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Cover crops and manure: 2 can be better than just 1

Cereal rye and manure, when combined, provide benefits to each other, resulting in greater overall benefits to livestock producers, their bottom line and the environment.

Research at the National Soil Tilth Laboratory in Ames, Iowa, focuses on identifying the benefits of rye when manure is applied in the fall. Manure helps decompose rye rapidly, releasing some of the nutrients in the rye tissue to the future corn crop. Capturing these manure nutrients with rye and keeping them in the root zone will lower the amount of commercial fertilizer required for crop growth.

Key Points

• Rye helps stabilize manure nutrients, and manure helps decompose rye rapidly.

• Exact quantity of nitrogen released by the cover crop and manure varies yearly.

• Rye is a versatile cover crop, which can recycle manure nutrients.


The exact quantity of nitrogen released by the cover crop and manure may vary from year to year in this system, making it important to base nutrient-management decisions on soil tests. The researchers have used the late-spring soil nitrate test to determine how much N the corn crop requires for maximum yield and profitability.

The research at the Iowa lab during the last three growing seasons used a 70% rye and 30% oat cover crop. Injecting swine slurry in the fall resulted in several important findings:

• Rye reaches its capacity to accumulate N in the top growth when about 200 pounds of manure nitrogen is applied per acre.

• Rye and manure does not lower corn yield.

• N captured by rye is not all released the following growing season but will likely be released over several years.

Manure, rye mutually beneficial

Cover crops provide many benefits to soil. They cover the soil to reduce erosion, add organic matter and capture nutrients that may otherwise be lost by leaching or runoff. A rye cover crop reduces the loss of nitrate in tile drains by as much as 60%. Actively growing roots and top growth capture manure-derived nutrients and recycle them for future crops. Rye helps stabilize manure and wastewater nutrients applied in the fall, winter or spring in plant tissue. In turn, nitrogen from the manure speeds decomposition of the rye residue, and the eventual release of nitrogen and other nutrients to the following crop.

Additional options with rye

Cereal rye is a versatile cover crop for livestock-based cropping systems beyond its ability to recycle manure nutrients. It can provide excellent pasture in fall and spring when perennial pastures are least productive and vulnerable to traffic and winter injury.

When green chopped in the boot stage, rye can produce 1 to 2 tons of dry matter per acre, preferably for the non-lactating herd. Allowing a few acres to mature will provide seed for next season. After harvest, there is straw for bedding and the stubble provides a midseason site for manure applications.

Rye can be established using multiple methods that include drilling, broadcasting and aerial seeding in standing corn and before leaf drop in soybean. Rye can be broadcast alone or with dry fertilizers, can be added to manure tanks for slurry seeding, or drilled (which provides the most consistent stands). Rye can germinate at temperatures as low as 34 degrees F, which provides a large window of opportunity to plant in the fall after corn grain or soybean. It begins growing in the spring at temperatures as low as 38 degrees.

Additional resources on manure management and specific recommendation for seeding rye this fall can be found at www.animalagteam.msu.edu.

Rector is the senior statewide nutrient management educator for Michigan State University Extension. You can reach her at rector@msu.edu.

This article published in the September, 2010 edition of MICHIGAN FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.