Reversing desertification by using dam reservoir sediments as agriculture soils

Abstract

Bottom sediments from two reservoirs in South Portugal were subject to chemical, physical and mineralogical study to test their suitability for agricultural use. In spite of large differences in geomorphic characteristics and lithology of the drainage basin, they have high levels of total, exchangeable and soluble forms of nutritional elements much needed for sustainable food-fibre production. Comparing our results with natural soils, we conclude that sandy sediments could be good agricultural soils on their own and the more clayey varieties, fertilizers for low quality soils. If sediment removal from the reservoirs becomes economically feasible, the suitability for agricultural use may eventually solve some classical problems such as: (1) the period of life of dam reservoirs filled with sediments, (2) the water quality, and (3) the scarcity of soils in some regions, turning a global problem into a global resource.