Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
10/1/02
FOR IMMEDIATE RELEASE
Contacts:
John Sawyer, Department of Agronomy, (515) 294-1923, jsawyer@iastate.edu
John Lundvall, Department of Agronomy, (515) 294-5429, jlundval@iastate.edu
Jean McGuire, Continuing Education and Communication Services (515) 294-7033,
jmcguire@iastate.edu
Using Manure as a Resource
Ames, Iowa – Most producers understand that manure is a valuable nutrient resource, not just a waste product. Applying manure using sound methods can reduce the need for commercial fertilizer thereby saving money on crop production inputs. Crediting manure nutrients is also good for the environment.
John Sawyer, Iowa State University (ISU) associate professor of agronomy, says producers need to take the time to work through several important steps before and during manure application to realize the full value of this resource. Sawyer suggests that producers use soil tests to determine crop needs, pre-sample manure and analyze for nutrient content, apply manure based on pre-samples and historical nutrient databases, calibrate manure applicators, and collect multiple manure samples during application.
Manure samples taken before application can help guide application rates, plus sampling during application is a way to check as-applied nutrient rates and adds to the manure nutrient database for each source. Send samples to a commercial laboratory for chemical analysis.
Applying manure where you can get the greatest yield response to nitrogen (N), phosphorus (P), and potassium (K) will provide the largest economic return. For P and K, the "very high" soil test category indicates that the nutrient supply in the soil already is greater than crop needs, and repeated additions can result in continued soil test increase. Sawyer also suggests that to slow nitrification, apply manure that contains a high proportion of ammonium in the fall after the soil temperature is 50 degrees Fahrenheit or cooler. Injecting or incorporating manure is preferred over broadcast applications as it reduces odor and decreases potential volatile loss of N and surface runoff of P.
Since livestock manure is applied to cropland for its nutrient value, getting an even spread of manure is important. Sawyer comments, "Correct manure applicator calibration, operating speed, and even application throughout the field is as important as properly sampling the manure."
The following publications, which can be ordered through any ISU Extension county office or downloaded from the Web, will help producers make informed manure application decisions.
PM 1558, Management Practices: How to Sample Manure for Nutrient Analysis
(http://www.extension.iastate.edu/Publications/PM1558.pdf)
PM 1688, General Guide for Crop Nutrient Recommendations in Iowa
($1.00 per copy if ordered through a county office or downloaded from
this site for free:
http://www.extension.iastate.edu/Publications/PM1688.pdf)
PM 1811, Managing Manure Nutrients for Crop Production
(http://www.extension.iastate.edu/Publications/PM1811.pdf)
The Nutrient Management Education Project is funded in part by the Iowa Department of Natural Resources through an EPA grant. More information about the Nutrient Management Education Project can be found on the Nitrogen and Phosphorus Knowledge Web Page (http://extension.agron.iastate.edu/NPKnowledge/).
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