Contribution of heterotrophic respiration to total soil respiration in a wheat field

Abstract

The contribution of soil respiration needs to be understood to evaluate the implications of environmental change on soil carbon cycling and sequestration. The response of soil respiration to varying environmental factors was studied in a wheat field. The continuous soil gradient method combined with the trench method was used to (1) determine the temporal variation of total soil respiration (Rs) and heterotrophic respiration (Rh) and (2) investigate the relative effect of soil temperature (Ts) and soil water content (Ws) which control soil respiration. The result showed that temporal variations of soil respiration were dominantly controlled by Ts during the days. The variation in Rs and Rh showed a similar pattern of seasonal change in Ts (0.69 to 4.17 μmol m-2s-1 and 0.45 to 2.95 μmol m-2s-1, respectively). Rh ranged from 36% - 86% of Rs. The Rs was limited by Ws while Ts played as a secondary role; Rh, however, appeared to be correlated with both Ts and Ws. These results suggested that the factors controlling the variation in soil respiration differed between Rh and Rs. Additionally, two-variable equations could be better used to model the relationships of soil respiration to both Ts and Ws together, with the R2 ranging from 0.53 to 0.83.