Study On N₂O Flux Of Returning Farmland To Grass In The Farming-pastoral Ecotone Of Inner Momgolia

Since the implementation of the project of returning farmland to forests and grasslands in the western regions where soil erosion is serious,the ecological environment has been improved.This study will evaluate the ecological function of returning farmland to grassland from the perspective of greenhouse gas revenue and expenditure.In this study,static dark box-gas chromatography was used to observe the N₂O exchange flux of farmland in the agro-pastoral ecotone of Inner Mongolia and returning grassland for many years,to study the effects of returning farmland to grassland on soil N₂O flux.The farmland includes Corn Field?CF?,Potato Patch?PP?,Abandon Land?AL?of past years,the grassland includes Ungrazed Grassland?UG?,Continuous Grazing?CG?and Rotation Grazing?RG?,a total of six seed treatment.The main findings of the study are as follows:?1?The N₂O emission flux of farmland soil is much larger than that of grassland,and the implementation of returning farmland to grassland can reduce the emission of N₂O greenhouse gas effectively.?2?N₂O emissions from farmland?CF,PP?are mostly concentrated in the crop growth period.N₂O emission from AL is mostly concentrated in the soil freezing and thawing period.There are no obvious major discharge periods for N₂O in the grassland?UG,CG,RG?for returning farmland to grassland many years.?3?The N₂O fluxes of CF,PP and AL in farmland were significantly correlated with soil temperature?P<0.05?,while the N₂O fluxes treated with grassland?UG,CG,RG?were not significantly correlated with soil temperature?P>0.05?.In addition to CG treatment,soil N₂O exchange fluxes treated with CF,PP,AL,UG and RG were significantly positively correlated with soil moisture?P<0.05?.?4?Except for CF treatment,the N₂O fluxes of other treatments?PP,AL,UG,CG,RG?were significantly positively correlated with soil ammonium nitrogen?P<0.05?.In addition to PP treatment,the soil N₂O fluxes of other treatments?CF,AL,UG,CG and RG?were significantly positively correlated with nitrate nitrogen?P<0.05?.It can be seen that the content of ammonium nitrogen and nitrate nitrogen in soil is an important factor affecting N₂O flux.