As weeds become harder to control than ever before, farmers are having to rethink their options. The Soil Association held a non-chemical weed control day to demonstrate how herbicides can be the last tool to reach for.
Sharing his own experiences of weed control in an organic arable system, Charles Hunter Smart, manager of Bradwell Grove in the Cotswolds, told how a three-pronged attack using livestock, mechanical weeders and cultural controls is tackling a variety of weed species on the 900-hectare mixed farm.
Made up of predominantly Cotswold brash with some heavy blocks, the estate converted to organic in 2005 following low grain prices, high fuel costs, and the discovery of resistant black-grass in some fields.
At the time, the main fears were of docks and couch, and a 12 metre Opico harrow comb was their only real weed control, Mr Hunter Smart said.
“We began to see some docks and bought a deep tine machine which loosens docks and has a rotor at the back that flicks them out. It worked well on heavy land but was expensive on stony land because the tines kept breaking.”
In 2007 the estate introduced sheep as a means of weed control, working alongside the Royal Agricultural University and another local farmer to create a roving sheep flock, which the two farmers still share today.
“Thistles were just beginning to appear, and sheep are good at nibbling them down,” Mr Hunter Smart said.
In 2012, extreme wet weather meant many farmers could not drill autumn crops, and the estate bought a second-hand combination drill to get through spring drilling.
“In 2014 we suddenly started seeing black-grass again, which we hadn’t seen since turning organic. It was simply because black-grass loves wet ground. It hit us like a thunderbolt.”
The farm has been fighting black-grass ever since, using cultural and mechanical methods to keep weeds at bay.
Around 2 per cent of land is kept fallow each year and grass leys have been extended from two to four-year rotations, while a Weed Surfer was bought to top weeds before seed set.
“The ploughing scenario as an organic farmer is a difficult one for all the reasons of losing carbon when we plough,” Mr Hunter Smart added.
“I’d love to try and get away from using the plough and occasionally when we have a nice, hot dry autumn you can just about do it.”
One of the most significant introductions was an 8m, 32 coulter Cameleon drill.
“It costs over £100,000 - There was no way we could afford to do that, so we started talking with our neighbours and managed to get a Leader grant. We planted our first crops in 2017 and the results are quite impressive.
“It works on wide spacing, but no one can really tell you what seed rates to use. We’ve now gone to band sowing because the amount you plant at that width is 8 per cent of soil covered, but by band sowing you can increase it to 32 per cent.”
Source: Lynn Tatnell – Senior Research Scientist Weed Biology, ADAS