19 June 1998

Farm trial for patch design

By Ian Marshall

IT HAS taken more than five years to become a reality, but Silsoe Research Institutes variable application rate patch sprayer is now at work in the field in north Lincolnshire.

The sprayer controller is the first – and so far only – commercial system to come out of the collaboration between Silsoe Research Institute and Micron Sprayers announced at last years Sprays and Sprayers Event.

This spring the sprayer started work on CGR Booth Farms Frogmore Farm, Thornton Curtis, where the company sees it as the means of achieving one of its main goals – to reduce its variable costs of production on the 293ha (725-acre) all-arable farm. The sprayers role is to apply liquid fertiliser – N, P and K – and all sprays at variable rates, the next phase in the companys exploitation of GPS technology.

"It is part of a long-term plan. We are confident that we have cut fixed costs to the minimum, the next step is to not only save on inputs but use them more efficiently; the only way we can do that is to match application rates site specifically to output," explains farm manager, Paul Steer, who has been yield mapping for the past four years with a Massey Ferguson Field Star system.

The control system is installed on a purpose-built 2500-litre GEMdemountable sprayer fitted with a 28m (92ft) boom and dual spray lines. This is fitted on a stretched Fastrac 1135 which has had its chassis extended by 75cm (2.5ft). The unit is also fitted with twin 240-litre/min (63 gal/min) diaphragm pumps.

"We need two to maintain an even flow across the width of the boom at our spraying speed of 10-12km/hr," says Mr Steer.

Rates are varied, on the move, by the Silsoe/Micron Sprayers computerised "implement control system", which automatically adjusts application pressure to achieve the selected volume.

CGR Booth Farms patch sprayers GPS link is through Massey Fergusons Fieldstar system, whose Datavision terminal is transferred from the combine to the Fastrac. In operation, a fields spray programme, based on the farms data bank of GPS yield maps, is generated on the office PC, then downloaded onto a smart card. This – which, in Mr Steers case, will take preparations for up to 121ha (300 acres) or 14 fields – is then placed in the Datavision terminal, which is linked to the implement control system.

Mr Steer has the system programmed to apply low volumes, of up to 85 litres/ha (9 gal/acre), through the front line. High volumes, of up to 150 litres/ha (16 gal/acre), go on through the rear line. Using both lines simultaneously gives up to 350 litres/ha (37 gal/acre).

In the field, the driver enters and confirms the field number he is working in on the Datavision terminal. The implement control system then takes over all application functions, automatically varying rates to match both application map and changes in forward speed. It also selects the spray lines relevant to the volume being applied and apporopriate line pressure to achieve the desired output.

Product application is through standard flat fan nozzles which are switched on and off by electro-pneumatic valves, powered by the tractors built in air supply.

The implement control system was customised for CGR Booth Farms and added £7000 to sprayer costs. The Fastrac – which will also see use on the front of a plough – and sprayer were budgeted for as a replacement for a seven-year-old MB-trac/GEM 24m (79ft) demountable unit.

Mr Steer confidently expects to recover the additional costs of the patch sprayer control system in two to three seasons, with increased yields through the more precise application of inputs and a reduction in their use.

A stretched Fastrac carries the 28m boom, 2500-litre patch sprayer and its control system, the first unit to come out of the collaboration between Silsoe Research Institute and Micron Sprayers.

Paul Steer, CGR Booth Farms manager confidently expects to recover the additional costs of the patch sprayer control system in two to three seasons. "In spring applications of liquid P and K alone, we have saved £2000 across the farm," he says.