Potassium fixation of some soils derived from different parent materials in Cross River State, Nigeria.

Abstract

Potassium fixation of some soils derived from different parent materials in Cross River State was studied being a major problem that affects the efficiency of K fertilizers. A total of eighteen soil samples were collected from three parent materials: Basement complex, Coastal plain sand and Shales. Six levels of potassium chloride (0, 25, 50, 100, 200 and 400 mg) were added to 1kg soil and replicated three times. Potassium was extracted with 1 N NH4OAc after one day, ten- and forty-two-days incubation. The amount of K fixed was determined and correlation between applied and fixed K was carried out. The soil pH ranged from 5.29 to 5.60, organic carbon varied from 1.33% to 2.18 %, the exchangeable cations are in order of abundance; Ca2+ > Mg2+ > K+ > Na+ and the ECEC of the soils varied from 4.86 cmol/kg for basement complex to 19.38 com/kg for shales. The mean proportion of K fixed varied from 2.06 to 279.05 mg/kg for Shales, 5.95 to 288.44 mg/kg for basement complex and 8.06 to 292.23 mg/kg for soils derived from coastal plain. There was significant correlation (P