Variations and factors influencing soil respiration in flue-cured tobacco fields under different fertilization treatments

In order to investigate the variations and factors influencing soil respiration rate in tobacco field during tobacco growing, a field experiment was conducted with three fertilization treatments, including no fertilizer (CK), inorganic fertilizer (NPK) and inorganic plus organic fertilizer (NPKOM). Soil respiration rate was determined by closed chamber-infrared method, and the effects of soil temperature, soil moisture content and tobacco root biomass on soil respiration rate were analyzed. The results showed that: 1) The variation of variation of soil respiration rate was affected by soil temperature and tobacco root biomass during tobacco growing. Soil respiration rate positively correlated to soil temperature to a significant degree, the contribution rates of soil temperature at the depth of 5 and 10 cm to the variation of soil respiration rate were 60.4%-67.6% and 67.9%-76.1%, respectively. Both fertilization and soil depth increased the temperature sensitivity (Q₁₀) of soil respiration. 3) Soil respiration rate increased first then decreased with the increase of tobacco root biomass during the whole tobacco growing period in field, however soil temperature influenced soil respiration rate more significantly at later growing stage.