Effect of Rangeland Use Change on Soil Physico-Chemical Characteristics with Emphasizing on Soil Aggregates Stability (Case Study: Salvatabad Rangeland, Sanandaj)

The aim of this study was to investigate the effect of conversion of rangeland into agricultural and horticultural land uses on important soil properties including aggregate stability in Salavatabad watershed in Eastern Sanandaj. For this purpose, simultaneously with the predominant growth of plants, four land uses including 1) rangeland 2) orchard 3) chickpea field 4) wheat field were selected as the study area and 42 soil samples were random-systematically collected. Then soil physico-chemical properties including aggregate stability, total nitrogen, total carbon and particulate organic carbon of each sample were measured in the laboratory. One-way ANOVA of the data showed that due to the conversion of rangeland into three uses of orchard, chickpea and wheat fields, aggregate stability, particulate organic carbon at the level of 5%, total organic carbon and total nitrogen in all three uses at the level 1% decreased significantly. As the aggregate stability in orchard, chickpeas and wheat 35.51, 25.94 and 19.56% respectively, particulate organic carbon in orchard, chickpeas and wheat 62.5%, 79.16 and 75%, respectively, total organic carbon in orchard, chickpea and wheat use decreased by 23.63%, 50% and 49.09%, respectively, and total nitrogen decreased by 31.25% in orchard, 62.5% in chickpea use and 75% in wheat use. According to the results of this study, the conversion of rangelands to any of the agricultural and horticultural uses is unacceptable, but in case of forced conversion, the use of the orchard is recommended because the orchard has less negative effects on soil quality factors than wheat and chickpeas. It is also emphasized in converting rangeland use to cropland, as much as possible to maintain the balance between the input and output of the plant residual into the soil bed, it should be prevented the exit or fire of remaining straw, or grazing livestock after harvest.