Fertility Levels of Soils under Selected Tree Vegetations for Efficient Agro-Forestry in Imo State, Nigeria

Abstract

In many parts of Nigeria, large areas of lands are dominated by tree crop vegetations for timber production and for fruits with land users not knowing the fertility status of soils in these vegetations. Continual evaluation of soil properties of these tree vegetations has become pertinent for agricultural sustainability. This study therefore was carried out to evaluate the fertility levels of soils under selected tree vegetations at National Horticultural Research Institute Okigwe, Imo State, Nigeria. Five tree vegetations that were over 20 years of establishment were selected namely: oil bean (Pentaclethra macrophylla Benth), African breadfruit (Treculia africana), mango (Mangnifera indica), Ogbonu (Irvingia gabonensis) and orange (citrus spp). In each of these tree vegetations, four soil samples were collected at uniform depths (0 – 20, 20 – 40 and 40 – 60 cm) at different locations using soil auger. The samples were analyzed using standard laboratory procedures. Data collected were statistically analyzed using analysis of variance. Results obtained showed that despite the ages of these vegetations, the soils were acidic, low in macronutrient and basic cation concentrations when compared to FAO standard. The highest exchangeable bases and organic matter (1.78%) was recorded on bread fruit vegetation. Therefore, there is need to increase the fertility status of these soils in these tree crop vegetations by adopting measures that will boost organic matter content of the soil irrespective of the duration of the vegetation and this will help in agro forestry and alley cropping.