Fertilizer Requirement Calculator
A 120:60:40 kg/ha recommendation met with DAP needs 130.4 kg DAP, 66.7 kg MOP and 209.83 kg of urea per hectare.
209.829867674858 kg
Full answer, then cut to fewer decimals (not rounded):
- 209.829867674858 kg
- 209.82986767485 kg
- 209.8298676748 kg
- 209.829867674 kg
- 209.82986767 kg
- 209.8298676 kg
- 209.829867 kg
- 209.82986 kg
- 209.8298 kg
- 209.829 kg
- 209.82 kg
- 209.8 kg
- DAP needed
- 130.4347826 kg
- Muriate of potash (MOP, 60 % K₂O)
- 66.66666667 kg
- Nitrogen supplied by DAP
- 23.47826087 kg
- Total in 50 kg bags
- 8.138626339 bags
Step-by-step solution
- DAP = P₂O₅ ÷ 0.46 = 130.4347826 kg/ha
- N from DAP = 0.18 × 130.4347826 = 23.47826087 kg/ha
- Urea = (N − N from DAP) ÷ 0.46 = 209.8298677 kg/ha
- MOP = K₂O ÷ 0.60 = 66.66666667 kg/ha
Fertilizer Requirement Formula
DAP = P₂O₅/0.46; urea = (N − 0.18 DAP)/0.46; MOP = K₂O/0.60
SSP = P₂O₅/0.16 when SSP supplies phosphorus
Worked Example
A 120:60:40 kg/ha recommendation for one hectare using DAP:
- DAP = P₂O₅ ÷ 0.46 = 130.4347826 kg/ha
- N from DAP = 0.18 × 130.4347826 = 23.47826087 kg/ha
- Urea = (N − N from DAP) ÷ 0.46 = 209.8298677 kg/ha
- MOP = K₂O ÷ 0.60 = 66.66666667 kg/ha
Muriate of potash (MOP, 60 % K₂O): 66.66666667 kg · Nitrogen supplied by DAP: 23.47826087 kg · Total in 50 kg bags: 8.138626339 bags
GATE tip
Rates are of nutrient, not product: always divide by the nutrient fraction of the fertiliser.
More Crop Inputs Calculators
-
Seed Rate Calculator
Seed rate = (10⁴/(row × plant spacing)) × seeds/hill × test weight / (10⁶ × germination × purity)
spacings in m, test weight in g per 1000 seeds
Example: Maize at 60 × 20 cm, one seed per hill, 300 g test weight, 90 % germination, 98 % purity: Seed rate = 28.3447 kg/ha.
Frequently asked questions
Why calculate DAP before urea?
DAP also contains 18 % nitrogen; working out the phosphorus source first avoids over-applying N.
What do the three numbers on a bag mean?
The percentages of N, P₂O₅ and K₂O: DAP 18-46-0, urea 46-0-0, MOP 0-0-60.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Fertilizer Requirement Calculator. Retrieved October 29, 2026, from https://scientificconverters.com/calculators/fertilizer-requirement-calculator/
IEEE
Scientific Converters, "Fertilizer Requirement Calculator," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/calculators/fertilizer-requirement-calculator/