Abstract

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 CaCl2-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 CaCl2-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 AlPO4 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.

Keywords

Alum; Dolomite; P stabilization; P sorption; Calcareous soil; Red soil

Published in

Environmental Science and Pollution Research
2019, Volume: 26, number: 5, pages: 4842-4854
Publisher: SPRINGER HEIDELBERG

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1007/s11356-018-3968-9

Permanent link to this page (URI)

https://res.slu.se/id/publ/113723