Producers need to work through several steps on manure application in order to reap the most rewards, suggests John Sawyer, Iowa State University ISU) agronomist.
Use soil tests to determine crop needs and pretest manure to guide application rates. Sampling during application helps check nutrient rates and adds to the manure nutrient database for each source. Have samples tested at a laboratory.
Sawyer also suggests to slow nitrification, apply manure that contains a high level of ammonium in the fall, after the temperature is below 50 degrees F.
Getting an even spread of manure during application is important to maximize nutrient value, he says. "Correct manure applicator calibration, operating speed, and even application throughout the field are as important as properly sampling the manure."
Sawyer can be reached at (515) 294-1923 or [email protected]  .