World record oilseed crop landed

 North Otago grower Chris Dennison harvested 64.37t off 10.2ha on Friday January 23, a yield of 6.31t/ha, comfortably beating the previous record of 6.14t/ha claimed by UK grower Tim Lamyman last July.

“It was quite surprising because during the day we didn’t think we were going to make it,” Dennison told Rural News.

“The combine yield meter was indicating it wasn’t quite good enough and as it turned out it was under-measuring the field area. When we got the actual yield off the weighbridge and divided that by the surveyed area, it made all the difference.”

Every load was checked across a certified weighbridge with two independent witnesses verifying the tonnage, and the yield corrected to the industry standard 9% moisture content. “The moisture ranged from 11.85% at start of the day to 7.8% on the final load.”

Two cultivars made up the crop: the hybrid Flash (7.2ha), which was grown for birdseed, and the high oleic Vistive for Pure Oil New Zealand.

Dennison says it was a good opportunity to compare the cultivars. The yield meter suggested Vistive had an edge but visually there was nothing to choose between them. “In terms of growth habit and disease levels you couldn’t tell them apart.”

Both cultivars were treated identically from cultivation to combining, sown in 30cm rows on April 3 following a five-pass cultivation programme to prepare the ground after straw from the preceding barley crop had been removed. “That sounds a lot of passes but they’re all 6m tools so it wasn’t many hours per hectare.”

Dennison says they’ve gone back to a more rigorous cultivation regime, using heavier, deeper tines for the third and fourth passes, having found the Wakanui silt loam soils were getting too compacted under a no-till or minimum till regime.

An April 4 pre-emergence spray of Magister (clomazone) and trifluralin took care of broad-leaved weeds. “Shepherds purse, fumitory, wire-weed: they’re the main ones we were chasing. Sometimes fumitory escapes but this time it worked really well.”

Endure (metaldehyde) slug pellets went on at 4kg/ha as the crop was emerging April 10, followed by 330ml/ha of Fusilade Forte (fluazifop-p-methyl) on April 24 to take out volunteer barley.

Grassweeds got another hit with Gallant Ultra (haloxyfop-p-methyl) applied with 0.7L/ha of prochloraz on July 30 to clean up phoma. Follow-up fungicides of 0.55L/ha of Folicur (tebuconazole) at early bud break and 0.6L/ha of Proline (prothiconazole) at mid-flowering to counter sclerotinia went on Sep 11 and Oct 21 respectively. “The Folicur acts as a growth regulator too,” points out Dennison.

The fertiliser programme began with a standard autumn maintenance application of 400kg/ha of potassic superphosphphate at pre-sowing, delivering 30kg/ha each of potash, phosphate and sulphur. On Aug 5 the crop had its first 77kg/ha of nitrogen, plus a top up of 36kg/ha of sulphur and 25kg/ha of potash delivered as 250kg/ha of Ammo 31 (an ammonium sulphate plus urea blend) with 50kg/ha of potassium chloride.

A month later 200kg/ha of urea completed the nitrogen input, taking the total applied to 167kg/ha.

“When you consider the yield, that’s not a lot of nitrogen,” notes Dennison. The paddock has been cropped for at least 20 years too so soil mineral nitrogen levels were likely low, especially after an unusually wet autumn, he adds.

“We didn’t mineral N test this year because we figured there was no point: the results would all have been low.”

The only other nutrient inputs were a foliar spray of 2L/ha of Borsolve and 50g/ha of sodium molybdate, applied with the Sep 5 fungicide. “It’s to make sure we’ve got the boron for flowering and pollination - it’s standard practice for brassica seed crops here – and it’s just a good place in the rotation to get the molybdenum on.”

All spreading and spraying was on 24m tramlines with the farm’s own machines, a Bog Balle spreader and Sands self-propelled sprayer, except for the final pass, 3L/ha of 540g/L glyphosate which was applied by helicopter on Jan 5. “We spray it off to toughen up the pods and reduce shatter, and even up the ripening.”

The helicopter was necessary because with the crop nearing 2m tall, even his high clearance sprayer would have pushed down quite a bit of crop, probably robbing some yield and making for harvesting headaches. “It was taller than I’d have liked and we did get a bit lodge.”

The crop was irrigated three times between Oct 20 and Dec 6 with 35mm applied each time. “Oilseed rape normally only needs one drink, or maybe two, and we’ve had a couple of years where it hasn’t needed any water at all, so you can tell how dry this year’s been,” he points out.

The headlands were harvested Jan 21 which confirmed the crop could be a record breaker. “At that point I got the surveyor in to check the area left and lined up two independent witnesses to verify the weights. It’s not an official Guinness record but we have got the paper trail to prove what we harvested.”

The precedent for removing the headland was set by previous record holder Lamyman, Dennison points out.

“I’d applied to Guinness two years ago when we had some very good oilseed crops to see if we could establish a record for canola yield, but they said there wasn’t wide enough public interest despite what I thought was quite a compelling argument given the world area of the crop. Perhaps now two of us have had a go at it, on opposite sides of the world, Guinness will reconsider.”

Having landed the official Guinness World Record for wheat in 2003, only to lose it four years later to fellow New Zealander Mike Solari, Southland, Dennison’s familiar with the Guinness process.

“I’ve had a few cracks at claiming that wheat record back and I was beginning to wonder if I should retire from world record attempts because they’re quite nerve wracking but this has given me renewed enthusiasm.”

He reckons he could raise the bar with oilseed rape / canola too.

“I know we’ve had better crops of it before and have had 6.85t/ha over the weighbridge but it wasn’t off a surveyed area or with the witnesses present so talking about it’s a bit like a fisherman telling you about ‘the one that got away’, so I’d rather you didn’t print that.”

Sorry Chris, but it was too good a way to finish the story! – Ed.