Assessment of nutritional status of soil supporting coconut (Cocus nucifera) cultivation in some localities of Edo State of Nigeria

Abstract

Coconut cultivation and information on the nutritional status of soils and fertilizers recommendations for its cultivation are limited in Nigeria. Since a high yield of coconut is related to the fertility status of the soil, a study was conducted to evaluate the status of soils supporting coconut cultivation. The evaluation of the surface soil (0 – 15 cm) and the subsoil (15 – 30 cm) of seven localities showed that the average pH was 5.75 ± 0.21 and 5.51 ± 0.15, respectively, indicating that the subsoil was slightly acidic than the surface soil. Highest values for the surface soil parameters were found to be 0.58 ± 0.08 gkg-1 for exchangeable acidity, 2.55 ± 0.02 gkg-1 for organic carbon (C), 0.13 ± 0.02 gkg-1 for total nitrogen (N), 20.24 ± 1.10 gkg-1 for the carbon : nitrogen ratio, 17.45 ± 0.60 for available phosphorus (P), 0.21 ± 0.02 Cmolkg-1 for sodium (Na), 0.14 ± 0.01 Cmolkg-1 for potassium (K), 2.91 ± 0.10 Cmolkg-1 for calcium (Ca) and 0.79 ± 0.06 Cmolkg-1 for magnesium (Mg). On the other hand, the subsoil parameters were 0.74 ± 0.15 gkg-1 for exchangeable acidity, 1.85 ± 0.03 gkg-1 for organic C, 0.09 ± 0.01gkg-1 for total N, 19.69 ± 0.67 gkg-1 for the carbon : nitrogen ratio, 10.15 ± 0.38 for available P, 0.16 ± 0.01 Cmolkg- 1 for Na, 0.09 ± 0.01 Cmolkg-1 for K, 1.59 ± 0.04 Cmolkg-1 for Ca and 0.46 ± 0.04 Cmolkg-1 for Mg. The results showed the samples were not generally ideal for coconut growth and production of good yields because of marginal deviation from acceptable limits. It is recommended that the soils in these localities need fertilization especially with nitrogen and potassium carriers for the purpose of coconut cultivation.