August 24, 2020 8:00 PM

Back to basics: seedbeds & moisture key to OSR establishment

  • Conserve or wait for moisture before drilling
  • Remove weed competition to improve even establishment

Despite very different approaches, and the creative use of old and new techniques, growers Julian Thirsk and David Bird agree, seedbeds are key to getting oilseed rape (OSR) up and away.

Julian has a 325ha North Yorkshire farm and is responsible another 7,800ha through his work as an independent agronomist. He acknowledges that the risk of cabbage steam flea beetle damage is lower here than elsewhere in country.

“You want a rape crop to establish as quickly and evenly as possible,” he says.

“Growing OSR is about getting the basics right and that means putting the effort into getting a good seedbed and conserving moisture.”

“I always like a leg to go through soils ahead of drilling OSR. The crop hates compaction,” he says.  “And with the rain we’ve had this year, I’m seeing a lot of pans at around 10” deep. While there’s a fair amount of soils now cracking in the heat, I’d question how far down the cracks go.”

David takes a very different approach on his 364 hectare family farm in Suffolk.  Having taken a break from OSR, the crop made a return to the farm two years ago. David’s Clearfield varieties are now grown one year in six, with a companion crop mix of mustard, buckwheat and burseem clover.

“When we can get OSR established and yielding, it’s a profitable break crop and there aren’t many out there,” observes David.  “We stopped growing it for a while, because the risks were too great. A combination of cabbage steam flea beetle, slugs and black-grass meant taking a break was the only sensible option.” 

“Technically we drill too early, but our OSR crops gets the moisture they need,” he says.

“By drilling directly into stubble, there are no clods for the flea beetle to hide in. The companion crops dilute the effects of cabbage stem flea beetles as well as competing with the black-grass. It also means the soil is covered during establishment, conserving moisture when it’s needed the most.”  

The companion crops are sown in alternate rows.  “We’ll have one row of rape with a low companion crop seed rate,  then a row with a high seed rate of companion crop and no rape. Come the spring, OSR ends up in wider rows when the companion crops have died back.”

David will be trialing a nitrogen and phosphate starter fertiliser for the first time this year.  In contrast, Julian prefers to spread organic manure spread ahead of the crop and benefit from the slow nutrient-release.

“I still like to use pre-ems on certain farms,” says Julian. “Where the OSR has been drilled in good growing conditions and there’s a known weed issue, for example, getting a timely pre-em on removes competition from weeds increasing the chances of a quick and even establishment.”

“The new chemistry does give us the option to assess a crop’s viability before investing but for many, pre-ems still have their place.”

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