15 August 1997

Early drilling worth a go?

Drilling of winter wheat early could be a good bet this year. Robert Harris investigates the techniques pros and cons

ADEQUATE soil moisture is crucial when sowing wheat early.

Last year, many growers had to redrill thin, gappy crops after seeds were left high and dry for several weeks after sowing.

This season, heavy June rains topped up by recent showers have moistened soils, which will encourage rapid germination and establishment, says Doug Stevens of Morley Research Centre in Norfolk.

The benefits of early drilling can be great, he notes. "On lighter land, it increases yield potential by promoting extra growth in autumn. That encourages better root development enabling crops to make better use of scarce water supplies in spring.

"In East Anglia on light soils, yield increases by about 1t/ha for every two weeks drilling date is brought forward between mid-September and mid-October."

On heavy land yield benefit may be half that. The main reasonfor early drilling here is to spread fixed costs, says Mr Stevens. "Crops can still be establishedby the end of October using fewer men and machines. Growerscan make better use of weath-ering rather than using expen-sive metal and diesel to createseed-beds."

But early drilling has drawbacks, he warns. "All sorts of management factors have to be considered."

Choosing the right variety and seed rate is vital. Tall, lush crops can lodge, and rapidly developing varieties suffer from winter proudness and frost damage. Early-drilled crops also tiller more, leading to high ear numbers and small grains if sown too thickly.

In a Morley trial in 1995, the highest yield from a Sept 9 sowing – 12t/ha – was produced from 131 plants a sq m. Where 227/sq m were established, yield fell by 0.5t/ha (0.2t/acre).

"Reduced seeding for early sowing seems appropriate, but the margin for error in the event of poor establishment is much less," says Mr Stevens.

The ideal variety would be stiff strawed, with good disease resistance and relatively slow apical development, he adds. "Unfor-tunately, there is no perfect choice."

Riband and Consort are safest for early-September drilling, he maintains. "They may not be best for disease, but they are fairly stiff and slow to develop." No frost damage was noted this season after a very cold night on Apr 21.

Buster, although stiff, develops too fast, and like Soissons, Rialto and Cantata showed significant damage. Caxton, Equinox, Reaper and Brigadier suffered some damage on advanced tillers.

Care with cultivations is vital, he notes. "The key is to consolidate seed-beds to preserve soil moisture." Ploughing and pressing are best, followed by as little cultivation as possible to achieve a seed-bed.

Weeds, especially blackgrass and sterile brome, are encouraged by early drilling, especially on heavy land. "The extra cost of control can soon outweigh the benefits," he comments.

Two or three sprays to prevent BYDV could be needed, as may Baytan (fuberidazole + triadimenol) seed treatment, adding £40/t to the seed cost. "If showery, cereal volunteers could provide a green bridge allowing the current very active strain of yellow rust to get off to a flying start." More fungicide may also be needed in spring, adds Mr Stevens.

"Forward crops can be heavily infected with septoria in late autumn, though it may lurk unseen until February." Eyespot can also take hold early and take-all can hit runs of wheat.

Growth regulators are a vital input, he says. But earlier crop development means earlier application, when low temperatures can inhibit chlormequat uptake. "Later growth regulators like Terpal may be needed."

Early drilling the right variety (insert) at the right seed rate into moisture will give wheat a flying start. But beware of pitfalls, says Morleys Doug Stevens.

EARLY DRILLING

&#8226 Higher yields on light land.

&#8226 Spreads fixed costs.

&#8226 Moist soils crucial.

&#8226 Watch variety and seed rate.

&#8226 More weeds, diseases and pests may need extra inputs.