18 August 1995

TAKING OVERVIEW ON UNDERNEATH…

Careful planning lies at the heart of soil operations for Bedfordia Farms, host to Cultivations 95.

Charles Abel examines the policy

CULTIVATIONS lay the foundations for good combineable crop yields. Indeed they are so important to Bedfordia Farms arable manager Bob Green that planning starts before the preceding cereal crop is even in ear.

The entire 2000ha (4940-acre) farm is walked in the company of ADAS soil scientist Selwyn Richardson and agronomist David Parrish in late May.

"It is whats under the ground that counts. You cant always tell a crop by what is on the surface," he says. "Compaction was probably the single most important thing that prompted us to introduce permanent 20m grassed-down set-aside headlands around most fields."

Spring crops in particular are difficult to establish on the heavy land if soil conditions are not right. Removing compaction early in the rotation ahead of oilseed rape also gives that crop its best start.

"A representative 30 out of the total 110 fields are subjected to detailed scrutiny, with 40cm (16in) inspection pits dug to check soil structure. "The critical depth is 10-14in down," comments Mr Richardson.

Such attention to the soil is vital. Fields range from Hanslope series chalky boulder clays to sandy river terrace with over 20 other soil types between. It is a legacy of the River Great Ouse cutting its way through the surrounding countryside.

Many fields have widely differing soil types within their boundaries.

Planning cultivations is vital, particularly if all the wheat is to be drilled by the Oct 15 target dates and the oilseed rape established in optimum seed-bed conditions.

"We dont want to be getting involved with recreational cultivations at this busy time," says Mr Green. He places great value on the summer soil tests. "I think we are really starting to see the benefits of it now."

The approach has helped minimise the use of the flat-lift sub-soiler. That is important, cutting out the task allows routine ploughing after cereals to start as soon as combines leave the field. "Early ploughing is the key. We need as much weathering on the soil after ploughing and discing as possible to help get a seed-bed," explains Mr Green.

Most straw is baled for the farms sow yards and dairy unit, leaving stubble to plough down with trashboards and skimmers. Discs are then used to slice ploughed land into "fist-sized" clods. Heavy Simba Mk IIB discs are usually first, followed by lighter Gregoire-Besson discs with double packer if needed.

Subsequent cultivations depend upon weathering. Discing can be enough if the clods get the right wetting and drying. A pass with Vaderstad tines can also suffice before drilling with the new Overum Tive D4008.

But if the weather is unhelpful, or time short, a 6m (20ft) Kuhn power harrow is brought in. Mr Green admits it is costly but "not uncommon" on such heavy land. "We have got to get the seed-bed level and consolidated." With an articulated 270hp John Deere 8640 tractor in front the operation is not particularly slow.

Timeliness and minimal passes are the key to containing costs, he reckons. To help both all the kit is on the large side. Four articulated, high hp John Deere tractors work a range of kit including a seven-leg Cousins flat-lift, 12-furrow Besson reversible plough and the 5.6m (18.4ft) discs. The only new tractor is a John Deere 8400, which pulls a six-furrow plough between contract baling.

The other tractors are all over 10 years old and are overhauled before each autumn by the farms fitter to reduce breakdowns. Mr Green also admits to being over capacity on horsepower. But with the machines already fully depreciated and further land purchase possible he does not consider it to be a luxury.

For break crops and after oilseed rape the cultivations strategy switches to minimal cultivations. Ploughing and sub-soiling is avoided unless soil pits show compaction. "But the aim is to detect that the year before so we can take it out during the cereals part of the rotation," comments Mr Richardson.

Tramline busting is largely avoided thanks to a prudent tyre policy and the use of near permanent wheelings. "We will bust them if we think we are going to have problems with breaking shear-bolts on the ploughs. But now we have permanent set-aside headlands we can mark where the wheelings are and keep them in the same place between years. So there is little effect on crop growth," says Mr Green. A radials-only tyres policy also helps.

Arable manager Bob Green puts the spade to good use checking for compacted ground on the demonstration site this summer.

High horsepower rules the roost at Bedfordia Farms. Turning heavy land over quickly behind the combines allows weathering to ease subsequent cultivations, explains arable manager Bob Green. Heavy and light discs, with a packer if needed, are used to form fist-sized clods.