生物炭与无机氮配施对稻田温室气体排放及氮肥利用率的影响

【目的】生物炭作为比表面积大、富含有多种营养元素的一种物质已被广泛应用于农业生产。弄清生物炭与化肥氮配合施用对稻田温室气体排放和氮肥利用率的综合影响,为合理使用生物炭提供科学依据。【方法】在武穴市花桥镇进行两年大田试验,设置4个处理,即不施氮肥(CK)、常规施氮(180 kg·hm^-2)(IF)、常规施氮+10 t·hm^-2生物炭(IF+C)、减氮30%+10 t·hm^-2生物炭(RIF+C)。采用静态箱-气相色谱法对2018和2019年水稻生长季节稻田CH4和N2O排放通量进行监测,并测定水稻产量,探讨生物炭配施不同量无机氮对稻田CH4和N2O排放、水稻产量以及氮肥利用率的影响。【结果】(1)稻季CH4和N2O排放呈现明显的季节性变化规律。CH4排放峰值主要出现在分蘖期和齐穗期,N2O排放峰值主要出现在氮肥施用和排水后。2018和2019年稻季各处理CH4排放通量分别为0.01—48.97mg·m^-2·h^-1和0.36—18.08 mg·m^-2·h

Effects of Biochar Plus Inorganic Nitrogen on the Greenhouse Gas and Nitrogen Use Efficiency from Rice Fields

【Objective】Biochar has been widely used in agricultural production due to large specific surface area and high concentrations in a variety of nutrients. The aim of this study was to investigate effects of biochar plus Inorganic nitrogen on the greenhouse gas and nitrogen use efficiency from rice fields, so as to provide a scientific basis for the proper use of biochar.【Method】A 2-years field trials in Huanqiao town Wuxue city were set up to investigate the effects of biochar combined with different amounts of inorganic nitrogen on CH₄ and N₂O emissions, grain yield and nitrogen use efficiency from paddy fields. Four treatments included no nitrogen (CK), conventional inorganic nitrogen (180 kg·hm ^-2) (IF), conventional inorganic nitrogen+10 t·hm ^-2 biochar (IF+C), and 30% reduction of inorganic nitrogen+10 t·hm ^-2 biochar (RIF+C). The CH₄ and N₂O emission fluxes from paddy soils were determined by static chamber-gas chromatography method, and the grain yield was also determined.【Result】(1) There were obvious seasonal trends in CH₄ and N₂O emissions during the rice growing seasons of 2018 and 2019. The CH₄ fluxes peaked at the tillering and heading panicle stages, and the N₂O fluxes peaked just after N fertilization and field drainage. The CH₄ fluxes ranged from 0.01 mg·m ^-2·h ^-1 to 48.97 mg·m ^-2·h ^-1in 2018 and 0.36 mg·m ^-2·h ^-1 to 18.08 mg·m ^-2·h ^-1in 2019, and the N₂O fluxes were -0.002-0.17 mg·m ^-2·h ^-1 in 2018, and 0.01-0.28 mg·m ^-2·h ^-1in 2019. Average CH₄ fluxes were 6.17-7.16 mg·m ^-2·h ^-1in 2018 and 5.16-5.83 mg·m ^-2·h ^-1in 2019, and average N₂O fluxes were 0.02-0.04 mg·m ^-2·h ^-1in 2018 and 0.05-0.08 mg·m ^-2·h ^-1 in 2019. (2) Compared with CK, the application of inorganic nitrogen fertilizers did not affect CH₄ emissions, but increased N₂O emissions by 32.6%-113.0%. Compared with IF, biochar treatments (IF+C and RIF+C) did not affect CH₄ emissions, but significantly decreased N₂O emissions by 33.4%-43.1% in 2018 and by 37.0%-39.5% in 2019. There was no difference in global warming potential (GWP) between IF and biochar treatments. No significant differences in CH₄ and N₂O emissions were observed between IF+C and RIF+C. CH₄ emissions played in a dominant in GWP, accounting for 84.4%-95.2% of the seasonal GWP. (3) Nitrogen fertilization significantly increased rice grain yields by 4.0%-6.0%. Compared with IF treatment, biochar treatments (IF+C and RIF+C) significantly increased rice grain yield by 9.9%-11.9%. There was no significant difference in rice grain yield between IF+C and RIF+C. Compared with IF treatment, IF+C and RIF+C treatment significantly increased nitrogen use efficiency by 7.7%-8.1%. Nitrogen partial productivity under RIF+C was increased by 57.1% and 52.3% in two years, respectively. 【Conclusion】The treatment of biochar + 30% reduction of inorganic nitrogen was a sustainable agronomic measure to effectively reduce N₂O emission and to increase rice yield and nitrogen use efficiency in rice fields. However, the mitigating effect of biochar on greenhouse gas emission from rice fields should be further studied.