Long-term management with lime and/or phosphogypsum (PG) can change phosphorus (P) forms across the soil profile. In this study, we used synchrotron-based spectroscopy and sequential chemical fractionation to investigate P chemical species after long-term (18 years) application of amendments in a subtropical Oxisol. The availability of nutrients increased with the combined use of lime and PG and a stratification of attributes was identified due to long-term broadcast applications. X-ray absorption near edge structure (XANES) spectra profiles revealed the predominance of P bounded to haematite (Hm) (48% on average) and also P bound to kaolinite (32% on average) species. Low proportions (16%) of calcium-phosphates in the uppermost soil layer (0–5 cm) were found in the treatment that received high calcium (Ca) inputs by lime and PG broadcast. Few correlations were identified between the proportions of P species obtained by XANES and P fractions operationally defined by sequential chemical fractionation (SF). Our results suggest that P-species bound to kaolinite can store stable P forms, which correlated (p < 0.05) with the residual P fractions obtained by SF, highlighting the importance of kaolinite as a legacy P store in Oxisols.

中文翻译：

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使用石灰和/或磷石膏 18 年免耕修正的可变电荷 Oxisol 中的磷形态和分布

使用石灰和/或磷石膏 (PG) 进行长期管理可以改变整个土壤剖面中的磷 (P) 形式。在这项研究中，我们使用基于同步加速器的光谱和连续化学分馏来研究在亚热带氧化溶胶中长期（18 年）应用修正后的 P 化学物质。随着石灰和 PG 的联合使用，养分的可用性增加，并且由于长期的播撒应用而确定了属性的分层。X 射线吸收近边缘结构 (XANES) 光谱图显示 P 与赤铁矿 (Hm) 结合（平均 48%）和与高岭石（平均 32%）结合的 P 占优势。在通过石灰和 PG 播撒获得高钙 (Ca) 输入的处理中，发现最上层土壤层 (0-5 cm) 中磷酸钙的比例较低 (16%)。在通过 XANES 获得的 P 物种的比例与由连续化学分馏 (SF) 操作定义的 P 分数之间几乎没有相关性。我们的结果表明，与高岭石结合的 P 物种可以储存稳定的 P 形式，这与 (p  < 0.05) 与 SF 获得的残余 P 分数，突出了高岭石作为 Oxisols 中传统 P 储存的重要性。