Fertiliser calculators

A useful collection of calculators to compare the return on investment and margin over fertiliser when using different fertilisers.

Wheat N Response S Barley N ResponseValue of Grass Nitrate vs Urea NS vs Straight N Compound vs Blend Tropicote Benefit

Nitrogen response on wheat

The optimum rate of nitrogen for wheat depends on the response of the crop to nitrogen, the crop value and the cost of nitrogen.  This calculator uses nitrogen response data to calculate the optimum rate of nitrogen at different wheat and nitrogen prices and also calculates the margin over fertiliser cost and return on investment for different applied rates of nitrogen.

Wheat nitrogen response calculator

To begin please enter the required values

Fertiliser details

Crop Details

Your results


Cost of nitrogen per kg

2.37 £ /kg N

Best Option

Optimum N Rate

Optimum N Rate

193 kg N/ha

Predicted yield

10.31 t/ha

Extra yield ?

3.69 t/ha

Extra crop value

997 £/ha

Cost of fertiliser applied

458 £ /ha

Return on investment

2.2 £/£ spent

Margin over fertiliser ?

539 £/ha

Comparison N Rate

Applied N Rate

160 kg N/ha

Predicted yield

9.96 t/ha

Extra yield ?

3.34 t/ha

Extra crop value

903 £/ha

Cost of fertiliser applied

380 £ /ha

Return on investment

2.4 £/£ spent

Margin over fertiliser ?

523 £/ha
results empty

Please enter the required values

The calculations of predicted yield and optimum nitrogen rate are based on actual n-response data derived from 15 years (2005-2021) of n-response trials using ammonium nitrate as the n source, as shown below.

Nitrogen response of winter wheat.png

It is possible to use the calculator for other sources of nitrogen such as CAN or liquid fertiliser but if using urea be aware that the nitrogen use efficiency may be reduced resulting in lower than predicted yields (of around 3-5%) which will affect the results.