Effects Of Different Fertilization Models On CH₄ And N₂O Emission Characteristics Of Paddy Fields In Tropical Areas

Due to the in situ observations of greenhouse gas emissions from farmland are concentrated in temperate and subtropical regions,greenhouse gas emissions from farmland soils in tropical regions are often overlooked.Studying the effects of greenhouse gas emission characteristics in Hainan rice fields under different fertilization modes is of great significance for accurately assessing CH4 and N2O emissions from farmland soils and formulating corresponding emission reduction measures.Five treatments were set up in this study:blank control(CK),conventional fertilization(CON),optimized fertilization(YH),optimized fertilization and slow-release fertilizer application(ZYH1),optimized fertilization,controlled release fertilizer and organic fertilizer.Shi(ZYH2),using static chamber-gas chromatography,through field plot experiments to study the dynamic characteristics of CH4 and N2O emissions in the early and late rice growing season,estimating global warming potential(GWP)and greenhouse gas emission intensity(GHGI),exploring CH4 and The relationship between N2O emissions and related functional microorganisms provides a theoretical basis for screening out the quantitative fertilization model suitable for high-yield and stable yield of rice fields in China’s hot regions.The research results are as follows:1.The characteristics of CH4 and N2O emissions in early and late rice are different.The CH4 emission of late rice is mainly concentrated in the early stage of rice growth,and the N2O emission is concentrated in the sun-dating period;the emission of CH4 and N2O in early rice is opposite to that of late rice.Compared with CON,the cumulative emissions of CH4 and N2O in the early and late paddy fields treated by YH,ZYH1 and ZYH2 decreased,and ZYH2 decreased the most.Soil temperature and Eh are the factors driving the change of CH4 emission in late rice,but the correlation between late rice N2O and early rice CH4 and N2O emissions is not obvious.3.CH4 is a major contributor to the integrated greenhouse effect.ZYH2’s comprehensive greenhouse effect(GWP)and greenhouse gas emission intensity(GHGI)have the lowest GWP and GHGI compared to CON in the late rice and early rice with nitrogen reduction of 22.7%and 22.4%,respectively.4.In the late rice season,the abundance of pmoA gene increased after the application of nitrogen fertilizer in the other treatments,which indicated that NH4+affected the activity of methane oxidizing bacteria.5.The reason for the higher CH4 emission in CK treatment in early rice season is that the abundance of mcrA gene is higher than that of pmoA gene,resulting in more CH4 production and less CH4 oxidation.6.In the process of rice field N2O production,ammonia-oxidizing bacteria play a major role rather than ammonia-oxidizing archaea.7.Different fertilization modes in early and late rice changed CH4 and N2O related functional microorganisms,resulting in differences in greenhouse gas emissions.Among all fertilization modes,ZYH2 yield and overall greenhouse effect(GWP)and greenhouse gas intensity are superior,which is a local weight loss model worth promoting.