Identification and quantitation of P compounds and its transformation products in a dual P band using X-ray absorption near edge spectroscopy (XANES)

这项研究的长期目标是显著提高作物对肥料磷的吸收效率。在短期内，我们的目标是i)使用X射线吸收近边缘结构(XANES)光谱来识别和量化在磷肥的两个波段中形成的磷化合物和硫酸盐；ii)使用XANES和III)及时跟踪这些初始磷化合物的转变，以确定那些将增加磷的溶解性从而提高植物对磷的有效性的盐组合。高pH土壤磷肥利用率低的主要原因是土壤-磷肥反应区磷素运移减慢。这是由于施入的磷与土壤成分如交换性钙、镁离子迅速反应进入土壤溶液所致。纠正这一问题的措施包括通过非磷酸盐与磷肥共施来改变土壤-磷肥反应区的化学环境。在最近完成的一项研究中，我们证明了铵的硫酸盐或碳酸盐与磷酸一铵或磷酸一钾一起使用增加了磷的溶解和化学扩散(Akinrem et al.2006)。这种增强归因于硫酸盐或碳酸盐与磷之间对置换的可交换或可溶钙的阴离子竞争。我们推测，CaSO4的形成减少了P的降水，从而增加了P的溶解。然而，沉淀P的化学形态尚不清楚，也没有直接证据表明土壤中存在CaSO4。这项拟议的研究将展示“最新”光谱技术在寻找磷肥利用率低的实际解决方案方面的应用。我们能够识别和量化在两个波段中形成的磷矿物，这将有助于我们努力找到正确的配方，以提高作物对磷的化肥利用效率。磷肥利用率的提高将通过降低投入成本和减少土壤残留磷为加拿大农民带来经济和环境效益。

The long-term objective of this study is to significantly increase the efficiency of fertilizer phosphorus uptake by the crop. In the short term, our objectives are i) to identify and quantify the phosphorus compounds and sulphate salts that are formed in dual bands of P fertilizer using X-ray absorption near edge structure (XANES) spectroscopy; ii) to follow the transformation of these initial P compounds in time using XANES and iii) to determine those salt combinations that will increase P solubility and thereby P availability to plants. Low phosphate fertilizer efficiency in high pH soils is primarily due to the slowing down of P movement in the soil-P fertilizer reaction zone. This is caused by rapid reaction of the applied P with soil components such as exchangeable Ca2+ and Mg2+ displaced into soil solution. Measures that have been taken to rectify this problem include the modification of the chemical environment of soil-P fertilizer reaction zone through the co-application of non-phosphatic salts with fertilizer P. In a recently completed study, we demonstrated that the application of sulphate or carbonate salts of ammonium with either monoammonium phosphate or monopotassium phosphate increased the solubility and chemical diffusion of phosphorus (Akinremi et al. 2006). This enhancement was attributed to anionic competition between sulphate or carbonate and P for the displaced exchangeable or solubilized calcium. We hypothesized that the formation of CaSO4 reduced the precipitation of P thereby increasing solution P. However, the chemical form of the precipitated P is unknown and there is no direct evidence for the presence CaSO4 in the soil. The proposed study will demonstrate the application of "state of the art" spectroscopic technique to finding practical solution of low phophorus fertilizer use efficiency. Our ability to identify and quantify the P minerals that are formed in a dual band will aid our efforts at finding the right formula for improving the fertilizer use efficiency of P by the crop. An increase in phosphorus fertilizer use efficiency will provide economic and environmental benefits for Canadian farmers through reduced input cost and reduced residual soil phosphorus.