Rape trials reveal optimum spacing for the best oil seed yields to be achieved (From Darlington and Stockton Times)

Rape trials reveal optimum spacing for the best oil seed yields to be achieved

3:07pm Friday 15th March 2013 in Farming

OILSEED rape growers were given an update on results from Agrovista’s Grow Crop Gold project at a recent open day, held on one of the trial sites at Croft-on-Tees.

Achieving the correct plant population is a key factor in maximising the yield potential of oilseed rape, Agrovista’s Chris Martin told delegates.

Narrow row spacings require a target 20-30 plants per square metre to be established in the spring, while wider row spacings, marked out at 50cms, for example, should containnomore than15plants per linear metre.

“In general, our trials have shownthat wider row spacings are the best option, in cases where we can improve rooting by exploiting the benefit of following a leg,” said Mr Martin.

“But this approach only succeeded in plots with a constant seed depth, good seed-to-soil contact and adequate consolidation. Lower seed rates also helped to avoid early competition within the row.Wide spacings open up the ground, making it more accessible to weeds, so robust herbicide programmes are essential.

“These management recommendations are mainly due to the fact that oilseed rape plants are highly vulnerable to competition from neighbouringplants, andthe firstpoint of competition is likely to occur within the row of sowing. Removing this competition increases the exposure of leaves and pods to sunlight, which in turn helps to fill the seeds.”

Greenareaindex (GAI)isanother essential component of yield maximisation, he said.

“The crop should have reached a GAI of 3.5-4 at the time of flowering. Growers who find GAIs difficult to estimate can download an app from a smartphone, which will work out the figure using a photograph of the crop.”

Other results from the Grow Crop Gold project, which was launched in 2008 and involves eight trial sites around the country, suggest that one-pass establishment techniques have no detrimental effect on yields, as long as the crop is managed with care. They offer several benefits, including lower costs andmore timelyplanting. Onepass systems may also help to retainmoisture inthe seedbed.

“Overall,the most successful crop was sown withaprecision drill, achieving 0-5t/ha more than the control.Butit must be remembered that this is usually one of the most expensive methods of establishment,” said Mr Martin.

The poor growing season last year has taken its toll on landinthe region,observedMr Martin.

He said: “Most soils are still cold and wet and slug populations are high. These conditions will present a challenge for oilseed rape growers. The crops on our trials site at Croft have suffered, but well-established oilseed rape is capable of high levels of compensatory growth. In areas which suffered prolonged flooding, the barley volunteers died out, but most ofthe rape has survived.”