14 March 1996

Save seed with variable spacing

By Peter Hill

FORAGE maize growers could, in future, be applying precision farming techniques to maximise yields and reduce establishment costs.

German precision seeder manufacturer Amazone unveiled its prototype variable seed spacing drill at the Precision Farming event. It could enable growers to use different plant populations to match yield potential of areas in fields.

"In Germany, research, has shown the technique can increase total yield while saving on seed," says Dietrich Baye of Amazone. "This has been achieved by increasing plant populations on poorer soils within the field and cutting back in areas where yield potential is better."

Modifying the standard Amazone ED drill, introduced to the UK last year, involves replacing the land-wheel drive to each seeder unit with a hydraulic motor drive coupled to an electronic control unit. In its basic form, this allows the operator to vary seed spacing in the row manually.But linked to a digital Global Positioning System data logger/ controller, the system could be pre-programmed to make seed spacing changes automatically.

In Britain, trials are focusing on the potential of narrow-row and cross-hatch drilling as a means of increasing crop density, while ensuring plants have an equal share of available growing space.

Maize Growers Association agronomist Simon Draper says that there is evidence thatthese sowing techniques could increase yields and drymatter. And the MGA is conducting field-scale trials to find out.

Earlier ground cover, reducing the need for herbicides or mechanical weed control, could be an additional benefit.

Conventional drilling, with rows 76cm (30in) apart and seed spaced at 11cm (4in), typically gives a plant population of 120,000 plants/ha (48,000 plants/acre). The French bed system, which places two rows 36cm (14in) apart at 76cm (30in) centres, achieves a 30% increase in plant density at 160,000 plants/ha (64,000 plants/ acre) using the same in-row spacing.

Trials in France have shown yield increases of 10-20% using this approach.

Cross-hatch drilling, where the crop is sown at conventional row spacing but drilled twice at right-angles and with in-row spacing increased to 20cm (7in), achieves 130,000 plants/ha (53,000 plants/acre) and arguably the most even ground cover.

"The practicality of such techniques have to be taken into account alongside any performance improvements. Cross-hatch drilling means sowing takes twice as long and is, therefore, costlier. And, as with narrow-row drilling, crops may need to be tramlined in order to avoid excessive plant losses during post-emergence spraying operations," says Mr Draper.

Amazones prototype variable seed spacing drill is conventional apart from its electronically controlled hydraulic drive for the seeding units.

Conventionally drilled maize could be a thing of the past if novel drilling patterns, which can increase yields, are adopted more widely.


&#8226 Conventional 120,000/ha.

&#8226 Cross hatch increases populations to 130,000/ha.

&#8226 French bed 160,000/ha.