Cutting-edge time savers

31 March 2001

Cutting-edge time savers

Deprived of his annual techie fix, thanks to a postponed precision event, Tom Allen-Stevens searches out whats new in variable rate applying

IF youre fond of beer, the ultimate job would be chief taster at a brewery. For chocolate connoisseurs, it would be quality control for Cadburys. Meanwhile, if the cutting edge of agricultural technology is your passion, you would be sorely envious of Robert Hale.

As farm manager at Silsoe Research Institutes 120ha (300-acre) farm, Mr Hale gets to try out for free many of precision farmings latest developments before they have even left the prototype stage. "It works well for me. With fewer staff these days, I need better equipment, and I get a real time saving from some of the kit Im using. It makes the job a lot more interesting too."

It started with Microns Patch Sprayer, used for applying pesticides at varying rates across a field. When it arrived at Silsoe for evaluation, someone was needed to operate it. Mr Hale was only too happy to put his name forward.

"It works well for manufacturers, too – they get their prototype out in a real farm situation straightaway. And its surprising how detached from practical farm situations they can be. For example, they werent aware how difficult it is to drive a combine and map weeds at the same time."

AGCO is one manufacturer making the most of this alliance. Fieldstar, AGCOs precision farming system, has now been on the market for five years in its present form. It has established itself in many combine cabs worldwide and produced reams of yield maps. Now the drive is on to make use of it in the sprayer, spurred on by AGCOs recent acquisition of Spra-Coupe sprayers.

"You can now specify Fieldstar spray control and monitoring as a factory option with a Spra-Coupe. Or you can fit out a tractor and purchase a compatible sprayer, or modify your sprayer for very little cost to work with an existing Fieldstar system," says AGCOs David Smith. The second Spra-Coupe to be fitted with Fieldstar spray control and monitoring has come to Silsoe and is being used by Mr Hale.

The sprayer itself has had few modifications, other than a new flow meter to allow measurement of low flow rates to the nozzles and a different ground wheel sensor to measure forwards speed. A variable rate application map is loaded into the Fieldstar terminal via a data card. Using the GPS receiver to set the position and the sensor to gauge forwards speed, the flow rate is varied automatically on the move.

The main limitation of the system is the nozzles themselves: this is a single-line system so they can be required to work outside their optimum range. "You can set the maximum and minimum pressures you want to work at and the system will beep at you if it goes out of these. Then its just a case of speeding up or slowing down," says Mr Hale.

Touch sensitive

By the same token, if the sprayer slows down, to negotiate a bump or on the headland approach, for example, the rate is automatically dropped. You can also manually adjust the rate if you want by simply touching the Fieldstar screen; the sprayer not only receives signals from the unit, but also sends back real time application information, so an actual application record map can be generated.

The first commercial version to hit the market will only be able to variably apply one herbicide – whatever is in the tank. But itll be a cost-effective way to variably apply, says Mr Smith: "Everything else on the machine is standard, which makes the cost of modifying the sprayer relatively low."

Also fitted to this Spra-Coupe is an experimental single line direct injection unit, that works independently of the main flow meter. "Ive found its quite useful to put IPU in the tank and Topik (clodinafop-propargyl) in the direct injection unit," says Mr Hale.

The disadvantage with direct injection is that the chemical takes time to reach the outer nozzles on a boom section, so you can end up with a chevron-shaped spray patch. The problem can be part alleviated by modifying the plumbing on the spray lines, and direct injection enthusiasts are likely to have to make do with a saw-tooth spray patch.

So how does the Spra-Coupe compare to the other smart sprayer Mr Hale is using – the Micron Patch Sprayer? "Essentially its very much the same, but the Micron is a dual-line sprayer, so the range is much greater. You dont have to worry about forwards speed and you can variably apply liquid fertiliser," says Mr Hale.

At each nozzle point there are two nozzles of different sizes, turned on or off by an air line. As the pressure is increased and one nozzle reaches its limit, the built-in computer automatically switches on to the larger nozzle, and then both as the pressure is increased still further. The result is that you can increase the rate by up to three times.


A variable application map in the Fieldstar unit controls the system, again. But there is no two-way communication with the sprayer, so no actual application record map can be drawn up. Its a very much more complicated system than the Spra-Coupe, which also means it is very much more expensive.

"The cost of precision farming is really coming down now," says Mr Smith. "This is mainly because GPS hardware costs have dropped dramatically. The perception is that it costs more than it actually does."

For Mr Hale cost isnt the issue, mainly because he gets some of the technology free. He feels the whole precision farming business is coming together and proving to be really useful: "My agronomist mapped my field using Patchwork software, and e-mailed me the file. I imported it into the Fieldstar software and sprayed with the Patch Sprayer. Once you combine the whole system it takes out much of the time and energy you had to throw at it before. Meanwhile Im cutting spray costs on the farm without compromising effectiveness."

&#8226 The Fieldstar software itself has undergone changes. Its main drawback – compatibility with other software and systems – has now been largely resolved, says Mr Smith, with facilities to exchange data in simple file formats with other software such as Farmade Amais and Farm Works Farm Site.

Version four of the software, about to be released, is more tractor-friendly. It provides a marker system so you can mark weeds or other relevant features in the field.

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