Dynamics, sources and supply charecteristic of microbial biomass nitrogen in soil applied with manure and fertilizer

صينى. 揭示有机氮肥的矿化-固持周转过程机理，为合理施用有机肥和化肥提供科学依据。运用同位素15N交叉标记示踪技术，通过盆栽试验，研究单施化肥、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5种施肥方式下，土壤中微生物量氮在玉米各生育时期的数量、来源的动态变化以及对玉米的供氮特征。各处理在同一生育期微生物量氮差异的原因主要是所施肥料种类的不同。不同处理的土壤微生物量氮在玉米各个生育期数量与来源不同，施入的有机肥对土壤微生物量氮贡献大，化肥对土壤微生物量氮的贡献较小，土壤氮仍是构成微生物量氮的主要来源。作物和土壤微生物对土壤氮素存在竞争关系，在氮素胁迫条件下，竞争作用突出，其竞争强度取决于氮源和能源的供应强度以及土壤氮素转化过程。同一处理的土壤微生物量氮在玉米的各个生育期数量差异很大，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竞争能力较强，作物的竞争能力较弱，随着土壤氮素转化过程的改变，作物的竞争能力逐渐增强，并显著超过微生物，微生物量氮减少。有机肥与化肥配合施用比单独施用化肥能降低土壤微生物量氮来自土壤氮的百分比；与单施有机肥相比能提高土壤微生物量氮来自土壤氮的百分比。

إنجليزي. The study was conducted to reveal the mechanism of mineralization-immobilization turnover(MIT) of organic fertilizer nitrogen and to provide scientific references for applying manure and fertilizer. Pot experiments with 15N isotopic tracer technique were carried out to study the dynamics of microbial biomass nitrogen in soil and their sources after application of nitrogen fertilizer, nitrogen fertilizer and wheat straw, nitrogen fertilizer and corn straw, nitrogen fertilizer and hog manure, and hog manure alone. Its supplying characteristic of microbial biomass nitrogen to the growth of corn was also investigated. The differences of the biomass N in different treatments in same stage were mainly caused by difference in fertilizers. The amount and resource of soil microbial biomass N in different treatments and stages of corn growth were various. The contribution of organic fertilizer to soil biaomass N was larger than that of fertilizer. The soil nitrogen was still a main resource of soil biomass N. Usually competition existed between plants and soil microorganism, which was more dramatic when the nitrogen was scarce. The matter of nitrogen, energy, and the process of nitrogen turnover in soil controlled the intensity of the competition. Microorganism’s competition ability was stronger than plant’s when carbon and nitrogen was ample. While the process of soil nitrogen turnover changed, the root of plant was more and more, intensive and the eflect is stronger than microorganism’s. 15NDFF% of corn was high during the earlier stage of growing period. With growth of the corn, 15NDFF% was lower than that in the earlier stage. But later, more soil microbial biomass nitrogen was mineralized and 15NDFF% increased again. It proved that soil microbial biomass nitrogen can be used even when it was immobilized. It is one kind of patterns to increase nitrogen fertilizer efficiency.