The dataset is from an incubation experiment which was carried out in the dark at the temperature of 15°C and the relative humidity of 40% for 72 days. The predominant soil is sandy loam, with sand, silt and clay percentages of 54%, 41% and 5%, respectively. The SOC content of the 0 – 10 cm layer is 4.2% and the pH is 6.9. Four treatments with four replicates were set up at the SWC of 12%, 24%, 43% and 61%, respectively. The average cumulative respiration of the four replicates and its standard deviation (SD) are provided in the dataset.

Fresh soil samples were collected from four separate locations several meters apart in September 2020. Plants and surface litter were cleared away before sampling and the soil from the 0 – 10 cm layer was collected. The soil samples were then transported to the laboratory in containers with ice. In the laboratory, rocks and plant materials were removed before the soil was homogenized and passed a 2-mm sieve. Soil samples were stored at -20 ℃ until the incubation experiment started. During the incubation, 66.3 g fresh soil (equivalent to 50 g air-dried soil) was put in a 200 ml open-top mason jar. The soil water content was maintained at the treatment levels by weighing the jars and adding the corresponding amount of water every day. All the jars were pre-incubated for seven days. During each measurement, the jar was covered by a rubber lid with two gas paths and connected to an LI-8100A infrared gas analysis system (LI-COR, USA). After stabilizing the system for 10 minutes, CO₂ concentration changes within one minute in the headspace of each jar were recorded to calculate the CO₂ emission rate. The measurement was conducted daily in the first eight days, every two days for the next 19 days, and every four days thereafter. Overall, there were 28 sampling occasions over the 72-day incubation.