Effect of extreme temperatures on soil: A calorimetric approach

Abstract The relation between soil organic matter dynamics and temperature is an important research topic, poorly understood yet. This study focuses on the effect of temperature on the heat rate of soil organic matter decomposition using different soil types, by simulating an extreme heat wave with a calorimeter. Heat rates were measured with an automated step-scan of temperature upward at 20, 30, 40, 50, and 60 °C, and downward at 40 and 20 °C to monitor how soil recovers after the heat wave. The results show enzyme-catalyzed bioprocesses are not the only reactions in soil mineralization. Other reactions can be distinguished from the shape of the curve of the heat rate versus temperature. These reactions coexist at normal environmental temperatures, and their relative contribution to soil organic matter mineralization rates varies with soil type.