N₂O And CH₄Emission And Influence Factors Of Pea And Spring Wheat Rotation Fields In Dry Farmland Area A Wet Year

Nowadays, with the enhanced greenhouse effect, climate change has already affected thepeople’s life, researches on greenhouse gases include N2O and CH4have gradually become studyhotspot. But, the emissions research of N2O and CH4on dryland farming is relatively few.Meanwhile, because of the obvious volatility of dryland agriculture ecosystem, especially afterrainfall, that has a great influent on the producer and reducer, so, study the emissions of N2O andCH4in wet year is meaningful. Therefore this article takes pea and spring wheat doublesequences rotation fields in dry farmland area as the research object, Test Site located in Dingxicity, trial since March22,2013to July31,2013, including the entire growth period of springwheat and pea, before seeding time and post-harvest. Using static chamber-gas chromatographictechniques to gather gases from study plot, and determining the N2O and CH4emission flux ofdifferent cultivation measures pea and spring wheat double sequences rotation fields.To study theeffect of cultivation measures、soil moisture content and soil temperature on N2O and CH4emissions in a wet year. Provide the basis for arranging cultivation measures of farmlandreasonably and reducing farmland N2O and CH4emissions. In this experiment, differentcultivation measures include conventional tillage without straw mulching (T)、no-tillage withoutstraw mulching (NT)、conventional tillage with straw mulching (TS) and no-tillage with strawmulching (NTS);Soil moisture contents include0-5cm、5-10cm and10-30cm three layers; Soiltemperatures include0cm,5cm,10cm,15cm,20cm and25cm temperatures. The resultsshowed that:1. Different tillage measures of pea and spring wheat double sequences rotation fields areN2O emission source in whole growth period of wet year. emission flux fluctuation range ofspring wheat is0.018mg/(m2.h)～0.146mg/(m2.h), emission flux fluctuation range of pea is0.024mg/(m2.h)～0.210mg/(m2.h), and the trend of flux show wave growth.But the volatilityand range of spring wheat flux is smaller than peas. N2O emission of spring wheat has twoemission peaks, and the average emission flux in the order of: T>NT>NTS>TS while N2Oaverage emission flux of pea in the order of T>NTS>NT>TS;2. Different tillage measures of pea and spring wheat double sequences rotation fields areCH4sinks in whole growth period of wet year. The absorbed flux fluctuation range of springwheat is0.051mg/(m2.h)～0.212mg/(m2.h)， absorbed flux fluctuation range of pea is0.057mg/(m2.h)～0.193mg/(m2.h). At the same time, the volatility of spring wheat flux is biggerthan peas.The CH4absorption fluxe peaks of spring wheat fields appear in seedling stage and filling stage while peaks of pea fields appear in branching stage and podding stage. Average CH4absorption fluxes of spring wheat in order of NTS>NT>TS>T while average CH4absorptionfluxes of pea in the order of NTS>TS>NT>T.3. Different cultivation measures have different effects on flux of N2O and CH4, and the N2Oand CH4fluxs of spring wheats less than peas, moreover, the difference between spring wheatsand peas is significant. Compared with T, TS、NT and NTS reduce emissions of N20effectivelyand increase the absorption of CH4;4. Compared with the dry year, the comprehensive influence of soil temperature and soilwater content to N2O and CH4emission of dry land agriculture in wet year is lower; meanwhilesoil water content shows greater weight than soil temperature, CH4flux affected by soil moisturecontent increase.5. After rainfall process, the comprehensive effect of soil temperature, soil moisture contentand WFPS to N2O flux is increase. Regression equation shows N2O fluxes effected by sixindicators and they could explain50.6%variation of the flux, which WFPS and moisture of0-5cm layer have greatest impact on fluxes;6. After rainfall process, CH4flux mainly affected by the20-30cm moisture, it can explain21%change of the flux, the other fluxes affected by other factors. The effect of soil moisturecontent is greater than soil temperature and WFPS.On the whole, soil often happen dry-wet alternate in wet year. This makes the effect of soilwater content and soil temperature to N2O and CH4emission more complicate. And water as themain limiting factors of dry land agriculture, its change often caused other factors change. Theimpact of other factors changes become bigger, still need further study.