Article taken from Farmers Guide, July 2017.
A large-scale precision farming trial in Cambridgeshire is examining the benefits that an integrated approach to the technology can deliver.
The Agrovista trial, taking place over several years at David Wakefield's Manor Farm near Ramsey, compares current farm practice with new techniques that use a range of precision farming technologies.
Agrovista's head of precision technology Lewis McKerrow says:""The aim is to bring together the various elements associated with precision farming to provide clear decision-making evidence in a commercial situation.""
The Plantsystems Technology prescription trials are taking place across four fields totalling 107 hectares (268 acres). Each has significant variations in soil type, water retention and aspect.
Concepts currently under test include soil zoning, variable seed rate, soil moisture measurements, weather information and crop sensing using drones and a tractor-mounted Isaria.
Soil zoning was carried out last summer using a Veris MSP3 sensor, which measures electro-conductivity to indicate soil type, pH, organic matter and topographical information such as elevation, slope and curve.
The resulting maps and previous yield maps indicate that curve, which indicates the lowest and highest parts of the field, has the biggest effect on yield, due to a combination of soil type and soil nutrient and water availability.
The fields were drilled after ploughing with winter wheat at the end of October.
Using one field as an example, half received 130kg/ha seed in line with farm practice. The other half received rates from 100-165kg/ha, in line with expected plant establishment, which ranged from 80-47 per cent.
Plant counts of 148-184/m2 compared with the farm's target for late-October-drilled wheat of 185/m2. Results will be assessed and the programme adjusted next season.
Variable-rate N was applied according to Isaria's measurement of crop biomass, yield maps and a crop biomass/N uptake scan taken by a drone fitted with a near-infrared camera.
Although too early to draw any conclusions, drone scans confirm that field variability has been smoothed to some extent in year one.
One key area being examined is how fields are managed once the variation within them has been identified.
""The first question to ask is, can we correct the cause of variability?"" says Lewis. ""Some we can, such as pH, some nutrient deficiencies, soil structure problems and organic matter levels.
""If that's the case, we should be managing to improve, using higher inputs to achieve higher outputs.
""However, some soil properties such as type, fraction and texture can't be changed, so we should be managing to optimise, looking at lower inputs to maintain output.""
Using the same 32ha (80 acres) field as an example, improving the second-best yield zone by 2t/ha, which should be achievable, would produce an additional 12.2t of wheat, worth about £1,600, says Lewis.
Optimising the worst performing area by reducing inputs by £75/ha would save £450, enough to pay for a T3 fungicide across the whole field, he adds.
A typical farm of about 200ha (500 acres) yet to embark on precision farming would expect to pay about £27 /ha for Agrovista's services, plus about £3.50/ha to retrofit a combine yield monitor.
""Overall the business would need to achieve 0.24t/ha more yield under the improve strategy to break even, or a 10 per cent reduction in N, P and K under the optimise strategy," says Lewis.