Fertilizer Calculator
Calculate exact fertilizer application rates, blend two products for balanced nutrition, and interpret N-P-K values to prevent soil burn. Includes a large database of organic and synthetic fertilizers.
Calculate how much of two different products to mix to hit specific N and K targets.
Product A
Product B
About
Nutrient management is the intersection of chemistry and economics in agriculture. Applying too little fertilizer limits yield potential through nutrient deficiency, while over-application results in fertilizer burn, environmental runoff, and unnecessary financial loss. Precision requires calculating the exact mass of a commercial product needed to deliver a specific elemental load of Nitrogen N, Phosphorus P, and Potassium K.
This tool solves the stoichiometry of soil amendments. It accounts for the varying bulk densities and nutrient concentrations of materials ranging from Urea (46−0−0) to organic Bone Meal (3−15−0). By using area specific inputs and safety thresholds, it helps maintain the Osmotic Potential of the soil solution within a range that supports root water uptake rather than inhibiting it.
Formulas
The core calculation derives the physical weight of the product required to meet a specific elemental target over a defined area.
When mixing two fertilizers (A and B) to achieve specific targets for Nitrogen (N) and Potassium (K), we solve a linear system:
Reference Data
| Material | Typical N-P-K | Release Speed | Primary Use |
|---|---|---|---|
| Urea | 46−0−0 | Fast | Rapid vegetative growth (Greening) |
| Ammonium Nitrate | 34−0−0 | Fast | Cold weather nitrogen source |
| Blood Meal | 12−0−0 | Medium | Organic nitrogen boost |
| Bone Meal | 3−15−0 | Slow | Root development & blooming |
| Potassium Chloride (MOP) | 0−0−60 | Fast | Disease resistance & water regulation |
| Triple Superphosphate | 0−46−0 | Medium | Establishing new lawns/crops |
| Feather Meal | 13−0−0 | Slow | Long-term nitrogen maintenance |
| Milorganite (Biosolids) | 6−4−0 | Slow | Non-burning slow release |
| Fish Emulsion | 5−1−1 | Fast | Quick liquid feed for transplants |
| Greensand | 0−0−3 | Very Slow | Soil conditioning & micronutrients |
| Diammonium Phosphate (DAP) | 18−46−0 | Fast | High P starter fertilizer |
| Cottonseed Meal | 6−2−1 | Slow | Acid-loving plants (Blueberries) |
| Bat Guano (High N) | 10−3−1 | Fast | Rapid growth organic booster |
| Bat Guano (High P) | 3−10−1 | Medium | Flowering stage booster |
| Sulfate of Potash (SOP) | 0−0−50 | Medium | Low-salt potassium source |