Abstract:

Study on soil CO2 flux of oasis cropland in arid area under different management mode and relationship with soil temperature and humidity. This study provided reference for CO2 contribution of oasis cropland ecosystem to atmospheric. Using LI-8100 Automated Soil CO2 Flux System, we determined the rate of soil carbon dioxide emission in oasis cotton field in the north of Tianshan Mountain, we also evaluated the influence of temperature and soil moisture on soil CO2 flux. The results indicated that: the diurnal fluctuation and monthly variation of soil CO2 flux was characterized by single-peaked curve for the farmland. The average rate of soil CO2 flux per month: drip irrigation field was 3.45 μmol/(m2?s), flooding field was 3.37 μmol/(m2?s), abandoned farmland was 1.63 μmol/(m2?s). In addition, the peak of rate of soil CO2 flux appeared at about 15:00 to 20:00 (Beijing time), and the valley value occurred at about 4:00 to 6:00. And soil CO2 flux was higher in June and July than other months. Correlation analysis showed that: exponential relationship between the rate of soil CO2 flux and temperature in different field, 5 cm ground temperature and air temperature showed positive correlation. But the soil CO2 flux represents different correlation with soil moisture from 0 cm to 20 cm and the correlation with soil moisture weaken with soil depth at 10 cm, 20 cm. Furthermore, the rate of soil CO2 flux sites tended to increase rapidly after typical wetting events (rainfall and irrigation). Soil temperature and moisture together controlled the soil CO2 flux, and explained 67.4% of the variance in cotton field and 79.6% in abandoned farmland.