Influence of Some Soil Properties and Temperature on Urease Activity in Wetland Rice Soils

2 Abstract: Soil enzymatic activities are the biological indices reflecting soil fertility and quality. In order to evaluate the influence of some physical and chemical characteristics wetland rice soils and temperature on urease activity, a lab experiment was carried out in Rice Research Institute of Iran. Thirty soil samples were selected from different wetland rice soils of Guilan province in north of Iran. Urease activities range from 17.5 to 66.3 and 11.2 to 45 µgNH /g soil/2hr at 24° and 16°C, respectively. A significant negative correlation 4 + (r = -0.62 at 24°C and -0.58 at 16°C) was observed between urease activity and soil pH reaction by quadratic ** ** regression equations. Relation of organic carbon with urease activity was generally quadratic correlated highly significantly with urease activity, with r values of 0.84 and 0.77 at 24°C and 16°C, respectively. While soil *** ***