After making any change, recalibrate the spreader. It may take several tries to get the proper adjustments for the desired rate. The fertilizer recommendations on Penn State soil test reports do not take into consideration any manure you are applying. If you included manure information on your soil test information sheet, the total manure nutrients will be noted on the soil test report. For soil samples taken after manure has been applied, the manure P and K amounts are measured as part of the soil nutrient levels and, therefore, should not be subtracted from the recommendations.
Environmental problems result from leached N or runoff of manure into surface water.
Not only are these nutrients lost to crop use, but their value as fertilizer replacement also is lost. Spread the manure uniformly and at a known rate. General guidelines for application rates suggest 10 to 25 tons per acre for cattle manure, and 3 to 5 tons per acre for poultry. Actual rates should be based on meeting crop nutrient needs. Do not spread manure on frozen slopes.