The manure application rate calculator determines how many tons of manure to spread per acre based on your target nitrogen rate, manure type, and field size. Proper application rates maximize crop nutrition while preventing nutrient runoff — over-application wastes a resource and risks environmental compliance issues.
Manure Application Calculator
Corn: 120–200 | Grass/hay: 80–150 | Soybeans: 0–30
How to Calculate Manure Application Rates
Manure is a valuable fertilizer resource when applied at appropriate rates. This manure application rate calculator determines how many tons per acre of manure to apply to meet crop nitrogen needs without overapplying nutrients that risk groundwater contamination.
Setting Your Target Nitrogen Rate
Base your nitrogen target on expected crop yield and soil test results. Corn typically needs 1.0–1.2 lbs N per bushel of expected yield — a 150-bushel corn crop needs 150–180 lbs N/acre. Subtract soil test residual nitrate and credit from previous legume crops. The remaining amount is your manure N target.
Incorporation vs. Surface Application
Incorporating manure within 24 hours of application conserves 80–90% of the ammonia nitrogen. Surface-applied manure loses 30–50% of ammonia N to volatilization, particularly from liquid manure or fresh poultry litter. Incorporate when possible for better nutrient efficiency and to reduce odor.
FAQ
Is this manure calculator free?
Yes, completely free. All calculations run locally in your browser with no data sent to any server.
How much nitrogen is in cattle manure?
Cattle feedlot manure contains approximately 40–60 lbs of total nitrogen per ton, with 20–30 lbs available to crops in the year of application. Availability depends on application method — incorporated manure has higher N availability than surface-applied.
How many tons of chicken manure per acre?
Broiler litter is high in nutrients — typically 2–4 tons per acre is appropriate depending on crop needs. It contains 60–80 lbs total N per ton. More than 4 tons/acre risks nitrogen and phosphorus buildup. Follow a nutrient management plan for commercial poultry litter.
How do I calculate manure application rate?
Determine your target nitrogen rate for the crop (e.g., 150 lbs N/acre for corn), find the available N in your manure from a lab test, then divide: application rate = target N ÷ available N per ton. This calculator uses typical values; a manure test gives more accurate results.
What is the phosphorus concern with manure?
Manure often has a higher phosphorus-to-nitrogen ratio than crops can use. Repeated manure application based on nitrogen rates can build up excess phosphorus, which can run off into waterways. Nutrient management plans consider both N and P balance.