Effects of land use/land cover changes on soil organic carbon stocks in Abarkooh region (Yazd province)

Conversion of desert soils to cropland may cause changes in some soil properties. The objective of this study was to analyze the effects of converting desert soils to cropland (wheat) and orchard (pistachio) on the soil organic carbon (SOC) content and storage, particulate organic carbon in Abarkooh region (Yazd province). Three land uses included wheat, pistachio, and desert soils were assessed. In order to compare the soil properties in different land uses, In September 2018, soil samples from desert, wheat, and orchard sites were taken from 0–20 and 20–40 cm depths. From each depth, 10 composite soil samples were taken. After pretreatments of soil samples, the soil properties including electrical conductivity, pH, gravel, sand, silt, clay, bulk density, organic carbon, calcium carbonate, were measured according to standard protocols. According to the obtained results, bulk density, gravel content and electrical conductivity decreased after the cultivation of desert soils. The SOC contents in the croplands and orchard were about 3.4-5.8 times higher than those in the desert soils. Also, the results showed an increase of 5.7 to 15.8 times of soil particulate organic carbon in the wheat fields and pistachio orchards compared to desert soils. The lowest SOC storage was observed in desert soils (0.19-0.24 kg.m-2) and the highest was obtained in pistachio orchards (1.08-1.12 kg.m-2). According to the findings of this study, it seems that sustainable cultivation and irrigation of desert soils could be an appropriate method which considerably enhances soil organic carbon sequestration in the study area.