Kinetics of Potassium Release and the Correlation of Potassium Release Characteristics with Soil Properties and Wheat Plant Indices in soils of Iran.
2009
Khademi, Zahra | Bazargan, Kambiz | Shahbazi, Karim | Asadi, Fatemeh | Malek Zadeh, Elaheh | Mansuri, Fatemeh | Tabbakhiyan, Sheyda | Yeganeh, Mozhgan
The rate of nonexchangeable K release from soils can have as significant effect on K dynamics and it's availability during the growing season. In this study, twelve soil samples that taken from different wheat cropping regions of Iran were used (i) to investigate the kinetics of nonexchangeable K release and (ii) to compare the ability of various kinetics equations (zero-, first-, second-order, parabolic diffusion, simplified Elovich and power function) to describe nonexchangeable K release by NaBPh4. The results showed that the recovery of K in this method was almost 100%. The release was initially rapid followed by a slower reaction. About 80% of total K released by the soils after 192h occurred in first 48h. The release of nonexchangeable K as a percentage of total K in the soils ranged from 12.8% to 55.8%.NaBPh4-extracted K in 5min showed a strong correlation with NH4OAc- extracted K(r2=0.78, p0.0001). Nonexchangeable K released in most soils was almost complete in 96h and comparison of coefficients of determination (r2) and standard errors of the estimate(SE) indicated that the power function, parabolic diffusion and simplified Elovich equations well described K released(r2a"was highly correlated to the fraction on nonexchangeable K released at very short reaction time. Also, rate constant of power function equation (b) was significantly correlated to clay content of soils.
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