A new range of tailor-made cover crop mixes includes options to help improve the structure and health of land left fallow this spring because of the wet weather.

Agronomy firm, Hutchinsons, thinks that with many fields in the wettest parts of the UK likely to take weeks, if not months, to dry out enough before spring drilling is possible, more growers will opt to leave land uncropped, rather than force a seedbed and damage soil structure in the process.

“This year, specifically, a lot of fields are in a mess after late-harvested crops like maize, potatoes and carrots, while others remain waterlogged,” said its bio-agri ecologist, Ed Brown. “We’re past the situation where winter wheat is viable, while spring barley prospects don’t look great given the saturated market and likely difficulties of creating a seedbed in time.”

Leaving fallow land bare and trying to rectify structural issues with cultivations alone is likely to worsen soil structure problems rather than alleviate them, so cover crops will have a vital role, he reckoned.

“You need roots in the soil to feed biology, restructure soils, build organic matter, and act as a water pump to manage moisture through the profile. The benefits of cover crops are well-proven.”

Mr Brown and a team of colleagues have assessed a range of soil types, cropping and agronomic situations, to develop five bespoke cover crop mixes, including two short-term spring/summer catch crop mixes alongside three options for overwinter cover.

Although the short-duration catch crop mixes were primarily developed for the narrow six to eight week window between harvest and autumn drilling, they could be just as effective on land destined to be left fallow this spring.

Experience with cover crops clearly shows that mixes based on a diverse variety of species are more effective than those featuring just one or two. Having a range of root and canopy characteristics spreads risk and delivered wider benefits to soil structure improvement, nutrient capture, and organic matter additions, Mr Brown added.

Diversity also helps mitigate potential ‘green bridge’ issues for pests and disease. “Growing a single or two-species cover crop mix based on a high proportion of a brassica species, for example, could potentially increase pest or disease risk in a following oilseed rape crop.

“However, that risk is virtually eliminated when you use a more diverse mix featuring a low proportion of brassicas,” he pointed out.

“We’ve based our mixes mainly on species of legumes, brassicas and forbes – non-woody herbaceous, broadleaf plants – that we know how to manage and that have proven effectiveness in UK conditions. We offer six-way and three-way mixes for our catch crop options, while the overwinter mixes each feature eight different species.”

However, cover crops must be established properly to maximise their benefits. This typically requires more effort than just spinning seed on to stubble with a fertiliser spreader, or slug pelleter, although the most appropriate technique depends on individual situations and soil types.

“Many growers choose to drill cover with a conventional seed drill, but equally, we’ve seen good results from using a seeder unit mounted on a shallow cultivator, or set of rolls.”

Where land is waterlogged and likely to take weeks to dry out enough before sowing, spring cover crops are ideal as they can be sown from mid-April, giving ample time for conditions to improve. They will grow rapidly in warm, moist soils and, in just 10-12 weeks, should deliver many soil health benefits, before providing a suitable entry for a following autumn-sown crop.

Mr Brown allayed concerns about cover crop volunteers in following crops, insisting the risks can be mitigated by identifying the species which may cause issues. “It is something to be aware of where cover grows rapidly, especially if mixes include brassica species such as mustard or radish which can be more awkward to control in some cash crops later in the rotation.”

Looking ahead, Mr Brown said that while glyphosate remained a key option for terminating cover crops, there is increasing interest in other methods, such as crimper rollers and grazing with sheep.

“Integrating cover crops with livestock is a good tool for improving soils, but it needs careful management and ensure whoever manages the livestock is on board with what you’re trying to achieve with the cover crop to tailor the grazing regime accordingly,” he said.