Nutrient release from cover crops (desk study)

Many more farmers now include cover crops in their crop rotations. This has been partly incentivised by payment opportunities, most notably from the Sustainable Farming Incentive (SFI) scheme.

In addition, the movement towards the adoption of regenerative agriculture, which has ‘keeping soil covered’ as a core principle, has encouraged cover crop adoption.

Cover crops have the potential to provide a wide range of benefits. The evidence for some of these benefits is clear, such as reducing soil erosion and nitrate leaching risks.

One of the biggest knowledge gaps is associated with legacy effects, especially the amount and timing of nutrient release from cover crop residues.

This gap is complicated by:

• The wide range of cover crop species mixes available
• The diversity of agroclimatic conditions across the country (e.g. soil types, cropping and weather)
• The different management practices adopted (e.g. sowing and destruction dates and methods)

At present, the AHDB Nutrient Management Guide (RB209) provides little information about the impact of cover crops on soil nitrogen supply (SNS) and no guidance on the release of other nutrients to cash crops.

Recent feedback from UK farmers highlighted how the lack of information hinders the creation of accurate nutrient management plans (NMPs) to help them target fertiliser applications to meet crop requirements. In fact, very few plans allow for nutrient supply from cover crops.

AHDB, with Anglian Water, Southern Water and Wessex Water (co-funding industry partners), want to help farmers integrate cover crops into their cropping systems.

This desk study will explore the potential to develop a decision support tool (DST) for the UK that accounts for nutrient release from cover crops and similar organic materials (such as companion crops).

With a focus on nitrogen, this project will build on tools available in other countries, such as:

• The MERCI nitrogen model (France)
• The cover crop nitrogen calculator (USA)

The work will also consider:

• The demand for a UK tool
• The potential accuracy of tools
• How tool recommendations could impact nutrient management

It will also consider related research projects, such as the nitrogen release from cover crops (NiCCs2) project, which examines the impact of destruction methods and timings on the nitrogen release from cover crops.

Initial results

Initial project results will be presented by Kate Smith (ADAS) during a webinar on the nutrient benefits of cover crops.

Starting at midday on 23 June 2025 (lasts one hour), the webinar will also share results from a related project on nitrogen release from cover crops.

Register for the webinar

We will also present initial results at the:

• Cover crop seminar at Cereals 2025 (day one, 11 June 2025)
• Cover crop clinic at Groundswell 2025 (2 to 3 July 2025)

Providing answers to your questions

This research project was funded via a levy-payer-led commissioning process.