Simulation on short-term emission of N2O from vegetable soil under long-term fertilization combined with DCD treatment
To investigate the effects of long-term dicyandiamide(DCD)application on N2O and other greenhouse gas flux from vegetable fields,an incubation experiment was conducted.Soil samples were collected from a long-term localization experiment using different fertilizers in conjunction with DCD,and the dynamic changes and cumulative emissions of CO2,N2O,and CH4 were investigated using gas chromatography.A short-term indoor simulated incubation experiment was conducted with five treatments:cattle manure(OM),chemical fertilizer(F),cattle manure+DCD(OMD),chemical fertilizer+DCD(FD),and 1/2 chemical fertilizer+1/2 cattle manure(FOM)at different temperatures for 15 days.The total CO2 emissions under 15℃ and 25℃ were 25.39-52.01 mg·kg-1 and 62.35-122.80 mg·kg-1,respectively;the total N2O emissions were 6.02-16.60 μg·kg-1 and 14.45-117.78 μg·kg-1 respectively,the total emissions of CH4 are-3.17-14.87 μg·kg-1 and 4.09-23.56 μg·kg-1.All treatments except FOM showed significantly higher N2O and CO2 emissions at 25℃ compared with 15℃ (P<0.05).Compared with OM and OMD,CO2 emissions under both temperature conditions were significantly reduced by the treatments of F,FD,and FOM.At 25℃,compared with OM and F,the peak and cumulative N2O emissions were significantly reduced by OMD,FD,and FOM(P<0.05).At 15℃,there was no significant difference in N2O cumulative emissions among all treatments.Short-term indoor simulated incubation experiment indicated that CO2 emissions were significantly positively correlated with soil pH and total nitrogen(TN)content,and negatively correlated with Olsen-P content.There was a significant positive relationship between CH4 emmissions and soil organic matter(SOM)under 15℃ conditions(P<0.01).The results of this study indicated that compared with manure or chemical fertilizer alone at high-temperature conditions,N2O emissions in vegetable fields could be reduced by long-term DCD application or manure combined with chemical fertilizer.The results of this study can provide a fundamental theory regarding greenhouse gas emissions resulting from the long-term use of DCD in vegetable fields.
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