Abstract:

To get better know the emissions of greenhouse gases (nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2)) and the end product of denitrification, dinitrogen (N2) in the typical grassland of Inner Mongolia, a gas-flow-soil-core technique with the helium-environment incubation system was used to measure these emissions from two grazing treatments. Two soil temperature (5oC and 20oC) and two levels of soil oxygen content (10% and 20%) were set for our laboratory expriement. The results showed that emission rates of N2, N2O, NO and CO2 were in the range of 0.3-2.0 [μg N/(h?kg)], 0.02-0.4 [μg N/(h?kg)], 0.08-0.7 [μg N/(h?kg)]) and 0.01-1.9 [mg C/(h?kg)], respectively. The N2 emissions were 8-17 times as high as N2O emissions. Due to the higher spatial variability, no significant differences of N2, N2O, NO and CO2 emissions and two grazing treatments were detected. Soil temperature and soil water content had a positive effect on N2, N2O and NO emissions, whereas the soil oxygen content had no effect on their emissions.