The Study on the variation of some physical indices of the loess soils quality along climatic transect in Golestan Province

Knowledge of soil erodibility and its evaluation is a useful indicators to assess soil erosion. Climate is one of the soil forming factors which has a major impact on this index. The present study has done in order to determination of different climates effect on quality physical indices of loess soils in Golestan province. In order to this study two transect of (North to South) and (East to West) in the loess hillslope of the Province with pasture but in different climate condition were chosen. Samples were taken from seven areas with six replicates and the depths of 0 to 30 and 30 to 60 cm along two transects. Amezketa, plasticity, soil specific surface, cation exchangeable capacity and soil texture indices were measured. Results showed that changes in these indexes in the first transect (north-south) and in the second transect (East to West) of the province follow the particular trend. Amezketa index of average Changes of during the first transect from 0/05 to 0/23 and in the second transect from 0/42 to 0/30 mm and soil specific surface in the first transect from 51.95 to 72.04 and in the second transect from 94.27 to 145.52 m2/gr was variable. Changes in plasticity, soil specific surface and cation exchangeable capacity during both transect increased and amezketa index during the first transect increased and during the second transect decreased. According to results aggregate making and aggregate stability with soil particle size ratio have a significant effects to reduce loess soils erodibility.