Fertilizer (NPK) Calculator

Enter your soil test N-P-K values and the tool calculates net fertilizer requirement after crediting available soil nutrients. Accounts for organic matter credits from FYM (25 kg N/ha), compost or vermicompost. Outputs Urea, DAP and MOP quantities per acre and total, with approximate cost. Includes a 3-split application schedule (basal + two top-dressings) and a full fertilizer NPK reference table.

How NPK Calculation Works

Crop nutrient requirement (kg/ha) minus soil available nutrients (from soil test) equals net fertilizer requirement. The calculator then converts net requirement to commercial fertilizer quantities based on NPK content of each fertilizer.

Fertilizer NPK Content

Urea: 46% N (Nitrogen). DAP (Diammonium Phosphate): 18% N, 46% P2O5 (Phosphorus). MOP (Muriate of Potash): 60% K2O (Potassium). SSP (Single Super Phosphate): 16% P2O5. NPK Complexes: Various ratios (10-26-26, 12-32-16, etc.).

Soil Test Interpretation

Nitrogen (N): Available N in kg/ha. Typically 200-500 kg/ha in Indian soils. Phosphorus (P): Available P2O5 in kg/ha. Range: 10-100 kg/ha. Potassium (K): Available K2O in kg/ha. Range: 100-400 kg/ha.

Organic Matter Credits

FYM (Farm Yard Manure): 5-10 tons/ha provides 25-50 kg N, 10-20 kg P2O5, 25-50 kg K2O. Compost: Similar to FYM. Vermicompost: 2-5 tons/ha provides 20-40 kg N, 10-20 kg P2O5, 15-30 kg K2O. Green Manure: Provides 40-80 kg N/ha.

Split Application Schedule

Basal dose at sowing: DAP + 1/3 Urea + full MOP. First top-dressing at 30 DAS (days after sowing): 1/3 Urea. Second top-dressing at 60 DAS: 1/3 Urea. This schedule improves nutrient use efficiency.