Phosphorus speciation in soils with low to high degree of saturation due to swine slurry application

• Published in: Journal of environmental management 2021-03, Vol.282, p.111553, Article 111553
• Main Authors: Gatiboni, Luciano Colpo, Souza Junior, Abelino Anacleto de, Dall’Orsoletta, Daniel João, Mumbach, Gilmar Luiz, Kulesza, Stephanie Brooke, Abdala, Dalton Belchior
• Format: Article
• Language: English
• Subjects: Agriculture; Animals; Chemical Fractionation; Phosphorus; Soil; Swine
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2020.111553

Soils with continuous application of swine slurry (SS) may present high phosphorus (P) content and high risk for environmental pollution. The aim of this study was to characterize the forms of phosphorus accumulation in 15 fields with increasing degrees of P saturation (DPS) in a watershed with a high density of swine farming. Soil samples collected from 0 to 10 cm were chemically characterized for water soluble phosphorus (WSP), DPS, Hedley chemical fractionation, and chemical speciation by P K-edge XANES. WSP increased linearly to a value of 137% of DPS, with subsequent stabilization at 2.7 mg kg−1. Only the inorganic fractions of the chemical fractionation changed with increasing DPS. Phosphorus forms considered labile increased up to 144% of DPS, with subsequent stabilization. The moderately labile fraction 0.1 M NaOH and non-labile 1 M HCl increased exponentially. Phosphorus K-edge XANES analysis demonstrated that P associated to apatite, amorphous aluminum minerals, and goethite were the main forms of P found and only the latter had a correlation with DPS (−0.57*). With increasing DPS, there are changes in the dynamics of P in the soil, with a reduction in forms associated to Fe and an increase in forms linked to Al. The forms linked to Al buffer the WSP and are recovered in the first inorganic fractions of the Hedley chemical fractionation. [Display omitted] •Swine slurry is waste from hog production and it's used as fertilizer.•The water soluble phosphorus is strongest related to labile forms of phosphorus.•High degree of phosphorus saturation is linked to the increase in aluminum associated phosphorus; .•The P forms associated to aluminum was shown to buffer water soluble phosphorus.