Methods for an investigation of urea-N loss in Arizona agriculutral waters due to urease activity

摘要

Four different methods were analyzed for the study of N loss from aqueously applied urea due to urease activity in irrigation waters. The Watt and Chisp method was found to be less sensitive than required. The Douglas and Bremner Test was found to be variable in the results obtained. A bubbler constructed for lab use assayed nitrogen volatilized from urease activity but is not adaptable for field studies. An acid trap designed for field studies lacked accuracy. Two tests of six different Arizona agricultural waters both revealed no urease activity. The results obtained with the Douglas and Bremner Test must be interpreted carefully since the urease may have been inactivated by the buildup of end products of the urea decomposition reaction.