Microstructural Study and Permeability Variations of Clayey Soils at the Presence of Phosphate Fertilizers

In the recent years the use of phosphate fertilizer has been increased. On the other hand, the use of phosphate fertilizer causes change in micro-structure and geotechnical properties of clayey soils. This may raise the risk for groundwater contamination. The main objective of this paper is to study the permeability and microstructural change of clayey soils after interaction with phosphate fertilizer. To achieve the above mentioned objective, series of geo-environmental engineering experiments was performed and the process of interaction of bentonite with phosphate fertilizer is studied. The evaluation of permeability variations, sedimentation tests, plasticity properties, soil pH variations and results of XRD and SEM experiments show that the presence of phosphate fertilizer changes the clay soil microstructure. Based on the results of this study phosphate fertilizer causes a reduction on the quantity of intensity of basal spacing of montmorillonite. Consequently the permeability might increases around1000 times at the presence of 10 percent phosphate fertilizer.