Evaluation of Tree Species for Agroforestry Practice on Entisols in the Sudan Sahel Region of Nigeria

Abstract

1) Background: Evaluation of Acacia nilotica, Acacia Senegal, Azadirachta indica, Eucalyptus camaldulensis, Khaya senegalensis, Leucaena leucocephala and Prosopis juliflora for growth and interactions with soil and crops for agroforestry development was undertaken on Entisols in the Sudan Sahel region of North Eastern Nigeria. One hundred trees of each species were established at 2 x 2m spacing on a sandy loam entisol by intercropping with beans (Vigna unguiculata) for the initial 2 years. Tree growth was regularly recorded and changes in soil properties as well as yield of Sorghum vulgare on them also evaluated. 2) Results: The tree species recorded more than 60% survival and grew rapidly. The highest annual mean tree girth growth rate of 3.65cm occurred in Leucaena leucocephala, followed by Acacia nilotica (3.61cm), Azadirachta indica (3.01cm), Eucalyptus camaldulensis (2.78cm), Khaya senegalensis (2.72cm), Acacia Senegal (2.55cm) and Prosopis juliflora (2.23cm). The trees accumulated sand and improved nutrient status of the soil under them. Sorghum vulgare crop grown on the forest soils produced higher dry matter yield than the surrounding field soil. The best crop yield of 3.22 g/plant occurred on Leucaena leucocephala soil, followed by Azadirachta indica (2.92 g/plant), Acacia nilotica (2.33 g/plant), Eucalyptus camaldulensis (2.22 g/plant), Prosopis juliflora (1.80 g/plant), Acacia Senegal (1.71 g/plant), the control (1.59 g/plant) and Khaya senegalensis (1.22 g/plant). 3) Conclusions: The study ranked species according to their growth and agroforestry qualities. It also observed some inter-tree species interactions which, when fully developed, will be very useful for scientific management of mixed species tropical agroforests.