Contribution of Root Respiration to Total Soil Respiration in a Cotton Field of Northwest China

To measure the contribution of root respiration (R-r) to total soil respiration (R-t) in arid cotton fields, eighteen plots, nine for girdling and nine control, were built in an arid cotton field in the Aksu National Experimental Station of Oasis Farmland Ecosystem, Xinjiang of China. Given the difference of soil respiration between girdled plots and non-girdled control plots, the components of soil respiration, root respiration (R-r) and respiration originating from decomposition (R-d) were divided. The temperature sensitivities of R-r and R-d were analyzed, respectively. The results showed that the average contribution of R-r to R-t in arid cotton field was about 32% during the study period. The temperature-response curve of R-r differed from that of R-d. The dynamic variation of R-d was more related to the change of soil temperature as compared to R-r. R-r and R-d had different responses to the variation of environment, and thus new models capable of differentiating between R-r and R-d are needed for evaluating the different factors controlling these two components of soil respiration in arid cotton field.