Growers should target a ground cover of 30 to 40 plants per square metre for oilseed rape (OSR) crops, according to the latest advice from Teagasc.
Tillage specialist Shay Phelan has said: “Where hybrids are concerned, this translates to a seeding rate of 50 to 60 seeds/m² or 3kg/ha. Most seed consignments now come in 4ha or 5ha packs.
“And they are based on the thousand seed weight, which the crop has for that year.”
Teagasc research scientist Dermot Forristal has looked at a number of OSR establishment systems at Oak Park, Co. Carlow.
He commented: “Over the past number of years we have assessed a number of establishment systems; from plough, till and sow; through to min-till and, finally, strip-till. Direct drill is another option.”
According to Forristal, OSR is amenable to establishment by all systems. But sticking to the basics must be adhered to.
“Growers will be working at a time of year when moisture conservation will be key,” he said. “So seed must be placed in a fine and compact soil area.
“Good seed-to-soil contact is crucially important.
“Rape seed are very dry; they contain very little reserves. This, coupled with the fact that ground can be quite dry at this time of the year, makes it imperative for the seed/soil contact to be very effective.
“So all establishment systems should be operated to allow this happen.”
Establishment for oilseed rape
Trial work at Oak park confirmed variable OSR establishment rates with strip tilling.
“But even with that, we didn’t find huge differences in final yields afterwards,” Forristal explained. “So all establishment options can work.
“At the end of the day, factors such as labour can have the biggest impact on deciding, which is the best establishment system to go with.
“Farmers are very busy at this time of the year. So they will be looking for a rape establishment system that requires the minimal amount of labour input.”
But seed rates must be varied to reflect the potential establishment rates that can be achieved by the various planting options.
“Row width was a not a determinant of final yield, even when we brought this figure up to 750mm,” Forristal continued.
“But in situations where seed is being placed on a semi-cultivated surface, a slightly heavier seed rate will be required.
“In these instances it might be appropriate to go up to a rate of perhaps 70 seeds/m².”