地膜覆盖稻—油轮作农田中温室气体的排放特征及影响因素研究

发布时间：2018-07-06 15:18

本文选题：地膜覆盖 + 水稻-油菜轮作农田　；参考：《西南大学》2017年硕士论文

【摘要】：近几十年来,大气中温室气体浓度不断增加,随之加强的温室效应已经成为一个全球性的环境问题,除了化学燃料燃烧外,农业是人类活动所产生的温室气体的重要源。地膜覆盖技术的使用是我国农业生产的一次“白色革命”,自上世纪70年代引进地膜覆盖技术以来,该技术在我国已得到广泛的推广运用。地膜覆盖后,地膜与土壤之间设置了一道物理阻隔,直接阻挡了水分的垂直蒸发,阻断了近地面层与大气之间的气流交换,增大了光热交换阻力,使膜内土壤温、光、水、肥、气等生态条件都发生了变化。地膜覆盖后对农田生态系统温室气体的排放以及碳的固定产生怎样的影响?在全球气候日趋暖化的背景下,这些都是需要迫切解决的科学问题。本研究选取西南地区普遍的水稻-油菜轮作农田为研究对象,在重庆市西南大学紫色土生态环境重点野外科学观测试验站,开展了地膜覆盖对农田主要温室气体(CH_4、N_2O和CO_2)排放的规律及其影响因素的研究。目前,对地膜覆盖水稻-油菜轮作种植农田温室气体排放的研究相对较少,并且考虑农田环境因素的复杂多变,因此,在已完成的第一年实验的基础上(2014年05月至2015年04月),继续增加了第二年的田间观测实验(2015年05月至2016年04月)。期望通过水稻-油菜轮作农田两年的田间观测结果的比较,从年际的角度更全面地了解地膜覆盖农田温室气体排放的规律及其影响因素。研究取得的主要结果如下:1.地膜覆盖对水稻-油菜轮作农田CH_4、N_2O排放的影响(1)在水稻-油菜轮作农田中,CH_4排放通量与温度呈显著正相关关系,CH_4的排放集中出现在水稻和油菜种植期间,且排放峰值并分别出现在水稻种植的中后期和油菜种植的前期,通过两年的实验发现,地膜覆盖可增加农田CH_4的排放,第一年和第二年覆膜排放量增加44%和110%。(2)在水稻-油菜轮作农田中,N_2O排放受温度影响小(n=47,P0.05),N_2O的大量排放往往与农田的施肥和土壤干湿交替有关,N_2O排放集中出现在农田施肥之后,油菜种植期间释放量占农田N_2O释放的大部分(90%以上)。地膜对农田N_2O排放的影响比较复杂:在多雨湿润的冬季覆盖地膜农田N_2O的排放量减少27%(第二年),而在少雨干燥的冬季覆盖地膜农田N_2O的排放量增加33%(第一年)。(3)在水稻-油菜轮作农田中,通过两年的实验发现:在水稻生长期间,农田中CH_4、N_2O两种温室气体的排放特征表现为“此消彼长”,并且在高温少雨的春季农田CH_4、N_2O两种气体的排放出峰时间差将增加。而在油菜生长期间,农田中CH_4、N_2O两种温室气体排放没有出现“此消彼长”的现象,总体上是同步的。2.地膜覆盖对水稻-油菜轮作农田CO_2净排放的影响(1)在水稻和油菜种植期间,农田表现为CO_2的汇,CO_2净排放与温度相关性不显著,CO_2的吸收主要是来自植物植株的贡献,土壤呼吸对CO_2净排放的影响小;在作物营养和生殖生长旺盛的中后期,农田中CO_2的吸收量增加明显,而且CO_2的吸收受天气状况(阴/晴)的影响显著。(2)在水稻和油菜种植期间,农田对CO_2吸收量的差异主要表现在作物生物量的不同。通过两年的实验发现:第二年覆膜增加农田CO_2的吸收量,覆膜比不覆膜增加9%;而第一年覆膜处理降低了农田CO_2的吸收量,覆膜比不覆膜降低27%。3.地膜覆盖对水稻-油菜轮作农田温室气体综合全球增温潜势(GWP)的影响(1)在水稻-油菜轮作农田中,农田整体表现为碳汇。三种主要温室气体(CH_4、N_2O、CO_2)的综合GWP为负值。第二年和第一年农田中覆膜/不覆膜的综合GWP分别为-34075/-29682 kg CO_2·hm~(-2)yr~(-1)和-16079/-24479 kg CO_2·hm~(-2)yr~(-1),第二年和第一年覆膜比不覆膜分别增加或减少了+15%和-34%。(2)在水稻-油菜轮作农田中,CH_4、N_2O温室气体的GWP为正贡献,第二年覆膜/不覆膜CH_4、N_2O的GWP分别为1059/503 kg CO_2·hm~(-2)yr~(-1)、4869/6352 kg CO_2·hm~(-2)yr~(-1),与第一年相比,CH_4、N_2O覆膜/不覆膜分别增加或减少了+41%/-3%、+49%/+155%。地膜覆盖降低农田CH_4、N_2O、CO_2三种气体的GWP贡献值,地膜覆盖使农田CH_4气体的GWP贡献值增加,而地膜覆盖对N_2O气体GWP贡献值的影响比较复杂。4.地膜覆盖对水稻-油菜轮作农田土壤理化特性的影响在水稻-油菜轮作农田中油菜生长期间,地膜覆盖使土壤含水率、微生物量碳(SMBC)、可溶性有机碳(DOC)、微生物量氮(SMBN)有不同程度的降低,覆膜土壤的温度、土壤有机碳、脲酶活性有不同程度的增加,而其他土壤理化性质覆膜和不覆膜差异不明显(如:pH值、土壤总氮、碱解氮等)。
[Abstract]:In recent decades, the concentration of greenhouse gases in the atmosphere has been increasing, and the enhanced greenhouse effect has become a global environmental problem. In addition to the combustion of chemical fuels, agriculture is an important source of greenhouse gases produced by human activities. The use of film mulching technology is a "white revolution" in agricultural production in China, from the last world. Since the introduction of film mulching technology in 70s, this technology has been widely used in China. After the film covering, a physical barrier between the film and the soil has been set up, which directly obstructed the vertical evaporation of water, blocked the exchange of air flow between the near surface layer and the atmosphere, increased the resistance of light and heat exchange, and made the soil temperature, light, and water in the membrane. The ecological conditions such as fertilizer and gas have changed. What are the effects of the film mulching on the emission of greenhouse gases and carbon fixation in the farmland ecosystem? In the context of the warming of the global climate, these are the scientific problems that need to be solved urgently. Elephant, at the key field scientific observation test station of the purple soil ecological environment in Southwestern University, Chongqing City, Chongqing City, the law of film mulching on major greenhouse gases (CH_4, N_2O and CO_2) emission and its influencing factors were studied. The environmental factors of farmland are complex and changeable, so on the basis of the completed first year experiment (from 05 months to 04 months of 2015 2014), the field observation experiment of second years (2015 05 months to 2016 04) has been added. The main results are as follows: 1. the effect of 1. film mulching on rice rape cropland cropland, N_2O emission (1) in rice rape cropland, CH_4 emission flux and temperature have a significant positive correlation, and the emission concentration of CH_4 appears in rice and rape planting. During the first and second years, the film mulching increased by 44% and 110%. (2) in rice rape cropland, and the emission of N_2O was less affected by temperature (n=47, P0.05) and N_2O in the first and second years. The emission of N_2O emissions is often related to the fertilization of farmland and the dry and wet soil of the soil. After the fertilization of farmland, the release amount of the rape during the cropland planting accounts for most of the release of N_2O in the farmland (more than 90%). The effect of the film on the N_2O emission of farmland is more complex: the emission of N_2O in the mulched farmland covered by the rainy and wet winter season is reduced by second years (second years). The emission of N_2O in the dry winter covered field covered farmland was increased by 33% (first year). (3) in rice rape cropland, the results of two years' experiments showed that during the growth of rice, the emission characteristics of two kinds of greenhouse gases, CH_4 and N_2O, were "this elimination" and two kinds of N_2O two species in spring farmland in the high temperature and less rain. The peak time difference between the gas emission and the peak time will increase. In the period of rape growth, the CH_4, N_2O and two kinds of greenhouse gases in the farmland did not appear "the difference". In general, the effect of the synchronous.2. film mulching on the net emission of CO_2 in the rice rape cropland was (1), during the planting of rice and rape, the farmland was expressed as the sink of CO_2, CO_2 The correlation between net emission and temperature was not significant. The absorption of CO_2 was mainly from plant plants, and the effect of soil respiration on the net emission of CO_2 was small. In the middle and late stages of crop nutrition and reproductive growth, the absorption of CO_2 in farmland increased significantly, and the absorption of CO_2 was significantly affected by the weather conditions (yin / sunny). (2) in rice and Rape Species During the period of planting, the difference in the amount of CO_2 absorption in farmland was mainly in the difference of crop biomass. Through two years' experiments, it was found that the second year film increased the absorption of CO_2 in farmland and increased the film mulching ratio by 9%, while the film mulching treatment reduced the amount of CO_2 absorption in the first year, and the film mulching was less than the film covered by the film covering the rice rape wheel. The influence of the integrated global warming potential (GWP) on farmland greenhouse gas (1) in the rice rape rotation farmland, the whole field of farmland is carbon sink. The comprehensive GWP of the three major greenhouse gases (CH_4, N_2O, CO_2) is negative. The second year and the first year of the farmland covered / non plastic film combined GWP are -34075/-29682 kg CO_2 hm~ (-2) yr~ 24479 kg CO_2. Hm~ (-2) yr~ (-1), second and the first years of film mulching increase or decrease respectively +15% and -34%. (2) in rice rape rotation farmland, CH_4, N_2O greenhouse gas GWP contribution, second years of film / no covering CH_4. Compared with the first year, the CH_4, N_2O coated / non coated film increased or reduced +41%/-3% respectively, and the +49%/+155%. film covered the GWP contribution of three kinds of gas, CH_4, N_2O, CO_2, and the film mulching increased the GWP contribution of CH_4 gas in farmland, while the influence of film mulching on N_2O gas GWP contribution was more complex. Soil moisture content, microbial biomass carbon (SMBC), soluble organic carbon (DOC) and microbial biomass nitrogen (SMBN) have different degrees of decrease in soil moisture content, soil organic carbon (DOC), soil organic carbon and urease activity, and soil organic carbon and urease activity in different degrees, and other soil in other soils. The physical and chemical properties of film mulching and no plastic mulching were not significantly different (such as pH, total nitrogen and alkali hydrolyzable nitrogen).
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S511;S565.4;X712

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