Avoid the companion cropping pitfalls – Farmers Guide

Companion cropping has become an increasingly popular option on arable farms, boosted by its inclusion within the SFI (CIPM3). But particular issues can arise when growers go into companion cropping on fields with underlying black-grass issues, for example, and then subsequently realise control options are more limited, says Hutchinsons foundation technical manager & agronomist, Alice Cannon.

“Beans or peas are your only real option if you still have black-grass and want the companion crop to survive pre-em grassweed chemistry,” she says.

While a combination of berseem clover and buckwheat is a popular and effective companion cropping option in oilseed rape, in wheat, buckwheat is too competitive if it gets established, and will not survive low temperatures, or many pre- em chemistry mixes, she adds.

Understand the aims – Companion crops can potentially deliver many benefits such as improve structure, nitrogen fixation, organic matter addition, weed suppression, trap cropping, and biodiversity and habitats for birds and invertebrates. Be clear about your aims and what can realistically be achieved. Also understand how it complements the commercial crop.

Establish it well – When growing beans as a companion with winter wheat, for example, make sure beans. are covered with soil as this helps to protect germinating plants from pre-em herbicides, especially where more complex ‘stacks’ of chemistry are being used for black-grass control. Beans can either be drilled before the wheat, or spun onto the surface before cultivating or drilling to bury seed; but either way, seedmust be covered.

Consider emergence timings – Because beans take longer to germinate than wheat, they can remain dormant while the main pre-em chemistry is being applied, germinating once activity is starting to decline. They can therefore be more resilient to bigger stacks of chemistry, providing seed has been buried.

Check seed rate carefully – When determining the optimum seed rate, growers need to weigh how much seed is needed to deliver the aims of the companion, without compromising the commercial crop, while also allowing for any potential establishment losses (e.g. due to the impact of pre-em chemistry). Generally, when companion cropping beans with winter wheat, aim to establish 10 bean plants/m2.

Plan termination in advance – Unlike bi- cropping, where both crops are taken through to harvest, companion crops are not present for the full growing period, and are usually terminated by the following spring. When choosing any companion crop, it is always worth considering how and when it will be taken out, as this may influence what you grow. Also consider how it can link with other stewardship options – for example, can beans be left until flowering, and terminated once a neighbouring legume fallow starts to flower, thereby providing a continuous nectar source for pollinators?

“Ultimately, whatever you do, make sure the companion crop will complement the commercial crop, not hinder it,” says Miss Cannon. “While the £55/ha payment that growers can receive for companion cropping via the SFI is useful, it isn’t enough to warrant not having a good commercial crop at the end of it.”

Lincolnshire grower David Craig, farm manager at Peter Moulds (Farmers) Ltd, has been growing companion crops for the past seven years and believes they, alongside overwinter cover crops, are delivering benefits to soil health across the 245ha arable farm.

“Since undertaking some 12m strip trials of various different oilseed rape companion crop mixes with Alice Cannon all of the farm’s oilseed rape (40ha) has been grown with a companion crop, comprising 60% berseem clover and 40% buckwheat. “We put on 10kg/ha with the subsoiler a week before we direct drill the OSR, which includes a bit of DAP fertiliser down the spout.”

The companion crop is generally terminated in late November/early December with an application of aminopyralid + propyzamide.

Given the success of companion cropping in oilseed rape, this coming season, all winter wheat and winter barley will also be grown with a companion crop of spring beans. “We’ll aim to establish 10-15 plants/m2, which we’ll broadcast on before drilling. There is sufficient movement of soil with a pass of the drill to cover them.

“We’ve seen before in fields that have grown beans, that where there’s a good plant stand of volunteers in the following winter wheat, they are bringing benefits to soil structure and nutrition. For the past few years, we’ve left beans until the spring, and taken them out using a herbicide with the T1 fungicide.”

The same approach will be taken to companion crops going forward, he notes. “Other than the cost of the bean seed and broadcasting it on, which is likely to be around £15-20/ha in total, it’s not really causing us any more work or significant cost, and we can get a small payment for doing it via the SFI, which helps. Financially, we’re much better off doing it, and there are the benefits for soil structure too.”