Evaluating a Rapid On-Farm Nutrient Determination Model for Use in Implementing Nutrient Management Plans

Government regulatory agencies recommend nutrient management plans (NMPs) for animal operations to reduce non-point source pollution. These plans require manure analysis for total nitrogen (TN) and total phosphorus (TP), and use indices to determine nutrient availability. This study evaluated a rapid on-farm method to predict TN and TP concentrations of swine slurries. A field investigation based on this rapid assessment procedure was used to evaluate the effect of a NMP on corn yield and soil fertility. Manure grab samples were collected to validate the rapid on-farm model for predicting TN and TP. A corn crop was raised on two phosphorus (P) soil test levels (medium and excessive) using three randomized complete blocks with two replications of three treatments. Rapid on-farm models were accurate (P ≤ 0.05) for predicting manure TN and TP. The rapid model manure application rate produced grain yields that were significantly higher than inorganic-N fertilization treatments (13,000 kg ha^?1 versus 9,000 kg ha^?1) (P ≤ 0.05). Potassium chloride extractable soil P and ammonium were not significantly different (P ≥ 0.05) in manure treatments compared with the inorganic-N treatment. Analysis of ear leaf N, P, and K and grain yields demonstrated that the rapid model manure application developed by a NMP met crop requirements.