牛粪化肥配施对双季稻田CH4和N2O排放的影响OA北大核心CSTPCD

Replacing chemical fertilizers with organic fertilizers from livestock and poultry manure is an important measure to reduce fertilizer application and recycle nutrients.A field experiment was conducted to study the effects of the combined application of cow manure and chemical fertilizers on CH4 and N2O emissions and related factors in a double-rice cropping system in Hunan Province.Gas fluxes were measured using the static chamber/gas chromatography method,and the dynamics of the soil chemical,physical,and biological properties were determined.The findings showed that compared to traditional fertilizer application,the combined application of manure had a significant impact on cumulative CH4 and N2O emissions.Specifically,throughout the two rice-growing seasons,the total CH4 emissions of 50%chemical nitrogen fertilizer replaced with cow dung(CM)increased dramatically by 43.2%compared with the conventional nitrogen fertilizer(CON)treatment.When comparing the CM and CON treatments,the cumulative N2O emissions were reduced by 45.2%.Soil pH,ammonium nitrogen,nitrate nitrogen,organic carbon,total nitrogen,and soluble organic carbon were all significantly improved by the CM treatment;however,soil Eh was significantly decreased.Owing to changes in soil properties,the mean copy numbers of genes that produce and oxidize methane increased by 79.1%and 13.0%in the early and late rice seasons,respectively.There was a significant increase of 35.8%,50.8%,and 7.1%in the average gene copy numbers of the fully ammonia-oxidizing amoA,denitrifying nirS,and denitrifying nosZ functional genes,respectively.In contrast,the gene copy numbers of the functional genes nosZⅡ and nirK decreased by 17.5%and 46.5%,respectively.Redundancy analysis revealed that the average emission flux of CH4,copy number of the gene that produces methane,and copy number of the gene that oxidizes methane were most influenced by soil organic carbon and soil total nitrogen content.In addition,soil organic carbon,soil ammonium nitrogen,and soil total nitrogen had significant impacts on the average emission flux of N2O,copy numbers of completely ammonia-oxidizing amoA functional genes,denitrifying nirS functional genes,denitrifying nosZ functional genes,denitrifying nirK functional genes,and denitrifying nosZⅡfunctional genes of bacteria.Considering the total greenhouse effect of CH4 and N2O emissions,greenhouse gas emissions(in CO2 terms)from the CM treatment significantly increased by 41.0%compared to the CON treatment.In conclusion,the combined application of organic and inorganic fertilizers in paddy fields changes the physicochemical and biological properties of the soil and increases greenhouse gas emissions,which should be considered when assessing the greenhouse effects in paddy fields.