Characterizing the release, dynamics and plant availability of phosphorus from recovered struvites

目前油菜等作物品种需要较高的磷素水平才能实现其高产潜力。由于磷与土壤成分的相互作用，磷在大多数农业土壤中的流动性很低，因此有必要将其放置在靠近根扩散区的地方，即种子行，以增加吸收。然而，油菜对土壤溶液中中等浓度的肥料养分很敏感，结果是在种行中放置高水平的可溶性磷肥会严重损害或杀死幼苗，从而降低产量。在加拿大大草原上，将种子和所有肥料一次性放置在种子行中是一种常见的做法；然而，对于油菜来说，大多数肥料必须放置在边带或行间带中，以避免种子损坏和幼苗死亡。磷的低移动性限制了带施磷在植物根系发育中的可获得性。我们盆栽研究的初步结果表明，鸟粪石的低溶解度，因此低盐指数可能允许(I)高磷水平的种子行放置而不会对幼苗造成危害，以及(Ii)低磷水平的应用可以产生与高水平的传统磷肥相同的产量。由于日益重视补充不可再生资源(P)和尽量减少过量P流失对环境的不利环境影响，从而导致地表水体富营养化，不同形式的鸟粪石正在变得越来越容易获得。尽管最近有证据表明鸟粪石在作物生产中有好处，但控制土壤中鸟粪石磷有效性和植物吸收鸟粪石磷的过程和机制还不是很清楚。需要这些知识来制定战略，以优化作物产量和质量，并最大限度地减少土壤中过量磷的积累，这些磷可以被输送到地表水质量并导致富营养化。我的研究将利用实验室、温室和田间技术来阐明控制植物在不同土壤中回收鸟粪石磷的有效性和移动性的过程，以及控制磷有效性动力学的环境变量。结果将有助于增加可安全应用于满足作物需求和优化产量的施用量，而不会冒着幼苗对油菜籽等敏感作物造成毒性的风险。除了使农民受益，从而使加拿大的农业经济受益，并将磷的环境损失降至最低，从而保护加拿大的地表水资源，我的研究计划还将培训HQP掌握广泛的研究技术，从建模磷的有效性、运输和命运过程，以及最先进的表征土壤中磷形态的仪器技术，到利用建模和分析结果来提高农作物田地的产量。我的HQP将从与公共和私营部门的合作者的互动中受益。

Current cultivars of crops such as canola require high phosphorus (P) rates to realize their high yield potential. Because of its interaction with soil components, P has very low mobility in most agricultural soils, which necessitates its placement near the zone of root proliferation, i.e., in the seed row, to enhance uptake. However, canola is sensitive to moderately high concentrations of fertilizer nutrients in the soil solution, with the result that placement of high rates of soluble P fertilizers in the seed row can seriously damage or kill seedlings, thereby reducing yield. Placement of seed and all fertilizer in the seed row in one pass is a common practice on the Canadian Prairies; however, for canola, most of that fertilizer has to be placed in a side band or mid-row band to avoid seed damage and seedling mortality. The low mobility of P restricts the accessibility of band-applied P to developing plant roots. Preliminary results from our pot studies suggest that the low solubility, hence low salt index of struvite may allow (i) seed row placement of high P rates without causing seedling toxicity and (ii) application of lower P rates to produce the same yield as higher rates of conventional P fertilizers. Different forms of struvite are increasingly becoming available due to the growing emphasis on replenishing the non-renewable resource (P) and minimizing the adverse environmental impacts of excess P loss to the environment, hence eutrophication of surface water bodies. Despite recent evidence of struvite benefits in crop production, processes and mechanisms controlling struvite P availability in soils and uptake by plants are not well-understood. Such knowledge is needed to formulate strategies for optimizing crop yield and quality and minimizing the build up of excess P in soils, which can be transported to surface water quality and cause eutrophication. My research will employ laboratory, greenhouse, and field techniques to elucidate the processes controlling plant availability and mobility of recovered struvite P in different soils, along with the environmental variables governing the kinetics of P availability. Results will help increase the rates that can be safely applied to meet crop demand and optimize yields without risking seedling toxicity to sensitive crops such as canola. In addition to benefiting farmers, hence Canada's agroeconomy, and minimizing environmental loss of P, thereby protecting Canada's surface water resources, my research program will train HQP in a wide range of research techniques, from modeling P availability, transport and fate processes, as well as state-of-the-art instrumental techniques for characterizing P forms in the soil, to utilization of modeling and analytical results to improve yields in crop fields. My HQP will benefit from interaction with collaborators from the public and private sectors.