【作者】 刘晓梅；

【导师】 冯虎元；

【作者基本信息】 兰州大学 ， 植物学， 2008， 硕士

【摘要】 土壤微生物是陆地生态系统中分解者亚系统的主要组成部分,参与了包括有机质降解、营养转化、植物生长的促进或抑制以及各种土壤物理过程在内的一系列反应活动。土壤微生物是土壤质量重要的生物指标,可以用来监控土壤质量的变化。微量热法是近几十年发展起来的一种快速测量微生物活性的新技术,广泛地应用于土壤微生物活性的研究。国内有不少用微量热法进行的研究,包括药物、污染物、重金属离子、稀土元素等对细菌生长、细胞代谢影响以及大分子功能或细胞之间的相互作用等,但鲜有其在土壤微生物领域应用的研究。本文应用微量热法研究了甘肃平凉高平试验地长期施肥及轮作条件下麦田土壤微生物活性的变化,实验中采集了耕层土(5-15cm)N(氮肥)、NP(氮磷合施)、SNP(秸杆与氮磷合施)、M(厩肥)、MNP(厩肥与氮磷合施)五个施肥样品和一个不施肥的样品CK(对照),并且以MNP和CK为代表,采集了不同深度(5-15cm、15-20cm、25-30cm、35-40cm、45-50cm)的土样,以探明长期施肥对水平空间和垂直空间的土壤微生物活性的影响。实验结果如下:1.不同施肥处理下的土壤微生物活性不同。不同肥料处理的土壤微生物代谢热功率-时间曲线形状有所不同,MNP、NP、SNP的曲线陡峭,M、N、CK的曲线平缓;MNP、NP、SNP三个样的微量热特征参数μ(微生物生长速率常数)、Q_t(微生物生长代谢过程中的总热)、P_h(功率-时间曲线的峰值功率)值均高,P_t(到达功率-时间曲线峰值的时间)值低,所以,厩肥与氮磷配施、秸秆与氮磷配施及氮磷合施显著增加土壤微生物活性;单施氮肥或单施有机肥的土壤微生物活性与对照没显著性的差别。2.微生物活性基本是随深度而下降的趋势,施肥增加不同深度的土壤微生物活性。施肥土壤和不施肥土壤的微生物代谢热功率-时间曲线形状不同,特别是表层土壤的(5-20cm),施肥土壤的曲线明显的比不施肥的曲线陡,而且侧翼也明显的短;施肥土壤的μ和P_h值都大于不施肥土壤的,而且施肥土样的P_t值都小于不施肥土样的。3.不同施肥处理中,施加厩肥的土壤细菌和真菌量最高(样M),再次是MNP、NP、SNP。样N中只增加了细菌数量。土壤细菌与土壤各养分含量的关系不一致,其中,与全磷含量达到显著相关;与微量热各参数的相关性都不太好。但不同深度的土壤中细菌数量同微生物活性(P_t值)相关性良好。出现这样的差别,可能主要是因为深层土壤受外界的扰动小,土壤微生物群落结构相对稳定。此外,施肥也增加了深层土壤中的细菌数量。4.土壤微生物活性受土壤速效磷的影响明显。微量热各参数之间相关性良好,微生物活性与其他土壤养分的相关性复杂。5.长期施加厩肥及其与氮磷肥配施,明显的增加了土壤各养分含量,秸秆配施氮磷肥增加了大部分的养分含量,氮肥、磷肥合施增加了有机碳、全磷和速效磷的含量,单施氮肥略增加了土壤有机碳含量,土壤其他养分含量相差不多或降低。总之,长期施肥条件改变了土壤的微生物活性和微生物数量,也改变了土壤养分条件。这表明长期施肥条件下,土壤中微生物群落结构或功能改变,而这种改变必然同土壤微域环境的变化密切相关,即土壤质量或土壤肥力发生了变化,这有可能会进一步的影响作物产量。更多还原

【Abstract】 Soil microbe is the major part of the decomposers in the continent ecosystem. As well it takes part in several physiologic activities including the decomposition of organic matter, the conversion of nutrition, the stimulation or depression of plant growing, and also all kinds of physical processes in soil. Microorganisms are really important bioindicators of soil quality, and thus they can be used to monitor the changes of soil quality. Microcalorimetry is a new technique to determine microbial activity rapidly, and so it is extensively applied in the measurement of the thermal effect produced by soil microbial metabolism. There were many researches using microcalorimetry in our domestic country, including the influence of drugs, pollutants, heavy metals and rare earth elements on the bacterial growth and cell metabolism, the function of macromolecules, or the interaction between cells etc., but rarely in the field of soil microorganisms. In this experiment, we collected five fertilizer samples in the surface of soil (5-15cm), including N (nitrogen), NP (application of nitrogen and phosphorus), SNP (application of straw, nitrogen and phosphorus), M (manure) and MNP (application of manure, nitrogen and phosphorus), and also a sample without fertilizer CK (the control). We took MNP and CK as the representative, collecting five soil samples respectively at different depths (5-15cm ,15-20cm ,25-30cm ,35-40cm ,45-50cm). In this paper, we studied the changes of soil microbial activity in level of horizontal and vertical space under the long-term fertilization and crop rotation in wheat fields. The main experiments results were summarized as follows:1. Different fertility treatments had different soil microbial activity. Shapes of thermal power-time curves of different fertility treatments are different. Curves of MNP, NP and SNP were steep, and curves of M, N and CK were flattening. Values of parameters of microcalorimetryμ(microbial growth rate constant), Q_t (the total heat of microbial metabolism), P_h (peak height of power-time curves) of MNP, NP and SNP were high, and value of P_t (time reaching the peak of power-time curves) was low. So fertility application treatments of manure plus nitrogen and phosphorus (MNP), straw plus nitrogen and phosphorus (SNP) and nitrogen plus phosphorus (NP) significantly increased microbial activity in wheat soil; application of single nitrogen fertilizer or single kind of organic fertilizer had no significant difference with the control (CK). 2. Microbial activity had the basic trend that decreased with the depth in soil. Fertilization increased microbial activity in almost all soil layers measured. There were different shapes of thermal power-time curves in no fertilizer application treatment(CK) and mineral fertilizer plus manure application treatment(MNP), particularly in the former two layers of soil samples. Curves of MNP are obviously steeper than the CK, and their shouders before the peak were significantly much shorter; the P_h andμvalues of MNP are greater than CK, and the P_t values of MNP were less than the CK.3. In different fertilization treatments, number of soil bacteria and fungi in sample M was the highest, then following with MNP, NP and SNP. Only the number of bacteria in sample N increased. The relationship between bacteria and different nutrients was inconsistent. And the relationship between the number of bacteria and total phosphorus achieved significant correlation level. When compared with the parameters of microcalorimetry, the relationship was not so good. However, the number of bacteria in different depths of soil has good correlation with microbial activity (value of P_t). Such a difference occurred may be mainly because there was small disturbance in the deep soil. So soil microbial community structure was relatively stable. In addition, fertilization treatments had increased the number of bacteria in the deep layers of soil.4. Soil microbial activity and the number of microorganisms were significantly affected by soil available phosphorus. The relationship between the parameters of microcalorimetry was good. The relevance of microbial activity and other soil nutrients was complex.5. Compared with the control, long-term application of manure and manure plus inorganic fertilizer remarkably increased the nutrient content in soil; straw plus phosphate and nitrogen increased most of the nutrient content in soil; application of nitrogen plus phosphate fertilizer increased soil organic carbon, total phosphorus and available phosphorus content; the single application of nitrogen fertilizer slightly increased soil organic carbon content; other soil nutrient content of was similar or much lower.In this study, long-term fertilization of soil conditions changed the number of microbes and microbial activity, and also changed the conditions of soil nutrients. This showed, in the long-term fertilization conditions, the soil microbial community structure or function were changed, and this change was closely related to changes in the environment in soil, that was the change of soil quality or soil fertility, which might be further affect crop yields.更多还原