The first technical session was about nutrient management on pastures. Three speakers were featured: Dr. Quirine Ketterings - Cornell University, Mr. Paul Cerosaletti - Cornell Cooperative Extension, and Dr. Edward Rayburn - West Virginia University. Whole farm nutrient balancing and precision feed management are instrumental in reducing excess soil nitrogen and phosphorus on dairy farms. Excess feeding of protein and phosphorus in dairy rations leads to soil build-up of nitrogen and phosphorus. Only a small portion of the imported nitrogen and phosphorus fed to the dairy stock as home grown or purchased feed leaves the farm in the milk or meat. The excess soil nitrogen and phosphorus can be lost to surface and ground water creating water quality problems locally and further downstream.
Pastures vary considerably in soil nutrient content due to livestock lingering in certain locations for prolonged periods of time, such as at hay bunks, water troughs, shade, and at gates. Therefore, if taking pasture soil samples for nutrient analysis to get fertilizer recommendations, it is best to do grid sampling that is geo-referenced (precision soil sampling). Five soil cores are taken within a 12-foot radius at each sampling point. Fertilizer and lime then can be variably rate applied with the proper equipment so that the nutrient hot spots are given less or no fertilizer and the deficient areas more.
It is also very important to sample pastures at shallow depths since all the fertilizer spread, either by grazing animal or equipment, is currently surface applied unless the pasture is tilled for replanting and the fertilizers are incorporated then. Permanent pastures should be soil sampled to a 2-inch depth only because of this. Sampling at greater depths can greatly understate the nutrient concentrations found in the upper 2 inches of the soil. This can lead to erroneously higher rates of recommended nutrients; that if applied, will only heighten surface soil nutrient concentrations. This can cause shallow rooted grasses, grass tetany in cattle, and increased nutrient concentrations in runoff water from these pastures.