Biosolids phosphorus forms, transformation and bioavailability in soil

磷(P)的回收非常重要，因为磷酸盐行业预测可用磷储量将在未来100至250年内耗尽。在农田上应用生物固体有助于结束农村-城市的养分循环。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、转化和生物可利用性。不适当的施肥量可能会导致作物产量损失或土壤中磷的积累，从而增加环境风险。生物固体中磷的总浓度一般在干重的1%到5%之间，其中70%到90%是无机形式。要了解添加到土壤中的生物固体磷的生物有效性，不仅需要了解这些材料中磷的形态和数量，还需要了解可以改变磷行为的元素或材料的形态和数量，磷的转化动力学及其与土壤和植物根系的相互作用。传统的形态形成方法对生物固体P化合物的鉴定提供了有限的洞察力。作为化学提取的替代方法，先进的光谱技术最近已被用于表征土壤和改良剂中的磷形态。X射线吸收近边结构技术是磷的固相形态形成的最新光谱工具之一，该技术可以区分磷的沉淀相和吸附相。生物固体中的不同磷化合物也通过P-31核磁共振光谱进行了鉴定，该技术提供了有机磷的直接分子和结构表征。通过温室和田间研究，将使用先进的分析技术来表征生物固体磷的形态。在研究期间，将评估土壤性质、水分和温度对生物固体磷转化的影响。此外，还将研究生物固体磷在土壤和根际的转化，其在土壤中的生物有效性和移动性。最后，对施用生物固磷在土壤中的残留效应进行量化。

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.