An Assessment of the Suitability of Soils Supporting Oilpalm Plantations in the Coastal Plains Sand, Imo State, Nigeria

Abstract

Oilpalm yields have been declining, thus soils in the coastal plains sand of Imo State that support Oilpalms have been investigated. Each of the 10 sites surveyed had a bulked sample obtained at 0–20 cm and 20–40 cm depths and analysed in the laboratory. The surface of the soil was dominated by sandyloam, but the subsurface was dominated by sandy clayloam. Ranges of values of parameters at the topsoil were: pH(4.1 – 5.6), ECEC (5.7 – 8.7 cmol/kg), BS (36 – 87%), OM (1 – 4.7 g/kg), TN (0.01 – 0.14 g/kg), Av. P (6 –  /kg), Fe (0 – 233 mg/kg), Cu (0 – 1.2 mg/kg), Zn (0.3 – 14 mg/kg), Mn (5.7 – 145.6 mg/kg). Fertility Capability Classification (fcc) identified in the soils the condition modifiers – g (gley – in the valleys), e (low cec), h (strong acidity), and k (low content of k). But by suitability rating, the main limiting factors were – OM (N), TN (S₃/N), K (S₃/S₂). In general, the soils were appropriate (S2). for Oilpalm growth. Slight drainage of alluvial sites, mild liming (especially of alluvial soils), liberal nitrogenous fertiliser treatment, and moderate potassium fertiliser application are all recommended. The parametric method of assessment was more realistic than the non-parametric method of assessment.