Phosphorus release kinetics in slightly and moderately calcareous soils induced by low molecular weight organic acids and amino acids

Release of phosphorus (P) from calcareous soils is an important index for evaluating the bioavailability of P. The study was conducted to evaluate the efficiency of low molecular weight organic acids and amino acids on P release from two calcareous soils. Different concentrations of organic acids and amino acids were added to slightly and moderately calcareous soils that were incubated at different incubation time intervals on a factorial completely randomized design. At the end of each period, samples were analyzed for available P to determine P release rate using kinetic models. Phosphorus release from both calcareous soils increased with time and concentration of both class of compounds. Phosphorus release by citric acid at a concentration of 100 mM reached the highest value after 1440 min of incubation in both soils. The simple Elovich and power function models were the best fitted equations to describe P release from calcareous soils.