Choose cover crops carefully to avoid problems later, growers urged

Simon Montgomery, ProCam technical lead for Field Options performance seeds, says cover crops can clearly offer multiple benefits – including building soil fertility, improving soil structure, suppressing weeds and helping to prevent soil erosion.

But it is important to avoid potential downsides that individual species might transmit to following crops, he says, by having a clear picture of your rotation and choosing cover crop mixtures appropriate to individual field situations.

“Cover crop choice is about assessing multiple factors,” says Mr Montgomery. “Know what you want to achieve from them, but also understand your site and any limitations.

“One watch out is the potential for disease transmission. For example, avoid cover crop mixes containing brassica species, such as mustard or radish, to reduce the risk of clubroot carryover if you have oilseed rape or other brassicas in the rotation.

“Similarly, in cereal-based rotations where take-all is a concern, avoid cover crops containing species, such as wheat or barley, that can act as a take-all host.

“Also, think about the impact that any volunteers of cover crop species could have on the next crop. Oats are fairly common in cover crop mixes, but you don’t want volunteer oats growing in milling oats in the rotation, in case they compromise the milling sample.”

Another practical factor to take into account when choosing cover crops, says Mr Montgomery, is the different seed sizes of the species in the cover crop mix.

He says although this is less of an issue with smaller capacity drills, where bigger drills are used to plant large areas of cover crops, seed species separation and settling out of the mix in the hopper can lead to these species being planted as straights.

“Selecting cover crop mixes containing species with similar-sized seeds can be a massive help if you’re looking to drill large areas with large drills. If in doubt, consult an agronomist,” he adds.