【作者】 于树；

【导师】 汪景宽；

【作者基本信息】 沈阳农业大学 ， 土壤学， 2009， 博士

【摘要】 土壤有机碳是土壤养分循环及肥力供应的核心,在维持土壤团聚体的稳定性,保持土壤耕作,提高土壤保水能力和缓冲能力等方面具有重要作用。土壤微生物本身是土壤养分的“源”和“汇”,对所生存的土壤坏境十分敏感,能对土壤生态机制变化和环境胁迫做出反应,被认为是土壤生态系统变化的预警及敏感指标。近年来,国内外的研究主要集中在土壤有机碳组分和土壤微生物学特性及多样性的单独研究上,缺乏系统的、全面的长期动态监测信息,特别是把土壤有机碳组分与土壤微生物多样性相结合的研究相对较少。本试验以沈阳农业大学20年棕壤长期定位试验站为研究平台,利用土壤有机碳组分分析法及微生物多样性PLFA法和PCR-DGGE图谱分析法,研究长期不同施肥处理及地膜覆盖措施下土壤有机碳及其组分与土壤微生物群落结构多样性的关系,为提高土壤肥力及微生物多样性,建立合理的农田管理措施,使土壤质量向健康方向发展提供科学依据。得出的主要结论如下:(1)20年不同施肥处理对土壤有机碳及其组分的影响大致表现为:M4处理、M4N2P1处理＞CK处理＞N4处理。其中,M4处理及M4N2P1处理土壤总有机碳分别较对照处理提高25.1%及35.4%,N4处理则降低1.7%;M4处理土壤易氧化有机碳占总有机碳中的比例较对照提高62.5%,而M4N2P1处理及N4处理则降低了12.5%及59.1%;N4处理、M4处理及M4N2P1处理土壤水溶性有机碳占总有机碳的比例比对照分别降低28.4%、27.6%及37.9%;M4处理及M4N2P1处理土壤微生物量碳占总有机碳的比例较对照分别升高了118.1%及5.6%,N4处理则降低45%;M4处理及M4N2P1处理土壤颗粒有机碳占总有机碳的比例较对照分别升高了65.3%及4.8%,N4处理则降低了21.8%。(2)20年地膜覆盖使土壤有机碳及其组分的影响大致表现为降低趋势。其中,覆膜使N4处理土壤总有机碳含量显著高于裸地处理,使CK处理土壤易氧化有机碳含量显著降低,使CK处理土壤水溶性有机碳含量显著升高,而使M4处理土壤水溶性有机碳含量显著降低,使CK、N4及M4处理土壤微生物量碳含量显著降低,对颗粒有机碳无显著影响。(3)不同施肥处理20年后土壤微生物PLFA总量表现为:M4N2P1＞M4＞N4＞CK处理:不同施肥处理使土壤微生物的群落结构发生明显变化,不同施肥处理改变了土壤细菌的群落结构,M4处理与M4N2P1处理及裸地与覆膜CK处理之间土壤细菌群落结构比较相似;有机肥能提高土壤细菌多样性,单施氮肥处理会降低土壤细菌的多样性。长期地膜覆盖对土壤微生物PLFA总量及图谱的影响都不显著;尽管土壤的施肥处理不同,但覆膜后土壤微生物群落结构有一致化的发展趋势;覆膜降低N4处理及M4处理土壤细菌多样性,而提高CK处理土壤细菌多样性。(4)土壤多样性指数及总有机碳都与易氧化有机碳、微生物量碳及颗粒有机碳之间关系密切,土壤有机碳组分可作为土壤肥力的指示指标,土壤微生物多样性既可指示土壤有机碳活性组分变化,又是土壤肥力及质量变化的预警信号。(5)单施高量氮肥不利于土壤有机质的积累及土壤肥力的良性发展,而施有机肥或有机肥与化肥配合施用是较为科学的管理措施。但在有机肥或者有机肥与化肥配施处理的同时进行地膜覆盖对土壤肥力的良性发展有削减作用,而在单施高量氮肥的同时进行地膜覆盖则会延缓土壤肥力向不良方向发展的速度。更多还原

【Abstract】 Soil organic carbon play a crucial role in the cycling of almost all the major plant nutrients, which keeps stability of aggregate and improves abilities on keeping water and cushion to sustain cultivation. Soil microorganism is the critical resource and pool of soil nutrients and soil microbial community is an important measure of sustainable land use and is sensitive to changes in the soil as the alarm signal and sensitive index. Recently, studies in home and abroad almost focus on organic fractions and microbiological characters and diversity respectively. The systemic and comprehensive studies about union between organic fractions and microbial diversity combining with dynamic monitor have been lack . Based on 20-years-old located brown earth experiment site at Shengyang Agricultural University, this paper adopt the methods of organic fractions and PLFA and PCR-DGGE to determine the change of organic fractions and microbial diversity in the long-time fertilization and plastic mulching soil in order to explore the effect on their inter-relation between soil organic fractions and microbial diversity. In order to develop soil health and microbial diversity it will provide scientific basis for setting up farm management measures for persistent resources.The main results were as follows:(1)The effect of 20-years-old fertilizations on organic fractions of soil: M4, M4N2P1>CK>N4. Thecontents of total organic carbon in treatments of M4 and M4N2P1 were 25.1% and 35.4% higher thantreatment of CK, respectively, while thoes of treatment of N4 was 1.7% lower than treatment of CK. Theproportion of labile organic carbon in the total organic carbon in treatment of M4 was 62.5% higher thantreatment of CK, while that in treatments of M4N2P1 and N4 were 12.5 % and 59.1 % lower than treatmentof CK, respectively. The proportion of dissolved organic carbon in the total organic carbon in treatments ofN4, M4 and M4N2P1 were 28.4%> 27.6% and 37.9% lower than treatment of CK, respectively. Theproportions of microbial biomass carbon in the total organic carbon in treatments of M4 and M4N2P1 were118.1 % and 5.6 % higher than treatment of CK, respectively. The proportion of particulated organiccarbon in the total organic carbon in treatments of M4 and M4N2P1 were 65.3%and 4.8% higher thantreatment of CK, while that of treatment ofN4 was 21.8%lower than treatment of CK.(2) After 20 year plastic mulching, the contents of total organic carbon and organic fractions weredecreased. The content of total organic carbon in covered treatment of N4 was higher than that ofuncovered soil signifigantly. The content of labile organic carbon in covered treatment of CK was higherthan that of uncovered soil signifigantly. While the content of dissolved organic carbon in coveredtreatment of CK was lower than that of uncovered soil signifigantly. The content of microbial biomasscarbon in covered treatments of CK、N4 and M4 was lower than that of uncovered soil signifigantly, whilethere was no significant difference in particulated organic carbon between covered and uncovered.(3) After 20 year long term cultivation, changing trend of total content of PLFA was M4N2P1 >M4>N4>CK. Soil microbial community changed obviously because of different fertilization. The bacteriacommunity structures were changed by different fertilizarions. Soil community structures were similar between M4 and M4N2P1 and between covered treatment of CK and uncovered treatment of CK. Application of manure could increase bactieral diversity, while single application of nitrogen could decrease it. There was no signifigant effect of long -term plastic mulching on the total content of PLFA. The microbial community structure in soil of different fertilization trend identical development despite of different fertilization treatments. The bacteria diversity in teatments of N4 and M4 was decrease by pastic mulching, while that of treatment of CK was opposite.(4) There are some intimate relations between shannon-wiener, total organic carbon and labile organic carbon, microbial biomass carbon and particulated organic carbon. The organic fractions could be indicative index to soil health. The microbial diversity of soil was also the indication of change on active organic fractions of soil and soil fertility.(5) It is tested that application of manure or co-application of manure and chemical fertilizers take advantage of enhance on soil fertility as scientific management and single application of nitrogen reverse the treatment of plastic mulching can hold back bad-behaved development of soil fertility by application of single application of nitrogen. In virtue of sensitive response to farm management treatments, particulated organic carbon and microbial biomass carbon in soil can be of indication and character used to evaluate the effects of farm management treatments.更多还原