Thursday, November 16, 2006 - 10:15 AM

Comparison of Connecticut Nutrient Management Plans with Nutrient Management Plans Based on P-Thresholds.

Haiying Tao1, Thomas Morris2, Richard Meinert1, Boris Bravo-Ureta3, Joseph Neafsey4, and Walter Smith4. (1) Univ of Connecticut, 1376 Storrs Rd, Storrs, CT 06269-4067, (2) 1376 Storrs Rd. Box U-4067, University of Connecticut, University of Connecticut, Plant Science Department, Storrs, CT 06269-4067, (3) Agricultural and Resource Economics, Univ of Connecticut, Storrs, CT 06269, (4) USDA, Natural Resources Conservation Service, 344 Merrow Rd, Suite A, Tolland, CT 06084-3917

Dairy farms in Connecticut voluntarily participate in Nutrient Management Plans (NMPs) funded by the Environmental Quality Incentives Program (EQIP) at the USDA Natural Resources Conservation Service. We compared three management strategies for P-based NMPs outlined in the USDA and the Environmental Protection Agency’s (EPA) Unified National Strategy for Animal Feeding Operations (AFO). We used the agronomic soil P threshold and two environmental soil P thresholds to direct manure applications at four representative dairy farms in Connecticut. The agronomic soil P threshold is the most restrictive strategy, and this strategy required the exportation of 13.57 million L of manure from farm one and 4.88 million L from farm two, with no exportation required from farms three and four. The environmental soil P threshold is less restrictive, but farm one still had to export 10.32 million L and farm two had to export 1.93 million L of manure when an environmental threshold of 45 kg ha-1 modified-Morgan P was used. Increasing the environmental P threshold to 224 kg P ha-1 and recommending manure applications based on N needs, still resulted in farm one having 1.36 million L of excess manure. We also compared the financial effects of using the three soil test P thresholds at the farm level. Statistical methods were used to evaluate the different thresholds. Partial budget analysis was conducted to compare the costs and benefits from using the three P thresholds.