Abstract: A field experiment was conducted to study the effects of different mulching measures on the diurnal and seasonal variations of winter wheat field soil respiration in dry land region of Loess Plateau. Four treatments were installed, i.e., 300 kg·hm^-2 straw mulching (M₃₀₀), 600 kg·hm^-2 straw mulching (M₆₀₀), plastic film mulching (PM), and no mulching (CK). In all treatments, the soil respiration rate had a decreasing trend from autumn to winter, but increased rapidly after winter and peaked at jointing stage. Comparing with CK, treatments mulching promoted the soil respiration obviously from wintering to maturing stage, with significant differences between treatment PM and the others. The average soil respiration rate in treatments M₃₀₀ and M₆₀₀ in whole growth period was 1.52 μmol CO₂·m^-2·s^-1 and 1.47 μmol CO₂·m^-2·s^-1, being 10.2% and 6.6% higher than the CK (138 μmol CO₂·m^-2·s^-1), respectively, and that in treatment PM was 3.63 μmol CO₂·m^-2·s^-1, 163% higher than CK. The diurnal variation of soil respiration rate in CK and in M₃₀₀ and M₆₀₀ presented a single peak curve and peaked at 12:00 and 14:00, respectively, but for PM treatment, the diurnal variation of soil respiration rate was similar with that in CK at jointing stage while presented a bimodal curve at maturing stage, with the peaks at 12:00 and 16:00, respectively. Soil respiration rate had an exponential correlation with soil temperature, and a parabolic correlation with soil moisture.

Key words: soil respiration, mulching, winter wheat, Loess Plateau dry land region