Mitigating soluble phosphorus loss in legacy phosphorus soils: Biosolids characterization and phosphorus-transformation studies

作者：Gurpal S. Toor, Emileigh Lucas, Fajun Sun, Quin Zabel, Taylor Roswall, Zachary Kiedrowski, Danielle Pressley · 发表于：Environmental Technology & Innovation · 年份：2025 · DOI：10.1016/j.eti.2025.104685 · 研究领域：Phosphorus and nutrient management、Soil and Water Nutrient Dynamics、Soil Carbon and Nitrogen Dynamics

Legacy phosphorus (P) from agricultural soils continues to leak into surface waters. We investigated how biosolids treated with metals (Fe, Al, and Ca) immobilize soluble P (water-extractable P, WEP) in soils while maintaining plant-available P (Mehlich 3-P, M3-P). Two complementary incubations (3–8 weeks; 25 °C) in non-legacy and legacy-P soils (M3-P: 58–139 mg kg⁻¹; 230–953 mg kg⁻¹) tracked WEP, M3-P, and M3-P saturation ratio (M3-PSR). Poultry litter and compost produced the largest WEP and the highest M3-P time-weighted means (TWM: 0.31 and 0.21 mg kg⁻¹ per kg of P), reflecting rapid P release. Fe/Al-treated biosolids (e.g., Bloom ±WTR)) showed small or negative WEP and lower M3-P TWM that declined with increasing application rate (0.12–0.04 mg kg⁻¹ from 1x to 4x). Thermo-hydrolyzed biosolid (low Fe) had a mid-range M3-P TWM (∼0.19 mg kg⁻¹) but the largest delta (Δ) over 8 weeks, consistent with sustained mineralization. WEP i TWM was –0.002–0.027 across products; increasing Bloom rates reduced WEP i TWM ( 0.007 to –0.0002 mg kg⁻¹) and Δ (–0.007 to –0.0005 mg kg⁻¹), confirming Fe/Al control of P solubility. M3-PSR changes mirrored product chemistry, with ΔPSR near zero for Bloom and minimal or negative for Fe/Al-treatments. Overall, Fe/Al-treated biosolids effectively reduced soluble P, while some products (e.g., thermo-hydrolyzed, lime-stabilized+WTR) gradually increased plant-available P. We suggest prioritizing Fe/Al-treated biosolids (±WTR) on legacy-P or sandy soils ...