Blog: Should I cut back on fertiliser application?

AHDB's Sarah Hurford explores farmers' current dilemma about whether to pay a premium for fertiliser to maintain grass growth or cut back and manage the consequences.

With the latest quoted prices for fertiliser topping the £600/tonne mark, triple the figures quoted just a year ago, many farmers will be thinking about their nitrogen application strategies.

Driver shortages and absences delaying deliveries are adding further complications, so decisions on fertiliser use this spring are more complicated than normal.

There is little expectation that fertiliser production will increase in the run up to spring as gas prices look likely to remain high. In addition, the winter heating period, and the need to refill storage facilities are expected to support demand, and prices, in the coming months.

With limited availability and potential delivery difficulties, postponing your purchases in the hope that prices will fall, does come with some risk, and needs to be balanced against any potential cost savings.

When making any changes to your farm business, it’s a good idea to do a partial budget to compare costs (extra or saved) and income (extra or lost) to see the impact on your business’s profit.

Reducing the application rate for first cut silage needs to offset the cost of buying in additional feed.

For example, assuming nitrogen costs £638 per tonne, reducing applications by 30kg N/ha over 15 hectares will save £830.

The trade-off is that silage yields reduce by 33 tonnes, costing an extra £924 if it had to be bought in (based on £28/ tonne). Overall, the hit to farm profits is a loss of £94.

Alternatively, a longer-term approach might be incorporate nitrogen-rich clovers into grazing leys enabling a reduction in artificial N.

As a result, the clover would supply 180kg worth of nitrogen, saving 7.8 tonnes of 34.5% ammonium nitrate fertilizer and delivering £4,976 worth of savings (based on £638 tonne. In the first year.

There are of course a multitude of options on how to adjust use of nitrogen on grasslands on your farm, but the same principles apply when assessing the impact on farm costs and budgets.

I’d encourage anyone who is reviewing their fertiliser options, to fill out a simple partial budget to help you make an informed decision. 

Review your nutrient management plans including nitrogen requirements of the crop using the RB209

• Section 3: grass and forage
• Section 4: arable crops

Keep an eye out for new N fertiliser guidance for grasslands which we’ve commissioned from ADAS.  The updated guidance will help with decisions around where feeding more purchased feed becomes more economically viable than applying N fertiliser, as well as which fields to prioritise and whether using variable rate nitrogen can help.

You’ll also be able to access a simple calculator (similar to that for cereals and oilseeds), which allows you to calculate the implications of reducing N application rates on grass and whether supplementation may be required.

Finally, if you’re a levy payer and you value independent, unbiased, and robust data, please register as part of Shape the Future via our website to have your say on how your levy is invested and where AHDB should focus over the next five years.

And if you are looking for support for future planning and decision making for your farm business sign up for our farm business review service as part of Defra’s Farm resilience fund and receive free consultancy advice. More details can be found on the Farm Business Review pages of the website.  

Partial budget example for reducing N applications

Partial Budget Example when incorporating clover into leys