Precision drilling of cereal and oilseed rape seeds isn’t new. In fact, the Stanhay Webb Dart drill was launched over a decade ago, and boasted cereals and oilseed rape among the seeds it could establish, alongside more mainstream precision-planted crops such as sugar beet and maize.

But as establishment costs continue to rise and wheat yield stagnates at around the 10t/ha mark, farmers and manufacturers are looking at whether precision drilling could hold the answer to improving yields.

Horsch

 It’s not just tillage that can be fine-tuned to boost yields and cut costs in the establishment process, says German company Horsch.

“Sowing technology is also the basis for maximising yields, and already many farmers constantly fine-tune placement depth and sowing rates,” explains UK company director Stephen Burcham.

However current mechanical and pneumatic seed distribution systems can be inconsistent, with seed placement varying between 90% and 120%. In the field, this can translate as misses and doubles.

“If several grains fall in one area, plant growth will be compromised due to high competition for light, root space and water. These plants often fail to tiller, and only develop a weak, unstable stalk,” says Mr Burcham. Horsch’s system involves distributing seed from a standard drill hopper via a central metering unit, with the pre-metered seed transferred pneumatically to the individual seeding unit. All fairly commonplace technology, but it’s in the final stages where things start to change.

A new TurboDisc coulter is fitted with a mounted metering unit for singling and placing seed. As seed begins to spin around the disc, it travels outwards and a single seed is picked from a group and redirected in a circular motion to a drop tube.

The remaining grains return to the starting point and start the process all over again. This metering disc is capable of metering cereal seeds at a rate of up to 120 grains a second, equating to a seed rate of 240 grains/sq m at 12kph with a row spacing of 15cm.

Both the volumetric metering and singling metering unit are controlled by the on-board electronic system, with the operator entering the desired quantity of grains/sq m, the thousand-grain weight and the germination rate. The system then calculates the metering quantity of the unit.

The speed of the disc changes according to seed size and spacing, and if you don’t want to use the singling unit you can still use the drill in its conventional pneumatic form.

Designed as a bolt-on metering system using standard TurboDisc coulters, the system will be available as an option on its Pronto DC and Focus TD drills, and can be retrofitted to existing machines if necessary.

Lemken

Lemken’s prototype Azurit precision seeder unit claims to give better longitudinal spacing and more accurate fertiliser placement between rows.

Instead of placing seeds in a single row, they are staggered, with two double-disc coulters for each seeding unit in an open row at intervals of 12.5cm. The distance between seeding rows remains at 75cm, so it’s ideal for maize and rape and there are no changes to harvesting. Variable spacing of up to 37.5cm can also be selected and travel speeds of 15kph are expected.

“By staggering seed placement the area between plants increases by up to 70%, giving more water and nutrient availability as well as greater rooting capacity,” says Lemken UK’s Mark Ormond.

An electrically driven singulation unit, which is mounted on the main frame to avoid vibration from the coulters, distributes seeds alternately to both coulters. Seed is administered on demand to this module, which houses a small reservoir.

“Fertiliser is typically delivered 5cm deeper than the seed at the front of the unit via double disc coulters exactly in the middle of the open seed row, while Lemken’s Trapeze packer rollers close the fertiliser grooves and shape the seeding furrow.

“Although it doesn’t have its own fertiliser tank, the Azurit can be connected behind a Compact Solitair or other unit in order to provide a measured quantity to the fertiliser coulters,” explains Mr Ormond.

Although still in its test phase, the Azurit will be placed with farmers in Germany for evaluation in the coming season.

Pottinger Aerosem

Justifying machinery investment is always a tricky business, especially as it’s often the case that one purchase can mean putting all your eggs in one basket.

Pottinger has come up with a nifty solution with its ‘precision combiseeding’, a concept that allows for both standard grain drilling and precision drilling in a single machine, thus reducing fixed cost in the process, explains UK general manager Shaun Groom.

Individual seed drilling units have been introduced to the Aerosem 1002 pneumatic seed drill. Ten individual seeding elements allow for row spacings of 12.5cm (only on the ADD model), 37.5cm or 75cm depending on the application. It’s also possible to apply fertiliser between the rows using the standard metering system with a distributor add-on.

“For those looking to undersow, grass seed can be sown simultaneously, thanks to a split seed hopper that can either hold fert or seed,” explains Mr Groom.

“Individual seed metering units are located beneath the additional funnel, with a maximum of 10 rows (4m working width) currently possible. Seed separation is mechanical, while individual grains are transferred to the coulter under pressure for equal spacing along the groove formed by the Pottinger’s dual discs.”

Operated via the in-cab terminal, row spacing, seed gap and seed/ha can all be entered, while seed flow can be altered without having to swap drive chains. “Conventional calibration is also a thing of the past with this system,” adds Mr Groom.

Longitudinal seed distribution is also monitored via an optical sensor and the terminal displays incorrect and double placement in the cab.

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