Kinetics and temperature relationships of mineralization and nitrification in Rothamsted soils with differing histories

Summary Mineralization of soil organic nitrogen measured in laboratory incubation experiments on Rothamsted soils with contrasting histories was most appropriately expressed by the simple zero‐order relationship N t = kt in which N t is the amount of N mineralized in time t. The rate constants ( k ) were well related to the absolute temperature by the Arrhenius equation. The approach in which ‘potentially mineralizable N’ ( N 0 ) is mineralized with first‐order kinetics could not be applied to these data. When the soils were incubated with added ammonium chloride, the increase in nitrate‐N and the decline in ammonium‐N were both linear with time, but were equal to each other in only one of the soils. These linear relationships did not reflect true zero‐order kinetics because the rates of ammonium‐N decline and nitrate‐N production both depended on the initial ammonium concentration. The Arrhenius relationships showed no significant difference between mineralization and nitrification in their sensitivity to temperature.