Nottinghamshire grower Keith Parker will be keeping a keener eye than usual on his oilseed rape this year as he eagerly waits to see how precision-sown crops compare with those established using his regular subsoiler technique.

“I’m hoping they turn out at least as good,” he says. “If they’re a disaster, we’ll know about it – and so will everyone else because the fields are right next to the main road.”

The experiment came about after the JW Parker & Sons farm and contracting business bought a new precision seed drill for sugar beet. A satellite positioning data link, electronically-driven seeding units and Kverneland’s GEO control software provides uniform spacing precision and no row overlaps at headlands.

While that has clear spacial distribution and easier harvesting benefits for sugar beet, as well as the potential for mechanical weeding in different directions, Mr Parker wanted to see whether the technology could bring any benefits to his oilseed rape crops.

“We’ve used the subsoiler sowing technique for some years now, and with reasonable results; yields are about 1.6t/acre on our mainly sandy soils,” he says. “The winged tines are set at 9-10in deep to give the roots somewhere to go, and seed is dribbled in line with the legs just in front of the packer to get good seed-to-soil contact.”

Lack of depth control

One downside of the technique, he acknowledges, is the lack of seeding depth control. Also, the five-leg Spaldings FlatLift tends to pull up soil when lifting out at the end of a run, especially on the farm’s heavier soils.

“I think we’ll try a little less wing this year because it leaves a bit of a crater and a rough headland,” he says.

Oilseed rape is grown at Corner House, Wellow, near Newark, in an alternating rotation as much as possible to take advantage of its proven benefits as a good entry for winter wheat. It has become a bigger crop for the Parkers this year as they cut back on rye after repeated problems with ergot.

There is about 140ha of oilseed rape in the ground this year, most of it established straight into stubbles during the first week of September using the FlatLift.

Read more: Depth control vital to high oilseed rape yields

The precision-sown crops went in a little later – 35ha after ploughing and pressing to bury rye stubble, and another 14ha or so following a pass with a strip till cultivator to see how that works out. An issue with the way the guidance system was set up meant the drill was offset for a couple of passes so there is also a bit of direct drilling to evaluate.

“Ideally, we’d have the two implements coupled together because even with RTK guidance you only need to shift a bit sideways to lose alignment,” Mr Parker points out. “But that wasn’t possible this time because the Kuhn Striger strip tiller we borrowed was half the width of our 12-row Monopill seeder.”

The Striger is one of several new strip tillage implements that manufacturers and growers are evaluating as a means of reducing cultivation costs for maize and oilseed rape. Each unit has an opening disc to cut plant debris, which is swept aside by a pair of angled finger wheels.

An adjustable tine – loosening soil down to 30cm – comes next; it operates independently from two wavy-edge discs positioned either side that prevent soil being thrown off the cultivated strip. A finishing tool levels and lightly consolidates the finished tilth.

Saving money

The first attraction of precision seeding became obvious as the crop was sown: a reduction of about one-third in the amount of seed used.

“We fitted cell wheel discs suitable for rapeseed and set up the units for a population of 40-50 plants/sq m,” he says. “We bought enough seed for 364ha, but the accuracy and lack of overlaps at headlands meant we actually had enough to plant six fields totalling 49ha.”

Thanks to the GEO system’s ability to precisely control the sowing units individually, the centre of each field could be sown first to avoid running over seeded headlands and there is no seed-wasting overlapping of rows, even where they meet the headland at an angle (see picture, left).

All the precision-sown crops established quite evenly, says Mr Parker, benefiting from moisture in the freshly ploughed or strip tilled soils, and with the trash kit fitted to the Monopill enabling it to cope with the small amount of direct sowing involved.

The crops came through in neat rows 50cm apart – as opposed to the more ragged 6-8in-wide bands at 60cm centres from the subsoiling seeder – and with single plants accurately spaced about 4.5cm apart within the row.

Animal damage

Rabbits were the first beneficiaries, says Mr Parker. “In places, they’ve grazed every plant in sections along the thin rows, whereas they’ll miss a few when the plants come up staggered from side to side,” he says.

“We’ve also had some pigeon damage in the strip-tilled fields, which don’t look as tidy because of all the untouched stubble.”

He hopes yields will be at least as good as from the crops established using his usual technique, but is hopeful there may be some improvement from the accurate sowing depth and even plant spacing. Time will tell, although it will be difficult to judge accurately because the precision-sown fields are quite variable in their soils and the farm has no easy means of recording yields on the combine.

Nonetheless, the Parkers have the seed cost savings in their pocket and have tramlines in their OSR crops for the first time.

Opico coulters get to grips with sowing depth control

The lack of sowing depth control with subsoiler- and cultivator-based oilseed rape seeding systems is being tackled by the Accu Disc coulters from Opico.

They bolt on behind a He-Va subsoiler or disc roller to place seed at a consistent and accurate depth behind subsoilers.

“This is the next step in the evolution of our Till-Seeding system, which involves drilling into stubble in line with the subsoiler legs,” explains James Woolway of Opico. “Till-Seeding leads to better overall crop establishment, improved root structure, stronger plants and growth, and ultimately better yields.

“But while crop establishment is already very good, drilling at a consistent depth gives even better results – it’s the key to improving germination and evenness of plant size,” he maintains.

Each Accu Disc unit consists of a double-disc coulter to open a slot in the soil and place the seed. The coulter is carried on a spring-mounted parallelogram, which enables pressure to be adjusted so it can accurately follow contours.

The discs are followed by a rubber press wheel to close and consolidate the seed slot and mounting the coulter assemblies on a toolbar provides central depth and pressure adjustment.

Opico trials in England, Scotland and Denmark over the past two years show that drilling at a consistent depth improves seed germination and plant size consistency. As a result, “significant” cuts in seed rate can be made.

The Accu Disc seeding system is available in 3m (five-leg), 3.5m, 4.4m folding and 5m (nine- leg) He-Va subsoilers, which are now available with “easy draft” legs for soils that do not have to be worked deeply to alleviate compaction.

Two versions of strip cultivator

❚ Kverneland’s compact strip cultivator will be available in plain and slurry injector forms, with 45cm strip spacing to suit oilseed rape, sugar beet and maize.

Rubber wheels either side of the front disc provide depth control and hold rape stalks and other material while it is cut before being cleared to one side by spring-loaded finger discs. A winged soil-loosening tine adjustable to 30cm working depth creates fissures through any compaction. It has a built-in outlet for placing granular fertiliser from a front-mounted hopper. Large discs either side of the tine prevent soil being thrown from the cultivated strip, which is consolidated by a choice of finishing tools – a crumbler, v-press roller and Flexroller for lighter soils.

All elements on the Kulti-strip are maintenance free and with mostly crank or pin-and-hole adjustment; the only tool needed adjusts the 
side discs from straight to angled to build up the soil and get more warmth into it before sowing maize.