BORON CONCENTRATIONS IN THE SENONIAN AQUIFER OF SENEGAL - THEIR EFFECT ON QUALITY OF IRRIGATION WATER

High boron concentrations (> 1 mgl-1), dangerous for many plants species, have recently been observed in the West central part of the Senegalese Senonian aquifer. These excessive boron concentrations in this zone unsuitable for irrigation because of bad water quality create additional contrainst. The use of these waters for irrigation is not adviced, but locally in the absence of any water ressources it could be tolerated after necessary precautionary measures. The close association between salinity and boron concentrations oblige that salinity should first be considered. Any precaution or treatment suggested for salinity has a positive influence on boron toxicity. The specific contrainst related to boron will be the choice of plants which are boron resistant.