Quantitative assessment of hydrolase production and persistence in soil

The aim of this work was to calculate indices of hydrolase production ( Pr) and persistence ( Pe) through simple arithmetical calculations. Changes in acid and alkaline phosphomonoesterase, phosphodiesterase, urease, protease, and beta-glucosidase activities were monitored under controlled conditions in seven soils with a wide range of properties, in which microbial growth was stimulated by adding glucose and nitrogen. Glucose mineralization was monitored by CO2 - C evolution, and microbial growth was quantified by determining the soil adenosine triphosphate ( ATP) content. Hydrolase Pr and Pe indices were numerically quantified by the following relationships: Pr= H/ t(H) and Pe=( r / H)Delta t, respectively, where H indicates the peak value of each measured hydrolase activity, tH is the time of the peak value, r indicates the residual activity value, and Delta t is the time interval t(r)- t(H), where t(r) is the time of the residual activity value. Addition of glucose and N- stimulated soil respiration increased ATP content and stimulated the production of the measured hydrolase activities in all soils; the measured variable reached a maximum value and then decreased, returning to the value of the control soil. Apart from beta-glucosidase activity, whose activity was not stimulated by glucose and N addition, the other measured hydrolase activities showed a trend that allowed us to calculate the Pr and Pe indices using the above-mentioned equations. Acid phosphomonoesterase and protease Pr values were significantly higher in soils under forest or set aside management;