Nitrous Oxide Flux from Long-Term Fertilized Black Soils in a Snowfall Process

Snowfall is a general natural phenomenon in winter-spring alternate season in northeast of China. Snow was melt with the increase of temperature, i.e. freezing-thawing alternations affects soil properties. Static chamber technique was used to monitor nitrous oxide (N₂O) flux from black soils in a snowfall process. The fertilization treatments are none (CK), 150 kg N ha^-1 (N1), 300 kg N ha^-1 (N2) and 150 kg N ha^-1 organic manure plus 150 kg N ha^-1 chemical nitrogen fertilizer (M1N1). Before snowfall, there is insignificant difference in N₂O emission from four treatments. After snowfall, N₂O emission from CK, N1, N2 and M1N1 is 9.56, 9.16, 9.86, 9.91 mg N₂O-N m^-2 during 55-hour monitoring period, respectively (p<;0.05). Snowmelt increase soil moisture content, which significantly stimulated the soil N₂O emissions, meanwhile, freezing-thawing alternations influences N₂O emission. The findings indicate that effect of snow on N₂O emission should be considered separately, i.e. before and after snowfall.