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Arable

Searching for heavy land success in spring crop conundrum Now in its fourth year, Agrovista’s ‘Project Lamport’ trial site in Northamptonshire continues to focus on approaches to reliably drill spring crops on heavy land, as growers look to them as a means to reduce burgeoning black-grass populations. Dominic Kilburn writes. Agrovista technical manager Mark Hemmant (rght) is in no doubt – controlling black-grass with herbicides has become a lottery. It’s essential, he stressed, that we look at other ways to reduce black-grass pressure and that starts with cultural control. Mr Hemmant was talking at the company’s heavy land trial site called Project Lamport, near Maidwell in Northamptonshire. The trial, now in its fourth year, consists of 14 different rotational systems and is set within high black-grass populations. In fact, ahead of the project starting and the entire site being ploughed, black-grass plants numbered 2,000/m2 – a legacy of the continuous wheat/oilseed rape rotation of the preceding 10 years. “Although we know spring cropping is one answer to the black-grass problem, no-one has actually provided growers with good information and advice on how to establish spring crops on heavy land,” he stated.

Different systems “Traditionally in this area of the country and on this type of land, it’s been extremely difficult to get good seedbeds in the spring with which to establish successful spring crops,” continued technical manager Stewart Woodhead (right). “So this project is all about finding the best ways to enable growers to reliably establish spring crops on heavy land while looking at everything possible to reduce black-grass pressure,” he explained. According to Mr Woodhead, over the life of the project, the trials have managed to demonstrate that crops such as spring wheat and spring barley can be reliably established on the site, albeit with help from cover crops in the rotation. The combination of spring crop and cover crop has helped to reduce black-grass infestation while also providing soil-enhancing benefits. However, what has also become clear over the past four years is that

attention to detail is key, warned Mr Woodhead. “While an important focus of the trial is to minimise soil disturbance in order to reduce the amount of germinating black-grass, we have seen that even the wrong tyre pressure on a tractor pulling the drill can stir up the soil and encourage black-grass to germinate in the crop,” he highlighted.

Success Developing into what is proving to be the most successful rotation at Project Lamport in terms of crop establishment and black-grass control, “System 3” has featured four years of autumn established cover crops followed by spring wheat. The latest crop, KWS Willow, was direct drilled for minimal soil disturbance on the 28th March at 500 seeds/m2. “We combi-drilled and then rolled our cover crop in early September following a pass with an X-Press disc harrow, and the idea with the cover crop is that it remains open enough to ‘trick’ the black-grass into germinating with it, as it would in a conventional crop,” said Mr Woodhead. “The important thing is that we are not smothering the black-grass to prevent it coming through,” he added. The cover crop was then burnt off with glyphosate in February, some four to six weeks ahead of drilling, followed by a second glyphosate close to drilling in March to kill off any remaining black-grass. “The cover crop has taken moisture out of the soil as well as ‘accidentally’ bringing out the black-grass to enable it to be sprayed off and to give us very good control,” he commented. “This is the only plot on the site with more than 98 per cent

Four years of autumn established cover crops followed by spring wheat is a rotation that is “working” at the trials site.

control of black-grass and, compared with some on the other plots where we have returned as much as 250 blackgrass seeds/m2, with this system we’re only putting back 40kg of black-grass seed/ha.” Mr Hemmant added that when direct drilling into heavy soils like this, 40–60 per cent crop establishment was typical and so it was critical that high seed rates should be considered to ensure the crop is sufficiently competitive against black-grass. “This particular rotation is working for the farmer. Yes, it’s a lot of money to grow and then spray off a cover crop, but what’s the alternative?”

Early destruction In a separate rotational plot where a cover crop was again followed by spring wheat, similarly good results in terms of black-grass control were achieved, but an earlier destruction of the cover crop – in December rather than February – has resulted in improved yields (an additional 0.5t/ ha in 2015 and 0.7t/ha in 2016). “We think the roots of the cover crop held the soil structure together and allowed the direct drilling to take place earlier. Once established the spring wheat was better able to cover the ground because of the earlier destruction of the cover crop,” pointed out Mr Hemmant.

Standard practice If growers on heavy land with traditional wheat/OSR rotations and increasing problems with black-grass ever needed reminding that they are going to have to do something different if they want to remain in business, then the aptly named ‘Standard Practice’ rotational plot is a demonstration of the stark reality some are facing, suggested Agrovista. “The initial plough was followed by a first wheat (and full herbicide programme) and gave quite good black-grass control,” said Mr Woodhead. “But three more years including a second wheat followed by OSR and then wheat again, brought all the black-grass back again – just four years after using the plough as the re-set button. This year we’ve spent around £150/ ha on black-grass chemistry, we’ve got 500 black-grass heads/m2 and I expect yields to be in the 5–7t/ha range.” Mark Hemmant added: “The question for anyone in this situation is what are they going to do now? Ploughing is not an option as we got 300 black-grass seeds/m2 two years

“The cost of cover crop seed is in excess of £40/ha but what is there to lose when you are spending £80–150/ha in herbicide cost and still getting blackgrass?” questioned Mark Hemmant.

after the plough and we can’t herbicide our way out of it. By the second year we’d already lost the benefit of the plough. “The cost of cover crop seed is in excess of £40/ha but what is there to lose when you are spending £80–150/ ha in herbicide cost and still getting black-grass?”

Strong tap root Along similar ‘Stand Practice’ lines, a late sown wheat was drilled after the plough in 2014, followed by Hyvido winter barley in 2015, winter OSR plus a companion plant (berseem clover) in 2016 and this year back to a first wheat (Lili drilled on the 28th October at 450 seeds/m2) following a catch crop of black oat and berseem clover. “The berseem clover dies with the first frost but it has a strong tap root to push down through the soil and this helped the OSR to establish,” explained Mr Woodhead. “However the catch crop was more there to take up the moisture before the late drilled wheat as it can get difficult to drill wheat after the first week in October in this area.” According to Mr Woodhead, half as much black-grass was found coming up through the first wheat compared with the other Standard Practice plot, both because of the competitive nature of the Hyvido barley and the late drilled wheat beforehand, he suggested. “We need 98 per cent control to keep levels of black-grass static. With this system we’ve had a full herbicide programme and several cultural controls including ploughing and late drilling, and we’ve used glyphosate, but after four years we are in trouble again, returning more black-grass to the seedbank than we are removing.” continued over...

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