Cover crops are creating a useful source of organic matter for two Kent growers, who believe biodiversity, soil health and blackgrass control are among the benefits of the approach. Geoff Ashcroft reports.
Will Steel has been growing cover crops for the last 10 years on 210 hectares at Little Pix Hall Farm, Hawkhurst.
He says their inclusion in a five-year rotation has helped boost earthworm populations, increase biodiversity and raise soil fertility. “Our silty clay loams which sit over sandstone tend to be wet in the winter and dry in the summer.
We don’t have a lot of topsoil, so I have been introducing more and more organic matter to boost soil condition, water holding capacity and fertility,” he says.
Mr Steel has managed the farm for the past 30 years, joining the business when the once derelict farm was bought by its current owner. In that time, he has spread various sludges, cakes, composts and manures on the land to improve soil health.
Rising cost But the rising cost of transport has made such materials harder to source and economically difficult to justify, and 10 years ago, Mr Steel turned his attention to cover crops to grow his own organic matter.
“I started experimenting with straight mustard or oat cover crops which we could incorporate into the top 80-100mm of our hungry soils,” he says. “We’ve also increased our use of no-till in the spring to preserve what organic matter we had built up. And five years ago, a switch to cover crop mixes offered even greater biodiversity.”
The mix of cover crop seeds is constantly being tweaked and developed with the help and knowledge of other local growers looking to improve soil condition. Their collective buying effort has also helped to make the cover crop mix more cost-effective.
Mr Steel believes growing a cover crop mix of seven or eight species planted in autumn ahead of spring crops means there is always something in the mix which will flourish, regardless of each season’s changing conditions.
“A mix of short and tall plants, for example buckwheat, vetch, oats and phacelia, offers different root structures and canopies, so they all work differently when it comes to their effect on soil,” he says.
“You have to be prepared to experiment with seed types.
Each season, we get different results, but there is enough diversity in the mix that different plants take over when others die back.
“And sowing a cover crop is much more cost-effective than throwing money at cultivations,” he says. “I don’t want to see bare soils. Mother Nature will fill the gaps with weeds or wash soils away in winter, so I’d rather put in a cover crop and make the most of what it has to offer.”
With half the farm growing winter wheat, the remainder is cover cropped. Spring cropping can be beans, linseed, oats or oilseed rape, depending on the season.
Using cover crops has helped Will Steel to cut herbicide use on spring beans on the 210-hectare Little Pix Hall Farm in Hawkhurst, Kent.
After combining wheat, Mr Steel says one pass with a straw rake is often enough to encourage a flush of weeds ahead of planting the cover crop.
Critically, the rake spreads trash more thoroughly than his Lexion 530 and is viewed as the first part of the establishment process.
Almost all straw is chopped and spread, to feed Little Pix Hall Farm’s worm population, and if he had the budget and the source, Mr Steel says he would buy-in black-grass-free straw for the farm’s cattle, to eliminate straw removal.
“Our worms can consume all the straw from a 10-tonne/ha wheat crop by Christmas,” he says.
“So it is important we give them enough to eat – they are great drainage contractors.”
If any compaction needs treating or there is a wet harvest, Mr Steel still has the option of making a shallow pass with a Sumo Trio.
Drilling is carried out using a 4.8-metre KRM Sola with four rows of narrow, low disturbance points. When it comes to sowing into cover crops – after spraying-off – Mr Steel has experimented with a front-mounted 4.8m Cousins press to push the crop canopy over and allow the drill to work.
“It is a heavy combination, though we try to use the one drill to do everything,” he says. “However, depending on conditions, I will make use of our local contractor who has a SimTech T-Sem 3m pneumatic drill which is better at cutting through the cover crop.
“We do need to be patient with drilling and we do need to tolerate a few more weeds, too,” he says. “Luckily, our black-grass population is manageable – we can hand-rogue and you can’t get resistance to rogueing.”
With the gradual progression of cover crops, Mr Steel says herbicide use on beans has been halved, and the farm has been able to trim back on the amount of herbicides it applies to wheat crops, too.
“Our six-year yield average on wheat is pushing 10t/ha and we’re heading in the right direction, helped by integrating cover crops on what is essentially poor soil,” he says.
Cover crops are boosting organic matter for Guy Eckley at Eckley Farms.
Guy Eckley, of nearby Eckley Farms, Staplehurst, Kent, is another cover crop convert.
He says: “We had fields sitting empty after harvest, destined for spring crops, and we thought Pedders Mix might be worth a try.
Rather than leave fields empty all winter, we thought we would try with a small area.”
Based on that initial trial, he has increased the cover crop area year-on-year.
Now in his fourth year of cover cropping, Mr Eckley says 25-40% of the 600ha farm will be sown to cover crops each autumn.
“Half the farm is wheat and everything else is break crop,” he says.
“This includes between 50-150ha of winter oilseed rape plus spring-sown beans, barley, wheat and oats. And all our spring-sown crops are preceded by cover crops.
“We do have a flexible approach when it comes to our rotation and things have been known to change at the last minute, depending on the season.”
His cover crop approach, like Mr Steel’s, involves using the same complex mix of cover crop species.
He reasons different soil types across the farm, combined with topography, means a diverse mix of seeds when compared to a singlespecies cover crop will naturally compensate when one of the components fails.
But unlike his nearby cover cropping neighbour, Mr Eckley relies upon a mix of drills – a Horsch CO4 and a John Deere 750A.
“Our goal was to adopt CTF and direct drill strategies so we could reduce compaction, cut costs and improve soil health,” he says.
“And the two drills give flexibility with min-till and zero-till methods.”
While Mr Eckley is a fan of the Horsch, which is used increasingly sparingly, he is less enamoured by the JD.
“The 750A is a complex piece of kit with some serious running costs,” he says.
“But the results from direct drilling into cover crops speak for themselves.”
He says the resulting cover crops are grazed lightly, with sheep, which are removed by the end of January to allow soils to recover.
The remaining crop is sprayed off before the 750A puts in spring crops in a one-pass process.
“Livestock helps to convert plant matter into manure, so we’re trying to advance the nitrogen cycle,” he says.
“Our soil structure continues to improve and we’re happy with the progress, even if we’re dragging our own research in our wake
Guy Eckley believes his cover crop strategy is leading the 600-hectare farm towards better management of black-grass populations.
“While we’ve had no quantifiable yield increases – our first two years in cover crops were wet seasons – we are happy with the process.
“What we have seen is an improvement in soil structure, better aeration through increased worm activity and biodiversity, while the trash contributes to better surface water retention and a reduction in run-off,” he adds.
“It’s clear our system is leading us towards better black-grass management too.”
The farm’s CTF system – 9m combine working at 8.8m with a 4.4m cut-down drill and 26.4m sprayer – helps to manage compaction. And all straw is chopped and spread, enabling organic matter to be put back into the soil.
Mr Eckley urges other growers to be brave, and to try small areas in fields or half-field scale trials to see what could work for them.
“We carried out lots of field trials with both drills to see what worked best and in what conditions,” he says.
“We’ve direct drilled successfully with the CO4.”
Though the two systems give him options, he says by reducing autumn cultivations, the farm has cut back on inputs.
“The money we saved on autumn seedbed preparations and establishment costs by switching to direct drilled, spring-sown crops has enabled us to invest in cover cropping,” he says.
This season, Mr Eckley will be trying a summer cover crop mix after oilseed rape and before winter wheat, and he is currently trialling companion cropping too.
“A fast growing, cheap mix of small seeds could prove a useful filler through summer, creating more organic matter ahead of wheat,” he says.
“My crop of spring wheat which was mixed with peas in the drill will be separated in the grain store when the crop comes off the combine.
“It seems the more we do, the less we really know.
Soil is a very complex component which needs more care and attention than we’ve been providing in the past. But the use of cover crops is helping to put more organic matter and different plant biology back into our soils,” he says.