A STUDY OF THE EFFECTS OF LAND USE CHANGES ON SOIL PHYSICAL PROPERTIES AND ORGANIC MATTER

Changes in land use can significantly affect soil properties. This study was conducted in the Taleghan watershed of Tehran Province, Iran, to determine the effects of land use changes on soil organic matter (SOM) and soil physical properties including soil aggregate stability, saturated hydraulic conductivity, infiltration rate, available water content, total porosity and bulk density (BD). In the present study, two sites contained adjacent land uses of natural pasture and dryland farming were selected. Soil samples were taken from depths of 0-15 and 15-30 cm for each land use. The results indicated that the conversion of natural pasture to dryland farming led to a significant decrease in SOM at 0-30 cm in the first and second sites (24.7 and 44.2%, respectively). In addition, a significant increase in BD was observed at a depth of 0-30 cm in dryland farm soils (1.39 g cm(-3)) compared to pastureland (1.20 g cm(-3)) at the first site. An increase in BD was also observed at the same depth of dryland farm soils (1.46 g cm(-3)) and pastureland soils (1.42 g cm(-3)) at the second site. In addition, total porosity, mean-weight diameter of aggregates, saturated hydraulic conductivity, available water content and estimated final infiltration rate showed significant differences between land uses. The results showed that the conversion of natural pasture to dryland farming alters soil properties that negatively affect soil productivity and erodibility. Copyright (c) 2010 John Wiley & Sons, Ltd.