Abstract :
A laboratory incubation experiment in a completely randomized design with three replications was carried out for 90 days to test the effect of zeolite and biochar application to calcareous sandy loam soil on potassium forms distribution and its release rate. The treatments included (1) Absolute control (C), (2) 10 g kg-1 zeolite (Z1), (3) 20 g kg-1 zeolite (Z2), (4) 10 g kg-1 biochar (B1), and (5) 20 g kg-1 biochar (B2). After incubation period, the concentrations of soluble, exchangeable, and non-exchangeable K and the release rate of K to 0.01 M CaCl2 during 200 min (10 successive extractions for soil samples of 20 min for each using CaCl2 solution) were determined. Results showed that zeolite application increased the soluble and exchangeable K concentrations. However, amending soil with biochar had a positive effect on all K forms. Addition of zeolite or biochar increased the cumulative K release. The parabolic diffusion, power function and Simple Elovich models described the kinetics of K release to CaCl2 solution well from all the soil treatments. Zeolite and maize stalks biochar may have an effective role in improvement of K availability and release in the calcareous sandy loam soil as well as may aid in increasing the ability of this soil to supply the different crops with K.
Keyword :
Potassium, Zeolite, Biochar, Kinetics.