Nitrogen From Fertiliser Grade
Calculator
Results
- Nitrogen supplied (kg/ha)
- 83.75
- Nutrient supplied (kg/ha)
- 83.75
- Cost per kg of nitrogen
- 1.253731
Farming results
| Nitrogen supplied (kg/ha) | 83.75 |
| Nutrient supplied (kg/ha) | 83.75 |
| Cost per kg of nitrogen | 1.253731 |
formula-map diagram
- Nitrogen supplied (kg/ha)
- 83.75
- Nutrient supplied (kg/ha)
- 83.75
- Cost per kg of nitrogen
- 1.253731
Formula map
Formula
N supplied = fertiliser rate × (N % ÷ 100)= 83.75
Note
Simplified agronomic model: results use the rates, grades and coefficients you enter and ignore soil type, weather, variety and local regulations. Confirm with a soil test, the product label and an agronomist before applying anything.
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See all →Frequently asked questions
What does the fertiliser grade number actually mean?+
A grade like 46-0-0 or 20-10-10 lists the guaranteed percentage of nitrogen, phosphate (P2O5), and potash (K2O) by weight in that order. The first number is what you use to calculate actual nitrogen supplied.
Why isn't the nitrogen percentage the same as the amount of nitrogen fertiliser I need?+
The grade tells you the concentration, not the quantity — a 100 kg bag of 20-0-0 supplies 20 kg of nitrogen, not 100 kg. You must multiply the product weight by the grade percentage to find actual nutrient delivered.
How do I compare two products with different grades on a cost basis?+
Convert both to a cost per unit of actual nitrogen (cost of the bag divided by kg of N it contains) rather than comparing price per bag or per tonne of product. This reveals which product is truly cheaper per kg of nutrient delivered.
Does the grade account for how quickly the nitrogen becomes available?+
No — the grade is a guaranteed nutrient content, not a release-rate or availability figure. Slow-release and conventional products can share the same grade number while behaving very differently in the field.
Why do blended fertilisers sometimes have inconsistent grade numbers?+
Blends mix multiple granular sources, and if particle sizes differ significantly, segregation during handling can make the actual nutrient distribution in a given scoop differ slightly from the bag's average grade. This is less of a concern with granulated, non-blended products.