Beijing Key Laboratory of Farmyard Soil Pollution Prevention-Control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China.
Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland.
Environ Sci Pollut Res Int. 2019 Feb;26(5):4842-4854. doi: 10.1007/s11356-018-3968-9. Epub 2018 Dec 19.
Surplus phosphorus (P) above agronomic requirements can negatively affect the water status of connected surface and subsurface water bodies. The in situ stabilization of soil P through soil amendment has been recognized as an efficient way to reduce this environmental pressure. However, the mechanism of how P is stabilized during this process and how plant available P is affected are unknown. This can be achieved by sequential chemical extraction and synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy investigations. Therefore, in the present study, P-enriched calcareous and red soils were amended with alum, dolomite, and a 1:1 mixture of alum and dolomite (MAD) at a 20 g/kg soil rate, and soil properties and P fractions were measured after a 45-day period. Results showed that alum amendment significantly decreased CaCl-P and Olsen-P contents in calcareous and red soils when compared with dolomite. However, dolomite incorporation maintained relatively high P availability and even increased CaCl-P and Olsen-P contents by 1.32% and 40.5% in red soil, respectively, compared to control. Amendment with MAD was not as effectively as the alum in P stabilization. Sequential inorganic P extraction indicated that alum dominantly contributed labile P transformed to Al-P in both soils. P K-edge XANES spectroscopy measurements further explained that alum adsorbed phosphate in calcareous soil and precipitated phosphate as AlPO in red soil. Results of P fractionation and Mehlich-3-extracted Ca showed that dolomite mainly adsorbed loosely bound P in calcareous soil and red soil. However, dolomite incorporation in red soil led to Al-P and Fe-P release. The P sorption isotherms showed that dolomite and alum increased soil P sorption maxima and decreased the degree of P saturation (DPS) in both soils, while dolomite declined the Langmuir bonding energy in red soil. Differences in P stabilization by alum and dolomite addition across soil types were closely related to their characteristics, and soil properties changed, especially soil pH.
土壤中超过农业需求的磷（P）会对地表水和地下水的水质产生负面影响。通过土壤改良来稳定土壤中的磷被认为是减少这种环境压力的有效方法。然而，在此过程中 P 是如何稳定的，以及有效磷是如何受到影响的，这些都还不清楚。这可以通过连续化学提取和基于同步加速器的 X 射线吸收近边缘结构（XANES）光谱研究来实现。因此，在本研究中，向富钙和红色土壤中添加了铝矾土、白云石以及两者 1:1 的混合物（MAD），添加量为 20 g/kg 土壤，在 45 天后测量土壤性质和磷形态。结果表明，与白云石相比，铝矾土的添加显著降低了富钙和红色土壤中的氯化钙磷和 Olsen-P 含量。然而，与对照相比，白云石的添加分别使红色土壤中的可利用磷和 CaCl-P、Olsen-P 含量提高了 1.32%和 40.5%。MAD 的添加效果不如铝矾土稳定磷。连续无机磷提取表明，铝矾土主要使土壤中的活跃磷转化为 Al-P。P K 边 XANES 光谱测量进一步表明，铝矾土在石灰性土壤中吸附磷酸盐，在红色土壤中沉淀磷酸盐为 AlPO。磷形态分析和 Mehlich-3 提取的 Ca 结果表明，白云石主要吸附石灰性土壤和红色土壤中松散结合的磷。然而，白云石在红色土壤中的添加导致 Al-P 和 Fe-P 的释放。磷吸附等温线表明，白云石和铝矾土增加了土壤的磷吸附最大值，降低了两种土壤的磷饱和度（DPS），而白云石降低了红色土壤的 Langmuir 结合能。不同土壤类型中铝矾土和白云石添加对磷的稳定作用的差异与它们的特性密切相关，土壤性质发生了变化，特别是土壤 pH 值。
