Co-effects of salinity and moisture on CO2 and N2O emissions of laboratory-incubated salt-affected soils from different vegetation types

Abstract

The temporal variation of precipitation and relevant salinity fluctuation can significantly affect greenhouse gas (GHG) emissions of salt-affected soils in the Yellow River Delta (YRD) of China. The current study aims to investigate the effects of salinity and moisture on CO2 and N2O emissions of saline soils. Soils collected from different vegetation communities were incubated in glass Mason jars under treatment of different levels of salinity and moisture. Gas samples were collected from the headspace of jars and analyzed using gas chromatography during the incubation period. Soil CO2 and N2O emission rates decreased steadily over time, and then were relatively stable during the final incubation. Cumulative CO2 and N2O emissions increased steadily across the incubation period in all treatments. However, cumulative N2O emissions in bare land with no vegetation cover decreased steadily. In general, production rate and cumulative emission of CO2 were highest in herbage communities, were intermediate in woody community, and were lowest in bare land under all treatments. The negative relationship between cumulative GHG emission and soil salinity was more significant in soils that contained low levels of salt, than that in other soils. The significant positive correlation between cumulative GHG emissions and soil moisture was found in all soils. The effects of salinity on GHG emission were stronger in soils with low levels of salt. Compared with soils collected from bare land with no vegetation cover, soils from different vegetation communities emitted more CO2 and N2O. Perhaps more attention, therefore, should be paid to pulse emissions of GHG as a result of destruction of vegetation in the course of exploitation and utilization of saline soil resources.