Interpreting the dependence of soil respiration on soil temperature and moisture in an oasis cotton field, central Asia

To determine how temperature and moisture affect soil respiration, we took half-hourly measurements of soil temperature, water content, and respiration under plants and between rows in a cotton field in central Asia from August through November 2009. We chose the Arrhenius model as the optimum temperature respiration model for this study on the basis of the temperature sensitivity of soil respiration. To normalize soil respiration, we calculated the ratios of measured soil respiration values to predicted soil respiration values. We obtained the effect of water content on respiration by analyzing the relationship between normalized soil respiration using the best fit of the Arrhenius function with soil temperature at a 10-cm depth and water content in the 0–10 cm soil layer. On the basis of these results, we created a two-dimensional model to describe the dynamics of soil respiration. We found that predictions of soil respiration were better when soil temperature and water content were combined into one equation than when the temperature-respiration equation was used. The effects of soil temperature and water content on soil respiration varied by location (under plants vs. between rows).