EVALUATION OF NUTRIENT STATUS OF SOILS OF OIL PALM PLANTATIONS IN ONDO, SOUTHWEST NIGERIA

Abstract

In order to judiciously apply fertilizers for soil health management, there is a need to ensure that the adequate nutrient needs of the crop to be fertilized in order to avoid over- or under-application. Evaluation of the nutrient status of the soils of Adeyemi Federal University of Education Oil Palm Plantation, Ondo, Southwest Nigeria, was carried out in 2022. The whole farm was divided into sections A, B, C, D, E, and F. Thirty (30) soil samples were collected from the sites at 0-30 cm depth. The soil samples were bulked according to each section, air-dried, sieved through a 2 mm sieve, and analyzed for soil pH, OM, total N, available P, exchangeable K, Ca, and Mg.  Others were Fe, Cu, Zn, and Mn, and soil textural classes. The pH of the soils ranged between 5.25 and 5.65. Organic carbon ranged between 0.25 and 1.48%, with a mean value of 0.93%. The sites were deficient in total N, with a mean value of 0.08%, ranging from 0.04% to 0.11%. The trends of N status in the oil palm plantation soils were 0.11, 0.10, 0.09, 0.08, 0.07, and 0.04% for sites E, A, C, F, B, and D, respectively. The order of available P ranged between 5.94 mg kg^-1 and 11.46 mg kg^-1 with a mean value of 8.52 mg kg^-1. Exchangeable K varied from 0.08 – 0.14 cmol kg^-1 with a mean value of 0.12 cmol kg^-1. The Mg status of the oil palm plantation varied from 0.25 to 0.78 cmol kg^-1 with a mean value of 0.47 cmol kg^-1. Available Ca concentration in the soil varied from 4.15 to 7.71 cmol kg^-1. The organic matter and ECEC were low, while the iron concentration ranged between 3.9 and 22.30 mg kg^-1.  Sites A and E were too high in Cu and do not require any Cu fertilizer, likewise Fe and Zn.