【作者】 郑国砥；

【导师】 韩晓日；

【作者基本信息】 沈阳农业大学 ， 植物营养学， 2001， 硕士

【摘要】 土壤有机氮矿化—固持过程（MIT）是土壤氮素肥力研究的一个十分活跃的领域。本文通过¹⁵N同位素示踪技术，采用盆栽试验，研究了¹⁵N标记有机肥和化肥氮在土壤当中的转化及其对玉米生长的影响，比较了单施化肥、单施猪粪、猪粪与化肥配施、玉米秸与化肥配施、麦秸与化肥配施等五种施肥方式下，土壤中微生物量氮和土壤速效态氮的动态变化及其氮素来源，它们的数量与作物氮素营养状况之间的关系。结果表明： 1．在等氮量施肥条件下，单施化肥的处理，在玉米技节期之前，对玉米生长状况的影响和单施有机肥或有机肥与化肥配施四种处理的效果区别不大。在拔节期之后，单施化肥的处理氮素供应能满足玉米生长的需求，而其它几个处理均不同程度地表现出缺氮症状，尤其是单施猪粪的处理缺氮现象非常严重，引起玉米单株产量与单施化肥的处理差异很大。因此，有机肥与化肥配施的各个处理在玉米拔节期，必需适量追肥，以满足玉米生育后期生殖生长的需求。 2．在等氮量施肥条件下，猪粪与化肥配施的处理由于猪粪比玉米秸与化肥、麦秸与化肥配施的处理中秸秆的碳氮比小，对土壤当中的速效态氮固定相对较少，因此猪粪与化肥配施的处理就能比秸秆与化肥配施的处理较好的满足玉米生长的需求。 3．在不同施肥处理中，玉米苗期植株吸收的氮素来自于肥料氮的百分比比较高，随着土壤对施入肥料的固定、微生物对速效态氮的固持、有机肥料矿化的减缓以及作物对氮素的吸收，作物吸收的氮素来自于肥料的百分比降低，但在玉米生育后期，由于微生物氮的重新矿化释放，作物吸收的氮素来自于化肥的百分比又提高。证明了肥料氮素以微生物量氮的形式固定后，仍可较易被矿化而供植物吸收，微生物量氮是土壤保氮减少无机氮损失的一种重要形式。 4．植物和土壤微生物对土壤氮素的竞争关系普遍存在，在氮素胁迫条件下，这种竟争作用尤为突出，其竟争强度取决于氮源和能源的供应强度以及上壤氮素转化过程。当土壤中微生物的碳源（能源）物质与氮源物质充足时微生物对氮素的竟争能力较强，植物的竟争能力变弱，随着土壤氮素转化过程的改变，植物根系的竞争能力逐渐增强，并显著超过微生物。盆栽试验表明，土壤微生物对作物供氮量较大，微生物提供氮量占作物吸收氮量的96．2％～156．3％。更多还原

【Abstract】 Nitrogen (N) is often considered to be one of the most important limiting factors for plants. In arable and forage cropping, N fertilization application can improve the fertility of the soil and provide a sufficient N supply for plants. The research about organic nitrogen mineralization-immobilization turnover(MIT) is in a very active field. Pot experiments with isotopic tracer technique were carried out to study the dynamic of microbial biomass nitrogen and quick-acting nitrogen in soil and their sources after applied of N-fertilizer, N-fertilizer and wheat straw (W+F), N fertilizer and corn straw (C+F), N-fertilizer and hog manure, and only the hog manure, and to study the relations between the growth of corn and the amounts of micro-biomass and quick-acting nitrogen. The results were summarized as follows: 1 .When applied equal quantity of nitrogen, there was no difference between the N-fertilizer and organic nitrogen fertilizer on the growth of maize during the earlier stage of growing period. But after that, a deficiency was diagnosed except the application of N-fertilizer, and a more serious diagnosis was observed on the treatment of only application hog manure. So N-fertilizer application is needed when corn enter the period of maximum growth. 2.For C/N of hog manure is lower than that of straw, quick-acting nitrogen in soil of the treatment applied M+F was immobilized less than that applied C or W+F. It led to the maize growing better by the treatment applied M+F than that applied C+F and W+F. 3. NDFF% of maize was high during the earlier stage of growing period. With growth of the corn, 7NDFF% was lower than its in the earlier stage. But in the later, lots of soil micro-biomass nitrogen was mineralized and NDFF% was increased again. It proved that soil micro-biomass nitrogen can be used even it was immobilized and it is one kind of patterns to increase N-fertilizer efficiency. 4.Usually competition was exited between plants and soil microorganism, which was more dramatically when the nitrogen was not enough. The matter of nitrogen, energy, and the process of nitrogen turnover in soil control the intensity of the competition. Microorganism’s compete ability was stronger than plant’s when carbon and nitrogen was enough. As the process of soil nitrogen turnover was changed, the root of plant was intensive more and more, and stronger than microorganism’s. The results of pot experiment showed that the amount of N offering by microbial biomass N occupied 96.2%- 156.3% of the amount of N uptaking by maize.更多还原