Two precision farming strategies put to the test

Article taken from Farmers Guardian, 26 May, written by Abby Kellet.

While gathering site-specific crop and soil data is becoming easier, knowing how to best use this information to benefit gross margins can be difficult, with growers having to decide whe­ther to maximise crop performance or reduce input spend for best results. As part of a long-term trial pro­gramme, Agrovista is investigating the use of 'improvement' and 'optimisation' precision farming strategies on wheat grown on a commercial farm in Ramsey, Cambridgeshire.

Agrovista's head of precision farm­ing Lewis McKerrow says: "There are two strategies we can employ: an improve strategy, where we are looking to gain higher outputs from higher inputs, so we are pushing areas of the field we know can perform.

"Or we can use an optimise strategy where we actually accept we may be putting too many inputs on. We may be putting a higher N rate than that part of the field can actually utilise, so if we lower our inputs in those areas, we can actually maintain output;"

Fields have been mapped for soil type, organic matter, crop biomass, soil moisture, field slope and field curve, using a range of technologies, allowing seed rate and nutrient application to be varied across the field.

The highest seed rate was applied on a particularly heavy area of the field, but germination was only 47 percent, leading to 148 plants/sq.metre.

To test whether this can be improved, next year seed will be sown at an even higher rate on some of the heavier land in an attempt to boost crop performance. On the rest, seed rates will be maintained, but the level of inputs will be reduced.

Field maps have highlighted areas of the field which are suited to one specific approach.

Mr McKerrow says: "When over-­laying a curve map with the historical yield map, it became obvious plants which were growing on top of any small ridges in the field were yielding less than those at the bottom of the ridges, because of the movement of nutrients down the slope.

"We may need to pull back on nitrogen rates in these areas and improve margins by reducing inputs.

"However, where historical yield maps show high yields and where crop biomass is high, it may be that more nitrogen is required to gain the best possible return."


Inevitably, both approaches deliver a return on investment in different ways, with the aim of the improve strategy to deliver greater yield, while the optimise strategy should result in an input saving.

"Either way, it is about reducing the cost per tonne of growing the crop," adds Mr McKerrow.

To equip a 200-hectare (494-acre) farm with the technology needed to produce an extensive range of soil maps, which enable variable seed and fertiliser application, he says an annual investment of about £31.20/ha would be required, assuming all technology was to be purchased.

To justify this outlay using the improve strategy, a 0.24 tonnes/ha (0.1t/ acre) yield increase would be required. Where an optimise strategy has been implemented, a 10 per cent reduction in N, P and K use would cover the cost of the investment.

Mr McKerrow says: "Realistically, most farmers are not going to be doing it all at once. Every farm is at a different place on the journey and many would not have to spend as much to be set up for this kind of system."


Annual precision farming costs

- Veris MSP3 for testing soil organic matter, pH and soil conductivity: £6/hectare

- Nutrient samples: £2.20/ha

Variable seed: £3.50/ha

- Drone (two flights): £6/ha

Yield mapping: £3.50/ha

- Weather/soil moisture stations: £7.50/ha

- Software forinterpreting data: ££2.50/ha

Total: £31.30


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