Agro-diversity, recipe against nitrates
By Denis Delbecq • February 11th, 2009 in 22:00 · Category: Actuality
A job of titan. Two American researchers searched a century of scientific data. They conclude from it that the more agricultural cultures are diversified, the less they pollute the water. (1)
Whitney Broussard and Eugene Turner reviewed available data since the beginning of last century on concentration in nitrogen of watercourses, and on usage of farmlands. They show that from the beginning of the XXth century, the American watercourses have already suffered an excess of nitrogen.
To obtain these results, both scientists of Louisiana studied accessible information on 56 basins American mountainsides the surface of which is included between thousand square kilometres (Mask to Fasten, Illinois) and two million ensconced themselves kilometres (Mississippi).
In a little more than a century, according to both researchers, the medium surface of farms in the United States doubled, when their number fell of two - third. They also confirm that the passage of animal force in mechanisation doubled by usage augmented by manure augmented the rejections of nitrogen in rivers. And show that, in a given hydrologic basin, the pollution of the water is all the stronger as monoculture developed.
The reason of this phenomenon seems logical, for Broussard and Turner, even if they underline that subject must again be dug. The more cultures are varied, the more farmlands are divided up, and therefore more zones-stamps between these cultures are numerous. These enherbées borders or wooded would tend to pick up the surplus of nitrogen linked for the use of manures, and therefore to avoid that they meet in watercourses.
For years one thousand nine hundred, the concentration of nitrates linked to the épandage of nitrogenous manures was multiplied by three-four on average in the United States, and by ten in the Iowa, one of the lofts with American corn. Eight times more manures in 2003 than forty years earlier were used there.
At the beginning of the XXth century, the relation between the cultivated surface and the rate of nitrogen of rivers was linear, explain Broussard and Turner. But from now on, this linéarité is not any more bet. Too much manures, too much draining multiplied the polluting quicklier nitrogen than farmlands advance. Sign that he is perhaps time to return to a mode of more reasonable production. To reduce losses to reduce pollution, bet of a less harmful agriculture for environment remains to be recovering.
(1) Frontiers in Ecology and the environment, February 11th, 2009
Picture: © Denis Delbecq
Article read 480 times. Tags:agriculture, nitrogen, manure, environment, the United States, pollution
Comments in 
On the other hand conventional agriculture is not the badly modern only one, far needs: to find him an alternative will not therefore be enough to leave our hellish spiral. Quid of economic growth? Of the exhaustion of fossil resources?
See the blog of gorgerouge between others.
Warmly,
Robin