Abstract: Effects of low-molecular-weight organic acids (tartaric acid and oxalic acid) on potassium (K) release from different K-bearing minerals (biotite, muscovite, and microcline) were studied with the continuous flowing method to explore an optimal model for describing K⁺ release kinetics and provide theoretical evidence to further evaluate plant available K of soil. Results showed that the amounts of K release from biotite, muscovite and microcline extracted by tartaric acid were 2.2, 3.3 and 2.6 times as high as that by water, respectively, while the amounts of K release extracted by oxalic acid were 2.7, 4.5 and 10.1 times as high as that by water, respectively. The amount of K release from Kbearing minerals with different extractions in continuous flow method was in order of biotite > muscovite > microcline. Parabolic diffusion, power function, Elovich equation and first order equation were used to describe the release of K from K-bearing minerals, and the result shows that the determination coefficients (R²) of the kinetic equations were from 0.591 to 0.999, showing significant correlations for biotite and muscovite. The effect of low-molecular-weight organic acids on microcline K release kinetics under the first order equation reached extremely significant level. Under the condition of continuous flow, lowmolecularweight organic acids can significantly improve K release in different K-bearing minerals.

Key words: carbohydrate, physiological integration, nutrient heterogeneity, Zoysia japonica, soluble protein