灌溉条件下土壤微生物空间特性研究

发布时间：2019-05-29 16:14

【摘要】：土壤微生物在农田生态系中对土壤生态、结构、水文等方面均有重大的影响。微生物在不同类型土壤中的数量和结构具有明显的差异,可反映土壤的环境和肥力状况,因此系统而科学地认识各微生物空间分布特征及其影响因素,对农田科学灌溉施肥、土壤微生物保护等具有重要意义。本研究采用大田原位试验与室内实验结合的方法,历时三年采样和实验,运用地统计学、经典统计学等理论,多角度分析土壤中细菌、放线菌、真菌、固氮菌、氨化细菌、硝化细菌和反硝化细菌的空间分布特性,及其对土壤环境因子的响应,研究结果如下:(1)土壤中微生物数量具有显著的垂直结构,随着土壤深度的增加微生物数量呈减少趋势,但在某一些深度上变异性较强,细菌、放线菌、固氮菌、亚硝酸菌、反硝化细菌数量在200cm深度附近变化显著。(2)同种微生物在灌溉入渗过程中响应不同,不同微生物对同一环境因子相关性大小有显著的差异。有机质与细菌数量的相关性在入渗中表现为灌后10天灌后30天灌后4天灌前,与固氮则表现为灌前灌后30天灌后10天灌后4天。(3)灌溉影响微生物的数量和组成,随着灌溉时间的推移,影响会逐渐的减小,大约30天后恢复至灌前的水平。灌溉入渗过程中,微生物数量与土壤有机质、总氮和C/N均呈正相关,与pH、水分、铵态氮呈负相关,而在不同灌溉时期影响程度也不同。(4)微生物半方差函数拟合表明,微生物在某一深度上具有较强的空间依赖性,变程大小可反应微生物变异性。灌前细菌、放线菌、真菌分别为线性模型、高斯模型、高斯和线性模型,而固氮菌、氨化菌、硝酸菌和反硝化菌在整个剖面上呈现不同的拟合模型,其中放线菌和固氮菌均表现出强烈的空间依赖性。灌溉入渗中浅层土壤中微生物空间变异性较强,深层减弱。(5)状态空间模拟表明,不同的季节模拟结果具有差异,在夏季土壤总氮、有机质和温度是影响固氮菌的重要变量,土壤水分、温度、pH、有机质以及氨氮、硝氮和总氮是影响春夏氨化细菌空间分布的重要因素;土壤有机质、氮素底物和温度是影响硝化细菌的重要变量,其中温度的作用在春夏远大于冬季;反硝化细菌空间分布受土壤温度的控制;春、夏、冬季中土壤有机质、温度、pH、水分和总氮、硝氮是影响细菌总数、真菌和放线菌的重要变量。根据模拟的结果,可用于区域上微生物分布特征的预测。
[Abstract]:Soil microorganisms have great influence on soil ecology, structure, hydrological and so on in farmland ecosystem. The quantity and structure of microorganisms in different types of soil are obviously different, which can reflect the environment and fertility of soil. Therefore, the spatial distribution characteristics of microorganisms and their influencing factors are systematically and scientifically understood, and the farmland is irrigated and fertilized scientifically. Soil microbial protection is of great significance. In this study, the method of field in situ test and laboratory experiment was used to analyze bacteria, actinomycetes, fungi, nitrogen fixing bacteria and ammonia bacteria in soil by means of geostatistics and classical statistics. The spatial distribution characteristics of nitrifying bacteria and denitrifying bacteria and their response to soil environmental factors are as follows: (1) the number of microorganisms in soil has a significant vertical structure. With the increase of soil depth, the number of microorganisms showed a decreasing trend, but in a certain depth, the variability was strong, bacteria, actinomycetes, nitrogen-fixing bacteria, nitrous acid bacteria, The number of denitrifying bacteria changed significantly near the depth of 200cm. (2) the response of the same microorganism to the same environmental factor was different, and the correlation between different microorganisms to the same environmental factor was significantly different. The correlation between organic matter and bacterial count in infiltration was as follows: 10 days after irrigation, 30 days after irrigation, 4 days after irrigation, and nitrogen fixation was shown as 4 days after irrigation 30 days after irrigation. (3) Irrigation affected the number and composition of microorganisms. With the passage of irrigation time, the effect will gradually decrease and return to the pre-irrigation level after about 30 days. During irrigation infiltration, the number of microorganisms was positively correlated with soil organic matter, total nitrogen and C / N, and negatively correlated with pH, moisture and ammonium nitrogen. The degree of influence is also different in different irrigation periods. (4) the fitting of microbial semi-variance function shows that microorganisms have strong spatial dependence at a certain depth, and the variable range size can reflect microbial variability. Before irrigation, bacteria, actinomycetes and fungi were linear model, Gao Si and linear model, respectively, while nitrogen-fixing bacteria, ammonia bacteria, nitrate bacteria and denitrifying bacteria showed different fitting models on the whole profile. Actinomycetes and nitrogen-fixing bacteria showed strong spatial dependence. The spatial variability of microorganisms in shallow soil of irrigation infiltration is strong and the deep layer is weakened. (5) the state space simulation shows that the simulation results of different seasons are different, and the total nitrogen of soil in summer is different. Organic matter and temperature are important variables affecting nitrogen-fixing bacteria. Soil moisture, temperature, pH, organic matter, ammonia nitrogen, nitrate nitrogen and total nitrogen are important factors affecting the spatial distribution of ammonia-fixing bacteria in spring and summer. Soil organic matter, nitrogen substrate and temperature are important variables affecting nitrifying bacteria, in which the effect of temperature is much greater in spring and summer than in winter, and the spatial distribution of denitrifying bacteria is controlled by soil temperature. Soil organic matter, temperature, pH, water and total nitrogen, nitrate nitrogen are important variables affecting the total number of bacteria, fungi and actinomycetes in spring, summer and winter. According to the simulation results, it can be used to predict the distribution characteristics of microorganisms in the region.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S154.3

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