Center for Regenerative Agriculture and Resilient Systems

Cover Cropping

cover crops in a walnut orchard

Cover cropping is used to keep the soil protected with plants that may or may not be used as an additional cash crop. The main purpose is to increase soil fertility and soil quality; to manage soil erosion; improve water retention; manage weeds, pests, and diseases; and to increase biodiversity and native wildlife. Cover crops can also be used for forage. Later in the season, the biomass left over after harvesting, grazing or after being mowed or roller crimped can be left on the ground to serve as mulch and to recycle nutrients back into the soil. When used in this way, cover crops are also sometimes referred to as “green manure.”

 Several studies (see below) have shown that green manure, when incorporated before cash crop planting can significantly increase yields. It also increases Soil Organic Matter (SOM) with important impacts on soil regeneration:

  • improved soil structure and ability to retain water
  • increased availability of soil nutrients such as calcium, magnesium and potassium
  • healthier and more biodiverse soil microbiology
  • and increased carbon sequestration with potentially useful impacts on global warming

The impacts increase over time with results varying based on water availability, initial soil quality, cover crop type or mixture, and timing of cover crop operations.

Download a printable fact sheet based on this page. (PDF)

Mentor Farmers Who Share Experiences Using Cover Crops

NRCS Videos

Cover Cropping an Almond Orchard, NCAT-ATTRA

This video documents Elias Cosio, an almond grower from near Modesto who has been collaborating with NCAT and NRCS as he plants the first cover crop in his orchard.

Cover Crops

USDA NRCS video shows how Charlie Roberts in Halls, TN is using this practice to protect soil health and increase water infiltration on his cropland.

Dr. Christine Jones - Quorum Sensing In The Soil Microbiome

Dr. Jones lays out a strong case for the importance of nurturing the biodiversity in the soil through the use of multispecies cover crops. The most diverse mix produces the best results both for the soil microbiome and for the productivity and resiliency of crops grown together in that soil.

Resources and Implementation Guides

How Can I Tell If My Soil is Healthy? • How Cover Crops Build Soil Health.
soil with earthwormGreat Powerpoint presentation overview of how cover crops build soil health by NRCS at a Soil Health & Assessments training, provided as an instant download pdf file. It covers nineteen ways that cover crops are beneficial, with illustrations and photographs showing the difference between healthy soil and soil that needs help.
(PDF)
No-Till Case Study, Richter Farm: Cover Crop Cocktails in a Forage-Based System
multi-species cover cropPublished by the National Center for Appropriate Technology, This case study details how the Richter Farm in North Dakota grows a multispecies cover crop after an early forage harvest to add needed residue, organic matter, and available soil nutrients for the subsequent cash crop.

Seeds and Seed Money

Research

Sacramento Valley Vegetable Crops Newsletter, October 2020
This issue of the newsletter from the University of California shares the results of two research projects: "Winter Cover Crop Performance in the Sacramento Valley" and "Healthy Soils Demonstration Project Results: Winter Cover Crops in Annual Rotations." Plus there is an article about "Equipment to Manage Cover Crops in Annual Rotations."
(PDF)
“Case Studies of Regenerative Agriculture,” by Roland Bunch, October 2017 (Revised April 2020)
man holding corn harvestRoland Bunch has been working with smallholder farmers using regenerative agriculture across the developing world. These case studies focus mostly on the use of green manure in Mali, Madagascar, Brazil, Guatemala, Honduras, Mexico, Cameroon, Malawi, and twelve African nations.
(PDF)
SARE 2013-14 Cover Crops Survey Report

This report documents yield boost from the use of cover crops in corn and soybeans, as well as a wide variety of other benefits. It also details the challenges and benefits farmers can expect from cover crops, data on the costs of seed and establishment, and insight into how farmers learn to manage cover crops.

(PDF)
Cover crop research review: How can it help almonds?
almond blossomsThis paper republished on "The Almond Doctor Blog" reports on the cover crop research trial in almond cover crops done at UC Davis.

Journal Articles

Chu, M., Jagadamma, S., Walker, F.R., Eash, N.S., Buschermohle, M.J. and Duncan, L.A. (2017), Effect of Multispecies Cover Crop Mixture on Soil Properties and Crop Yield.(opens in new window) Agricultural & Environmental Letters, 2: 170030. 

Daryanto, S. et al. 2019. Valuing the ecosystem services of cover crops: barriers and pathways forward.(opens in new window) Agriculture, Ecosystems and Environment 270-271:76-78

Meyer, N. et al. 2020. Cover crops reduce drainage but not always soil water content due to interactions between rainfall distribution and management.(opens in new window) Agricultural Water Management 231:105998

Nevins, C. et al. 2020. The synchrony of cover crop decomposition, enzyme activity, and nitrogen availability in a corn agroecosystem in the Midwest United States.(opens in new window) Soil & Tillage Research 197:104518 

Ponti, S. et al. 2020. Crop intensification with sustainable practices did not increase N2O emissions.(opens in new window) Agriculture, Ecosystems and Environment 292:106828

Rocha, K. et al. 2020. Cover crops affect the partial nitrogen balance in a maize-forage cropping system.(opens in new window) Geoderma 360:114000

Thapa, V. et al. 2019. Conservation Systems for Positive Net Ecosystem Carbon Balance in Semiarid Drylands(opens in new window).  Agrosyst. Geosci. Environ. 2:190022

Wittwer, R. et al. 2020. Cover crops as a tool to reduce reliance on intensive tillage and nitrogen fertilization in conventional arable cropping systems.(opens in new window)  Field Crops Research 249:107736

Wittwer, R. et al. 2017. Cover crops support ecological intensification of arable cropping systems.(opens in new window) Scientific Reports 7:41911