Abstract: Controlled release fertilizer of zinc sulfate micro nutrient is prepared with flyash and sand inert matrix. Particle size, fractional content of inerts and binder influenced the release rates. The release rates were found to follow zero order kinetics with respect to fractional fertilizer content in pellet. The rate constant increased with the increase in particle size, flyash fraction and decreased with binder fraction of pellet for flyash system. The rate constant increased with increase in fractional sand content while that decreased with particle size and fractional binder for sand system with in the variables covered in the present study. Correlations for rate constants with parameters covered in the study is presented here under
Zinc sulfate – Flyash – Cement system
kZFC = 5.89 fb-0.09 fi5.94 (dp/d) 0.19
Zinc sulfate – Sand – Cement system
kzsc = 0.89 fb-0.13 fi2.53 (dp/d)-0.1

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