IDEAL spraying conditions helped a Wiltshire farmer achieve top level blackgrass control this season despite a big move to min-till.
With 1130ha (2800acres) of heavy loam over chalk at Manor Farm, Berwick Bassett, David White took a huge plunge last autumn, switching from ploughing and power harrowing all his land, to putting about 70% into minimum tillage.
It was a bold decision because conventional wisdom suggests the farms blackgrass problem would be better tackled by ploughing. But he is enthusiastic about the results.
After the wettest winter for 300 years, he believes it was the right season to try the new approach, and both he and son Edward have learned valuable lessons. This year he is considering 85% minimum tillage. "Of course we wondered at times whether we were doing the right thing," says Mr White.
"We didnt drill particularly early, because minimal tillage and early sowing are totally incompatible. You have to use a stale seed-bed to help get rid of any blackgrass to start with."
Key lesson has been in managing land after cereals. "Where we were planting straw crops after straw crops, for example second wheats or oats after wheat, we made the mistake of chopping the straw which turned into a mulch and created a skid pan."
Mr White also tried discing to only 2.5cm (1in), but found that was too shallow. Now 7.5cm (3in) is felt to be better.
He admits one of the perceived problems with minimum tillage is blackgrass control, because more seeds are left in the top few inches of soil.
But his experience to date has not borne this out. "We all know ploughing gives good blackgrass control. But we have had less blackgrass this year than weve ever had.
"This is possibly because non-inversion of the soil avoided bringing seeds back to the surface. But weve also used a Hawk + Lexus mix which gave us excellent results.
"Because it was such a wet autumn, we ended up spraying 1000 acres in January. But the conditions were ideal and it did a 99.8% job."
In the past, 1.7litres/ha of Hawk (clodinafop-propargyl + trifluralin) was adequate. "But after trials work on the farm we have been finding we need 2.5litres/ha," says Mr White.
As well as post-emergence treatments, the Whites also use pre-emergence glyphosate, applied to a stale seed-bed. Here too, lessons have been learned.
"Where you use minimum tillage and you get blackgrass to germinate before drilling, you must spray it off with glyphosate no later than three leaves. If you let it tiller you can still kill it with a spray, but the roots hold the moisture. This makes the land slower to dry out, so it is harder to drill."
Because of the volume of straw it remained necessary to plough after some wheat last year. But a new rotation (see box) should get round that. "Well no longer have crops to plant after wheat in the autumn," he explains. *
• Winter barley
• Winter OSR
• Winter wheat
• Set-aside or winter beans
• Winter wheat
• Spring barley
MANOR FARM MIN-TILL
• Best ever blackgrass control.
• Ideal late spraying conditions.
• Pre-drilling glyphosate vital.
• Rotation revamp planned.