Implementation, Demonstration, and Evaluation of BMPs for Water Quality: Application Methods (” Manure Injections”) for Improved Management of Manure Nutrients

Implementation, Demonstration, and Evaluation of BMPs for Water Quality: Application Methods (“Manure Injections”) for Improved Management of Manure Nutrients. Bill Jokela, Sid Bosworth and Don Meals. September 1995.

Field application of fertilizer and manure on dairy farms is considered an important source of nutrients, especially phosphorus, entering Lake Champlain and contributing to water quality problems (NY-VT Strategic Core Group, 1992). Because of the major role of dairy farming in the Lake Champlain Basin, management of manure plays a critical role in determining the amount of phosphorus available for delivery to surface waters in agricultural runoff. In a sampling of nine farms in the St. Albans Bay RCWP during 1987-1989, 71 % of the phosphorus and 80% of the nitrogen applied to fields was from manure with the remainder applied as fertilizer (Jokela, 1991). Almost two­thirds of the manure phosphorus and nitrogen was applied to cornland.

At the present time, Extension and the Natural Resource Conservation Service (NRCS) recommend spring application of manure on corn with same-day incorporation to provide most efficient utilization of manure nutrients and to minimize surface and ground water quality impacts. However, because of limited manure storage and other practical circumstances on many farms, significant amounts of manure are applied in the fall and much is not incorporated the same day. Application of slurry manure with equipment that injects below the surface would result in immediate incorporation without tillage, thus largely preventing loss of manure phosphorus and nitrogen in surface runoff and loss of N by volatilization of ammonia. It would also allow application of manure as a sidedressed application into the growing crop, giving farmers another window of application on cornland before the post-harvest period in the fall. Sidedressing supplies nitrogen at the optimum time for efficient N uptake by the crop and would minimize nitrate leaching. It would also make possible the use of the Pre-sidedress Nitrate Test (PSNT) as a tool to adjust manure N rates to crop need. Nutrient loss in runoff would likely be very low because of immediate incorporation and because of the low probability of runoff events at that time of year compared to fall and early spring.

The overall purpose of this project was to demonstrate alternative manure application techniques to improve management of phosphorus and nitrogen from manure and commercial sources on silage corn, and to evaluate the effects of these techniques on corn yields and nutrient losses via surface runoff and leaching.