Welcome return for wheat after tackling blackgrass

• System works ‘fantastically well’

• Soils were smothered in weeds

• Problem is now being managed

A profitable return to early winter wheat on land with a serious blackgrass history is raising hopes for growers.

Trials consultant and coordinator Niall Atkinson wondered what he was getting involved with when he first set eyes on Agrovista’s flagship Lamport AgX site a decade ago. The background blackgrass population was around 2000 plants/m³ on heavy, difficult soil.

The silty clay soils were smothered in the weed – typical of this area of Northamptonshire and many other arable areas. It followed years of close-cropped winter wheat and oilseed rape, intensive cultivations and struggling chemistry.

“When I first saw the site it frightened the life out of me,” said Mr Atkinson, at a recent Lamport AgX open day. “I had never seen grass weeds growing like they did here.”

Testing ground

The site has proved an ideal testing ground for the work that has since been carried out. The initial focus was blackgrass control, which resulted in Agrovista’s proven technique of combining overwintered cover crops and spring cropping, which drastically reduced blackgrass populations.

The emphasis has now switched to the bigger soil health picture.

The trials site is now examining how rotations, cover cropping and regenerative agriculture principles can interact to improve soil health and yields while maintaining blackgrass levels at manageable levels.

“We have found that soil health improvement and good grass weed control seem to go pretty much hand in hand, and we’ve created a system that works fantastically well,” said Mr Atkinson.

“We’ve proved to a lot of local growers that that we can grow successful spring crops on heavy, challenging soil, and control blackgrass at the same time.”

However, given the profit potential of a good first winter wheat, many farmers want to know when they can start growing it again.

“It’s a question that is even more relevant today, given the price of wheat,” said Mr Atkinson. “We’ve now found that you can return to growing first wheats, but you need stick to the guidelines or risk going backwards.”

Patience certainly pays if the results at Lamport are anything to go by. First wheats grown after a run of cover crop and spring cereals look clean and healthy, with scarcely a blackgrass head to be seen.

“I am very proud of these wheat plots and what we have achieved, knowing the extent of grassweed pressure here on this site, particularly as these are September-sown wheats, not drilled at the end of October or into November which can be fraught with problems on this land.”

Cover cropping

Previous cropping consisted of a black oat-based cover crop followed by spring oats in 2019/20, followed by cover crop then spring beans last season. The winter wheat was direct drilled on 28 September at 300 seeds/sq m into a cheap linseed/berseem clover cover crop that was blown into the preceding crop.

“The main reason the cover crop was there was to provide a bit of insurance – had it turned wet, it could have been left overwinter ahead of spring-sown wheat.”

The first wheats received full rate chemistry to control blackgrass – Proclus Liberator and Avadex followed by full-rate flufenacet early post emergence. 

“We know even new chemistry, whether Proclus or Luximo, applied in a stack is not good enough where blackgrass numbers are high,” said technical manager Mark Hemmant. 

“We have to get to the stage where we’ve reduced the weed seedbank to a low enough level that herbicides can give us this sort of result.”

Mr Atkinson cautions against pushing too far. “The next question growers ask is whether they can follow with a second winter wheat. We would say that is the last thing to do. You are locked into high input costs and losing money while making blackgrass worse again. At a site like this we would always advocate a cover crop followed by a spring crop after returning to a first wheat.

Cover cropping

“However, we have put in winter wheat in after spring wheat. But note the previous cropping – it’s been cover crops followed by spring wheat for the past four years.

“We’re not advocating September sowing of the winter wheat; this was drilled on 14 October.

“There is a bit of grassweed, but nothing we can’t deal with by following with a black oat-based cover crop this autumn then spring wheat. We’ll then go back into winter wheat.

“We could perhaps break after two or three years and put spring beans in – we’ll see where it goes. If it works, it could be quite a nice rotation.”