How Predictable is Nitrogen for Corn Production?
It turns out that with liquid swine or dairy manure the question is easier to answer if the manure was injected than if it was broadcast and later incorporated. Nitrogen availability as measured by corn yield response to manure rate was much closer to published University predictions (University of Minnesota Extension Bulletin 03553, “Manure Management in Minnesota”) for injected than for broadcast-incorporated manure on an individual field basis. Research scientist Michael Russelle indicated that the greater variability for broadcast-incorporated manure was likely due to ammonia losses from manure that were higher or lower than average due to weather conditions (rainfall, temperature, and windspeed) after application and before incorporation. The conclusion is that direct injection by knives or sweeps is recommended to get the best and most predictable value from manure nitrogen. Results from the field trials are described in a new Extension publication, “Nitrogen Availability from Li
