Greenhouse Gas Emission Characteristics And Simulation Of Main Crops In Growing Season In Longnan Mountain

The greenhouse gas emission from agricultural production activities is an important source of greenhouse gas emissions in China.The carbon emissions of agricultural production in China account for 16%to 17%of the total greenhouse gas emissions,and the mountainous area in Longnan is a typical agricultural planting area.The main influence factors of greenhouse gas emission flux are discussed,and the comprehensive evaluation simulation of environmental factors and greenhouse gas flux is fitted to predict the greenhouse gas emission fluxes of agricultural land soil in specific areas.This research is helpful to identify the mechanism of carbon cycle in the agricultural land ecosystem of Northwest China,and reveal its influencing factors and mechanisms.It has important theoretical significance for the rational planning of agricultural production,the effective use of land resources,accurate estimation of the concentration of greenhouse gases in the atmosphere,reducing the emission of soil greenhouse gas and controlling the continuous rising of the global temperature.Therefore,taking the typical agricultural ecosystem of Longnan mountain as an example,the daily dynamic and monthly dynamic characteristics of the greenhouse gas emissions from three kinds of wheat,corn and rice,as well as the effects of soil physical and chemical properties on greenhouse gas emission fluxes are analyzed.On this basis,the greenhouse gas emissions are carried out by the regression model.The following main research results are obtained:1.The greenhouse gas of wheat,corn and rice soil in Wenxian of Longnan showed that the soil showed a state of both CO₂ and N₂O emission,and the small part of CH₄ showed a state of absorption,most of which showed emission state and N₂O showed a state of absorption.2.In the daily dynamic change of soil greenhouse gas absorption and emission flux,the mode of action of CH₄ shows two ways of absorption and emission.In April,May,June,from 6:00 to 12:00 noon,the CH₄ emission of three crops increases with the increase of temperature,and the discharge value of CH₄ in paddy soil is obviously larger than that of wheat land and jade in the same period.The rice field showed that the CH₄ emission from flooded paddy fields was very obvious.In the middle of September,the CH₄ action mode of the three crops changed from emission to absorption;The CO₂ emission trend showed a single peak curve trend,and all reached the peak at 12:00 at noon;the N₂O emission flux was smaller and the maximum emission flux appeared at 18:00 p.m.in the June corn field.3.In the seasonal dynamic changes of soil greenhouse gas flux,the CH₄emission flux of wheat and corn soil in April,May,June,September,the overall emission flux basically remained the same.In June,the soil CH₄ emission flux in the soil of June was significantly higher than that of the wheat and corn soil soil CH₄emission flux,mainly because of the flooding of rice.The field provides a good environment for CH₄ emissions.The total flux of soil CO₂ emission in April,May,June and September was basically consistent in the different land use ways,and the maximum value appeared in September.The absorption flux of N₂O was basically consistent in April,May,and the total absorption flux under different land use methods.The maximum value appeared in June.4.The emission flux of greenhouse gas is positively related to the surface temperature of the soil,but the surface temperature of the wheat soil is very weakly related to the emission of N₂O,and the rest are strongly correlated.The soil surface temperature in maize field is strongly correlated with CH₄ emission flux.5.There was a weak correlation between the total nitrogen content of wheat and the flux of CO₂ emission,and a moderate correlation between the flux of N₂O and the flux of CO₂.The total phosphorus content of wheat and the flux of CO₂ emission were in a moderate degree,but were negatively correlated with the emission flux of CH₄and N₂O;the total phosphorus content and total nitrogen content and three kinds of gas emission fluxes in the corn field There was a negative correlation between them.6.Box temperature has a significant effect on soil ammonium nitrogen,nitrate nitrogen and available phosphorus in several land use ways,and has a negative correlation.With the decrease of box temperature,the utilization of ammonium nitrogen,nitrate nitrogen and available phosphorus in soil soil decreases,and the box temperature has no significant influence on the content of available phosphorus in soil soil,and it has a weak correlation..There was a significant positive correlation between box temperature and soil available phosphorus in wheat field.7.Regression model show that the effect of the absolute value of the standard coefficient（Standardized Coefficients）beta on the CH₄ emission flux is in turn:total nitrogen>ammonium nitrogen>box temperature>ground temperature>total phosphorus>nitrate nitrogen>quick acting phosphorus;the effect of CO₂ emission flux is in turn:box temperature>quick acting phosphorus>.Total phosphorus>total nitrogen>nitrate nitrogen>ammonium nitrogen>soil temperature.The effect on N₂O emission flux is in turn:ground temperature>box temperature>nitrate nitrogen>ammonium nitrogen>quick acting phosphorus>total nitrogen>total phosphorus.8.the results of the regression simulation showed that the soil temperature and total nitrogen content had the greatest impact on the emission of three kinds of greenhouse gases（CH₄,CO₂,N₂O）,which was the most important factor,which was the same as the experimental results.