Effects Of Conservation Tillage On Greenhouse Gases Flux From Farmland Soil In Dry Land Of The Loess Plateau

Based on long-term conservation tillage experiment in Lijiabu Town of DingxiCity conducted by Gansu Agricultural University，using carbon dioxide analyzer andstatic chamber-gas chromatographic techniques continuously measured, by comparingthe conservation tillage and other cultivation,diurnal and seasonal variation of thegreenhouse gas emission flux and environmental factora affecting its emission fiuxhas been studied in the Arid Soil.The result has been listed as follows:1. Fields were sources of atmospheric CO₂and N₂O and the sink of atmosphericCH₄under thetwo tillage treatme. Daily dynamics of CO₂, N₂O and CH₄flux changedremarkably. CO₂emission flux under conventional tillage was obvious higher thanthat under conservation tillage.the maximal emission flux of CO₂appeared at12:00p.m, whilethe minimum emission appeared at0:00a.m. The maximal emission flux ofCO₂appeared at16:00p.m while the minimum emission appeared at0:00a.m.Conservation tillage treatment could increase N₂O emission. The maximal absorptionflux of CH₄appeared at14:00p.m under thetwo tillage treatme, while the minimumabsorption appeared at22:00p.m under conservation tillage, but the minimumabsorption appeared at2:00a.m under conventional tillage treatme. Conservationtillage could increase CH₄absorption. The land surface temperature and soiltemperature at the depth of5cmsignificantly related to CO₂emission flux, and thatthere was a significant exponential correlation between CO₂flux and the soiltemperature. The fluxes of N₂O were significant related to soil temperature atdifferent depths in fields, and that there was a significant linear correlation betweenN₂Oflux and the soil temperature. The fluxes of CH₄were significant related to soilsurface temperature.2. The seasonal dynamics of greenhouse gases in the period of crop growth wasfound the magnitude of CO₂emissions of wheatare as follows: TS>T>NTS>NT; N₂Ofluxe were:T>NT>TS>NTS;CH₄absorption fluxes were: NTS>NT>TS>T.Comparative study of three Greenhouse Gases Fluxes pea growth period obtained CO₂emissions order: T>TS>NTS>NT; N₂O emission flux were: T>NT>NTS>TS;the absorption flux of CH₄were:NTS>NS>NT>T. Conservation tillage measures cansignificantly reduce emissions of soil CO₂,N₂O and promote the absorption of CH₄flux than other measures. The reduction of greenhouse gas emission of farmlandecosystem has significant effect.3. Temperature is positively related to crop growth period of soil CO₂and fluxesand soil in different depths, H4absorption fluxes and different soil water content hadnegative correlation. Regression analysis on it, are linear functions of theirrelationship. Among them, CO₂and soil surface temperature were of the highestcorrelation, along with the increase of soil depththe correlation between temperatureand CO₂flux was not significant. The most significant correlation between N₂O fluxand10cm soil temperature. CH₄is influenced by soil water content was relativelysignificant, the most significant correlation between CH₄and0-5cm soil watertemperature.4.Under different tillage treatme, the tendency of temparatue increase in field ofwheat showed that: T>TS>NT>NTS;,and filed pea showed that: T>NT>NTS>TS.Therelative effect between CO₂and N₂O showed positive effect,CH₄showed a negativeeffect,and greenhouse effect mainly showed that CO₂greenhouse effect. The potentialof temperature increase was significantly lower in the field of Lucerne than that of thewheat and pea.