short-term effects of barley residue management on urease and alkaline phosphatase activities

soil enzyme activities can be used as indicators of soil quality for assessing the sustainability of agricultural ecosystems. the objective of this study was to determine the effects of barley residue input rate, burning, urea fertilizer and tillage management on activities of alkaline phosphatase and urease under field conditions, after a period of 90 days. the experiment was carried out based on a completely randomized design with a factorial arrangement in two replications. the treatments included two levels of barley residue input rate (3 and 6 t ha-1), burning (without and with stubble burning), urea fertilizer (0 and 125 kg ha-1) and tillage systems (no-till, conventional tillage). results showed that 6 t ha-1 crop residue treatment increased enzyme activities in comparison with 3 t ha-1treatment at 0-5 cm. whereas stubble burning and tillage treatments significantly decreased urease and alkaline phosphatase activities. the urea fertilizer had no effect on alkaline phosphatase activity, whereas urease activity positively affected by urea application. urease activity was affected more than alkaline phosphatase activity by management practices in soil. the results of this experiment showed that no-tillage system along with crop residue retention of 6 t.ha-1 and without stubble burning systems would be the most effective management to protect and promote soil alkalin phosphatase and urease activity.