On the 90 molecules sought only 30 were found in the land

France soils are not dead. "The first diagnostic soil scientists of Inra expose this week at the Salon of agriculture is not desperate. But he confirmed that this new research problem should be treated well before. A year ago, the Inra and its partners have completed a first wave of systematic analyses of the quality of the soils of France ("Les Echos" from February 4, 2008). Sampling were previously carried out without consistency, they targeted the trace analysis metal due to the spreading of sludge for example. The interpretation of these huge volumes of data begins to emerge a few strong signals, but a complete atlas of the State of the soil will be published only after 2010-2012.

DNA of the Earth

Dominique Arrouays, the Inra d ' Orléans Infosol Unit Director, confirms a long-standing intuition: "most agriculture is intensive and specialized, less there are micro-organisms." Geology took five hundred years to produce each 5 cm of Earth. Based on the inputs and the monoculture agriculture has deteriorated in sixty years many soil functions. Contrary to organic agriculture, which generally promotes the vitality of soils.

The degradation of biodiversity in the soil begins to be well documented. A measurement program routine of the DNA of Earth began 2,200 areas to estimate qualitatively the diversity of microbial wildlife. Quantification of biomass, it already has conducted a region-wide, in Breton soils. Biologists should have clearly shown that prairie is the most respectful cultivation practice of the earthworm. The biomass there reached 5 tons per hectare against 500 kilograms for the same area of intensive monoculture of maize. The amount of micro-organisms, it is divided by two or three. One such parcel damaged to return to the initial state, it must be thirty-five years, believe the scientists. In contrast, Dominique Arrouays condemns the catastrophism of some scientists who say for example that the lands of the Beauce are dead: "There are 1 in 10 billion organisms per gram."

The measurement of pollutants is still sensitive to some 90 drawn substances. Each test costs 1,000 euros and should sometimes identify concentrations of the order of a billionth of a gram per kilogram of Earth. On the 90 molecules sought, only 30 were found in the land. But 5 or 6 detected compounds belong to the family of 20 prohibited substances. "The more bad surprise came from lindane, an organochlorine insecticide that technicians did not measure two or three years ago," said Dominique Arrouays. WHO classified this nerve in the category of the moderately hazardous, the France banned it ten years ago. Yet, the compound was found in areas where researchers tested their protocol: North, Pas-de-Calais, Somme and Seine-Maritime. Not reassuring for our plates. The measures also show that pollution of urban areas by diffusion contaminate agricultural land, as attested by the land sealed by an automobile in a radius of 100 kilometres of Paris.

"Innovative practices".

Erosion is another phenomenon that affects nearly 20 of French surfaces, mainly under the effect of stormwater runoff, in the North and the Ile-de-France. It translates into a maximum loss of substrate of 1 millimetre in thickness per year. The territory is however saved by salinization of soils, a very serious problem in the countries of the South.

Strong of their data, researchers now wanted to model the behaviour of the Earth. "We hope simulate all phenomena, including feedback to secular scale." "It will be able to assess the effect of innovative practices such as the abandonment of the plough or cover permanent soil", provides Guy Richard, Director of research at the Inra.