Effects of poultry manure and pistachio compost on the kinetics of copper desorption from two calcareous soils

Land disposal of organic waste materials may alter the heavy metal status of the soil by affecting metal solubility or dissociation kinetics. The aim of this investigation was to study the influences of two organic matters (poultry manure and pistachio compost) on copper desorption of two calcareous soils of Iran and determine the best models for description of the kinetics of Cu release in this soils. Organic matters were added to soils at the rate of 300 g kg(-1), and samples were incubated at 24-25A degrees C and near field capacity for 90 days. For Cu desorption studies, samples were extracted with 0.01 M EDTA at pH 7.0 with shaker for periods of 5 to 2,880 min. Results showed that during the reaction periods from 5 to 2,800 min, desorption of Cu from two soils increased with time. In the all of samples, copper release was rapid at first and then became slower until equilibrium was approached. In the two soils, desorption of Cu, which increased in poultry manure and decreased in pistachio compost treatments than the control soil, and two-constant rate and simple Elovich were the best equations for description of Cu desorption from soils.