Precision can pay, says crop project

27 September 2001

Precision can pay, says crop project

By Tom Allen-Stevens

THE KEY to making the most of precision farming equipment is to measure the plant density of a crop, a major research project has found.

Where there is an accurate measurement of how the plant population varies over a field, margins can be increased by 25/ha by applying fertiliser to match density.

The 300-page report of the five-year, 700,000 study was handed to the Home Grown Cereals Authority, who funded it, on Wednesday (26 September).

Part of the project involved variably drilling a field to generate a plant density of 100-2000 shoots/m2 to investigate the value of variable rate nutrition.

One of the researchers behind the project, Dick Godwin of Cranfield University, gave visitors a taste of the findings at a Precision Update Event at Silsoe, Bedfordshire.

“Where you can quantify the variation in the number of shoots/m2 in a field, this enables decisions in real time on variable-rate nitrogen applications.

“We achieved an average yield increase of 0.3t/ha from variable nitrogen management across the plots. In seven of eight plots the financial result was positive.”

The aim of the project has been to produce practical management guidelines for precision farming – a definitive use for the yield maps generated.

Prof Godwin pointed out that knowing to put more inputs on high-yielding areas and less on low patches is not enough – it must be quantified.

The key variable was found to be plant density, which tied in with other HGCA-funded research. This can be mapped used aerial infra-red photography.

“This has to be calibrated in the field and varies over time and variety, but we believe it will still only cost the grower about 7/ha to map plant density.”

Nitrogen rates can then be tailored to suit the crop, and with the crop fed no more than it will take up, this means less nitrate pollution, says Prof Godwin.

In the last few months the project has been looking at the cost to benefit ratio of precision kit worth from 4,500 to 18,000.

Tooling up can cost add 1-2 up to 15 per ha to production costs, depending on farm size and level of investment, according to the report.

The HGCA is due to publish the full details of the research in the next couple of months.

The other partners in the project have been Arable Research Centres, Agco, Hydro Agri and Shuttleworth Farms.


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