Potassium Status of Soils under Three Different Parent Materials of the Oil palm (Elaeis guineensis Jacq)

Abstract

Potassium quantity/intensity relations were studied in soils of three different parent materials of the oil palm to determine their potassium status and management. This was done by equilibrating 2.5g of the soil samples in 25 ml of 0.01M CaCl 2 at room temperature containing known concentrations of K. Potassium saturation was computed over ECEC. The quantity factor (Q) was determined as the difference in concentration between added K and soil solution K after equilibrating. The Q factor was plotted against the intensity factor. Results showed that the soils were generally acidic while organic matter and total nitrogen decreased with increasing soil depths in all the locations. Potassium activity ratio, its activity, its activity coefficient, ionic strength, free energy of replacement and potassium saturation differed due to the influence of the three different parent materials. In soils under alluvium, ECEC was significantly correlated with potassium activity (r = 0.941*), potassium activity coefficient (r = 0.925*), PBC K (r = 0.953*). In soils under basement complex rocks, ECEC had a significant correlation with potassium activity (r = 0.975**) and calcium activity (r = 0.996**). In soils under shale mixed with sandstone and clay, potassium saturation had a significant correlation with calcium activity coefficient while exchangeable acidity had a significant correlation with potassium activity coefficient. There were high values of potassium activity ratio but low values of ionic strength, free energy of replacement and labile K in all the locations. Conclusion: It follows that adequate maintenance of the ECEC status of soils under alluvium and Basement Complex Rocks through deliberate maintenance of cover cropping and frequent K fertilization could suffice in maintaining the soils K and Ca potential in contrast with soils under Shale Mixed with Sandstone and Clay that requires the application of K fertilizers blended with a little bit of lime. Keywords: Potassium status, potassium activity ratio, ionic strength, potential buffering capacity and labile K. DOI: 10.7176/CMR/14-2-01 Publication date: May 31 st 2022