What is a stronger determinant of soil respiration: soil temperature or moisture?

Increased atmospheric concentrations of greenhouse gases have led to global warming and climatic changes. Both experimental and modelling studies are necessary to predict and to quantify gas exchange in agroecosystems. We studied the effect of the important environmental factors (soil moisture and temperature) on CO2 emission from agricultural soil (Orthic Luvisol developed from loess) under field and laboratory conditions. In the field experiment (winter wheat, permanent meadow or black fallow), the in situ CO2 efflux form the soil, soil moisture and temperature were measured from April to December 2013. The CO2 efflux was influenced by plant cover (F=7.96; p<0.001), and was related to both, soil temperature (p<0.001) and slightly less by soil moisture (p<0.01). In the second experiment, soil was collected from a depth of 0-10 cm, air-dried, and passed through an 2 mm sieve. Next, soil samples were rewetted to obtain soil moisture in a range from water saturation (pF 0) to plant wilting point (pF 4.2), and incubated at different temperatures (from 5oC to 30oC). Multifactor analysis of variance has shown that the soil respiration, as measured under controlled conditions, was much more affected by soil temperature (F=237.0; p<0.0001), than by soil moisture (F=4.99; p