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Accurate seed placement key to improving yields


In search of the ultimate establishment system for oilseed rape, one Norfolk grower has turned to a precision drill to guarantee seed placement accuracy. Geoff Ashcroft reports.

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Chris Eglington is no stranger to growing oilseed rape. Over the past 20 years, the crop has been a key part of his rotation at 404-hectare North Hill Farm, Letton.


Throughout that time, rape establishment methods have been continually refined as he looks for the most suitable solution on his soils to give a highly efficient, low cost establishment process.


As a result, his latest crop is one he thinks will be difficult to improve upon. It was established with a Kverneland Monopill precision drill more commonly used for sugar beet, and this gave Mr Eglington the precise seed placement – depth and down the row spacing – he sought.


“I’ve always believed rape is one of the most cost-effective crops to establish, but a lot has hinged on seed placement accuracy,” he says. “And precision seeding of oilseed rape is, I believe, the only way to guarantee accuracy with low seed rates without compromising yield and profitability.”


Mr Eglington’s search for perhaps the ultimate establishment system led him into subsoiling and planting using an old Accord drilling system. He soon progressed to an Opico Varicast system for better accuracy with the subsoiler, but he still wasn’t seeing the results he believed were achievable.


“One of the biggest issues was getting an accurate seed rate,” he says. “Broadcasting seed from outlets behind a sub-soiler is immensely inaccurate. While plant numbers and seeds per hectare weren’t even a consideration at that time, we were just blowing seed onto and in some.”

Crop failure

It took a near crop failure to enable Mr Eglington to see just how far rape could go, and also to reveal how it had the ability to recover.

“One part of a field had a rape crop so thin, you could easily walk through it,” he says. “While tempting to just rip it up and start again, I chose to leave the crop standing.”


Soil types 1

“We have 13 soil types across the farm, and most of our soils do slump, so the plough has a role to play in getting air back into the ground,” he says. “Using a sub-soiler for rape establishment means the entire farm is sub-soiled every four years, which also boosts aeration.”


A min-till regime then follows barley ahead of oilseed rape and again after rape ahead of wheat – but as a single pass to deal with stubbles.


On-farm trials quickly revealed the precision drill worked best, with seed having a 1,000-grain weight between four and six.


“Below four, we would get doubles, and anything above six would create seed cracking,” he says. “So I chose to have my rape seed sized to 5.5, and we now plant precisely 21 seeds/sq.m – the equivalent of 1kg/ha.”


Following winter barley, the rape establishment process starts with a pass with disc harrows to chop and disperse stubbles. A stale seedbed period then follows before the sprayer cleans up any weeds and volunteers ahead of drilling.


The Monopill precision seeder is carried on a three-point linkage at the back of a four-metre TWB subsoiler, behind the packer roller. This allows the drill to be removed should any additional subsoiling be required.

frame modifications

Frame modifications

The TWB implement has however, had its frame heavily modified by its creator to give Mr Eglington the highly effective one-pass system now in use.


With seven legs on the subsoiler, this required a drill frame equipped with seven electrically driven seeding units to give 570mm row spacings across the 4m working width.


Behind the TWB’s seven legs sits a liquid fertiliser nozzle, while a slug pellet outlet follow inline, but behind the packer roller. The location of nozzles ensures positioning of nutrients and pellets in a band where the rapeseed will be placed.


Immediately after drilling, the seedbed is then double-rolled, using a 50% overlap from a 16.3m set of rolls which adheres to recently adopted 8m controlled traffic farming (CTF) regime. The additional consolidation means Mr Eglington rarely needs to apply slug pellets post-drilling.


“It sounds simple but it took two seasons to find the most suitable means of integrating the precision seeder into the subsoiler,” he says.


“We initially mounted the drill under the middle of the sub-soiler frame for our first season,” he says. “There was too much soil movement and seed was placed too deep. Because of this, we only successfully planted six of the seven

rows – the central row simply became lost in the flow of soil beneath the machine.


“So TWB changed the configuration of the machine to suit our requirements.”


Putting the drill at the rear of the subsoiler gave space under the main frame to mount an additional packer roll. This irons out any ridging from the centre sub-soiling leg, where the machine’s two-piece hydraulically folding packer roller meets.


And being fractionally wider than 4m, the packer roller overlaps on adjacent passes, creating a totally level finish.


“Despite the first season’s drawbacks, we saw yields of 4.8 tonnes/ha at 7% moisture over the farm weighbridge during the 2014 harvest,” he says. “I do think our yield average would have nudged 5t if all seven rows had come through.”


Second season

Second season

Now in his second season of precision planting oilseed rape, he says his current crop using the conventional variety Tactic is one he is looking forward to putting over the weighbridge this summer.


“The crop got off to a good start and establishment costs could not be lower or germination no better,” he says. “What we want to achieve is a plant spaced 3.5-4in apart, down the row. And after just two seasons of precision planting, we’re 98% there.


“Down-the-row seed spacing is tremendously even and the drill has proved so precise we used just 74kg of seed to establish 70ha of oilseed rape.”


Output, behind the farm’s Versatile 435 tractor, is 20ha/day, with RTK guidance keeping the farm on the right wheelings with CTF.


“Despite running on 520/85 R46 dual wheels, the whole outfit sits nicely within our CTF system,” he says. “I’m not a fan of rubber tracks, and with the recent combine swap from a Lexion 570 and 7.5m header to a Lexion 750 and 9m header, we are well on the way to managing and controlling compaction.”


Mr Eglington believes correctly set tyre pressures on all his machinery – tractors, harvester, sprayer and trailers – should help to contain any compaction within the top 12.5cm of topsoil.


“We plough to 10in, which means it is relatively easy to deal with any compaction issues.”


While precision planting oilseed rape is still in its infancy at North Hill Farm, Mr Eglington is pleased with the establishment system in use.


“We still have a long way to go, but I am happy with the route we have chosen,” he says. “And because of the increased accuracy achieved by the Monopill, I’m hopeful we’ll soon be producing consistent yields of 5t/ha.”


SS Eglington and Son

  • Farm: North Hill, Letton, Norfolk
  • Size: 404ha
  • Soil types: From loamy sand to heavy silty clay loam
  • Cropping: Winter wheat, winter barley, oilseed rape
  • OSR establishment: 4m TWB subsoiler with seven-row Monopill precision drill
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