【作者】 陈旸；

【导师】 李忠佩； 周立祥；

【作者基本信息】 南京农业大学 ， 环境工程， 2007， 硕士

【摘要】 土壤生态系统中，微生物时刻进行着活跃的新陈代谢，是土壤有机质和养分分解转化的主要动力。微生物对环境变化十分敏感，土壤微生物和生物化学指标可以灵敏反映土壤质量的变化情况。研究集约农业利用措施对土壤微生物生物量的影响，对于正确认识土壤质量退化机制，进而制订可持续发展的土壤生态系统保育措施具有重要的实践意义。本文通过盆栽实验、野外采样测定以及布置室内培育实验，研究了不同施肥量水平和不同施肥措施对江西地区红壤水稻土微生物生物量、微生物呼吸和作物产量的影响，观测了不同肥力水平和施肥处理下，微生物生物量的动态矿化过程，探讨了影响微生物生物量氮矿化的因素及其矿化量对土壤总氮矿化的贡献盆栽实验结果表明，施肥量增加，土壤速效养分浓度增加，但微生物生物量并不一直增加，其变化与母质和土壤肥力水平有关。土壤微生物生物量碳随施肥量增加的变化规律性不强，土壤间差异明显。不同土壤微生物生物量氮随施肥量的变化趋势较为一致，超过1.5倍常规施肥量后呈下降趋势，不同土壤间则表现为第四纪高肥水稻土＞第三纪高肥水稻土＞第三纪低肥水稻土＞第四纪低肥水稻土。不施肥条件下，土壤的基础呼吸强度随原土有机碳含量增加而升高，施肥条件下，红壤水稻土的基础呼吸强度在超过1.5倍常规施肥量后，即随施肥量增加而下降。不同土壤呼吸熵随施肥量变化并没有一致的规律。不同施肥制度和养分循环处理下微生物生物量的研究表明，化肥+有机物循环处理可以增加微生物生物量碳含量，但增加量不如单施化肥。在不同化肥基础上有机养分循环利用均能较大幅度提高土壤MBN，化肥+1／2有机物循环对微生物生物量的增加量与对照无明显差异。不同施肥处理下，作物产量变化为NPK+C＞NPK+1／2JG＞NPK＞NP＞N+C＞C＞NK＞CK＞N。有机物循环的产量显著高于非循环处理。化肥配施+1／2有机物循环能极大的增加作物产量。产量与土壤养分和MBN间存在极显著关系。好气淋洗、长期室内培养实验显示，不同肥力水平红壤水稻土微生物生物量氮矿化可分为两个过程：快速矿化阶段(前4周)和缓慢矿化阶段(第5周开始)。微生物生物量氮培养前4周的矿化速率为培养10-12周的10倍左右，矿化量和矿化速率随土壤肥力水平提高而增加。随培养时间延长和土壤有机质含量提高，微生物生物量氮矿化量占土壤总氮矿化量的比例增加。施肥对微生物生物量的矿化具有明显的促进作用。微生物生物量碳矿化量为NPK＞循环＞NPK+循环＞CK，分别为167.71mg／kg，123.22mg／kg，117.18mg／kg和40.75mg／kg。NPK+循环处理的微生物生物量氮矿化量较高，为37.45mg／kg。单施化肥以及有机物循环能显著增加易矿化MBC含量。总之，增加施肥量以及在高养分含量土壤中实施有机物循环并不一定增加微生物生物量及基础呼吸，应根据不同土壤制定不同施肥措施。化肥配施基础上有机物循环能使土壤保持较高的养分水平，显著增加微生物生物量氮和作物产量。微生物生物量氮具有较高的矿化效率，对土壤总氮矿化的贡献随肥力水平提高而增加，高肥力土壤中微生物氮的矿化量仍相当可观。更多还原

【Abstract】 In soil ecosystem, microorganisms is the major power to decompose and transform the soil organic matters and nutrients. The biological and biochemical index could be sensitive indicators for the change of soil quality. Investigation on the changes of soil biochemical properties under intensive agricultural management would be of practical significance to understand deeply the mechanism of soil degradation, and then propose rational measures for sustainability of soil ecosystem.In this paper, effects on microbial biomass, basal respiration and biomass yield in red paddy soils of Jiangxi province under different fertilities were investigated through potted experiment, field sampling and incubation experiment. Dynamical mineralization of microbial biomass in different soil fertility levels and treatments were also observed. Factors influencing microbial biomass N mineralization and its contributions to soil total N were discussed.The results from potted experiment showed that soil available nutrients increased with fertilizer application. But microbial biomass didn’t increase constantly, change of which also related to original soil and fertility level. Soil microbial biomass C changed irregularly in different levels of fertilization. Microbial biomass N in different soils changed similarly, which all decreased after 1.5 times of conventional fertilizer application. Changes in different soils were: Quaternary red clay with high fertility level(CH)> Tertiary sandstone weathering product with high fertility level(SH)> Quaternary red clay with low fertility level(CL)> Tertiary sandstone weathering product with low fertility level(SL).Soil basal respiration increased with soil organics in no fertilization treatment. In fertilization treatment, basal respiration in paddy soils of subtropical China decreased after 1.5 times of conventional fertilizer application. Metabolic quotient in different soils changed irregularly.Researches on microbial biomass under different fertilizations and crop residue cycling demonstrated that microbial biomass C increased significantly in fertilization + crop residue cycling treatment. And microbial biomass C in only fertilization even increased more quickly. Crop residue cycling in different fertilizations could significantly increase the content of microbial biomass N. Microbial biomass N increase in fertilization+1/2 crop residue cycling treatment had no significant difference with control treatment. In different fertilization treatments, trends of grain and traw yield were: NPK+C > NPK+1/2JG > NPK > NP > N+C > C > NK > CK > N. The grain and traw yield in crop residue cycling treatment was higher than non-cycling treatment. Crop residue cycling on fertilizations could significantly promote the grain and traw yield, which had extremely significant relationships with soil nutrient and microbial biomass N.In the aerobic leaching incubation experiment, microbial biomass N mineralization could be divided into two parts: quick mineralization(first 4 weeks)and relatively slow mineralization(later 8 week). Mineralization rate of microbial biomass N in first 4 weeks was almost fourfold the rate in 10-12 weeks. The mineralization amount and rate increased with soil fertility. The proportion of microbial biomass N mineralization in total N mineralization increased with incubation time and soil organics.Fertilization evidently increased the amount and rate of microbial biomass mineralization. The amount of microbial biomass mineralization were: NPK > C > NPK+C > CK, and 167.71mg/kg, 123.22mg/kg, 117.18mg/kg, 40.75mg/kg, separately. Microbial biomass N in NPK+C treatment is 37.45mg/kg, which was relatively higher than other treatments. Fertilization only and crop residue cycling could significantly increase microbial biomass C.In conclusion, fertilization application and crop residue cycling on high fertility soil would not always increase microbial biomass and basal respiration. Fertilization treatment should be made based on different soils. Fertilization with crop residue cycling treatment would make soil keep high fertility and increased microbial biomass N and crop yield. Microbial biomass had high mineralization efficience. Its contributions to soil total N mineralization increased with fertility level. Microbial biomass N mineralization amount in high fertility soil was high.更多还原