Effect of land use changes on soil enzyme activity in Sulduz plain (Naqadeh-West Azarbaijan)

Soil is a vital component of environment which its quality and health maintenance should be considered as an important factor. Land use changes mainly affect soil quality and health. Soil microorganisms respond to these changes and have special capability to assay these criteria. This research was carried out as factorial on the basis of randomized complete block design with two factors in 200 ha of Mirabad region, Suldoz plain in West Azerbaijan of Iran. Three types of land uses (pasture, crops and apple orchards) and two soil depths including 0-30 and 30-60 cm were considered in this experiment as main factors. Soil enzyme activity including dehydrogenase (DHA), cellulase (CA), urease (UA), acid and alkaline phosphatases (ACP and ALP) activities were measured as biological indices. Some important soil physical and chemical properties such as organic carbon, pH, EC, calcium carbonate equivalent (CCE), soil texture and water aggregate stability (WAS) were also determined. Results showed that soil quality and health indices were significantly decreased in apple orchard and crop production fields compared to the intact grassland. Decline of urease activity in orchards and crop fields at 0-30 cm depth were 65.5 and 72.7% and in grassland with increasing soil depth (30-60 cm) were 77.5, respectively. Soil enzyme activities were significantly decreased in apple orchard and crop production fields compared to the intact grassland.