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Modeling transport kinetics in clinoptilolite-phosphate rock systems
E R Allen1, D W Ming, L R Hossner
1Dep. of Agronomy, Oklahoma State University, Stillwater 74078, USA.
Soil Science Society of America Journal. Soil Science Society of America
|January 1, 1995
Summary
Nutrient release from clinoptilolite-phosphate rock systems is diffusion-controlled. The power-function model best describes ammonium (NH4), potassium (K), and phosphorus (P) release kinetics.
Area of Science:
- Environmental Science
- Soil Science
- Geochemistry
Background:
- Nutrient release from soil amendments like clinoptilolite-phosphate rock (Cp-PR) systems is crucial for plant nutrition.
- Understanding the kinetics of nutrient release informs soil amendment design and application for sustainable agriculture.
- Clinoptilolite and phosphate rock are key components in slow-release fertilizer formulations.
Purpose of the Study:
- To model the transport kinetics of nutrient release (NH4, K, P) in clinoptilolite-phosphate rock (Cp-PR) systems.
- To identify empirical models that accurately describe nutrient release rates.
- To determine the primary diffusion-controlling processes governing nutrient release.
Main Methods:
- Utilized Texas clinoptilolite (Cp) and North Carolina phosphate rock (PR) as experimental materials.
- Employed a continuous-flow thin-disk technique to simulate nutrient release under controlled conditions.
- Evaluated various kinetic models including zero order, first order, second order, parabolic diffusion, Elovich, and power function.
Main Results:
- The power-function, Elovich, and parabolic-diffusion models effectively described the release of ammonium (NH4), potassium (K), and phosphorus (P).
- The power-function model was identified as the preferred model due to its simplicity and adequate fit.
- Kinetic modeling indicated that nutrient release from Cp-PR systems is primarily diffusion-controlled.
Conclusions:
- Nutrient release from clinoptilolite-phosphate rock systems is governed by diffusion processes.
- The power-function model provides a simple yet effective means to describe NH4, K, and P release kinetics.
- Observed nutrient release likely results from a combination of interacting transport mechanisms.
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