Solid-Phase Speciation and Solubility of Phosphorus in an Acid Sulfate Paddy Soil during Soil Reduction and Reoxidation as Affected by Oil Palm Ash and Biochar

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• 作者：Worachart WisawapipatKamolchanok Charoensri ; Jirawat Runglerttrakoolchai
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2017
• 出版时间：February 1, 2017
• 年：2017
• 卷：65
• 期：4
• 页码：704-710
• 全文大小：441K
• ISSN：1520-5118

文摘

Understanding phosphorus (P) speciation and how redox conditions control P solubility in acid sulfate paddy soils with limited P availability is crucial for improving soil P availability. We examined P speciation and extractability in an acid sulfate paddy soil incorporated with oil palm ash (OPA) and biochar (OPB) during soil reduction and subsequent oxidation. Phosphorus K-edge X-ray absorption near edge structure (XANES) spectra of the soil samples revealed that P in the soil mainly occurred as P adsorbed to ferrihydrite and P adsorbed to gibbsite. During soil reduction, gibbsite-bound P was transformed into variscite, which was back-transformed to gibbsite-bound P during soil reoxidation. Sequential extraction results confirmed the dominance of Fe/Al (hydr)oxides-bound P (average 72%) in the soils. The OPA incorporation increased the exchangeable P pool concurring with the decrease in gibbsite-bound P. The OPB incorporation enhanced the dissolved P from the residual pool presumably due to electron shuttling of biochar with Fe(III) minerals during soil reduction. Our results highlight P dynamics in paddy soils, which are of immense importance for effective P-management strategies in rice cultivation.