12 January 1996

One step nearer to quest for precision

Field scale evaluation of satellite-assisted precision farming at Shuttleworth Farms is bearing fruit. Andrew Blake reports

ENCOURAGING results from adjusting cereal drilling rates on the move have emerged from trials at Shuttleworth Farms, Beds. But matching rates to the state of seed-beds was twice as rewarding in 1995 as adjusting them to yield potential.

The field trials are the latest and logical steps in the precision farming quest begun by Shuttle- worth, in collaboration with Massey Ferguson, in 1992, explains farm manager Brian Welti.

"The results are by no means conclusive, but they do indicate a positive response to varying seed inputs."

Changing seed, fertiliser and pesticide rates should be considered only when the potential of different parts of fields has been established over several years, stresses Mr Welti. It is also vital that limiting factors under growers control are first eliminated. "There is no point in varying nitrogen if compaction is restricting output."

Four seasons data from a MF satellite-linked yield mapping combine at Shuttleworth has revealed "distinct yield trends" across fields, even where a winter bean break was inserted into a run of winter wheats.

Adjustable inputs

Combining such information with soil texture and nutrient maps should allow inputs to be adjusted to achieve the goal of precision farming, he reasons. "The ultimate aim should be to influence the gross margin map by making the poorer areas equally as profitable as the good areas."

Having accepted that everything had been done to raise output in the low yielding parts of fields it was time to move on to vary inputs.

Key questions the new trials aim to answer are:

&#8226 Should low yielding areas get more?

&#8226 Should high yielding areas get less?

&#8226 What are the environmental considerations or limitations?

Three fields were chosen last season, each with an established yield database. Prototype machinery allowed one input in each (seed, fertiliser or herbicide) to be varied according to preset application plans.

The trials were laid out so that 12m (39ft) wide strips of standard "blanket" application rates alternated with 12m bands of variably applied inputs across the fields.

For the seed rate experiment the field was split in two. In one half the rate was linked to the condition of the seed-bed – poor areas getting 20% more seed.

In the generally higher yielding half, where the decision was based on the potential yield map, reverse tactics were tried. "Higher-yielding areas got more seed and the low-yielding parts got less," explains Mr Welti. "The yield data base was used as the basis for walking the fields and plotting seed-bed conditions."

Increased yield

The results (see table) show that tuning seed to seed-bed conditions boosted gross margin by £22/ha (£8.90/acre). "This was mainly due to increased yield," he notes.

"By varying seed according to economic factors, in other words using more in the traditionally high yielding parts, we were able to increase the gross margin by £11/ha. This was both a function of saving seed and raising yield."

The trials are being repeated this season to add to the picture.

"Weve proved that the equipment works and has an effect. We are now starting a period of really serious trial work to assess the long-term benefits."

Results from adjusting nitrogen according to a soil mineral N map have not yet been fully analysed. But patch-spraying linked to a weed map last season against blackgrass and cleavers suggested savings of £10/ha (£4/acre) are possible, says Mr Welti. Repeat trials in conjunction with Silsoe Research Institute are under way to confirm that potential. &#42

Shuttleworth Precision Farming in 1995

&#8226 Positive response to varying seed rates.

&#8226 Adjustment in line with seed-bed more rewarding than to mapped yield potential.

&#8226 Patch spraying savings about £10/ha (£4/acre).

Variable seed rate trials at Shuttleworth College 1995

Far Highlands fieldAreaTotal grossAverage gross



Seed varied }Standard seed rate2.501870748

according to }

seed-bed }Variable seed rate2.411856770

conditions }

Seed varied }Standard seed rate3.152458780

according to }

economic }Variable seed rate2.962344791

factors }

Raising seed rate where the seed-bed was poor paid off better than following maps of yield data in last years Shuttleworth trials.

Planting wih this GPS-equipped tractor and drill saved £22/ha in seed costs at Shuttleworth Farms last year. Programmed with yield map and other data, the drill automatically varied seed application rates to reflect differences in growing ability from one part of the field to another.