Newly-formed minerals in rhizosphere soils and its relevance in accelerated soil formation and to nutrient cycling

我们最近的工作促进了对根际土壤（RS）和其他陆地微环境（如地衣/岩石界面）中生物介导的矿物分解和养分循环的理解。该建议将提供新的信息，如镁在羟基层间粘土矿物（HIM）中的储存-一个可能的新概念，通过控制粘土矿物的形成来评估非施肥土壤的可持续性。主要实验包括生长室实验，了解普通农作物（如大麦、苜蓿）和森林物种（如杂交云杉、亚高山冷杉）RS中初级矿物质形成HIM的过程。伊利石、绿泥石、云母和长石将与酸洗渥太华砂混合，为每种植物创造实验生长介质。将使用微型吸盘从RS中收集土壤溶液，并在生长期结束时收集粘土样品。根际土壤和地衣/岩石界面材料将在几个实地地点收集。实验室和现场样品将使用x射线衍射、扫描电子显微镜和红外光谱分析粘土矿物成分。其他分析方法包括同步辐射（例如，x射线吸收光谱）来确定主要元素的氧化状态（例如，绿泥石和云母中的铁），核磁共振和电感耦合等离子体原子发射光谱仪，以及用于土壤，岩石，植物和水样化学表征的毛细管电泳。RS和地衣/岩石界面样品中的生物身份将通过16S rDNA技术确定，而有机酸和土壤溶液组成将使用毛细管电泳估计。我们希望强调生物在生物地球化学过程中的关键作用，因此需要研究土壤系统中微环境的马赛克，以及提高人们的认识，即从复合样品和散装样品中测量的特性很少代表“功能”土壤环境。

Our recent work has advanced the understanding of the biologically-mediated mineral breakdown and nutrient cycling in rhizosphere soils (RS) and other terrestrial microenvironments (e.g., lichen/rock interface). The proposal will provide new information such as magnesium storage in hydroxy-interlayered clay minerals (HIM) - a possible new concept to evaluate the sustainability of non-fertilized soils through manipulation of clay mineral formation. The main experiments include growth chamber experiments to understand the formation of HIM from primary minerals in RS of common agricultural crops (e.g., barley, alfalfa) and forest species (e.g., hybrid spruce, sub-alpine fir). Illite, chlorite, mica and feldspars will be mixed with acid-washed Ottawa sand to create the experimental growth medium for each plant. Soil solution will be collected from the RS using microsuction cups and clay samples will be collected at the end of the growing period. Rhizosphere soils and lichen/rock interface materials will be collected in several field sites. Laboratory and field samples will be analyzed for clay mineral composition using x-ray diffraction, scanning electron microscopy and infrared spectroscopy. Other analytical methods include synchrotron radiation (e.g., x-ray absorption spectroscopy) to determine the oxidation state of major elements (e.g., Fe in chlorite and mica), nuclear magnetic resonance and inductively-coupled plasma atomic emission spectrometers, and capillary electrophoresis for chemical characterization of soils, rocks, plants and water samples. Identity of the organisms in RS and lichen/rock interface samples will be determined by 16S rDNA technique while organic acids and soil solution composition will be estimated using capillary electrophoresis. We hope to emphasize the critical role of organisms in biogeochemical processes and therefore the need to investigate the mosaic of microenvironments in soil systems, as well as raise awareness that properties measured from composite and bulk samples seldom represent the "functional" soil environments.