| Farmland soil is an important source of greenhouse gas emissions,biochar applied to the soil can slow down the carbon cycle and improve the physical and chemical properties of the soil.In this study,the field experiment was carried out to study the effects of biochar addition on paddy field ecosystem in Fuzhou plain.By measuring the flux of CO2,CH4 and N2O,the change of greenhouse gas emission under the condition of biochar addition was revealed.The response of soil and plant to biochar addition was revealed by measuring soil nutrient and organic carbon content and plant nutrient and physiological index.And the influencing factors were analyzed by statistical analysis and ecological stoichiometry method,and the effects of biochar addition on paddy field ecosystem were discussed comprehensively.The main findings and conclusions are as follows:(1)The average CO2 emission flux of early rice growing season of Fuzhou Plain was 549.69±28.11 mg·m2·h-1,in the late rice season was 500.96±45.09 mg·m-2·h-1,the biochar addition treatment(10 t·hm-2,20t·hm-2 and 40 t hm-2)was 579.67±76.17 mg·m-2 ·h-1,554.14±41.76 mg·m-2·h-1,542.64±71.24 mg·m-2 ·h-1,in the late rice season was 813.04±99.16 mg·m-2·h-1,451.96±92.97 mg·m-2 ·h-1,722.46±60.55 mg·m-2 ·h-1.The average CH4 emission flux of early rice was 0.50±0.07 mg·m-2·h-1,in the late rice season was 5.24±0.64 mg·m-2·h-1,10 t·hm-2,20t·hm-2 and 40 t· hm-2 treatment was 0.37±0.09 mg·m-2·h-1,1.01±0.02 mg·m-2·h-1,1.50±0.19 mg·m2·h-1,in the late rice season was 3.88±0.71 mg·m-2·h-1,4.48±0.20mg·m-2·h-1,3.85±0.58 mg·m-2·h-1.The average N2O emission flux of early rice was 38.94±26.43?g·m2·h-1,in the late rice season was 11.14±10.90 ?g·m2·h-1,10 t·hm-2,20t·hm-2 and 40 t·hm-2 treatment was 57.96±21.00 ?g·m-2·h-1,72.31±17.58?g·m-2·h-1,73.98±25.22?g·m-2·h-1,in the late rice season was 18.25±16.11?g·m-2 ·h-1,23.88±12.87 ?g·m-2·h-1,10.77±12.10?g·m-2·h-1.Only late rice growth season 20t·hm-2 treatment inhibited CO2 emissions under the conditions of biochar addition in paddy fields in Fuzhou plain,and the effect of different biochar treatment on CO2 emission was different between early and late rice season.Early rice biochar addition mainly promoted CH4 emission and late rice inhibited CH4 emission.Most of the treatments of early rice and late rice under the condition of biochar addition have increased the N2O cumulative emission.(2)The addition of soil TC and TN in the paddy field of Fuzhou plain increased with the growth of the plant,which indicated that the biochar had enhanced the soil carbon fixation and nitrogen fixation in the rice growing season.The content of soil TP was decreased by biochar treatment in early rice season,but increased in late rice season.(3)The changes of soil DOC,MBC and EOC were not obvious.Biochar addition increased soil catalase and soil polyphenol oxidase activities.Biochar addition increased soil C/N,to a certain extent,reduced soil nitrogen supply potential;biochar addition significantly increased the soil C/P,reducing the release potential of soil phosphorus.(4)The biochar addition increased the TC in rice roots and decreased the TC in stems and leaves.The late rice increased the TN in stems and leaves,while the early rice reduced the TN in stems and leaves,biochar improve the TP of rice roots,changing the distribution of nutrients in various organs of rice plants.C/N of roots,stems and leaves increased in early rice season,while C/N of stems and leaves decreased in late rice season.Biochar with high added amount(40t·hm-2)had obvious effect on reducing C/P in stem leaves of early and late rice.The middle amount of biochar(20t·hm-2)has the effect of reducing N/P of early and late rice.(5)Biochar decreased NGHGE in early rice season and increased carbon sequestration in paddy soil.Under the condition of existing farming system in paddy field in Fuzhou plain,add of 10t·hm-2 biochar in early paddy field and 20t·hm-2 in late paddy field is helpful to achieve the goal of carbon sequestration and stable yield increase in the paddy fields in Fuzhou Plain. |
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