3 September 1999

Considering direct drilling

DIRECT drilling into stale seedbeds can cut establishment and herbicide costs, boost yield potential and benefit the environment. But wet UK autumns still pose problems, so it is likely to remain a contract option on most farms.

Results from the Focus on Farming Practice trials at CWS Broadoaks Stoughton Estate near Leicester, show direct drilling can cut wheat establishment costs by £40-60/ha (£16-24/acre) and produce an equally well established crop.

Faster drilling rates of up to 48ha (120 acres) a day also boost final yield. Five years of trials on Stoughtons heavy soils show drilling in September gives 1t/ha (0.4t/acre) more yield than drilling in October.

A 6m Vaderstad Rapide now complements the traditional plough, press and combination drill for establishing 800ha (2000 acres) of wheat at Stoughton. "The two systems start at different ends of the farm and hopefully meet in late September," explains project co-ordinator Alastair Leake. "The direct drill should do 80%, but if conditions turn wet it stops and the plough system carries on, hopefully finishing before October anyway."

A further benefit tested in the CWS/Profarma/Hydro integrated crop management study is the ability to reduce inputs. "Stale seedbeds are used to chit surface weed seed in late summer and because direct drilling doesnt bring up any more seed there is scope to reduce or even avoid autumn herbicide altogether," says Mr Leake.

Surface trash also seems to confuse aphids, allowing BYDV sprays to be dropped in the trials. No BYDV has been seen in the last seven years.

So far the best results have come after set-aside and grass leys. Set-aside is disced and rolled in mid-July to destroy cover, then left to green. "Annual meadow grass, brome, wild-oats and broad-leaved weeds are our main concerns," notes Profarma agronomist Graham Edwards.

Weed seedlings are knocked down with a low cost 1l/ha of Roundup Biactive (glyphosate) immediately pre-drilling. "Weeds dont die quickly at that rate," Mr Edwards admits. "But while it may be slow visually, physiologically it is doing the job. The trick is to leave it as late as possible to allow maximum chit and good weed growth for uptake."

Applied in 100litres/ha of water 120ha (300 acres) is possible in a day. "There is scope to go up to seven days post-drilling, but you do run the risk of missing that slot, so just pre-drilling is best," he says.

Grass leys get a tight third silage cut and after a few days of regrowth 3l/ha of Roundup is applied to kill the sward and annual meadow grass. Direct drilling follows a few days later. "After two years of silaging most weeds have been mown out, eaten or died, so the surface should be clean," says Mr Leake.

In both cases seed goes in at 125kg/ha (111.5lbs/acre) at 4cm (1.5in) depth to avoid slug damage. "If conditions are dry and there is a high population of slugs still in the soil, we will put pellets in with the seed. But usually there is no need," comments Mr Leake. Drill set-up is important to ensure the slot closes properly.

After grass 20-30kg/ha (16-24 units/acre) of nitrogen may be needed. "Although there is N in the soil, because there is no cultivation there is no mineralisation, so very little is released. The crop needs something extra to get it going."

Relying on weed and BYDV effects would be unacceptable across a whole farm, admits Mr Edwards. But certain fields could benefit, allowing insecticide savings and lower herbicide rates or wider spray windows thanks to reduced weed and aphid pressure, he notes.

Other direct drills give similar benefits, but all are expensive and all struggle in the wet, Mr Leake accepts. Few farms could justify both a direct drill and the conventional approach needed for wet autumns.

"It is probably a case of looking for a contractor or a large farming neighbour to bring the drill into those fields where the biggest savings can be made. For a lot of farmers that could be very worthwhile," Mr Leake concludes. &#42