We need your views on how cover crops impact weeds

A first-of-its-kind AHDB initiative will gather commercial experience and review the evidence on the impact of cover crops on arable weeds. Siobhan Hillman, an AHDB Crop Protection Scientist, explains.

Cover crops have become a staple part of many crop rotations.

The uptake of regenerative agriculture, to keep soil covered to reduce erosion and nutrient losses, and environmental payment opportunities, have underpinned their popularity.

In recent years, we've invested in several projects to close major knowledge gaps on cover cropping, including an active investigation into how cover crops take up and release nitrogen.

I am now leading an in-house scoping review to tackle the tremendous uncertainty on how cover crops impact weed populations.

It's the first time we've focused solely on this topic. Although, it has formed part of wider AHDB research projects in the past.

The potential weed-suppressing effects of cover crops (including as a rotational break) were considered during our review of weed control in UK cropping systems in 2019. However, this unearthed little in-field evidence.

Similarly, our review of cover crop destruction approaches and soil health impacts in 2025 also found very little UK-relevant evidence on the risk of cover crops increasing weed burdens.

It's a complex topic, as many factors combine to influence weed dynamics, including:

• Current weed pressures/profiles
• Tillage systems
• Rotations
• Cover crop species and mixes
• Management, including how cover crops are terminated

It's a classic example of where farmers are often ahead of the research, which is why the new scoping review will collate real data from real farms.

I am reaching out to farmers and advisors, from arable and mixed-farming systems, who can provide critical real-world evidence to shape the review, as well as researchers active in this field.

Next month, I'll run structured interviews (up until Friday 17 April) to gather intelligence on cover crop usage, with an emphasis on field experience of weed management implications.

Each one-to-one interview is likely to take less than half an hour.

We will anonymise all responses in the project outputs and keep you up to date with project progress.

If you would like to be interviewed, please email me: siobhan.hillman@ahdb.org.uk

Please state your preferred method of communication (telephone, online or email) and times when you will be available for interview.

In the review, I will consider the main cover crop types (brassicas, legumes, cereals, grasses and herbs), the common management approaches and the influence of environmental schemes, such as the Sustainable Farming Incentive (SFI) scheme in England and the Ecological Focus Areas (EFA) scheme in Scotland.

A thorough literature review will also put all evidence in one place, along with information on the strength of the evidence base.

The scoping review’s findings will be considered by the AHDB Research & Knowledge Exchange (R&KE) committee during the summer to set investment priorities, with results made publicly available shortly afterwards.