MSU Extension Cover Crops

Overview 

Written by Dale R. Mutch - Retired Senior Educator, Michigan State University Extension
Updated by Erin C. Hill - Cover Crop Specialist, Michigan State University

Using cover crops in farming systems is not a new practice. Prior to the development of manufactured fertilizers, cover crops were commonly used to improve soil structure and productivity. Recent economical and environmental concerns have fueled a resurgence in cover crop use. This information sheet is the first in a series designed to provide cover crop information. A team of researchers, MSU Extension agents and Michigan farmers are producing them to address specific cover crop questions. The information comes from research and demonstrations conducted at Michigan State University and on farms throughout Michigan.

Cover crops are planted to improve soil quality - not for harvest and resale. They enhance soils by protecting, improving and providing nutrients and have many purposes, including:

Nitrogen management

Cover crops can enhance N production and/or reduce leaching. Overseed legume (clovers, medic, etc.) cover into corn, frost-seed into wheat, or late summer-seed to provide nitrogen for future crops. Grass (annual ryegrass, cereal rye, wheat, oilseed radish) can be used to take up excess nitrogen and reduce the potential for groundwater leaching. Erosion control: Cover crops can be used to reduce wind and water erosion. Maintaining ground cover through fall, winter and early spring drastically reduces soil loss. Improving soil quality: Cover crops enhance soil structure while increasing soil biota activity. They reduce soil compaction while increasing water percolation and retention. Cover crops help soils maintain a higher organic matter level than continuous row cropping without cover. They also improve soil aggregation, infiltration and bulk density.

Weed suppression

Cover crops can play a role in managing weeds by shading and interfering with weed germination and establishment. Cereal rye produces allelochemicals which suppress weeds. Unfortunately, cover crops can also become weeds. MSU researchers are currently investigating using cover crops for weed control without reducing crop yields.

Insect management

Cover crops will play an important role in future biological insect control. They have increased Trichograma wasp survival for European corn borer control in seed corn. MSU researchers are investigating using cover crops for biological control programs.

Pastures

Cover crops can be used as a forage crop and feed source. There are many other uses for cover crops which will be discovered as we increase their use.

• Cover Crop Choices for Michigan: This bulletin summarizes cover crop information from research and demonstrations conducted at the Michigan State University W.K.Kellogg Biological Station and on farms throughout Michigan.
• Cover Crop Choices for Michigan Vegetables: This bulletin summarizes information from case studies at Michigan State University and on farms in Michigan. 
• Cover Crop Choices Following Winter Wheat: This bulletin give species suggestions for cover crops to be planted following winter wheat or other small grains from mid-July through August.
• Midwest Cover Crop Council Selector tool: Explore cover crop options for your particular county, soil drainage type, and cash crop through the interactive selector tools available for both field crops and vegetables. 
• MSU Extension Beginning Farmer Webinar Series (2015):
  • Cover Crops in Field Crop Rotations
  • Cover Crops in Organic Vegetable Rotations

• Seeding Methods and Equipment: Cover crop seed application is as important as commercial seed application and the method used will affect seed germination rate and stand quality. Using equipment that allows accurate application at the correct rate will save money and help ensure sufficient cover.
• Termination: Management considerations need to be made while choosing a cover crop to best fit your rotation, including method and timing.
• Michigan Field Crop Ecology - Cover Crops: The cover crops chapter reviews key concepts answers questions about cover crops including what cover crops are, how cover crops influence carbon and nitrogen cycles, and others. 
• Cover Crops and Manure Because cover crop roots and top growth act like a sponge to capture, contain, and reuse manure nutrients, they can be an effective way to retain soil nutrients and reduce fertilizer costs.