Nitrogen fertiliser adjustment calculator for cereals and oilseeds

Based on RB209 fertiliser guidance, use this tool to establish the economic optimum amount of nitrogen to apply to crops.

Based on RB209 fertiliser guidance, use this tool to establish the economic optimum amount of nitrogen to apply to cereals and/or oilseeds crops. Accounting for fertiliser and grain prices, it suggests potential adjustments to your typical farm nitrogen rates.

Why did we develop this tool?

An energy crisis contributed to unprecedentedly high fertiliser prices in 2021. This led to a new ‘economic optimum’ – or the point at which the value of extra grain produced is not worth the cost of the extra nitrogen applied (break-even-ratio) – for nutrient management.

To account for higher prices, we commissioned a review to extended RB209 fertiliser price tables:

  • By up to £2.50 per kilogram of nitrogen (equivalent to £863 per tonne of ammonium nitrate)
  • By up to £350 per tonne for cereals and £700 per tonne for rapeseed (to account for stronger prices)

The tool is based on the revised figures.

How best to respond to costly fertiliser nitrogen for use in 2022 (research review)

How should farmers manage costly nitrogen fertilisers? (blog)

Latest RB209 update ‘on track’

What does the tool calculate?

For a specified crop, this tool calculates*:

  • Cost of nitrogen fertiliser (£/kg)
  • Break-even-ratio (kgs of grain required to pay for a kg of nitrogen fertiliser)
  • An estimated change to nitrogen application* (kg/ha)
  • An estimate of the effect on yield/income (£/ha)
  • An estimated impact on nitrogen fertiliser costs (£/ha)
  • Total nitrogen fertiliser product required for the specified crop area planted (t)

*Compared to your typical nitrogen rate. Estimates provided can guide decision making. However, local adjustments may be required to fit specific circumstances.

What figures (inputs) are required by the tool?

Each crop calculation is based on five figures:

  1. Fertiliser product price (£/t)
  2. Fertiliser product nitrogen content (%)
  3. Expected grain price (£/t)
  4. Typical nitrogen rate (kg/ha)
  5. Crop area planted (ha)

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