Kinetics of K Desorption from Soils in a Constant Electric Field （Electro—Ultrafiltration） and Its Application
摘要
K desorption from soils in a constant electric field(field strength:44.5V cm^-1) by means of electro-ultrafiltration (EUF) followed second-order kinetics and could be described by the equation dd/dt=k(D-d)^2.From the equation,such inetic parameters relating to K desorption from soils as the maximum desorbable quantity D,quantity of K desorbed within 40 minutes d40,initial desorption rate Vo,desorption rate constant k and half time t1/2 could be calculated.An expression which describes the relationships between the kinetic parameters on the one hand and the responses of barley to fertilizer-K in the field experiments in different sites and the potassium-supplying power of soils on the other was established.Vo,D and d40 were significantly correlated with barley relative yield,K uptake by barley and the content of soil available potassium.The rate constants of K desorption varied between 4.42×10^-4-1.80×10^-3kg mg^-1 min^-1 and highly correlated with the relative yield of barley.The kinetic parameters including Vo,D,d40 and k were successfully used to estimate the K-supplying power of soils.