Time-based evaluation of bioavailable phosphorus in a calcareous soil after the application of anaerobically digested sewage sludge

Abstract Nowadays, phosphorus natural reserves are being depleted, while P fertilizers demand is increasing. Phosphorus well contained in waste materials such as sewage sludge. Only a small amount (1–3%) of the soil total bioavailable for plant nutrition. More detail, present study focuses on determination kinetics concentrations sandy calcareous after application A centrifuged (C) and dried (D) anaerobic digestate from sludges obtained same wastewater treatment plan were separately tested to fertilize soil. Falcon tubes (50 mL) containing negative control (T) treated with C D incubated 1 90 days. Soil fractionation was performed SMT method bioavailable-P extracted through Olsen method. spectrophotometrically quantified by molybdovanadate Lastly, soils evaluated using four kinetic models. fractions constant throughout experiment. Conversely, significantly decreased day (from 34.9 ± 2.9 23.8 1.5 ppm) T 4.2 1.2 0.3 0.6 ppm). This decrease might be due precipitation calcium; fact, high concentration Ca 2+ ions alkaline pH can induce sequential formation calcium phosphates, even less soluble over time. Whereas showed peak 14 (26.6 3.0). trend could organic carbon compounds, competitive sorption metal bridging. The fitting experimental data revealed that Elovich model best described adsorptive-precipitate process ( r 2 = 0.90) 0.93). none models satisfactorily behavior samples. increases knowledge P-related phenomena designing optimizing reducing their drawbacks eutrophication.