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Opposite effects of nitrogen fertilization and plastic film mulching on crop N and P stoichiometry in a temperate agroecosystem

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Journal of Plant Ecology 2019年第4期12卷 682-692页

作者： Fan Ding Shuangyi Li Xiao-Tao Lü Feike A.Dijkstra sean schaeffer Tingting An Jiubo Pei Liangjie Sun Jingkuan Wang College of Land and Environment Shenyang Agricultural UniversityShenyang 110086China Institute of Applied Ecology Chinese Academy of SciencesShenyang 110016China Sydney Institute of Agriculture School of Life and Environmental SciencesThe University of SydneyEveleighNSW 2015Australia Department of Biosystems Engineering and Soil Science University of TennesseeKnoxvilleTN 37996USA

Aims Crop nitrogen(N)and phosphorus(P)stoichiometry can influence food nutritive quality and many ecosystem ***,how and why N and P stoichiometry respond to long-term agricul-tural management practices(e.g.N fertilization and film mulching)are not clearly *** We collected maize tissues(leaf,stem,root and seed)and soil sam-ples from a temperate cropland under 30-year continuous N fer-tilization and plastic film mulching treatments,measured their C,N and P concentrations(the proportion(%)relative to the sample mass),and used structural equation models to uncover the re-sponding mechanisms for crop N and P contents(the total amount(g/m2)in crop biomass).Important Findings Long-term N fertilization increased N concentrations in all crop tissues but sharply decreased P concentrations in vegetative tis-sues(leaf,stem and root),thereby reducing their C/N ratio and increasing C/P and N/P *** drop in P concentration in vegetative tissues was due to the dilution effect by biomass in-crement and the priority of P supply for seed *** con-trast,film mulching decreased N concentration but increased P concentrations in most crop tissues,thereby increasing C/N ratio and reducing C/P and N/P *** mulching increased crop P content by increasing soil temperature and moisture;whereas,mulching showed little effect on crop N content,because a posi-tive effects of soil temperature may have canceled out a negative effect by soil *** indicated a decoupling of P and N uptake by crops under film *** conclusion,N fertiliza-tion and plastic film mulching showed opposite effects of on crop N and P stoichiometry.

关键词： long-term soil stoichiometry soil moisture dilution effect maize tissues

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粘土矿物参与微生物利用木质素形成矿物-菌体残留物的结构特征研究

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光谱学与光谱分析 2018年第9期38卷 2903-2909页

作者：王帅徐俊平陈殿元姜帅李兴吉盛炳翰 schaeffer sean 吉林农业科技学院农学院吉林吉林132101 Institute of Agricalture The University of Tennessee

粘土矿物在催化木质素形成腐殖质方面具有重要贡献。为有效阐明微生物-木质素-粘土矿物三者间的关系,探明矿物-菌体残留物的结构特征,采用液体摇瓶培养法,以木质素为碳源,通过添加高岭石和蒙脱石,在接种复合菌剂后启动110d液体培养,期... 详细信息

粘土矿物在催化木质素形成腐殖质方面具有重要贡献。为有效阐明微生物-木质素-粘土矿物三者间的关系,探明矿物-菌体残留物的结构特征,采用液体摇瓶培养法,以木质素为碳源,通过添加高岭石和蒙脱石,在接种复合菌剂后启动110d液体培养,期间动态收集矿物-菌体残留物,利用傅里叶红外光谱及扫描电子显微镜技术对其结构特性进行了研究。结果表明:高岭石颗粒边缘多由管状体卷曲而成,在参与微生物利用木质素形成矿物-菌体残留物后,连片状细小颗粒结构进一步团聚,结合更加紧凑,短管状结构增多,但整体仍保持多水高岭石的结构特征;在初始富营养条件下,高岭石能够促进微生物繁衍,使大量菌体聚集于高岭石表面,掩蔽了Si—O和Si—O—Al键,且矿物-菌体残留物中脂族碳结构比例增加;菌体中多糖物质通过含氧官能团与高岭石表面的水化层在多个部位形成氢键,氢键的形成对于高岭石稳定木质素及其降解产物具有重要作用,芳香碳结构比例和多糖类物质含量随培养时间逐渐增加,而后复合菌株对掩蔽在矿物表面的菌体进行二次利用,使高岭石Si—O—Al键重现;蒙脱石多由浑圆的颗粒结构组成,接种微生物可使其表面产生溶蚀,团粒结构遭到破碎;与10d相比,历经30d培养所得矿物-菌体残留物中的多糖类物质增多,使原本归属蒙脱石Si—O—Si及Si—O结构的1 034~1 038cm-1处吸收峰强度增加,而后因多糖类物质与蒙脱石表面羟基发生缔合,又使该处吸收峰强度减弱,同时发生了氢键键合,该作用是蒙脱石-微生物-木质素间相互作用、形成矿物-菌体残留物的主要机制;高岭石在稳定有机碳方面的能力要高于蒙脱石,更易促进HS前体物质的形成。

关键词：傅里叶红外光谱扫描电子显微镜粘土矿物木质素矿物-菌体残留物

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Investigating Land-Use Change on Street Tree Ecosystems

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Open Journal of Forestry 2014年第5期4卷 467-480页

作者： Thomas Turnbull Sharon Jean-Philippe Raymond Albright David Buckley sean schaeffer P. Eric Wiseman Department of Forestry Wildlife and Fisheries University of Tennessee Knoxville US Department of Biosystems Engineering and Soil Science University of Tennessee Knoxville US Department of Forest Resources & Environmental Conservation Virginia Tech Blacksburg US

In the early 1940’s, during the early stages of the Manhattan Project (WWII), of rural communities in Anderson County, Tennessee was rapidly converted into laboratory facilities and the city of Oak Ridge. The environment that became Oak Ridge experienced not only pollutants from the laboratory activities, but also alterations from the land-use change?from rural to urban areas. Therefore, a study was conducted to determine the impacts of land-use change from rural to urban area on 1) street tree diversity and performance;and 2) the biological, chemical and physical properties, and nutrient dynamics of street tree ecosystem soils. There were a total of 607 street trees, composed of 37 different species, on the five main roadways in Oak Ridge, Tennessee. The street tree inventory revealed that the street tree ecosystems had a high relative abundance of Acer rubrum (21.91%) and Pyrus calleryana (19.93%). Chemical, rather than physical, soil and site properties in street tree ecosystems had the greatest impact on street tree performance. Soils differed street by street in their biological, chemical, and physical properties but were not influenced by traffic rates. There were also differences in soil microbial biomass carbon (MBC) during the winter on streets based on their diversity of trees;however, the most diverse street was among the lowest in soil microbial biomass. Seasonally, the winter proved to have not only greater amounts of soil microbial biomass carbon and nitrogen (MBN), but significantly less extractable organic carbon (EOC) and nitrogen (EON) and total labile carbon (TLC) than that in the spring. Overall, this study provided insights into the post urbanization impacts on the street trees, soils, sites, and nutrient dynamics within street tree ecosystems of Oak Ridge.

关键词： Street Trees Soil Microbial Carbon Soil Microbial Nitrogen Tree Condition Urban Forestry Urban Soils

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