Potassium release rate characteristics of twenty low-hilly red soils under electric field strength of 44.4 V/cm and 88.8 V/cm were described with a second-order kinetic equation. The rate equations of K release and the initial K release rates (v₀) were calculated from the second-order equations. The values of vo ranged from 1.17 to 21.23 and from 1.93 to 61.58, with an average of 5.36 and 9.54 mg(kg·min)^-1 at the electric field strength of 44.4 and 88.8 V/cm, respectively. The relative grain yield, relative total dry matter yield and K uptake in NP plots of 20 corn experiments and the available K, NHO₃-soluble K and slowly available K of soils were used as reference standards to assess the practical applicability of v₀.The correlation analysis showed that v₀ was very significantly correlated(P=0.01) with the above six reference standards, with the correlation coefficients of 0.6275^**, 0.5645^**, 0.6624^**, 0.7277^**,0.7843^** and 0.6299^**,respectively, at electric field strength of 44.4V/cm. v₀ was significantly correlated with relative total dry matter yield(P=0.05, r=0.5445^**) and very significantly correlated with the other five reference standards, with the correlation coefficients of 0.6064^**, 0.7216^**, 0.7523^**, 0.8202^** and 0.6686^**, respectively, at the field strength of 88.8V/cm. It was suggested that v₀ could be used to estimate the supplying power of soil K and to characterize K status in soils.