Most growers would consider a combination of wet weather, heavy soil and spring cropping a stern test at best. However, by growing a suit-able cover crop and spraying it off at the right time, a following spring cereal crop can be established successfully and on time even in such testing conditions, says Agrovista technical manager Mark Hemmant. The work was undertaken this spring at the Project Lamport site in Northamptonshire, where Agrovista, with the support of Bayer, is investigating new concepts to control black-grass on heavy land. Key among these ideas is the growing of overwintered cover crops that are open enough to allow black-grass to establish freely in the autumn, but that have enough biomass to draw moisture out of the heavy land from depth so the following spring wheat can be drilled in good time. The cover crop/black-grass mix is sprayed off two weeks before drilling. ""Both 2014 and 2015 springs were kind, with plenty of dry weather to help us establish spring wheat after the cover crops in good conditions.”We used a Great Plains Saxon direct drill. Its design, in conjunction with the cover crop debris, helped us keep soil disturbance to a minimum, greatly reducing the chances of a fresh black-grass flush. ""We achieved exceptionally clean crops with practically no black-grass that yielded almost 9t/ha in 2014 and 10t/ha last year."" This season proved a sterner test. Spring wheat sowing was delayed where cover crops were sprayed off at the usual early March timing. Instead of being drilled two weeks later, the wheat went in on 11th April. ""All the cover crops trapped moisture on the surface. This was part of our original intention — use cover crops over the winter to dry out soil at depth but use the debris to conserve enough moisture to encourage a rapid chit. ""This worked very well in 2014 and 2015. This spring, it rained every day and we couldn't get going any earlier."" There were marked differences between the cover crops in the trial. Agrovista's standard black-grass reducing cover crop, Chlorofiltre 25, a mixture of black oats and common vetch, did a good job in drying the soil to depth, and also allowed the surface to dry better than other cover crops. The Saxon drill did an excellent job in the conditions and performed well where other black oats mixtures had been grown, says Mr Hemmant. Brassicas and tame oats in particular tended to hold too much moisture at the surface. ""You could see very clearly after plots were drilled which was which," says Mr Hemmant. For the first time, black-grass itself was also trialled as a cover crop, says Mr Hemmant. ""Some farmers have said they have so much black-grass, why not use it as the cover crop?"" However, it turned in the worst performance, leaving soils very wet, even deep down. A further area was left fallow with overwintered volunteers. This also remained very wet, illustrating the soil-conditioning value of a cover crop, he adds. The trial is also examining the effect of cover crop destruction date on crop establishment, and the work suggests timing could be manipulated in a wet year to obtain a drier soil surface. One area sprayed off in early February was drilled on 22nd March. There was less cover crop biomass and therefore less debris. ""The soil surface was practically bare and able to dry out more quickly," says Mr Hemmant. ""Usually we spray off the cover crop later to get the maximum soil conditioning and black-grass control, but it appears we still achieved both those aims and the spring wheat looks excellent. In a wet spring, there is a potential benefit to spraying off early," Mr Hemmant explains. The performance of several different drills and how they cope with cover crop debris is also being investigated this year. ""We may find that certain cover crops are suited to certain drills, especially where larger amounts of residue keep the surface wetter for longer, as this year"" says Mr Hemmant.
PROJECT LAMPORT OPEN DAYS
Readers can see for themselves how the difficult season has affected crop establishment and black-grass emergence as well as drill perform-ance by attending one of several open days at Agrovista's Project Lamport site, towards the end of June (dates to be confirmed). Guided tours will be available covering the whole of the Project Lamport, which aims to look beyond current cultural control tech-niques for black-grass to help maintain prof-itable crop production. The five-year rotational study set up by Agro-vista and supported by Bayer is comparing the effectiveness of different rotations to control very heavy infestations of black-grass on the heavy-land site. These include spring wheat drilled after an overwintered cover crop, September versus October-sown winter wheat! OSR rotation, fallow, hybrid rye whole-cropped for anaerobic digestion plants and cover crops left to grow through the season. ""Over the past two years that Project Lam-port has been running it has been relatively easy to establish spring crops," says Mr Hemmant. ""This year has been very different, and there will be some very interesting com-parisons to be made highlighting the challenges a difficult spring can produce."" Nearby trials examining winter wheat herbi-cide efficacy, the performance of ethofumesate which has recently been approved on winter wheat, as well as spray application work will also be available to view on the open days.