Phosphorus (P) derived from the application of fertilizers to agricultural land can often reach surface water bodies through tile drainage systems. Phosphorus fate and transport are dependent on the geochemistry and biological activity of both the soil macropore linings/walls and soil matrix. Macropores can be especially important contaminant transport pathways to groundwater and tile drainage networks. In this study, we investigated P geochemistry and the soil microbiome of a macroporous clay loam soil under corn and soybean cropping practices typical for eastern Ontario, Canada. We used spectroscopic techniques including P K-edge X-ray absorption near-edge structure (XANES) spectroscopy, micro-X-ray fluorescence mapping, and micro-XANES for P speciation. We also used quantitative PCR to investigate the capacity of the soil microbiome to mobilize and transform organic (targeting the genes phoC, phoD, and phnX) and inorganic (targeting the gene pqqC) P pools. Phosphorus was retained in the soil predominantly as β-tricalcium phosphate and P sorbed to calcite. The microbial communities in both the macropore linings/walls and the matrix were functionally capable of transforming P from both organic and inorganic sources, with organic P cycling functions more abundant in surface soils and macropore domains and inorganic cycling P functions equally distributed throughout the soil. As a whole, the diverse biological capacity to cycle the different forms of P found in the soil represents a consistent source of crop-available P. The results of this study augment our understanding of the fate and transport and biogeochemistry of P in the matrix and the more highly transmissive macropores of agricultural soils.

农田施肥所产生的磷 (P) 通常可以通过瓷砖排水系统到达地表水体。磷的归宿和运输取决于土壤大孔衬里/壁和土壤基质的地球化学和生物活性。大孔是通往地下水和瓷砖排水网络的特别重要的污染物传输途径。在这项研究中，我们调查了加拿大安大略省东部典型的玉米和大豆种植实践下大孔粘壤土的磷地球化学和土壤微生物组。我们使用了光谱技术，包括 P K 边 X 射线吸收近边结构 (XANES) 光谱、微 X 射线荧光映射和用于 P 形态形成的微 XANES。phoC、phoD和phnX）和无机（靶向基因pqqC) P 池。磷主要以β-磷酸三钙和吸附在方解石上的磷形式保留在土壤中。大孔衬里/壁和基质中的微生物群落在功能上能够从有机和无机来源转化磷，有机磷循环功能在表层土壤和大孔域中更为丰富，无机循环磷功能均匀分布在整个土壤中。总的来说，循环土壤中不同形式磷的多样化生物能力代表了作物可用磷的一致来源。这项研究的结果增强了我们对基质中磷的命运和运输以及生物地球化学的理解。农业土壤的高渗透性大孔隙。