Influence of Soil Temperature and Water Tension on the Decomposition Rate of Carbon-14 Labeled Herbage

The relation of decomposition rate of carbon-14 labeled blue grama (Bouteloua gracilis) to soil water content and temperature was examined in laboratory studies. Soil samples amended with ground herbage were incubated at various temperatures (3, 10, 25, 40, 50, and 60°C and water contents (.009, .03, .06, .60, 5.8, and 113 atm water tension). The oxygen concentrations in the decomposition vessels were determined to evaluate the possibility that oxygen became limiting in the experiments. Radiocarbon losses were assessed and the results used to develop a multiple regression equation, which predicted percent carbon loss per hour as an exponential function of water tension, time, temperature, and the inverse of temperature.