Biosolids phosphorus forms, transformation and bioavailability in soil

由于磷酸盐工业预计在未来100至250年内可利用的磷储量将耗尽，因此磷的回收利用非常重要。在农业用地上施用生物固体有助于关闭农村-城市养分循环。然而，为了有效地管理农业生态系统中的生物固体磷，需要更好地了解生物固体磷的形态，转化和生物有效性。不适当的施用量会导致作物产量损失或磷在土壤中积累，增加环境风险。生物固体中P的总浓度通常在1至5%干重的范围内，其中70至90%是无机形式。了解生物固体磷的生物利用度后，除了土壤需要了解这些材料中的磷的形式和数量，但也的形式和数量的元素或材料，可以修改P的行为，动力学的P转化及其与土壤和植物根系的相互作用。传统的形态分析方法对生物固体磷化合物的识别提供了有限的见解。作为一种替代化学提取，先进的光谱技术，最近已提供了表征磷物种在土壤和修正案。X射线吸收近边结构技术是用于P的固相形态分析的最新光谱工具之一。该技术可以区分P的沉淀相和吸附相。生物固体中的不同P化合物也已经使用P-31核磁共振光谱进行了鉴定，该技术提供了有机P的直接分子和结构表征。通过温室和田间研究，生物固体磷的形式将使用先进的分析技术进行表征。在研究期间，土壤性质，水分和温度对生物固体磷转化的影响将进行评估。此外，还将研究生物固体磷在土壤和根际中的转化，以及生物固体磷在土壤中的生物有效性和移动性。最后，将量化施用的生物固体P在土壤中的残留效应。

Recycling of phosphous (P) is exteremly important as the phosphate industry predicts exhaustion of available P reserves in next 100 to 250 years. Land application of biosolids on agricultural lands helps closing the rural-urban nutrient cycle. However, to effectively manage biosoilds P in agro-ecosystems, a better understanding of biosolids P forms, transformation and bioavailability is required. Improper application rates can result in either losses of crop yield or P accumulation in soil with increased environmental risks. Total concentrations of P in biosolids generally fall in range of 1 to 5% dry weight basis, 70 to 90% of which is in inorganic forms. Understanding the bioavailability of biosolids P after addition to soil requires an understanding of not only the forms and amounts of P in these materials, but also the forms and amounts of elements or materials that can modify P behaviour, kinetics of P transformation and its interactions with soil and plant roots. Traditional speciation methods provide limited insight into identification of biosolids P compounds. As an alternative to chemical extraction, advanced spectroscopic techniques have been recently offered for characterization of P species in soil and amendments. The X-ray Absorption Near-Edge Structure technique is one of the latest spectroscopic tools for solid phase speciation of P. This technique can distinguish between precipitated and adsorbed phases of P. Different P compounds in biosolids have also been identified using P-31 Nuclear Magnetic Resonance spectroscopy, a technique that provides direct molecular and structural characterization of organic P. Through greenhouse and field study, biosolids P forms will be characterized using advanced analytical techniques. Effects of soil properties, moisture and temperature on biosolid P transformation over the study period will be evaluated. As well, biosolids P transformation in soil and rhizosphere, its bioavailability and mobility in the soil will be investigated. Finally, the residual effect of applied biosolid P in the soil will be quantified.