Farm trial suggests a new mindset is needed to conquer black-grass menace
PUBLISHED: 09:07 11 May 2018 | UPDATED: 09:14 11 May 2018
After years of traditional ploughing, a farm near the Norfolk-Suffolk border is trying a radical new “low disturbance” approach to cultivation in a bid to beat a persistent black-grass problem. CHRIS HILL reports.
It is a familiar adversary for East Anglia’s arable businesses – but farmers may need to take a leap into the unknown if they hope to defeat the menace of black-grass.
The yield-killing weed is the focus of a trial at a farm near the Norfolk-Suffolk border, where radical changes have been made to traditional cultivation practices to assess the effect on black-grass plants.
It is part of the Arable Weed Control programme run by agro-chemical firm BASF, which used an independent team of experts to offer a range of cultural and chemical strategies for participating farmers.
Some of this advice was a complete shift away from previous thinking, which the firm says “may have a put a few potential trialists off” – but one of only two farmers who decided to take the trial forward was Andrew Colchester, of Church Farm in Thrandeston, near Diss.
On a 7ha field with a worsening black-grass problem, he has been convinced to ditch his reliance on the plough in favour of a “low-disturbance” system which, once the weed seeds have been safely buried deep under the earth, moves the focus onto treating the top layers of soil.
“Over the last 10 years we have tried a number of different chemical approaches with conventional ploughing, and we still have black-grass,” he said. “You cannot keep banging your head against a wall without learning from it. You have to look at other options.
“To me, this is a little bit like going to the dark side, as a I am a traditional Suffolk boy who loves his plough and power harrow. But this is a good way of putting a toe in the water to see what options are available to us.
“With the trial this year, I was initially comparing things to the rest of the farm and saying:’ Oh my God, this is not going to work’. But in the last few months things have come on in leaps and bounds.
“There are still areas I am concerned about, but generally the crop is improving and the proof will be in the pudding when the combine goes through and we see how many black-grass heads we have to show at harvest, what the yield is, and what the cost is.
“The farm has to turn a profit. We don’t have the advantage of scale, so we have got to make the best of what we have got, at the lowest cost.”
Mr Colchester said the 186-acre farm has sandy clay loam soil used in a traditional arable rotation, including potatoes on the best land. Straw is taken off the land to be baled and sold, and manures are used to replenish nutrients in the soil.
Independent soil and cultivations expert Philip Wright outlined the benefits of organic matter on soil structure, and the effects of compaction damage from heavy machinery, which could restrict drainage and create the wet conditions which give black-grass plants a competitive advantage over arable crops.
But a key part of the strategy is to bury black-grass seeds more than 10cm underground – and then park the plough for four or five years.
Instead he recommends loosening the soil with cultivation tines which will lift and stretch a shallow band of earth, creating vertical cracks and draining channels without re-inverting the soil and bringing dormant black-grass seeds back to the surface.
“Black-grass loves being re-inverted,” he said. “The approach needs to be good ploughing, bury it properly, and then treat the surface in the intervening years in such a way that you are not re-inverting the seeds back to the surface when their vigour is still there.
“If you can drill the next crop with minimum disturbance into a shallow zone that does not affect the horizons in the soil, then you are giving your crop the best chance to compete properly.
“Once you have got your foot on its throat, keep pushing. I am not against ploughing, as it can be integrated into a system brilliantly. But every time you plough you are hitting the reset button on soil structure.
“If you have been used to a ploughing system, these kinds of techniques are often viewed sceptically. But that resistance has become outweighed by the farmer’s realisation that he has to do something to control black-grass.”
Changes to the trial field’s herbicide regime were also made to demonstrate the optimum possible combination of chemical and cultivation tools.
BASF’s Norfolk agronomy manager Hugo Pryce said it was given the “Rolls Royce treatment” of pre-drilling, post-drilling and pre-emergence herbicides
Mr Colchester added: “It cost a fortune, but it has done a good job. If we get to harvest and we see black-grass massively lower than we had before, then it proves that although what I was putting on before was half the cost it was not doing the job. Then obviously we have got Philip’s other techniques on top of that.”
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