Conductimetric determination of soil urease activity

Abstract

Abstract A fast and sensitive method to determine urease activity in soils is described. It involves extraction of NH4‐N with 1 N. KC1 : 0.01 N HC1 and measurement of NH4 concentration by electroconductivity using a steady state flow system across a membrane. Sampling was done directly from the extracts with an automatic sampler at 40 samples per hour. The detection limit for NH4‐N was below 0.05 ppm in the extract. Extracts could be stored at room temperature for 17 hours before measuring NH4. No post‐treatment hydrolysis of urea occured.