POTASSIUM EXCHANGE BEHAVIOUR IN SOME SOILS OF EGYPT

Abstract

This work was carried out to study the potassium status, available potassium, potassium supplying power, influence of anions on potassium supplying power, the maximum adsorption capacity, the bonding energy of potassium and the fixation capacity of potassium in four surface soil samples (0-30 em) taken to represent the Nile alluvial soils (EI-Kanater and Beni-Suef) and calcareous soils (Borg EI-Arab and EI-Hammam). The obtained results showed that the amount of soluble and exchangeable K represent the least cationic amount in the investigated soils. The total K in the studied soils tends to be relatively high in each of fine and medium textured soil samples, while the low values were recorded in the coarse textured soil samples. The amounts of available K extracted by the different methods gave the following descending order: amounts extracted by successive extractions with boiling in N HN03 > the extracted K by N HN03 > the extracted K by 0.01 N CaCI2 > the extracted K by concentrated H2S04 > the extracted K by 0.5 N HCI. The obtained data of potassium Q/1 showed that potassium buffering capacity in soils becomes higher as the texture becomes finer. Using 804= instead of cr leads to decrease the value of the potassium buffering capacity.

The bonding energy for K in the calcareous soils was higher than those of the alluvial ones.

The maximum adsorption capacity for K in the alluvial soils was higher than those of the calcareous ones.