四川盆地不同轮作方式和氮素管理对农田温室气体排放及净温室效应的影响

发布时间：2018-04-28 13:23

  本文选题：温室气体 + 玉米-小麦轮作　； 参考：《中国农业大学》2016年博士论文

【摘要】：针对不同轮作系统中氮肥过量及不合理施用和未来水资源紧缺将会成为四川盆地农业可持续发展的限制因子,从2012年起本人在重庆市江津区进行单季稻转换为不同轮作系统的田间试验,动态监测土壤N_2O、CH_4和生态系统CO2排放通量及农业生产投入带来的当量CO2排放,采用基于土壤的方法计算农田净温室效应(net Global Warming Potential,简称net GWP)。探讨不同轮作体系下N_2O、CH_4的排放规律及净温室效应,分析影响温室气体排放和净温室效应的主控因子,提出针对性减排措施,为该地区农业的可持续发展提供理论指导。试验设早旱轮作(玉米-小麦,MW)、水旱轮作(水稻-小麦,RW)、水稻-冬水休闲(水稻-休闲,RF)三种轮作体系为主处理,每种轮作体系设不施氮对照(N0：不施用氮肥)、优化施氮(Nopt:小麦季96 kg N h-1,玉米季或水稻季150 kg N ha1).传统施氮(Ncon:小麦季180 kg N ha-1,玉米季或水稻季225kgN ha-1)3个副处理。温室气体采用静态箱-气相色谱法进行田间原位测量,每周1-3次,共2周年。得到以下主要结果：(1)氮肥施用是农田土壤N_2O排放的重要来源,主要是通过增加土壤无机氮含量而促进N_2O排放,降雨强度是玉米季土壤N_2O排放年际变化的主要原因。不同轮作体系比较,N_2O排放以MW RW RF;不同施氮水平比较,N_2O排放以NconNoptN0。小麦季、玉米季、水稻季Ncon和Nopt处理的N_2O平均排放因子分别为0.68～0.82%、3.16%、0.35～0.36%以及0.48～0.73%、2.23%、0.21～0.22%。这些结果表明,传统处理较优化处理有较高的N2O排放风险；稻麦轮作改为玉麦轮作,增加N2O排放,而将稻麦轮作改为水稻-冬水田轮作,则减少N_2O排放。(2)农田CH_4排放以RF系统最高,RW次之,MW最低。由于施肥,灌溉和降雨的影响,小麦季、玉米季、水稻季土壤5cm的温度仅能解释6%、13%、14%的CH_4排放,同时稻季水层深度可解释19%的CH_4排放。2013年度(第一年)单季稻改旱作,MW玉米季有明显甲烷排放,2014年度(第二年)则未出现；RW系统两年甲烷排放量无显著差异；单季稻改为冬水田后,甲烷排放在第二年明显增加。MW、RW、RF三轮作系统的两年平均值均表现出甲烷的净排放,并以水稻或玉米季为主。大量施氮后,抑制RW和MW系统甲烷排放,对RF系统无影响。MW、RW、RF体系第一年的甲烷排放量分别为13.5、26.7和89.8kg CH_4-C ha-1,第二年为第一年相应体系的6.2%、85.1%和263.1%。在NO处理中,MW、RW、RF系统两年平均的CH_4排放量分别为9.1、28.2、156.6 kg CH_4-Cha-1, Nopt处理分别为相应对照处理的91.3%、107.9%、108.9%,Ncon处理分别为相应对照处理的46.1%、54.5%、103.5%。(3)农田生态系统呼吸存在明显的年际变异,生态系统呼吸以2013年度2014年度；不同轮作体系比较,MW系统的农田生态系统呼吸通量最高,RW系统次之,RF系统最低；随着施肥量的增加,农田生态系统呼吸明显增加。农田生态系统呼吸排放变化受温度控制。小麦季CO2排放与箱内温度有较好的相关性,玉米季和水稻季CO2排放与5 cm土温有较好的相关性,分别能够解释38.3%、28.6%、48.9%的生态系统呼吸。小麦季、玉米季CO2呼吸与WFPS有明显的负相关,但仅能解释9.3%、8.5%的生态系统呼吸。(4)N_2O和CH_4产生的GWP和GHGI (Greenhouse Gas Intensity,指单位产量的温室气体排放强度)中,RW系统均为最低,RF系统均为最高；施肥处理的N_2O贡献了MW系统GWP的90%,RW系统GWP中不低于40%,RF系统GWP中不足8%。MW和RW的净温室效应中,除了监测到的温室气体产生的当量CO2排放,由于生产效率较低,肥料投入也是很重要的一面；RW稻田灌溉是干旱年份温室效应的主要贡献者,而RF系统中,最主要的贡献是CH_4排放。从单季稻转变为水旱轮作、旱旱轮作和冬水田之后,土壤有机碳发生了明显的变化,旱旱轮作土壤有机碳表现为排放,冬水田土壤有机碳表现为明显的碳固定,水旱轮作表现为弱的碳固定。旱旱轮作的net GWP和net GHGI均最高,而冬水田的均最低。
[Abstract]:Excessive nitrogen fertilizer and unreasonable application in different rotation systems and the shortage of future water resources will be the limiting factors for the sustainable development of agriculture in Sichuan basin. From 2012, the field experiment of single season rice conversion to different rotation systems in Jiangjin area of Chongqing city was carried out to dynamically monitor soil N_2O, CH_4 and CO2 emission fluxes in the ecosystem. And the equivalent CO2 emissions from agricultural production input, the net greenhouse effect of farmland (net Global Warming Potential, referred to as net GWP) was calculated based on the soil method. The emission laws of N_2O and CH_4 under different rotation systems and the net greenhouse effect were discussed, and the main controlling factors affecting the emission of greenhouse gas and the net greenhouse effect were analyzed, and the targeted reduction was proposed. In order to provide theoretical guidance for the sustainable development of agriculture in this area, the experiment set up three kinds of rotation systems, namely, early drought rotation (maize wheat, MW), water and drought rotation (rice wheat, RW), rice winter water leisure (rice leisure, RF), each rotation system without nitrogen control (N0: no nitrogen application) and optimized nitrogen application (Nopt: wheat season 96 kg N H -1, maize season or rice season 150 kg N HA1). Traditional nitrogen application (Ncon: wheat season 180 kg N HA-1, corn season or rice season 225kgN HA-1) 3 side treatments. Greenhouse gases were measured in situ using static box gas chromatography, 1-3 times a week, a total of 2nd anniversary. (1) application of nitrogen fertilizer is an important part of the field soil N_2O emission. The source, mainly by increasing the content of soil inorganic nitrogen to promote N_2O emission, the rainfall intensity is the main reason for the interannual variation of soil N_2O emission in the maize season. The N_2O emission is MW RW RF compared with the different rotation system, and the N_2O emission is based on the NconNoptN0. wheat season, the jade rice season, the Ncon and Nopt treatment of the rice season. The results were 0.68 to 0.82%, 3.16%, 0.35 to 0.36%, 0.48 to 0.73%, 2.23%, and 0.21 to 0.22%., the results showed that the traditional treatment had higher N2O emission risk than the rice wheat rotation, and the N2O emission was increased, and the rice wheat rotation was changed to rice winter water Da Waku, and the N_2O emission was reduced. (2) CH_4 emission from farmland was RF system Due to the effects of fertilization, irrigation and rainfall, the temperature of soil 5cm in wheat season, corn season, and rice season can only explain 6%, 13%, 14% CH_4 emissions due to fertilization, irrigation and rainfall. At the same time, the depth of the rice season water layer can be explained by 19% CH_4 emissions in.2013 year (first year) to dry rice, the MW corn season has obvious methane emission, 2014 (second years) is not in the 2014 year. There was no significant difference in methane emission in RW system for two years. After the single season rice was changed to winter water, the methane emission was obviously increased by.MW in second years. The average annual value of the RW and RF three wheel system showed the net methane emission and was dominated by rice or corn season. After a large amount of nitrogen application, the methane emission of RW and MW systems was suppressed, and.MW and RW were not affected to the RF system. The emission of methane in the first year of RF system is 13.5,26.7 and 89.8kg CH_4-C HA-1 respectively. The second year is 6.2%, 85.1% and 263.1%. in the first year of the corresponding system. The average CH_4 emission of MW, RW and RF systems in the two years is 9.1,28.2156.6, respectively, and the treatment is 91.3%, 107.9%, 108.9%, respectively. The respiration of ecosystem respiration in 46.1%, 54.5%, 103.5%. (3) farmland ecosystem has obvious interannual variation. The respiration of the ecosystem is in 2013 year 2014. Compared with the different rotation system, the respiratory flux of the MW system is the highest, the RW system is the second, the RF system is the lowest; as the amount of fertilizer increases, the farmland ecosystem calls The respiration rate of the farmland ecosystem was controlled by temperature. The CO2 emission from the wheat season had a good correlation with the temperature in the box. The CO2 emission from the corn season and the rice season had a good correlation with the 5 cm soil temperature, which could explain the ecological respiration of 38.3%, 28.6%, 48.9% respectively. There was a significant negative phase between the wheat season and the maize season CO2 respiration and WFPS. But it can only explain 9.3%, 8.5% of the ecosystem respiration. (4) GWP and GHGI produced by N_2O and CH_4 (Greenhouse Gas Intensity, the greenhouse gas emission intensity of unit output), RW system is the lowest, RF system is the highest, and the N_2O of the fertilizer treatment has contributed 90% of MW system GWP, not less than 40%. In the net greenhouse effect of RW, in addition to the monitoring of the equivalent CO2 emissions produced by greenhouse gases, fertilizer input is also an important aspect of the low production efficiency; RW rice field irrigation is the main contributor to the greenhouse effect in the drought years, and the most important contribution of the RF system is the CH_4 emission. After the winter water field, the soil organic carbon changed obviously, the soil organic carbon in the dry and dry rotation soil was discharged, the soil organic carbon in the winter water field was marked carbon fixation, and the water and drought rotation showed weak carbon fixation. The net GWP and net GHGI of the drought and drought rotation were the highest, while the winter water fields were the lowest.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S181
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本文编号：1815449