Catenary Variation of Soil Properties under Oil Palm Plantation in South Western Nigeria

Abstract

This study characterizes variations in soil properties in a catena under a 30-year oil palm (Elaeis guineesis) plantation established on sedimentary soil in south-western Nigeria. A 300 metre transect was delimited in an oil palm plantation adjoining a tributary of Ossiomo River at Okhuo, near Benin, Nigeria. The transect was divided into upper, middle and lower slope segments. Each segment was further subdivided into ten 10 by 10 metres quadrats, making a total of 30 quadrats. Five soil samples were randomly collected from 0-20cm layer of each quadrat and analysed for particle size composition, organic carbon, macronutrients and micronutrients.
Exchangeable calcium and cation exchange capacity were significantly higher in the middle slope segment of the catena due to the combined influence of soil organic matter and clay which were also higher in the middle slope than in the upper and lower slopes. Soil pH was highest in the upper slope and declined down slope.
There were no significant variations in the levels of extractable manganese, copper and zinc between the upper, middle and lower slopes but extractable iron was significantly higher in the lower slope due to the occurrence of more moist and acidic soils in the lower slope. Topographic position and ground slope are the main factors accounting for variations in soil properties along the catena. There is the need to manage parts of oil palm plantation on different topographic positions differently, taking cognizance of variations in soil properties along the catena, in order to ensure long term sustainability.

Key words: Oil palm, catena, soil, macronutrients, micronutrients, Nigeria