Abstract: Soil heterotrophic respiration can indicate the CO₂ efflux from the decomposition of soil organic matter, the major pathway of soil carbon into atmosphere. The difference between soil heterotrophic respiration and ecosystem net primary productivity is crucial to determine whether the ecosystem is a carbon source or sink. In this paper, the operations, merits, and drawbacks of the methods used to measure soil heterotrophic respiration, including those of laboratory incubation (incubation with rootremoval soil or soil core) and in situ investigation (root-exclusive method, stand girdling method, and isotopic method), were introduced. The dependence of soil heterotrophic respiration to temperature has received considerable interest in studying the carbon cycle and its potential feedbacks to climate change. Temperature, soil moisture, and the availability of soil organic carbon are the major factors affecting the temperature sensitivity of soil heterotrophic respiration (Q₁₀). Under normal condition, the Q₁₀ value decreases with the increase of temperature. When the desiccation stress happens or the soil water content is far above the field capacity, the dependence of soil heterotrophic respiration to temperature will be weakened. The availability of soil organic carbon also affects the sensitivity of soil heterotrophic respiration to temperature change. The Q₁₀ decreases with decreasing availability of soil organic carbon. The temperature sensitivity of soil heterotrophic respiration differs when soil organic carbon has different turnover rate, and this respiration has a lower sensitivity to labile organic carbon than to inert organic carbon.

Key words: Surfactants, Sorption, Soil