Decline in soil quality as a result of land use change in Ghareh Aghaj watershed of Semirom, Isfahan, Iran

Abstract

Land use change, if not based on proper scientific investigation affects physical, chemical, and biological properties of soil and leading to increased destruction and erosion. The objective of this study was to investigate the effects of changing rangelands into farmlands on certain soil physical, chemical, and biological properties. Undisturbed soil samples were collected from a 10 cm depth of soil surface in Ghareh Aghaj watershed of Isfahan Province with following land uses: pasture with good vegetation cover, pasture with medium vegetation cover, abandoned dry land farming, and degraded dry land farming. The results indicated that soil organic matter, cation exchange capacity, microbial respiration, and available K decreased by 66.6, 38.8, 81.8, and 70 percent, respectively, from pasture with good vegetation cover to degraded dry land farming. Calcium carbonate content, however, showed changes in the reverse order. Total N showed its highest content in pasture with good vegetation cover but available P did not indicate any significant difference. The most aggregate stability was measured in pasture with good vegetation cover and degraded dry land farming. Based on the results obtained, it seems that land use change may lead to lower soil quality and increase its degradation with undesirable consequences. Key words: Land use change, soil quality, soil degradation.