Animal manure is commonly used as a fertilizer and soil conditioner. Nutrients from manure (nitrogen, phosphorus, and potassium) help build and maintain soil fertility and improve soil properties by adding organic matter. Proper land application of animal manures can yield an economic return by wisely using the available nutrients to meet crop nutrient needs. Excess application of manure is wasteful and can lead to excess nutrients in the soil, pollute surface and ground water, harm crops, and contaminate soil. A buildup of phosphorus beyond a soil-test level of 300 pounds Bray P, can result in a recommendation that no manure be applied for crop production purposes. Application rates of incorporated manure or manure applied to low-runoff-potential sites with a soil-test level of 250 pounds Bray P, may be limited to the crop nutrient removal rate, which is the amount of nutrients removed from the soil by the harvested crop. The same application restrictions may hold for surface-applied on high-runoff-potential sites with a soil-test level greater than 60 pounds Bray P1.
The study goes on to provide an illustration of how to determine the amount of land required for manure application based strictly on crop nutrient removal rates and raw-manure nutrient production rates. For more information refer to “Manure Management Worksheet” and “Determining Recommended Manure-Application Rates”.