TEMPERATURE-DEPENDENCE OF NITROGEN MINERALIZATION RATE-CONSTANT - A THEORETICAL APPROACH

Experimental evidence suggests that nitrogen (N) mineralization procee ds differently under fluctuating temperature conditions than it does a t constant temperature. Although N mineralization is believed to follo w first-order kinetics, and the mineralization rate constant is believ ed to follow Q(10) temperature dependence, no effort has been made to use this information to predict the effect of fluctuating temperature on N mineralization. In this paper, we present solutions to the first- order N mineralization equation for a rate coefficient with Q(10) temp erature dependence. Solutions are presented for a number of simple pat terns of temperature fluctuation in time. Example calculations show th at the nonlinear temperature dependence of the Q(10) relationship caus es mineralization under fluctuating temperature conditions to exceed t hat occurring at constant temperature. Sensitivity analysis shows that the Q(10) constant and the amplitude of the temperature fluctuation s trongly influence the difference in mineralization obtained for the tw o temperature patterns. These results can be used to improve the desig n of experiments conducted to study the effect of temperature fluctuat ions.