Phosphorus species, fractions, and leaching risk in vermicompost-amended calcareous sandy loam soil

Purpose Organic matter has significant effects on phosphorus (P) retention in soil. Applying vermicompost (VC) as an organic amendment is an eco-friendly approach to increase sustainability in agriculture. There is a high potential of P loss by leaching or surface runoff from coarse-textured soils. Column leaching experiments were conducted to determine the effect of VC on P mobility in a P fertilized sandy loam soil­.Method Soil columns were amended with different VC dosages (2% VC, 3% VC, and 5% VC w/w) and leached with distilled water for 31 days. Phosphorus, base cations and anions concentration, EC, and pH were analyzed in leachates and P species, leaching rate, and fractions in amended soils were determined, too.Results The HPO4^-2 and MgHPO4 (aq) were the dominant species in the leachates and their highest total concentration was observed in 5% VC-amended columns. Vermicompost increased P leaching and its leaching rate ranged from 0.41 mg kg^-1day^-1 for control to 0.59 mg kg^-1day^-1 for 5% VC-amended columns. With increasing VC dosage Res–P, NaOH–P, and KCl–P fractions decreased, but the HCl-P fraction increased.Conclusion Results indicate that the VC with increasing moderately labile P fraction (HCl-P) and HPO4^ -2 and MgHPO4 (aq) species can enhance P leaching from sandy loam soil­.