ISPA, Bordeaux Sciences Agro, INRA, 33140, Villenave d'Ornon, France.
MaIAGE, INRA, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
Glob Chang Biol. 2017 Aug;23(8):3418-3432. doi: 10.1111/gcb.13618. Epub 2017 Feb 15.
Phosphorus (P) availability in soils limits crop yields in many regions of the World, while excess of soil P triggers aquatic eutrophication in other regions. Numerous processes drive the global spatial distribution of P in agricultural soils, but their relative roles remain unclear. Here, we combined several global data sets describing these drivers with a soil P dynamics model to simulate the distribution of P in agricultural soils and to assess the contributions of the different drivers at the global scale. We analysed both the labile inorganic P (P ), a proxy of the pool involved in plant nutrition and the total soil P (P ). We found that the soil biogeochemical background corresponding to P inherited from natural soils at the conversion to agriculture (BIOG) and farming practices (FARM) were the main drivers of the spatial variability in cropland soil P content but that their contribution varied between P vs. P . When the spatial variability was computed between grid cells at half-degree resolution, we found that almost all of the P spatial variability could be explained by BIOG, while BIOG and FARM explained 38% and 63% of P spatial variability, respectively. Our work also showed that the driver contribution was sensitive to the spatial scale characterizing the variability (grid cell vs. continent) and to the region of interest (global vs. tropics for instance). In particular, the heterogeneity of farming practices between continents was large enough to make FARM contribute to the variability in P at that scale. We thus demonstrated how the different drivers were combined to explain the global distribution of agricultural soil P. Our study is also a promising approach to investigate the potential effect of P as a limiting factor for agroecosystems at the global scale.
土壤中的磷（P）供应限制了世界上许多地区的作物产量，而土壤中过多的磷会在其他地区引发水生富营养化。许多过程驱动着农业土壤中磷的全球空间分布，但它们的相对作用仍不清楚。在这里，我们将描述这些驱动因素的几个全球数据集与一个土壤 P 动态模型相结合，以模拟农业土壤中 P 的分布，并评估不同驱动因素在全球范围内的贡献。我们分析了易分解的无机磷（P i ），这是一个与植物营养相关的池的代表，以及土壤总磷（P t ）。我们发现，农业转化时土壤的生物地球化学背景（BIOG）和农业实践（FARM）是农田土壤 P 含量空间变异性的主要驱动因素，但它们的贡献在 P i 和 P t 之间有所不同。当在半度分辨率的网格单元之间计算空间变异性时，我们发现几乎所有的 P i 空间变异性都可以用 BIOG 来解释，而 BIOG 和 FARM 分别解释了 38%和 63%的 P t 空间变异性。我们的工作还表明，驱动因素的贡献对描述变异性的空间尺度（网格单元与大陆）和感兴趣的区域（例如全球与热带）敏感。特别是，各大陆之间农业实践的异质性足以使 FARM 在该尺度上对 P 的变异性产生贡献。因此，我们展示了如何将不同的驱动因素结合起来解释农业土壤 P 的全球分布。我们的研究也为在全球范围内研究磷作为农业生态系统限制因素的潜在影响提供了一种有前途的方法。
