Precision suits units ICM approach

28 January 2000

N-Sensor will score well on variable sites

"ON this site at CWSStoughton, in Leicester, there was probably not very much variation across the field, the real issue was what the overall rate should be," says project manager, Alastair Leake.

"But elsewhere the N-Sensor could really come into its own, adjusting rate in response to changes which are not even apparent to the farmer."

Over 100 field trials and 35,000ha of commercial use around the world show early season N-Sensor maps tie in very well with final yield, even on apparently uniform fields, adds Hydro Precise managing director Tony Robinson.

Typical margin boost is £10.88/ha, based on an average 2% yield boost in an 8t/ha crop of wheat worth £68/t, comments Mr Robinson.

No field tested showed less than a 40kg/ha variation in N demand and many varied by up to 120kg/ha of nitrogen, adds Jargon Wolfing, technical director for Hydro Precise.

"There is absolutely no doubt that variable rate fertiliser can give yield and quality benefits," continues Mr Robinson.

"You will see plus or minus 30% variations in N demand on even the most apparently uniform fields."

Precision suits units ICM approach

Precision use of nitrogen

benefits the environment and

your pocket. Charles Abel

reports the latest experiences

from the Focus on Farming

Practice project in Leics

PRECISION technology boosted income by over £5500 on a single block of winter wheat last year at CWSs Stoughton Estate near Leicester, host of the Focus on Farming Practise project.

Sponsored by CWS, Hydro Agri and Profarma the project has studied integrated crop management for over six years. Last year, manager, Alastair Leake, was called in to deal with 100ha (250 acres) of wheat on profoundly lodging-prone old pasture land.

"Every year it has been in cereals the land has lodged, despite a full pgr programme. Last year the manager asked me to look after it using ICM principles," says Mr Leake.

The variety was Equinox, rated nine for standing power, and February populations were acceptable, although not as low as liked under ICM conditions.

"What really struck me was how lush the crop was and how unconsolidated the soil was compared with ICM fields where minimum tillage is the norm."

Initial sampling of the heavy clay loam to 90cm gave a mineral N content of 68kg/ha and 2.6% organic matter, little different from the farm averages of 50kg/ha and 2.2%. Based on those figures Hydros Precision Plan software recommended 180kg/ha of bagged N, much the same as the rest of the farm.

Sensing something was amiss Mr Leake resampled by horizon, at 0-30cm, 30-60cm and 60-90cm. That revealed a very different picture. "Organic matter content was 6% in the top 30cm, leading us to a recommendation of just 100kg/ha of nitrogen. That just shows the importance of knowing what you are dealing with."

Actual rate applied was 110kg/ha, the second split going on using a spreader fitted with Hydros N-Sensor, which varies rate across a field according to crop greenness.

Checks using the farms hand-held N-Tester showed the rate was giving the crop what it needed for optimum yield. "The farm manager could not believe it, especially when I said the tester suggested there was still a risk of lodging."

A full pgr programme kept the crop standing and final yield was 0.8t/ha over the estate average, despite delayed cutting. Across 100ha with wheat worth £68/t that boosted income £4800, more than covering testing and variable application costs.

"Add the benefits of easier harvesting, less drying, better quality and 70kg/ha less bagged N required and there are real savings to be had. It certainly convinced our farm manager of the need to manage fields separately," Mr Leake comments.

In time soil sampling becomes less necessary, he adds. "We have been doing it for over five years now and have enough data to be able to estimate soil N levels for any particular soil type and position in the rotation. That helps, because there is a cost to testing."

Hydro Precise managing director, Tony Robinson goes further. He believes soil mineral N testing could be missed out altogether, farmers relying on N-Tester and N-Sensor results alone to guide application rates. "You can get just the same result by asking the plant what is needed, rather than the soil," he says.

But before making that switch Mr Leake is keen to do a split field evaluation. "We do need to measure new techniques against existing best practice before making changes."

Using precision management techniques to guide N inputs helped Alastair Leake boost wheat margins at CWS Stoughton, near Leicester, last year.

PRECISIONN

&#8226 Hand-held N-Tester checks N demand of crop – £320 a year rental.

&#8226 Precision Plan recommendation software calculates field rates.

&#8226 N-Sensor – tractor mounted real-time assessment of crop N need and variation of N rate around field average accordingly.

&#8226 23 N-Sensor units used world-wide on 35,000ha in 1999.

&#8226 8 units in UK on 8000ha.

&#8226 Unit costs £7-£8/ha based on 500ha cereals and £10,000 purchase price or £3500 a year rental, plus £1000 a year calibration.

&#8226 15-20 units destined for UK in 2000.

&#8226 Germany and Scandinavia adopting more rapidly.

&#8226 N-Sensor now being calibrated for sugar beet, potatoes and oilseed rape.

&#8226 Scope to use to guide pgr and fungicide rates according to crop density and level of infection.