28 February 1997

Putting it where its needed


Precision fertiliser application is taking off in the UK. Andrew Pearce talks to a Suffolk farmer to see how hes faring with the Massey/Amazone system

BY the end of 1995 and with three years worth of yield maps under his belt, Suffolk farmer Stuart Scarff was itching to move deeper into precision farming. The maps had already helped tie yield loss to headland compaction around Fenns Farms 263ha (650 acres). But with that sorted out, variations of up to 4t/ha (1.6t/acre) were still unexplained.

One 5ha (12-acre) patch in a 28ha (69-acre) field had under-delivered for two seasons. So in the autumn Mr Scarff tested the area separately, and was surprised to find very low phosphate levels. "We had sampled the field in the usual W pattern and averaged the result, ending up with an index between 1 and 2," he explains. "And then dressed the field accordingly. But in doing so, we had missed a problem area completely."

That suggested closer sampling might pay off elsewhere. So Mr Scarff divided a second field – one already yield mapped, and due for winter wheat again – into 50m (164ft) squares and got busy with his global positioning system-equipped ATV and slightly lower-tech spade. Once more there were big variations in phosphate levels, and although these corresponded only roughly with yield and known soil variations, he was keen to do something about them. The obvious thing was to adjust application rate to level nutrient status.

Initially, he varied application manually through his existing spreader. Then last summer Amazone announced its M-tronic system (see box for details). Mr Scarffs local dealer offered one on trial, along with the use of a 6100 Series tractor and the new Fieldstar/ Datavision II terminal. In autumn 1996 two-thirds of the farms 0-30-20 compound went over its discs.

How were rates decided? Some 40ha (98 acres) had already been sampled on a 50m (164ft) grid and its nutrient status was known. Targets for the rest of the farm were derived from the previous three seasons yield maps, with soil checked in high, medium and low-yielding areas for confirmation. "Sampling on a 50m grid is expensive," points out Mr Scarff, "so I am probably going to move up to 100m squares and farm the resulting 1ha blocks individually."

Idiot proof

"The equipment is pretty idiot-proof," he confirms. "All you do is tell the system the field you are in and then start and stop it. We made a point of buying good quality material which went through the machine well. Amazone calibrated the spreader at the start of work and we had the whole farm done inside two days."

How does Mr Scarff see the future? "We want to bring nutrient levels to indices 2 and above. Soil sampling small areas has shown big variations, and although we cant yet be sure how these affect yield, balancing them lets us cross one variable off the list.

"As yet the systems cost-effectiveness cant be judged. But we can use lower rates where soil indices are good, choosing only to balance nutrients taken out by the crop; or we can target fertiliser to areas where a need for more input shows up. From our experience so far the equipment is easy to set up and use, and as long as calibration is accurate I can see no reason why it should not deliver the right result." &#42

Talking partners: Amazones ZA-M MAX-tronic spreader varies application rate on cues from MFs Fieldstar-compatible Datavision II terminal (inset).

The system

Last year Amazone introduced the M-tronic version of its existing 24m (78.7ft) ZA-M twin disc spreader, which dovetails with Masseys Fieldstar system. The main hardware parts of the latter is the Datavision II terminal – a monitor/control device that can be moved between combine and tractor – and its plug-in communications unit. While in the combine the main box uses GPS satellite information and the MF yield meter to log both position and yield every 1.2sec, recording the info on a palm-sized data card. The card carries those results to the farm computer, inside which Fieldstar software generates yield maps.

The farmer and agronomist pore over these and, after pulling in other information like nutrient status variation (achieved by soil sampling), decide on fertiliser treatment for different-yielding areas. The computer then generates application maps, which go by data card back to the Datavision II terminal. This, meanwhile, has been moved to the tractor (either a 6100 or 8100 Series Massey), which carries its own GPS aerial and mounting hardware.

Amazones spreader has a second computer. On hooking spreader and tractor together the two boxes shake electronic hands, and Datavision II puts a graphic of the Amazone on its screen. The driver goes to the field, tells the system he has arrived, and starts work. Datavision II talks constantly to the Amazone, telling it when – and by how much – to alter application rate as the outfit tracks across the ground. Spreader adjustments are made electro-hydraulically, with Datavision II showing both tractor position and the varying application rate.

A 24m (78.7ft) ZA-M MAX-tronic costs from £7000, with Masseys side of the operation adding £1060 for the tractors GPS unit, fitting kit and software.

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