Manure Fertilizer N-P-K Calculator
Estimate the nitrogen, phosphorus, and potassium content of your livestock manure and calculate how much to apply to meet your garden's nutrient needs.
How It Works
Livestock manure is an excellent organic fertilizer that supplies nitrogen (N), phosphorus (P), and potassium (K) along with organic matter that improves soil structure. The nutrient content varies significantly by animal type, diet, and the amount of bedding mixed in. This calculator uses average fresh-weight nutrient percentages to estimate what your manure provides.
Why Nitrogen Availability Matters
Manure nitrogen comes in two forms: ammonium (immediately available) and organic nitrogen (slow-release). Only about 50% of the total N is available to plants in the first year. The rest becomes available over the next 2–3 years, so avoid over-applying by accounting for residual N from previous years' applications.
Manure Safety Tips
Compost first: Fresh manure can contain pathogens (E. coli, Salmonella). Compost it to 131°F for 3 days before using on food crops.
Avoid fresh manure on edible crops: Apply fresh manure at least 90 days before harvest for crops that touch the soil, and 120 days for root crops.
Rabbit and sheep manure are "cold": They won't burn plants and can be applied fresh directly to the garden.