长期施肥对土壤钼含量和固氮微生物区系的影响

发布时间：2019-05-11 15:31

【摘要】：生物固氮是土壤氮素补充的主要途径,该过程主要依赖土壤中的固氮微生物,它们能利用体内的固氮酶将空气中分子态的氮还原成氨态氮,进而被植物吸收利用。固氮微生物的群落结构和丰度与固氮效率的高低密切相关,影响丰度和群落结构的主要因素是外界条件如水、热、营养物质等,而这些外界条件又与人类的耕作方式、施肥制度等密切相关。本文选取了中国农业科学院祁阳和乌鲁木齐两个长期定位试验点的四个不同施肥处理的土壤:不施肥(CK)、施化肥(NPK)、施有机肥(M)、化肥有机肥混施(NPKM),研究不同施肥处理对土壤全钼含量、有效钼含量、理化性质、固氮微生物群落结构的影响;利用二维红外光谱技术,研究了梯度浓度钼酸钠溶液滴定过程中,不同施肥处理的土壤可溶性有机质(DOM)的动态变化。主要研究结果如下:1.与对照CK相比,祁阳和乌鲁木齐各施肥处理的土壤全钼含量均有增加,并且M和NPKM处理的效果较好,能显著提升土壤全钼含量;祁阳各施肥处理有效钼含量与对照相比,M和NPKM有显著提升,NPK处理则显著降低,乌鲁木齐各施肥处理土壤的有效钼含量均显著高于对照;祁阳的M和NPKM处理能显著提升土壤pH,NPK则会显著降低土壤pH,乌鲁木齐各施肥处理的土壤pH与对照相比无显著差异;祁阳和乌鲁木齐各施肥处理的土壤有机质和全氮含量与对照相比,均有所增加,并且M和NPKM的效果要好于NPK,达到显著水平。2.一维红外光谱显示,在钼酸钠滴定培养过程中,各施肥处理在不同浓度相酸钠滴定下的土壤可溶性有机质(DOM)的谱图十分相近,仅在峰的强度上有所变化,而二维红外谱图则可以对它们进行更细致的区分。结果表明,NPK和M处理的土壤可溶性有机质(DOM)组成基本相近,均由纤维素、多糖、脂肪类物质以及矿物颗粒构成,但是M处理在900-1800cm-1波谱范围,出现了 NPK处理中所没有的Si-O伸缩振动峰,表明M处理中形成了非晶性纳米矿物如水铝英石[Al2O31.22SiO22.5H2O]或伊毛缟石[(OH)3Al2O3SiOH],而非晶性纳米矿物的形成可能有助于降低土壤中钼的淋失。3.实时荧光定量PCR的结果发现,不同施肥处理条件下土壤固氮微生物的丰度以M为最多,NPKM和CK次之,NPK处理中固氮微生物的丰度最低,且NPK与M的差异达到显著水平。4.高通量测序的结果表明,各施肥处理中,NPK对土壤固氮微生物群落结构影响最大,M和NPKM则相对较小,且M和NPKM在固氮微生物群落组成相似性上较为接近;NPK会显著降低土壤固氮微生物丰富度和多样性。
[Abstract]:Biological nitrogen fixation is the main way of soil nitrogen supplementation, this process mainly depends on nitrogen-fixing microorganisms in soil, they can use nitrogenase in the body to reduce molecular nitrogen in air to ammonia nitrogen, and then be absorbed and utilized by plants. The community structure and abundance of nitrogen-fixing microorganisms are closely related to the efficiency of nitrogen fixation. The main factors affecting abundance and community structure are external conditions such as water, heat, nutrients and so on, which are in turn related to human farming methods. The fertilizer system and so on are closely related. In this paper, four different fertilizing soils of Qiyang and Urumqi, Chinese Academy of Agricultural Sciences, were selected: unfertilized (CK), fertilizer, (NPK), fertilizer, organic fertilizer, (M), fertilizer, organic fertilizer, (NPKM), organic fertilizer, organic fertilizer. The effects of different fertilizer treatments on soil total Mo content, available Mo content, physicochemical properties and nitrogen fixing microbial community structure were studied. The dynamic changes of soluble organic matter (DOM) in soil under different fertilizer treatments during titration with gradient concentration sodium molybdate solution were studied by two-dimensional infrared spectroscopy. The main results are as follows: 1. Compared with the control CK, the soil total Mo content of Qiyang and Urumqi fertilizer treatments increased, and the effect of M and NPKM treatment was better, which could significantly increase the soil total Mo content. Compared with the control, the available molybdenum content in each fertilization treatment in Qiyang was significantly higher than that in the control, while the available molybdenum content in each fertilization treatment in Urumqi was significantly higher than that in the control, while the available molybdenum content in the soil under the NPK treatment was significantly lower than that in the control. The treatment of M and NPKM in Qiyang could significantly increase soil pH,NPK, but significantly decreased soil pH, in Urumqi. There was no significant difference in soil pH between the two treatments. The contents of soil organic matter and total nitrogen in each fertilization treatment of Qiyang and Urumqi were increased compared with the control, and the effect of M and NPKM was better than that of NPK,. 2. One-dimensional infrared spectroscopy showed that in the course of sodium molybdate titration culture, the (DOM) spectra of soil soluble organic matter under different concentration of sodium titrate in different fertilization treatments were very similar, but only changed in the intensity of the peak. Two-dimensional infrared spectra can distinguish them in more detail. The results showed that the (DOM) composition of soluble organic matter in soil treated with NPK and M was basically similar, which was composed of cellulose, polysaccharide, adipose matter and mineral particles, but M treatment was in the range of 900-1800cm-1 spectrum. The appearance of Si-O stretching vibration peaks not found in NPK treatment indicates that amorphous nano-minerals such as Al2O31.22SiO22.5H2O or (OH) 3Al2O3SiOH have been formed in M treatment. The formation of amorphous nanomaterials may help to reduce the leaching of Mo in soil. 3. The results of real-time fluorescence quantitative PCR showed that the abundance of nitrogen-fixing microorganisms in soil was the highest under different fertilizer treatments, followed by NPKM and CK, and the abundance of nitrogen-fixing microorganisms in NPK treatment was the lowest, and the difference between NPK and M was significant. 4. The results of high-throughput sequencing showed that NPK had the greatest effect on soil nitrogen-fixing microbial community structure, while M and NPKM had little effect on soil nitrogen-fixing microbial community structure, and M and NPKM were similar to each other in composition similarity of nitrogen-fixing microbial community. NPK significantly decreased the richness and diversity of soil nitrogen-fixing microorganisms.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S153.6;S154.3

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