Defra’s proposed urea fertiliser rules to be introduced to the Red Tractor farm assurance scheme from April 2023 have been delayed by a year.

The original plan was for Red Tractor-assured farms in England to use only untreated urea fertilisers between 15 January to 31 March, and urease inhibitor-treated products thereafter.

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But given the current climate of nitrogen supply issues and price volatility, a formal request from an industry consortium – including Niab, Association of Independent Crop Consultants and NFU – has been made to delay the introduction until 1 April 2024, ahead of the 2025 fertiliser season.

Defra has told Farmers Weekly the implementation is now postponed, but it will monitor progress on industry action and regulate if necessary.

The advisory body stands by its agreed plan to reduce ammonia emissions through an industry-led approach via the Red Tractor assurance scheme.

However, Red Tractor has not been contacted by Defra to formally impose any new standards.

Once issued by Defra, the mandate is expected to take about a year to be introduced to the farm assurance scheme – a considerable delay to the current timeline.

A Red Tractor spokesperson said: “Red Tractor is there to support industry should it require new Red Tractor standards and is ready to respond when asked to do.

“However, we have had no forthcoming request from Defra to implement any potential new mandates on the use of urea fertiliser.”

Why is urea under the spotlight?

Defra plans to reduce ammonia emission levels by 16% (48,000t) by 2030, from the base year of 2005.

Typically, UK N volatilisation losses are about 20% for urea, but in extreme situations, these can be as high as 40%.

Urea is a key component of crop nutrition programmes, thanks to its high nitrogen content, larger supply and cheaper cost than ammonium nitrate.

Through a process called hydrolysis, urea must react with water in the soil to produce ammonium.

If urea is not effectively incorporated into the soil post-application, it is at risk of volatilisation, where nitrogen is lost in the form of ammonia gas.

Besides reducing a farmer’s bottom line, ammonia emissions negatively impact the environment and pose a risk to human health, habitats and water supply.

How inhibitors can help

Urease inhibitors work by slowing hydrolysis, blocking the enzyme urease to reduce the amount of ammonia released.

Protected urea fertilisers, therefore, reduce the risk of N volatilisation and increase nitrogen use efficiency.

However, inhibitors only partially delay urea hydrolysis for 7-14 days. Dependent on field conditions and inhibitor type, they can be between 20-70% effective and cost between £7-£23/ha per 100kg of N applied.

This makes treated urea fertilisers only marginally cheaper than ammonium nitrate.

The following general good practice alongside inhibitor is recommended to reduce ammonia loss:

• Time applications when soil temperatures are low, the soil surface is wet, or ideally before rain is expected
• Do not apply urea to moisture-limited soils or to saturated soils, which can lead to run-off.