| 椰糠生物炭对热区双季稻田N2O和CH4排放的影响 |
| 摘要点击 6159 全文点击 643 投稿时间：2020-11-29 修订日期：2021-01-26 |
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| 中文关键词 椰糠 生物炭 热区 双季稻田 温室气体 增温潜势(GWP) |
| 英文关键词 coconut chaff biochar hot area double-cropping rice fields greenhouse gas global warming potential (GWP) |
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| 中文摘要 |
| 基于稻菜轮作模式，选择海南双季稻田为对象进行氧化亚氮（N2O）和甲烷（CH4）排放的原位监测，探究椰糠生物炭对该系统稻田温室气体排放的影响.试验设当地常规施肥对照（CON）、氮肥配施20 t·hm-2生物炭（B1）、氮肥配施40 t·hm-2生物炭（B2）及不施氮对照（CK）4个处理，采用静态箱-气相色谱法监测整个水稻种植季稻田N2O和CH4排放，并估算增温潜势（GWP）和温室气体排放强度（GHGI）.结果表明，早稻季N2O排放动态与土壤矿质氮含量密切相关，排放集中在水稻苗期与分蘖期施肥后，各处理早稻季N2O累积排放量为0.18~0.76 kg·hm-2，相较于CON处理，生物炭处理减排18%~43%，其中B2处理达显著水平；生物炭可能通过促进N2O的还原减少早稻苗期N2O排放；提高土壤硝态氮含量而增加了早稻分蘖期N2O排放.晚稻季N2O排放集中在抽穗期和成熟期，累积排放量为0.17~0.34 kg·hm-2，B1处理减排37%，B2增加3%，差异均不显著.稻田CH4排放高峰出现在早稻季后期与晚稻季前期.各处理早稻季CH4累积排放量为3.11~14.87 kg·hm-2，CK较CON处理增排39%，生物炭处理可能提高土壤通气性限制早稻季产CH4能力，B1和B2处理分别较CON减排28%和71%；晚稻季CH4累积排放量为53.1~146.3 kg·hm-2，排放动态与NH4+-N含量极显著正相关，CK和B1分别较CON处理增加52%和99%，B2处理显著增加176% CH4排放.早稻季B1和B2处理较CON分别增产12.0%和14.3%，晚稻季分别增产7.6%和0.4%.由于晚稻季甲烷排放的增加，施用生物炭增加了双季稻田总增温潜势（GWP），其中高量生物炭达显著水平；不同施用量生物炭对双季稻田温室气体排放强度（GHGI）无显著影响.椰糠生物炭在热区稻田温室气体减排方面的应用仍需进一步研究. |
| 英文摘要 |
| Based on the rice-vegetable crop rotation model, in-situ measurements of nitrous oxide (N2O) and methane (CH4) emissions were conducted in double-cropping rice fields in Hainan to determine the impact of coconut chaff biochar on greenhouse gas emissions. The experiment involved four treatments:conventional farming fertilization (CON), nitrogen fertilizer combined with 20 t ·hm-2 biochar (B1), nitrogen fertilizer combined with 40 t ·hm-2 biochar (B2), and no nitrogen fertilizer, as the control (CK). The N2O and CH4 emissions were measured using static chamber-gas chromatography during the two paddy seasons, and the global warming potential (GWP) and greenhouse gas intensity (GHGI) were also estimated. The results show that N2O emission dynamics during the early rice season are closely related to the mineral nitrogen content of the soil. The N2O is emitted at the rice seedling and tillering stages after fertilization. The cumulative N2O emission during the early rice season was 0.18-0.76 kg ·hm-2. Compared with the CON treatment, the biochar treatments reduced N2O by 18%-43%, and the B2 treatment resulted in a significant reduction. The addition of biochar may promote the reduction of N2O at the early rice seedling stage and increase N2O emissions by improving the soil NO3--N content at the early rice tillering stage. During the late rice season, N2O is emitted during the heading and maturity stages, and the cumulative N2O emission was 0.17-0.34 kg ·hm-2. The B1 treatment reduced emissions by 37%, and B2 increased emission by only 3%, which is not a significant difference. The peak of CH4 emissions from rice fields appeared in the late phase of the early rice season and prophase of the late rice season. The cumulative emission of CH4 in the early rice season was 3.11-14.87 kg ·hm-2. Compared with CON, the CK treatment increased emission by 39%. The biochar treatment may increase soil aeration and limit the ability of CH4 production in the early rice season, as B1 and B2 treatments reduced CH4 emissions by 28% and 71%. The cumulative CH4 emission in late rice season was 53.1-146.3 kg ·hm-2, and the emission dynamics were significantly positively correlated with NH4+-N content. CK and B1 treatments increased CH4 emissions by 52% and 99%, respectively compared with CON, and the B2 treatment significantly increased CH4 emissions by 176%. Compared with CON, the B1 and B2 treatments increased the yield by 12.0% and 14.3% when applied in the early rice season and by 7.6% and 0.4% when applied in the late rice season, respectively. Due to the increased methane emissions in the late rice season, biochar amendment increased the GWP of the double-cropping rice field, in which the high amount of biochar reached a significant level; different amounts of biochar had no significant effect on the GHGI of the double-cropping rice field. Thus, the application of coconut chaff biochar for the reduction of greenhouse gas emission, from rice fields in hot areas, requires further research. |
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