Soil erosion determinations by using 137 Cs technique in the agricultural regions of Gediz Basin, Western Turkey

Gediz Basin is one of the regions where intense agricultural activities take place in Western Turkey. Erosion and soil degradation have long been causing serious problems to cultivated fields in the basin. This work describes the application of two different 137 Cs models for estimating soil erosion rates in cultivated sites of the region. Soil samples were collected from five distinct cultivated regions subject to soil erosion. The variations of 137 Cs concentrations with depth in soil profiles were investigated. Soil loss rates were calculated from 137 Cs inventories of the samples using both proportional model (PM) and simplified mass balance model (SMBM). When PM was used, erosion and deposition rates varied from -15 to -28 t ha -1 year -1 and from +5 to +41 t ha -1 year -1 , respectively; they varied from -16 to -33 t ha -1 year -1 and from +5 to +55 t ha -1 year -1 with SMBM. A good agreement was observed between the results of two models up to 30 t ha -1 year -1 soil loss and gain in the study area. Ulukent, a small representative agricultural field, was selected to compare the present data of 137 Cs techniques with the results obtained by universal soil loss equation (USLE) applied in the area before. © 2007 Springer-Verlag.