POSSIBILITIES OF POTASSIUM CONCENTRATE ES TIMATE IN SOIL SOLUTION FROM THE SOIL TEST MEHLICH-2 AND KVK-UF

Relationships between potassium content in soil determined by two soil tests (Mehlich 2 and KVK-UF) and potassium concentration in simulated soil solution obtained from centrifugation from saturated soil paste by water were studied in a set of 380 soil samples acquired from the t opsoil of plots of distinguished agricultural entreprises. Observation s were aimed at specification of suitable soil supply with potassium i n the Czech Republic where is a great variability and disharmony in so il supply with potassium and magnesium. Information on variability and basic characteristics of nutritive condition of soil of the used set of soils is presented in Tabs I and II. The correlations found between parameters of the soil tests applied and potassium concentration in s imulated soil solution are in Tab. III. Point field of relationships u nder observation and set up functional trends are in Figs 1 to 5. The transformation of determined potassium content in soil into the ratio K/root Ca+Mg or simplified ratio K/root Ca improved the closeness of t he relationship between the used soil tests and potassium concentratio n in soil solution. The most marked improvement of the closeness of re lationship was attained in the case of the soil test KVK-UF which incl udes also determination of characteristics of cation echange capacity (KVK) when the soil supply with potassium was expressed in the form of percentage of saturation of the KVK value with potassium equivalents. To estimate the potassium concentration in soil supply, the regressio n relationship can be used as the best one: Y=4.115x(1.1882), where Y is potassium concentration in soil solution (mg K/dm(3)) and x is perc entage of saturation of sorptive complex by potassium equivalents set up on the basis of the soil analysis by KVK-UF procedure.