How best to control blackgrass when land returns to cropping

Farms bringing land back into production after the Sustainable Farming Incentive could see an unintended increase in blackgrass.

Cover crops could be a good option to manage any increase in blackgrass populations that occur within SFI options when land returns to cropping, says Alice Cannon, technical manager for the Hutchinsons Foundation.

Growers putting land into an SFI option might even be better off longer-term from accepting the slightly lower payment and increased investment associated with stacking multi-species cover crop options, says Ms Cannon.

Control strategy

These options – such as SAM2/CSAM2, SOH2 and SOH3 – allow for blackgrass control, she explains. Options such as winter bird food might appear more lucrative because they are paid at a lower rate – but they don’t allow for blackgrass control.

“The first step would be to sow a winter cover,” says Ms Cannon. “That would be sprayed off in March, followed by a spring-sown cover crop, which would remain in the ground from March until June. The next stage would be the summer-sown cover, lasting from June until August. The total support payment would be £455/ha per year, which is often better than spring bean gross margins.”

Clean seedbed

“This regime offers a break in rotation, plus three opportunities to bring blackgrass under control – and the potential to provide a clean and fertile seedbed which would boost first wheat yields,” she says.

Selecting the right mix is key to maximising cover crop benefits, says Ms Cannon. Multi-species mixes provide more advantages than simple two-way blends, such as mustard and oats, she adds.

“Use at least six different plant species taken from three or four families. We have made some bespoke cover mixes that achieve the aims within Hutchinsons Maxi Cover range.”

Water storage

Farms with a history of blackgrass are particularly at risk of a resurgence. The diversity of growth habit and root structure helps build a more resilient soil structure, and improves aeration and water management, she adds.

“The soil will have greater ability to store water lower down in the profile in times of prolonged drought. It will also ensure moisture is not lost closer to the surface through run-off in high rainfall situations.”

If growing legume fallows in black-grass situations, Miss Cannon advises growing a mix containing grasses and legumes to increase competition against blackgrass.

“They can be mown as required within the first 12 months once blackgrass begins to head, however continuous mowing can lead to black-grass growth habit switching to a short profile and becoming more difficult to tackle, she says. “In year two, fallows can be mown between March and mid-June, leaving eight weeks uncut in the summer.”