1 March 1996

Varying rates of liquid fertiliser set for UK trials

By Peter Hill

FIRST UK trials of variable-rate liquid fertiliser application will be part of Hydro Agris contribution to Shuttleworth Precision Farming Alliance work at Shuttleworth Farms, Beds, this year.

The newly formed alliance (see p66) aims to monitor precision farming research with a practical, down-to-earth outlook.

York-based Hydro Machinery will supply equipment for the trials, a 3000 litre/24m trailed applicator equipped with a satellite-guided control system.

"Rather than using an ad hoc system, we are buying a commercially available control package made by Rockwell in the USA," says Alan Thorpe of Hydro Machinery. "This includes a receiver for the satellite GPS signals, a processor and the necessary software to initiate different application rates."

One attraction of the system, Mr Thorpe adds, is that it can be linked up to the applicators standard rate controller with very little, if any, modification.

Hydro Agri has already seen positive results from its variable-rate trials in Germany using solid fertilisers. Rates considered optimum for particular agronomic conditions ranged from 75-230kg/ha in the trial field – a far broader range than researchers expected. Hydro Agris head of agronomy, Geoff Paulson, is cautious about the single-year results, but is encouraged by the yield and £40/ha (£16/acre) increase in margin that variable rate application achieved in comparison with a blanket approach.

The growing diversity of yield mapping and implement control systems will not encourage farmers to take up precision farming technology, warns Brian Welti, manager at Shuttleworth Farms and of the Shuttleworth Precision Farming Alliance.

But a common standard for GPS implement control software is unlikely, believes Mark Moore, yield mapping development manager at Massey Ferguson.

"A universal standard would be almost impossible to achieve and could quickly become out of date; it could, therefore, stifle introduction of new developments," he says. "I can appreciate farmers wanting to use any control system with any implement but I think the chances of that are remote."

Meantime, work is continuing on yield mapping systems for non-combineable crops such as potatoes, sugar beet and field vegetables, calibration of remote sensing images to gauge crop yields from space and of GPS-regulated irrigator controllers. The latter would allow growers to vary application rate in tune with the different water retention characteristics of different soils or to irrigate different crops at different rates in one continuous operation.

lFor a preview of the Precision Farming 96 event and ADASs views on mapping technology, see page 70. &#42

Precision farming – the story continues… Trials with variable rate liquid fertilisers are set to take place for the first time in the UK this year.