Soil enzyme activities and their relationship with physicochemical factors in Yutian oasis of the Keriya river watershed

Soil samples of 0 ~ 20 cm layers under different soil types( oasis soil,brown desert soil,saline soil and aeolian sandy soil) were collected across Yutian oasis of the Keriya river watershed. By analyzing soil enzyme activities and physicochemical factors,this study made an attempt to discuss the relationships between soil enzyme activities and physicochemical factors by the methods of path analysis. The results showed that various soil enzyme activities and soil nutrient content of oasis soil was significantly higher than other soil types,while that of aeolian sandy soil was the lowest soil type. Oasis soil had the highest soil moisture content,and saline soil,brown desert soil and aeolian sandy soil in turn followed. The order of soil bulk density of all four soil types was aeolian sandy soil saline soil brown desert soil oasis soil. All four soil types presented high soil salinization degree,and weak alkaline with no significant difference among each soil type. Groundwater depth ranged largely between different soil types. Path analysis showed that soil moisture,bulk density,organic matter,total nitrogen and groundwater depth had significant relationships with four soil enzyme activities. Speicifically,available phosphorus had significant effect on alkaline phosphatase,organic matter was the main factor influences the catalase activity,and bulk density had a relative large direct positive effect on catalase activity. Soil organic matter was the main factor that affect invertase activity,while total nitrogen was the key factor that influenced urease activity.