Manure Spread Rate
Calculator
Results
- Total manure (t)
- 200
- Nutrient supplied (kg/ha)
- 137.5
- Plant-available nutrient (kg/ha)
- 55
Farming results
| Total manure (t) | 200 |
| Nutrient supplied (kg/ha) | 137.5 |
| Plant-available nutrient (kg/ha) | 55 |
formula-map diagram
- Total manure (t)
- 200
- Nutrient supplied (kg/ha)
- 137.5
- Plant-available nutrient (kg/ha)
- 55
Formula map
Formula
Nutrient = manure rate × nutrient per tonne × availability= 200
Note
Simplified agronomic model: results use the rates, grades and coefficients you enter and ignore soil type, weather, variety and local regulations. Confirm with a soil test, the product label and an agronomist before applying anything.
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See all →Frequently asked questions
Why is manure spread rate not as simple as a fixed number for all manure?+
Nutrient content in manure varies widely by animal species, bedding type, storage method, and moisture content, so the same volume of manure from different sources can deliver very different amounts of nitrogen, phosphorus, and potassium. A manure nutrient test is the only reliable basis for an accurate rate.
Should I base the spread rate on nitrogen or phosphorus content?+
Rates set to match crop nitrogen needs often oversupply phosphorus over repeated applications, since manure's N:P ratio is usually narrower than what most crops use. Many regulations now require phosphorus-based rates specifically to prevent long-term soil phosphorus buildup and runoff risk.
How much of the nitrogen in manure is actually available to the crop this season?+
A significant share of manure nitrogen is organic and mineralizes slowly over one to several years, so only a fraction — commonly 30-60% depending on manure type and incorporation method — is considered plant-available in the application year.
Does incorporation timing affect how much manure I need to apply?+
Yes — surface-applied manure left unincorporated for more than a day or two can lose a large share of its ammonium nitrogen to volatilization, effectively reducing the delivered nutrient value below what the raw analysis suggests. Incorporating within hours preserves more of the nitrogen.
What happens if I apply manure at a rate calculated for a different crop?+
Crops differ substantially in nutrient removal, so a rate calculated for corn will oversupply a lower-demand crop like a cereal grown for straw, risking nutrient runoff and lodging. Always recalculate the rate for the specific crop and its realistic yield goal.