the SARE topic brief Cover Crops for Sustainable Crop Rotations, which summarizes the usefulness of rotating cover crops in any cropping system. For organic farming, see the Organic Transitions business planning guide.

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Estimating Plant-Available Nitrogen Release from Cover Crops

This Oregon State University fact sheet explains the basics of plant-available nitrogen (PAN); when to kill cover crops for the maximum PAN benefit; step-by-step instructions on how to perform site-specific measurements to predict PAN from your cover crop; and case studies from the Willamette Valley.

A Sunn Hemp Cover Crop for Soil Health and Nematode Management

These University of Hawaii fact sheets and virtual field day explain how to use sunn hemp as a cover crop to control weeds, nematodes and other pests, add soil nutrients, prevent erosion, and contribute to a more robust and complex community of beneficial nematodes. Available fact sheets include:

Sustainable Agriculture Farming Systems Project

Public concerns regarding pesticide misuse, food safety, water use and contamination, and depletion of non-renewable resources have motivated the reevaluation of some of the practices of conventional agriculture and the exploration of alternative, more sustainable approaches to growing food. In 1988, the Sustainable Agriculture Farming Systems (SAFS) project was established at the University of California’s […]

Cover Crops in Organic Systems: California

This is a collaborative project to build the capacity of conservation professionals to assist organic and transitional farmers in planning and implementing conservation practices through the Environmental Quality Incentives Program Organic Initiative. This guide is part of a series of guides created by Oregon Tilth for use by NRCS staff in the Western Region. This document provide an overview […]

Nutrient Management Plans: Idaho

This is a collaborative project to build the capacity of conservation professionals to assist organic and transitional farmers in planning and implementing conservation practices through the Environmental Quality Incentives Program Organic Initiative. This guide is part of a series of guides created by Oregon Tilth for use by NRCS staff in the Western Region. This document is […]

Nutrient Management Plans: California

This is a collaborative project to build the capacity of conservation professionals to assist organic and transitional farmers in planning and implementing conservation practices through the Environmental Quality Incentives Program Organic Initiative. This guide is part of a series of guides created by Oregon Tilth for use by NRCS staff in the Western Region. This document is an instruction […]

Cover Crops in Organic Systems: Oregon

This document provides an overview of how the USDA Natural Resources Conservation Service NRCS Cover Crop 340 conservation practice can be implemented on organic operations in Oregon.

Cover Crops in Organic Systems: Idaho

This document provides an overview of how the USDA Natural Resources Conservation Service NRCS Cover Crop 340 conservation practice can be implemented on organic operations in Idaho.

Cover Crops in Organic Systems

This document provide an overview of how the USDA Natural Resources Conservation Service NRCS Cover Crop 340 conservation practice can be implemented on organic operations in the Western Region.

Fresh Growth Podcast

Fresh Growth: Approaches to a More Sustainable Future from Western Ag Practitioners introduces you to farmers and ranchers from around the western United States who are finding innovative sustainable practices that enrich the natural resources we all care about. These successful multi-generational operations experiment with new ideas and are making it pay. Listen in as […]

Organic Fertilizer and Cover Crop Calculator

This free online tool compares the nutrient value and cost of cover crops, organic and synthetic fertilizers and compost. Use this Excel Calculator to develop well balanced and cost effective nutrient management programs for your farm.