Greenhouse Gas Emission Characteristics And Its Influenc Ing Factors Of Dry Land Farming Under Differe Nt Tillage Measures

In recent years,the problem of greenhouse effect caused by global climate change has become the focus of global attention.And agricultural production activities have a significant impact on global greenhouse gas emissions.The field experiments were conducted from 2001at the Dingxi experimental station of Gansu Agricultural University,in Dingxi,Gansu province,northwest China.The experime nt was a fully phased design with 4 treatments,including Conventional tillage（T）,Conventional tillage with stubble incorporating（TS）,No till with no stubble（N T）and No till with stubble retention（N TS）.The static box-gas chromatography,LI-8100A portable CO₂ analyzer under different cultivation measures on2017 bean wheat double sequence rotation farmland soil CH₄,N₂O and CO₂ emission flux of continuous observation for the whole year,and discusses the soil temperature and soil water content and the relationship between the greenhouse gas emissions.The main conclusions are as follows:1、Under different tillage measures,the soil of soybean and wheat in the whole observation period was the source of CO₂ emission.The seasonal variation trend of CO₂emission in wheat field and pea patch was consistent,it has obvious seasonal characteristics which was the highest in summer,the second in spring and autumn and the lowest in winter,with obvious seasonal characteristics.In wheat field,NTS has the highest CO₂ emission flux and NT was the lowest;In the pea field,the treatment of T has the highest CO₂ emission flux and NT was the lowest.Under different tillage measures,the farmland soil was CH₄absorption in the whole observation period was CH₄ absorption,and it all had obvious seasonal variation.The average absorption flux of C H₄ in wheat field was:NTS>NT>TS>T.The average absorption flux sequence of C H₄ in each of the peas was:NTS>N T>T>TS.No-tillage straw mulching and no-tillage treatment can significantly increase the absorption of CH₄ in farmland.Under different tillage measures,the soil of soybean and wheat in the whole observation period was N₂O emission source.The variation trend of N₂O flux in wheat field and pea patch was consistent,the curves of soil N₂O flux have a single-peak,it raised at first and then decreased.The treatment of T has the largest N₂O emission flux in wheat field and pea land,NT,TS and NTS has a low emission of N₂O.It can be seen that no-tillage and straw mulching can significantly reduce N₂O emission compared with traditional tillage treatment.2、The comprehensive GWP of CH₄,CO₂ and N₂O under each treatment of wheat for the whole year is:T>NT>TS>NTS.The treatment of Thas the most contribution to atmospheric greenhouse effect and it was the 1.2,1.22 and 1.26 times of NT,TS and NTS.The comprehensive GWP of CH₄,CO₂ and N₂O under pea was:T>TS>NT>NTS,which of the T has a maximum of 3448.63kg（CO₂）hm^-2,NTS was lowest and minimized the contribution of the greenhouse effect,reduced effect on greenhouse gases.3、There was the significant relationship between absorption flux of CO₂ and soil moisture content under 0⁵cm、5¹0cm layer.The correlation between soil moisture content of wheat ground CH₄ flux and 0⁵cm and 5¹0cm layer was relatively high,showing positive correlation.There was no significant negative correlation between N ₂O of wheat and soil water at all levels.There was a negative correlation between CO₂ absorption flux and soil moisture content in pea land.The correlation of soil moisture content in the soil moisture content of pea land was higher than that of 0⁵cm,5¹0cm and 20⁴0cm layer,showing positive correlation.The N₂O of pea land had no significant negative correlation with soil moisture at all levels.There was a significant positive correlation between CO ₂ absorption flux of wheat and soil temperature in each layer.The CH₄ flux in wheat showed negative correlation with soil temperature.The N₂O of wheat was positively correlated with soil temperature at all levels.There was a significant positive correlation between CO ₂ flux in pea land and all layers.The CH₄ flux of pea land was negatively correlated with soil temperature at all levels.The N₂O of pea land is the same as wheat field,and has a significant positive correlation with soil temperature at all levels.