At what point does the cost of N fertiliser negate the profit from a greater yield?

As the energy crisis begins to bite, driving fertiliser prices to new unforeseen heights (with no peak yet reached), part one of a two-part study, funded by AHDB and complied by ADAS, has just been published to help arable growers and advisers decide if a reduction in N applications will help their overall profitability and by how much they can potentially reduce by.

The goal of the research is to find the ‘economic optimum’ – the break-even price point at which the value of the extra grain is cancelled out by the cost of the extra N applied. The results should help growers optimise their nutrient management plans before applications begin in the spring.

The research brought together past N response curves for  three crops – wheat, barley and oilseed rape. The results indicate that if grain and rapeseed prices were held at £200/tonne and £500/tonne, the optimal reduction in use of ammonium nitrate fertiliser due to its price doubling from £345 to £690/tonne would be 50 kg/ha N. The resulting impacts on yields would be small, -0.36 t/ha in cereals and -0.16 t/ha in oilseeds respectively.

The review also assessed the way current price adjustments are listed in the RB209 and whether new evidence required a recalibration.

“However, the sharper shape of barley’s response to N was not entirely convincing from recent trials results, so we concluded that adjustments for the high prices should remain the same for both barley and wheat” said Roger Sylvester-Bradley, who led the study.

The second half of the review is due in January 2022 will look at a wider range of arable crops, how N should be prioritised if prices remain high and the long-term implications for fertiliser rates and N management.

Read the full report here

The need for precision nutrition

For Agritech Week on 8 November 2021, ADAS scientists Daniel Kindred and Kate Storer were joined by leading fertiliser performance experts to review methods and strategies to maximise nitrogen use efficiency in the light of both spiralling fertiliser costs and growing demands both from within and outside the industry to reach net zero agricultural emissions.

Watch back below