Soil health crops are attracting increasing interest due to their ability to improve soil structure by breaking up compaction, improving drainage and helping raise the organic matter content of the soil.
A mixture of species is often beneficial, as growers can exploit a range of differing rooting depths. For example, oilseed radish produces deep tap roots, while rye and Japanese oats have more fibrous root systems that work in the upper layers of the soil.
However, customers will have their own aims, so what works for one field on one farm might not be the best option elsewhere.
Two Kent growers have been making good use of soil health crops over the past few years, and now grow RAGT species and varieties sourced through Ashford-based merchant T Denne and Sons.
Tom Reynolds, Pent Farm
Tom Reynolds is joint manager at S Salbstein Ltd’s Pent Farm, Postling, near Hythe in Kent. Soils on the 170ha farm range from very heavy clay through to chalk downland, and the aim is to establish wheats using direct drilling only.
Drainage, including plenty of mole ploughing, has been a key focus on the cold wet clay to help get on top of black-grass and to encourage better crop rooting and earlier spring growth.
The farm operates a diverse rotation to help maximise fertility, including winter wheat, winter and spring barley, grass seed, linseed and oilseed rape.
A range of soil health crops has also been introduced to improve soil structure and to capture nutrients and improve their availability for the crops in the rotation.
“I have been working with cover crops for the past six to seven years,” says Tom. “The main aim is to build soil resilience and organic matter levels, using cover crops between winter and spring crops, and on occasion as a summer cover between OSR and winter wheat.”
A range of species and mixtures are used depending on the situation, including oats, phacelia, sunflowers, vetch, radish, linseed and buckwheat.
For example, oats provide a fibrous root system that helps improve organic matter levels and friability in the upper spoil layers, while oil radish produces a strong taproot that improves drainage on the heaviest soils. Phacelia produces strong autumn growth that captures nitrogen.
“We are also using cover crops to integrate livestock into arable cropping to improve fertility. We have grazed these covers, but on heavy soil types this must be done very carefully, or soil damage can result. A close relationship between sheep grazier and farmer is critical.”
Tom has worked closely with the team at T Denne and Sons, producing cereals, pulses and grass seed. For the past two years he has also bought cover crop seed from the company.
“We purchase cover crop seeds with a small group of like-minded farmers, to attempt to gain some economies of scale with our buying. This also provides a fabulous knowledge resource.
“A cover crop seed budget is a critical factor in the success of growing covers. It is difficult to quantify the total benefits and thus a balance must be achieved of cover and the cost. I aim for a maximum cost of £20-28/ha.”
Tom Sewell, Sewell Farms
Tom Sewell is passionate about soil health. The 420ha of clay loams he farms at Sewell Farms, near West Farleigh in Kent are in good shape, and he intends to keep them that way.
There is no fixed rotation for the farm. Cropping, which includes winter wheat, oilseed rape, winter oats and spring beans, is decided on a field-by-field basis. All crops are established using a no-till Cross Slot drill.
He aims for as much first wheat as possible, growing for milling and achieving a farm average of more than 10t/ha.
He applies the same attention to detail to his soil health crops, which he has been growing for at least six years. He now focuses on two types.
A summer catch crop consisting of linseed, buckwheat, sunflower and phacelia follows oilseed rape. “I don’t want to see any soil on my farm,” says Tom.
“Cover crops add green manure and prevent erosion by wind and water. A window of five to eight weeks is worth exploiting – the right cover crop will grow knee-high in that time.”
The following wheat crop is then direct-drilled into the standing cover crop using a Cross Slot drill after the cover crop has been sprayed with glyphosate.
He also grows overwintered cover crops ahead of his spring-sown crop, based on linseed, oats, vetch, phacelia, buckwheat, adding oil/tillage radish sometimes beans/clover. “It's always changing!” says Tom.
Key aims are to benefit soil health, grow carbon, protect the soil surface, capture nutrients, and benefit insects, worms, bacteria and fungi.
The whole system is becoming more sustainable, he says. “Our soils are now alive and are full of worms.”