Effect of Land Use on of Some Physical and Chemical Properties of a Calcareous Soil

Soil degradation is one of the most important issues facing humanity.Since land use change affects soil properties, this study aimed to investigate the effects of land use on some soil physical and chemical attributes. Experiment was conducted at 25 experimental locations on a relatively regular network design with 5×5 meter distance intervals in each three studied land uses including annual cultivated field (ACF), perennial alfalfa field (PAF) and orchard field (OF) in Bajgah region, Fars Province.  Soil samples were collected from 0 to 20 cm depth, air dried, and passed through a 2 mm sieve and some physico-chemical properties were determined. Clay content, fractal dimension (D), soluble sodium (Na), potassium (K) and magnesium (Mg), sodium adsorption ratio (SAR) and soil cation exchange capacity (CEC) in PAF in comparison with ACF showed significant decreases of 15.9%, 1.05%, 70.1%, 50.1%, 36.5%, 69.5%, and 12.9%, respectively. However, values of sand, silt, electrical conductivity (EC), soluble calcium (Ca) and calcium carbonate equivalent (CCE) in the soil of PAF in comparison with ACF showed significant increases of 32.8%, 8.85%, 37.4%, 29.7%, and 15%, respectively. There were no significant differences between the mean values of bulk density (BD, respectively with 1.24 and 1.27 g cm-3), saturation moisture (0.28 and 0.27 cm-3), structural stability index (SI, 2.54 and 2.52%), pH (8.03 and 8.03), organic matter (OM, 2.44 and 2.39%) and carbon sequestration (CS, 352 and 352 ton ha-1) between the ACF and PAF land uses. Land use change from ACF to OF caused a significant decrease of 3.36%, 34.8%, 2.46%, 6.07%, 1.0, and 16.7% in silt, clay, D, saturation moisture, pH, and CEC, respectively. However, ACF to OF land use change caused significant increases of 404%, 83.5%, 68.8%, 53.7%, 57.1%, 107%, 65.7%, 58.7%, 81%, and 33.3% in sand, SI, EC, OM, Cs, soluble Na, K, and Ca, SAR, and CCE, respectively. There were no significant differences between BD and soluble Mg in the soils of ACF and OF. Generally, land use change affected many soil physical and chemical properties influencing soil quality. Therefore, proper land management is essential to protect soil resources.