Effects Of Straw And Nitrogen Fertilizer Adjusted C/N Ratio On Greenhouse Gas Emission And Properties In Alluvial Soil

In order to investigate the effects of straw application with N-fertilizer on the properties and greenhouse gases emission characteristic of sandy Alluvial soil,providing theory gist to reduce greenhouse gas emissions while proving soil fertility by reasonable straw application and N-fertilizer,the constant temperature incubation experiments were carried out under the condition of adding quantitative straw to the soil,the different C/N ratios(9,12.5,25,40,71)were adjusted by urea,and the single nitrogen treatment(N)was applied,while the original soil(no fertilizer)was used as a control(CK).The main results are as follows:1.The results showed that the CH4 emission was negative,and the CH4,CO2 and N2 O emission were promoted by straw with nitrogen fertilizer combined application treatment during 37 days culture experiments.The emission rate and cumulative emissions of CH4 both declined with the decreasing of the C/N ratio,but they were increased on CO2 and N2 O.2.The 360 days constant temperature incubation experiment indicated that:1)Adjusted C/N ratios with different amount of N-fertilizer could improve the organic carbon,active organic carbon,total nitrogen,NH4+-N,NO3—N,microbial carbon and microbial nitrogen content.Soil NH4+-N,NO3—N content were increased with the decreasing of the C/N ratio during the whole culture period and they achieved the highest values when C/N ratio was 9.Soil organic carbon,active organic carbon and total nitrogen were enlarged during the early stage of incubation with the increase of nitrogen fertilizer(C/N ratio declined).Soil SMBC and SMBN content achieved the highest when the C/N was 25 as a whole.2)The addition of straw perfected the soil structure and improved the aggregation of soil particles that the content of >0.25 mm macro aggregate increased,the soil stability enhanced significantly.The C/N = 12.5 treatment had a great advantage.3)The activitiy of soil polyphenol oxidase,urease and catalase were increased under straw with nitrogen fertilizer combined application treatments.On the whole the activity of soil,ureasepolyphenol,oxidase and catalase achieved the biggest values respectively on the ratio of 9,71(only addition of straw)and 12.5.