Soil enzyme activities have been recognized as suitable indicators in assessing the effect of management systems and land use type on soil quality. In such investigations, the spatial variability of enzyme activities should be considered. Despite the importance of soil enzyme activities, particularly phosphatase, in soil quality assessment studies worldwide; such studies have not been carried out in Iran. Therefore, this study was conducted in a hummocky landscape around the city of Semirom, which is a representative area for dissected alluvial plains in the Zagros region. The objective of the study was to evaluate soil phosphatase activity associated with land use type and landscape position. Three similar landscapes under three different land uses namely an apple garden, a rangeland site and a dryland farming area were selected. In each land use, two parallel transects, about 20 m away from each other, covering different landscape positions were laid out. Surface soil samples (0-15 cm) were taken at an interval of 15 m along each transect resulting in 30 samples per each land use (a total of 90 soil samples). Phosphatase activity, organic carbon content and the respiration rate were measured in all soil samples. Results showed that the landscape under apple orchard had more C content and phosphatase activity than under rangeland and dry farming areas. In contrast, the soil in dryland and rangeland sites had been greatly to moderately degraded. The highest phosphatase activity was found in soils occurring on footslope positions, whereas the soils on shoulder and summit had the least amount of phosphatase activity. This study further confirms the fact that the activity of phosphatase in soil well differentiates the effects of land use and landscape position on soil quality.
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