#06-118

Complete

Date Full Report Received

04/11/2008

Date Abstract Report Received

04/11/2008

Investigation

Institution:
Primary Investigator:
Co-Investigators: H.M. Keener, Brian McSpadden-Gardner, Rosa Raudales, Clay Dygert, Jon Rausch

Environmental concerns regarding the application of nitrogen containing manure to soybean fields have been raised recently across the Corn Belt. The concern is that because soybeans are leguminous plant species (able to fix atmospheric nitrogen) application of supplemental nitrogen may result in an increase in the amount of nitrate-nitrogen that may be lost to the environment and negatively impact water quality. Additionally, some research has shown that application of organic amendments may have beneficial impacts on soil-borne pathogens. The purpose of this research was to determine the potential threat of swine manure application to water quality by monitoring soil nitrate levels throughout the growing season and to determine if some benefit may be derived from the application of swine manure to soybeans in the form of soybean cyst nematode (SCN) suppression. Findings from one year suggest that applications of manure that do not supply more than 120 pounds of nitrogen per acre should represent a minimal risk of nitrate-nitrogen loss. There is a greater risk of nitrate-nitrogen loss early, but mid- and late-season losses appear unlikely at nitrogen rates at or less than 120 pounds per acre. Soybean yields were increased when swine manure was supplied most likely as a result of supplementation of both phosphorus and potassium since the site was nearing deficient levels. Finally, the application of swine manure did decrease nematode infection level when manure was surface applied and incorporated with tillage especially at the early stages of soybean growth. The injected manure treatments on 30” centers did not show the same response suggesting that soil contact may play an important role in determining suppression.