REU: Collaborative Research: Influence of Rhizosphere- Mycosphere Chemistry on Phosphorus Dynamics in an Arid Ecosystem

以前的研究表明， 真菌毒素利用来自“稳定”无机库的磷， 暗示CO2和草酸盐在邻位磷池的差别使用中。 此外，一些早期的殖民物种（例如， 盐生草（Halogeton glomeratus）、猪毛菜（Salsola kali）产生草酸盐， 假设植物或相关真菌的相互作用 分泌物与土壤基质在磷素动态中起着关键作用 在干旱的生态系统中。 本研究主要集中在两个方面 风化剂、CO2和草酸盐，起到增强P的作用 从无机池中释放出来。 反过来，P的诱导位移 池之间的分配影响演替。 的假设 将通过一系列实验进行测试， 生态系统水平。 实验是一个逻辑的过程 对假设的评价。 具体而言，该项目 将决定： 1. 过去存档土壤中草酸盐的存在 在蒸渗仪和田间土壤中进行演替研究; 2. 草酸盐驱动的钙磷矿物风化作用 继承; 3. 不同磷浓度体系中草酸盐的生成速率 可用性; 4. CO2或草酸盐与土壤矿物质的反应速率 参与磷的释放; 5. 草酸盐降解的潜在速率; 6. CO2的动态和平衡条件模型， 草酸盐与钙磷酸盐矿物反应; 7. 磷化学模型的室内试验、蒸渗仪试验和野外试验。 这些实验的结果将提供一种机制 影响磷循环的一些过程的模型和早期 半干旱生态系统的演替。 调查人员有资格进行这种类型的调查， 研究和设施是足够的。

Previous studies have demonstrated the importance of mycorrhizae in utilizing P from "stable" inorganic pools and implicated CO2 and oxalate in differential use of ortho-P pools. Moreover, the ability of some early colonizing species (e.g. Halogeton glomeratus, Salsola kali) to produce oxalate has led to the hypothesis that interactions of plant or associated fungal exudates with the soil matrix plays a pivotal role in P dynamics in arid ecosystems. The proposed research focuses on two weathering agents, CO2 and oxalate, which act to enhance P release from the inorganic pool. In turn, the induced shift in P partitioning among pools influences succession. The hypotheses will be tested through a series of experiments at theoretical and ecosystem levels. The experiments are a logical progression toward evaluation of the hypotheses. Specifically, the project will determine: 1. The existence of oxalate in archived soils from a past successional study, in lysimeter and in field soils; 2. The effect of oxalate driven Ca-phosphate mineral weathering on succession; 3. The rates of oxalate production in systems of varying P availability; 4. The rate of reaction of CO2 or oxalate with soil minerals involved in P release; 5. The potential rate of oxalate degradation; 6. Models of dynamic and equilibrium conditions for CO2 and oxalate reactions with Ca-phosphate minerals; 7. Laboratory, lysimeter and field tests of P chemistry models. The results of these experiments will provide a mechanistic model of some processes which affect P cycling and early succession in a semiarid ecosystem. The investigators are well qualified to perform this type of research and the facilities are adequate.