Phosphorus : sources, flow and roles for plant production and eutrophication

Abstract

Phosphorus is a strategic element for life on earth because of its low availability in most environments. World reserves, mainly consisting of apatite deposits, are limited. At the present rate of exploitation they risk being exhausted in about a hundred years, but this does not prevent surplus amounts reaching watercourses. These are the primary cause of eutrophication of certain aquatic environments, the control of which necessarily involves the reduction of emissions, and in particular those known as localised emissions.

In spite of its essentially diffuse character, phosphorus transfer into the hydrological network attributed to agricultural activities is far from negligible. This is particularly true in livestock rearing regions where the farms are very often producing a permanent excess of recycled phosphorus due to manures, slurries and other effluents which are spread on the cultivated land. Because of this, the reduction of P emissions from animals is undoubtedly the main way in which agriculture can contribute to the collective effort to control the problem of eutrophication.