Sugar data by satellite

Satellite data can now help predict the yield of the national sugar-beet crop, saving the industry nearly Pounds 2 million a year in the United Kingdom and more than Pounds 20 million across Europe.

The British National Space Centre is promoting innovative uses for satellite data.

A consortium led by Logica, British Sugar and researchers from the University of Nottingham, and Broom's Barn Experimental Station have collaborated to exploit the data.

Mike Steven, a senior lecturer at Nottingham, is refining techniques of remote sensing developed for use with helicopters. But high costs meant helicopters could only be used for up to 350 fields, about 1 per cent of the total, checked three or four times during the growing season.

Using satellites, the whole of the national crop could be checked but in practice half is sufficient to provide accurate estimates for the catchment area of each processing factory.

Satellite data is costly and the Department of Trade and Industry has provided financial sponsorship through the BNSC of Pounds 1.2 million for the project.

Dr Steven explained that the technique works by measuring the spectrum of sunlight reflected from the crop. "Vegetation has a special spectral signature and during the summer the spectrum changes. Bare soil in May reflects 5 to 10 per cent in the red and near infrared part of the spectrum," he says.

"A dense crop of vegetation reflects about 5 per cent in the red and 50 per cent in the infrared, with half-cover roughly half way in between. So you can measure what fraction of the ground is covered by leaves and we can then assess the fraction of available solar energy captured by the plant and used for photosynthesis and some of that energy turns into sugar."

There are two problems with satellites; they have to look through the atmosphere, which is pretty murky these days, and the timing of a pass is not always at the best moment: reflected sunlight cannot be measured through clouds or at night.

The most recent generation of satellites, including the European ERS-1 and France's Spot series, can reduce these difficulties. Spot can be directed, so it can look to one side or the other, around clouds and ERS-1 has radar which can see through clouds and function in darkness.

The BNSC funding was also used by Logica to develop computerised image processing and interpreting systems. The consortium hopes the predictions will enable processing and distribution of sugar to be done more efficiently and cheaply.