Article taken from Arable Farming Magazine
Seed rates, spring cropping and close attention to cover cropping agronomy are just some of the techniques being used to combat black-grass as part of Agrovista's Northamptonshire-based Project Lamport, now in its third season. Despite later drilling dates due to poor weather conditions this spring, spring cropping has continued to work well as a black-grass, control method in the five-year project.
Agrovista technical manager Mark Hemmant describes how spring wheat following a cover crop has achieved good control of the weed. ""This year was challenging; wet with limited drilling opportunities, but the system has worked again even in a difficult year."" He advises drilling wheat in the same direction as a previous cover crop. ""If you drill crossways there is more soil disturbance."" Spring wheat is less costly than winter wheat to grow but can yield similarly, says Mr Hemmant. ""In year one we had 8t/ha and in year two, 9.5t/ha. This year will be less because of less sunlight and later sowing on April 11.""
High seed rate
With spring crops it is important to have a sufficiently high seed rate, he says. ""There has been very little agronomy work done on spring wheat for many years. It was recommended at 350 seeds/sq.m for light soils with 90% establishment. But it should be SOO for heavy soils with 60% establish-ment. You need competition. Spring wheat will not tiller as well as winter wheat.""
Where cover crops are grown, spraying them off early can be important to spring crop establishment, says Mr Hemmant. ""For the first two years we sprayed the crop off in December. Cover crops can lock up nutrients to the detriment of a spring crop. When direct drilling there is no mineralisa-tion of nutrients. When you burn the cover crop off early there is chance to mineralise some of the nutrients. ""Last autumn we sprayed the cover crop off in November. We tried to drill on March 22 and the surface had dried off. None of the other plots drilled satisfactorily. I like the idea of early destruction."" As well as seed rate, seedbed nitrogen is also important to allow spring crops to compete effectively against black-grass, says Mr Hemmant. ""It should be going down the spout at 90kg/ha. Some are not applying nitrogen until the crop is up. They are missing a trick:'
Flexibility
Although spring wheats are likely to generate a higher income than spring barley, for growers looking for a more flexible drilling date and early entry for oilseed rape it is a good option, says Mr Hemmant. ""Spring barley has more herbicide choices and if you don't do it exactly right it doesn't matter. Barley is out of the ground quicker and covers the ground quicker."" For those believing they can grow cover crops followed by a spring cereal for a couple of years then revert to winter cropping, Mr Hemmant urges them to think again. ""The assumption you can plant a spring crop to clean it up doesn't work. You are back to a high population of black-grass:' Companion crops are also being studied as part of Project Lamport and have shown significant benefits in terms of oilseed rape yield. Berseem clover was sown in oilseed rape rows and between rows. While oilseed rape alone yielded 4.06t/ ha, that with clover in the row only, yielded 4.54t/ha and between rows, 5.1t/ha. ""Companion plants improve soil structure, crop rooting and capture nutrients. They trap the equivalent of 40kg N/ha," says Mr Hemmant.