Dynamics in Physico–chemical Properties of Soils Under Oil Palm Plantations of Different Ages

This research investigated the changes in the physicochemical properties of soils under oil palm plantations of different ages. Soil surface (0-20 cm) and subsurface (20-40 cm) samples have been obtained from various ages of oil palm plantations (0-5, 5-10, 10-15 and, 15-20 years). Two distinct samples were taken on the same farm, under alleys and heaped pruned fronds. Soil samples used as a standard (control) were collected from adjacent forest land. Analyses of particle size showed that the soils were sandy loam to sandy clay loam texture soils. Bulk density was low to moderate (0.93 – 1.25 g/cm3), and varied with age and depth. The soils were moderate to neutral pH (5.38 – 6.81), low to moderate organic carbon (11.6 – 21.7 g/kg) and total nitrogen (1.18 – 2.03 g/kg), and relatively low available phosphorus (4.43 – 6.21 mg/kg) contents. Based on the standard ratings, cation exchangeable capacity content was low (4.93 – 6.15 cmol/kg), while high percent base saturation (85.3 – 93.2%) was observed. The soil properties determined showed that soil nutrients under alleys fluctuated with age whiles that under heaped fronds increased. Research findings have shown that the soil properties of different ages of oil palm plantations vary and should be handled differently based on their characteristics. Accumulation of organic residue on the floor of the plantations should be encouraged as this will help increase organic matter levels.