I came upon this story while trying to do research on a totally different issue. Interesting stuff!
"FOR farmers, working out the optimal amount of seed, fertiliser, pesticide and water to scatter on a field can make, or break, the subsequent harvest. Regular laboratory analyses of soil and plant samples from various parts of the field can help - but such expertise is costly, and often unavailable. A new and cheaper method of doing this analysis, though, is now on offer. Precise prescriptions for growing crops can be obtained quickly, and less expensively, by measuring electromagnetic radiation reflected from farmland. The data are collected by orbiting satellites.
The spectrum of this radiation - which can be in the form of either natural sunlight or artificial radar - can reveal, with surprising precision, the properties of the soil, the quantity of crop being grown, and the levels in those crops of chlorophyll, various minerals, moisture and other indicators of their quality. If recent and forecast weather data are added to the mix, detailed maps can be produced indicating exactly how, where and when crops should be grown. The service usually costs less than $15 per hectare for a handful of readings a year, and can increase yields by as much as 10%.
Such precision farming using satellite-based intelligence is in its infancy. Even so, it is catching on quickly. Five times a year, for example, a satellite-surveillance service provided by a cereal-growers' co-operative called Sevepi (based in Douains, France) e-mails its members a map of their fields, divided into three or four colour-coded zones per hectare. For each zone, one of about 50 fertiliser formulae is recommended. On top of this, if the stems of the wheat are tall and rain is expected, an appropriate dose of growth-regulator is recommended for each zone. (Long, fragile stems snap more easily in downpours.) Farm vehicles equipped with global-positioning-system locaters automatically mix and apply the prescribed dose to each area.
L'espace, c'est moi
France is the leader in this sort of surveillance. More farmland is analysed by satellite there than in any other country, according to Infoterra (a subsidiary of EADS Astrium, a European space giant), the firm that is France's largest provider of such information. Moreover, Henri Douche, head of Infoterra's agriculture sales in Toulouse, reckons the amount of monitored farmland will increase as the climate changes and farmers can no longer rely on the past as a guide to the future. When confounded by the yield variations that new weather patterns bring, even technophobic farmers will sign up, he says.
Inexpensive data on the productivity of land is valuable to governments, too. Areas where fertilisers and pesticides are being applied excessively can be pinpointed, studied and regulated by environmental and land-use agencies. Guy Lafond, an agronomist with Agriculture and Agri-Food Canada, a government agency, says satellite data are proving useful for a study of fields with declining productivity in Saskatchewan. Overkill with nitrate fertilisers (which are also a source of greenhouse gases) appears partly responsible. And according to RapidEye, a German satellite operator, insurance companies are also studying satellite data with a view to selling crop-insurance policies to governments of countries that might be threatened by famine.
In March, RapidEye began selling data that help forecast harvests. Too often, farmers limit productivity by managing fields uniformly, says Frederik Jung-Rothenhausler, head of product development at the firm's headquarters in Brandenburg an der Havel. The company's data, which cover both Europe and the Americas, break field productivity down into patches just five metres square.
Nor need the boon of precision farming be restricted to rich countries. In Africa, where many soils have become badly depleted of nutrients, better fertiliser management would go a long way. As a consequence, the World Agroforestry Centre in Nairobi has begun cataloguing the radiation signature - and thus agricultural potential - of about 100,000 samples of African soils. It is giving this detailed information to the International Centre for Tropical Agriculture, based in Colombia, so that it can build a database called the Digital Soil Map. When ready, this will provide farmers with free forecasts, developed with regularly updated satellite imagery, across farmland in 42 African countries. For a hunger-ravaged continent, that is good news indeed."