The spade has become the most important tool for Northamptonshire farmer and winner of the Farmers Weekly/Michelin cost savings challenge Stephen Goodwin. Tom Allen-Stevens finds out why
As Stephen Goodwin’s spade eases a perfect oilseed rape tap root from his soil, you realise the care he’s taken to look after the soil structure has really paid off. The crop off his heavy clay yielded a staggering 6.25t/ha, and as the root emerges, the soil drops off in perfect lumps, teeming with worms.
“Soil is the most important asset we have on this farm. If you don’t look after it you never get a good crop,” he says.
As A and G Farming, Mr Goodwin and partner Stephen Atkins farm a total of 730ha (1,800 acres) of ironstone brash with clay near Banbury, on the Northamptonshire/Oxfordshire border, under various contract farming agreements.
From the moment the combine enters the field to when the sprayer leaves after the final application, Mr Goodwin takes good care to ensure the structure of his soil is never compromised. The spade is the essential tool that monitors the job.
“A lot of people like to see a level surface on their field. But the important thing to me is that when the seed is planted it must get its roots down. Oilseed rape in particular is a lazy rooter,” he notes.
So compaction on the clay becomes a critical issue at certain times of year. “Because of that we no longer plough – everything is direct-drilled or min-tilled.”
Travelling on the fields is kept to a minimum – straw is chopped wherever possible and the New Holland combine empties on the headland. Oilseed rape is established with a subsoiler-seeder, but otherwise soil disturbance is kept to an absolute minimum. If establishing a spring crop to help tackle a blackgrass problem, a cover crop is used over winter to minimise slump.
“Because we’re not carrying out deep cultivations the structure has improved so the crops are rooting better – I was amazed at how well they hung on in such a dry year.”
There’s a cost benefit too – soil that needs little shifting keeps establishment costs down. “We’ve noticed the land will carry more, although we try to keep tyre pressures low.” And this is where compromises have had to be made. Running tyres at the correct pressure is a crucial part of maintaining soil structure. But as a contractor, Mr Goodwin spends much of his time travelling between fields.
“There’s a lot of road work. One day you’re on corn-carting, the next you’re drilling. You should adjust tyre pressure to suit the job. But in practice you don’t.”
Running tyres at low pressure on the road or for corn-carting can damage the inner wall. The flexing that occurs at high speed in a relatively narrow band of the tyre builds up heat.
Now his Massey Ferguson 6490 is fitted with a brand new set of Michelin Xeobibs. The tyres are designed to flex more, claims the manufacturer, so you can run them at the same low pressure on the road as in the field with less damage to the side walls.
Mr Goodwin won the tyres after taking part in the Farmers Weekly/Michelin cost saving challenge. It was his attention to the soil that impressed the judges – his top tip was always carry a spade.
“Dig a small hole to check soil structure and set the machine up to just below any compaction layer. Fuel will be saved by not going too deep and areas identified as not compacted will not need lifting at all, saving time as well as diesel,” was his winning entry.
He’s already noticed the difference the new tyres make on the road. “They feel like they travel a lot firmer, even though you’re running at a low pressure.” But his approach in the field is still very much the same. “The spade is the first thing we use before we start any cultivations – it’s a policy we’ve got.”
Pressure points to keep out compaction
The pressure you exert on your soil will be equal to the pressure in your tyres, so keep this as low as possible and aim for a long footprint, advises Michelin’s Andy Balfour. But too low and the lugs pull on the side wall.
“You should have a static laden radius – the measure from the centre of the wheel hub to the ground should be constant, whatever the load,” says Mr Balfour.
The correct pressure should be set according to the loading you need on the tyre to get the required traction. The ideal weight is the horsepower available multiplied by the traction coefficient, which ranges from around 35kg/hp for light sand to 65kg/hp on rock-hard clay.
So a 200hp tractor working a medium, 50kg/hp soil should apply a weight to the tyres of 10t to get optimum traction. Based on a 60:40 loading, that puts 3t on each back tyre.
“With a Xeobib you can reduce the traction coefficient, which means lower weight, less fuel used and lower pressure,” says Mr Balfour.