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🧪 Fertilizer Blend Calculator — N-P-K Mixing

Calculate the exact blend of nitrogen, phosphorus and potassium fertilizers to meet your crop's nutrient requirements. Save money by mixing your own instead of buying proprietary blends.

Quick answer: To apply 50 kg N/ha using Urea (46% N): 50 ÷ 0.46 = 109 kg/ha. For a custom blend, solve each nutrient independently using the fertilizer's analysis.

🧪 Calculate Fertilizer Blend

From soil test and crop removal
From soil test and crop removal
From soil test and crop removal
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Total Fertilizer (kg/ha)
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N Fertilizer
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P Fertilizer
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K Fertilizer

📐 How Fertilizer Blend Is Calculated

Fertilizer rate (kg/ha) = Nutrient required (kg/ha) ÷ (Fertilizer analysis % ÷ 100)
  1. Determine nutrient requirements — from soil test and crop nutrient removal
  2. Select fertilizer products — based on availability and cost per kg of nutrient
  3. Calculate each product rate — divide required nutrient by fertilizer concentration
  4. Sum total fertilizer — add all products for total kg/ha to spread

📊 Worked Example

Wheat crop needs 50 kg N, 20 kg P, 15 kg K per hectare. Using Urea (46% N), DAP (20% P), MOP (41% K).

Urea = 50 ÷ 0.46 = 109 kg/ha
DAP = 20 ÷ 0.20 = 100 kg/ha
MOP = 15 ÷ 0.41 = 37 kg/ha
Total blend = 246 kg/ha

DAP also contains 18% N. Adjust N from DAP: 100 kg × 0.18 = 18 kg N, so reduce Urea to (50-18) ÷ 0.46 = 70 kg/ha. Final blend: 70 Urea + 100 DAP + 37 MOP = 207 kg/ha.

❓ Frequently Asked Questions

Fertilizer rate (kg/ha) = Nutrient required (kg/ha) ÷ (Fertilizer analysis % ÷ 100). Example: Need 50 kg N/ha using Urea (46% N) = 50 ÷ 0.46 = 109 kg/ha.

Urea: 46-0-0, DAP: 18-20-0, MAP: 10-22-0, MOP: 0-0-41, Triple Super: 0-46-0, NPK blends: 25-5-10, 15-15-15, 20-10-10.

Multiply kg/ha by 0.405 to get kg/acre. Example: 100 kg/ha × 0.405 = 40.5 kg/acre.

Blends are convenient. Straight fertilizers are cheaper per kg of nutrient. Large farms often custom-blend to save 10-20% on fertilizer costs.

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