The Interactive Effect of Flooding and Organic Matter Treatments on Phosphorus Adsorption on Calcareous Soils

Authors : Süleyman Ören, Veli Uygur

Pages : 83-92

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Publication Date : 2025-12-26

Article Type : Research Paper

Abstract :Phosphorus (P) availability in calcareous soils is limited due to strong adsorption and precipitation reactions, which hinder plant uptake and complicate nutrient management. This study explored how flooding duration (0–40 days) and farmyard manure (FYM) application (0 and 4 g per 100 g soil) affect P adsorption in five calcareous soils with varying physical and chemical properties. Using batch equilibrium experiments, P sorption was modelled with Freundlich and Langmuir isotherms. Flooding increased adsorption capacity, as indicated by higher KF and Smax values, due to redox-driven dissolution and re-precipitation of Fe/Mn oxides, which created more sorption sites. Initially, FYM reduced adsorption strength because of organic ligands and labile P inputs. However, with prolonged flooding, FYM enhanced adsorption through organo-mineral interactions and secondary oxide formation. Soil characteristics such as carbonate content, clay fraction, and organic matter influenced these effects. The modified Langmuir model provided the best fit, emphasizing the role of both native and added P in adsorption dynamics. Overall, the study shows that flooding and organic amendments interact to regulate P retention in calcareous soils, offering insights for sustainable phosphorus management under conditions of climate variability and increased waterlogging.
Keywords : Adsorption parameters, waterlogging duration, Langmuir isotherm, Freundlich isotherm

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