Effect of climates different on variation of loess soil erodibility indices 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 was designed to determine the effects of different climates on the erodibility indices change of loess derived soils in Golestan Province. Two transects in the loess hillslope with different climatic conditions 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. Wischmeier and Smith، Chen and Bouyoucos indices were measured. The results showed that characteristics measured in the first transect from north to south as well as second transect (East to West) Province follow the specific trend، so that، organic matter content and saturation percentage of moisture rose with increased rainfall and reduction temperature. Organic carbon average changes in both transcet from 0. 4 to 3. 5 percentage was variable. lime content and electrical conductivity decreased with increase in rainfall. Bouyoucos’ index changed from 2. 09 to 14. 2 and Chen’s index was from 59. 05 to 447. 61 cmol/lit and both indexes in both transcet were decreased. Soil erodibility indices have been changed from 0. 040 to 0. 083 Mgr. h/Mj. mm and in both transect were demonstrated a decreasing trend. Results showed that the particle size increased due to increase in weathering of loess derived soils. 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 was designed to determine the effects of different climates on the erodibility indices change of loess derived soils in Golestan Province. Two transects in the loess hillslope with different climatic conditions 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. Wischmeier and Smith، Chen and Bouyoucos indices were measured. The results showed that characteristics measured in the first transect from north to south as well as second transect (East to West) Province follow the specific trend، so that، organic matter content and saturation percentage of moisture rose with increased rainfall and reduction temperature. Organic carbon average changes in both transcet from 0. 4 to 3. 5 percentage was variable. lime content and electrical conductivity decreased with increase in rainfall. Bouyoucos’ index changed from 2. 09 to 14. 2 and Chen’s index was from 59. 05 to 447. 61 cmol/lit and both indexes in both transcet were decreased. Soil erodibility indices have been changed from 0. 040 to 0. 083 Mgr. h/Mj. mm and in both transect were demonstrated a decreasing trend. Results showed that the particle size increased due to increase in weathering of loess derived soils.