Direct sowing given solid thumbs-up
SOWING oilseed rape directly into cereal stubble is now a credible alternative to the more costly and time-consuming method of sowing separately, says the HGCA.
It has issued a topic sheet covering the use of the Autocast system, which broadcasts seed into stubble from a hopper attached to the back of the combine header.
In trials, Autocast crops have yielded as well as conventional ones, despite establishment costing under £40/ha, compared with over £100/ha with a plough and disc-based system. But farm experience shows careful management is vital to ensure success.
"We have sown using Autocast for three seasons now, and have so much confidence in it that were sowing 750 acres in the fourth season," says Cambs grower James Peck.
"We use 8kg of seed per hectare and mix in Wetex slug pellets. We dont use the mini slug pellets as we found they block the hopper and are not as effective at preventing slugs.
"Our herbicide bill is lower and spray days are increased because the tramlines are already formed," says Mr Peck. "Each year we have compared Autocast with the plough and disc methods of seeding, and this year we expect it to out-perform them both."
However, Autocast is less reliable with a compacted soil surface. "In the first two years we had a 50% failure rate. The problem was that we used the Autocast then left it," says Mr Peck.
"To overcome this, we now follow the combine with a press and roll combination within one hour, two at the most. That gives the seed full soil contact and compacts the soil, which also helps reduce the slug problem."
Users should roll or press immediately after drilling and should roll again if significant rainfall follows and seed has not germinted, he advises.
The technique should only be used on heavy soils with a good surface tilth, the HGCA notes. It is also important to choose the right prior crop. Later-maturing wheat varieties are ideal. Autocast should not be used if previous crops have had high diflufencan or sulfonyl-urea doses, it adds. *
More info on Topic Sheet 59 available from the HGCA (020-7520 3920, email@example.com or www.hgca.com).