Environment and Ecology Research 5(2): 161-166, 2017 http://www.hrpub.org DOI: 10.13189/eer.2017.050210 Evaluation of Tree Species for Agroforestry Practice on Entisols in the Sudan Sahel Region of Nigeria Ioryisa Verinumbe College of Forestry and Fisheries, University of Agriculture Makurdi, Nigeria Copyright©2017 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract 1) Background: Evaluation of Acacia nilotica, African Sudan Sahel region, naturally regenerated trees are Acacia Senegal, Azadirachta indica, Eucalyptus the major source of domestic wood, medicinal extracts, camaldulensis, Khaya senegalensis, Leucaena leucocephala supplementary food, dry season feed, and soil replenishment and Prosopis juliflora for growth and interactions with soil (Barrott [1], Verinumbe [2] and Hubert [3]). As a result of and crops for agroforestry development was undertaken on inadequate management, the trees have low productivity, and, Entisols in the Sudan Sahel region of North Eastern Nigeria. according to N.A.S. [4], they cannot adequately meet the One hundred trees of each species were established at 2 x 2m present demand for their goods and services. They are spacing on a sandy loam entisol by intercropping with beans therefore over-exploited leading to ecosystems degradation, (Vigna unguiculata) for the initial 2 years. Tree growth was desertification and further reduction in productivity (Glantz regularly recorded and changes in soil properties as well as [5], U.N. [6]). yield of Sorghum vulgare on them also evaluated. 2) Results: To improve tree regeneration and growth and to conserve The tree species recorded more than 60% survival and grew the environment in order to increase food and wood rapidly. The highest annual mean tree girth growth rate of production on sustained basis, De Troyer [7], Maydell [8], 3.65cm occurred in Leucaena leucocephala, followed by King [9], Huxley [10, 11] and Verinumbe [2] suggested the Acacia nilotica (3.61cm), Azadirachta indica (3.01cm), sequential and simultaneous planting of fast growing, soil Eucalyptus camaldulensis (2.78cm), Khaya senegalensis rejuvenating and socio-economically accepted trees with (2.72cm), Acacia Senegal (2.55cm) and Prosopis juliflora crops. However, in the West African Sudan Sahel region, a (2.23cm). The trees accumulated sand and improved nutrient major problem hindering the development of the technical status of the soil under them. Sorghum vulgare crop grown packages for successful implementation of this is the lack of on the forest soils produced higher dry matter yield than the systemic information on the potential tree species. The surrounding field soil. The best crop yield of 3.22 g/plant present study had the objective to contribute to the occurred on Leucaena leucocephala soil, followed by resuscitating qualities of four exotics and three local Azadirachta indica (2.92 g/plant), Acacia nilotica (2.33 potential farm tree species in a Sudan Sahel region of North g/plant), Eucalyptus camaldulensis (2.22 g/plant), Prosopis Eastern Nigeria. The exotics include Eucalyptus juliflora (1.80 g/plant), Acacia Senegal (1.71 g/plant), the camaldulensis, Leucaena leucocephala, Azadirachta indica control (1.59 g/plant) and Khaya senegalensis (1.22 g/plant). and Prosopis juliflora while the indigenous ones include 3) Conclusions: The study ranked species according to their Acacia nilotica, Acacia Senegal and Khaya senegalensis. growth and agroforestry qualities. It also observed some inter-tree species interactions which, when fully developed, Materials and Methods will be very useful for scientific management of mixed species tropical agroforests. The study site was an abandoned farm land on the outskirts of Maiduguri town in the Sudan Sahel region of Keywords Trees Evaluation, Agroforestry Practice, North Eastern Nigeria (11053’N, 13016’E). The mean annual Entisols, Sudan Sahel Nigeria rainfall for the past 30 years was 589.07 ± 148.47mm. Mean monthly temperatures were 26.780c while daily evaporation was 5.23± 1.03mm. The soil was a sandy loam entisol described by Klinkenberg and Higgins [12] as a juvenile soil 1 . Background on Aeolian sands. About half a hectare available land was demarcated into Among the predominantly rural farmers in the West seven plots of 20 x20m each. Seedlings of the seven species 162 Evaluation of Tree Species for Agroforestry Practice on Entisols in the Sudan Sahel Region of Nigeria were raised in polythene pots at the nursery. After 3 months, 2. Results and Discussions the seedlings were planted out on the plots in pure stands at 2 x2m spacing. Where species shared boundary, the between Tree Survival and Growth plot spacing was also 2m. Each plot therefore contained 100 trees of a single species. Since the available land was very The survival rates and growth data on tree species are small and largely uniform, the experiment was not replicated. presented in Tables 1-3. The indigenous Acacia nilotica and In addition to weeding and intercropping with beans (Vigna Acacia Senegal demonstrated superior survival qualities by unguiculata) during the first 2 years, the trees were also given recording over 95% survival. They were followed by the supplementary irrigation during the first dry season. exotic Prosopis juliflora, Leucaena leucocephala and Total number of surviving trees in each plot was counted Azadirachta indica. Although Khaya senegalensis is a local and percent tree survivals determined after the trees had species it is naturally more adapted to areas more humid than grown for 66 months. Collar girths of the centrally located the Sudan Sahel. This may explain its relatively low survival trees in each plot were measured at age intervals of 3, 15, 33, (76%) which was still better than the exotic Eucalyptus 45 and 66 months and compared. camaldulensis (59%). On visual observation in the fourth year that boundary Mean girths of the tree species (Table 1) increased from trees from species that shared common boundary and had 2.61cm in the first 12 months to 19.82cm at the end of 66 both intra and inter plot spacing of 2m grew differently from months giving mean annual increment of about 3.3cm. other ones, a quantitative assessment was made. Girths of the Acacia nilotica recorded the largest final girth (24.42cm) affected boundary trees were measured and compared with followed by Leucaena leucocephala (22.58cm), Azadirachta tree of the same species that grew at the centre of the plot. indica (21.17cm), Khaya senegalensis (18.88cm), Also, in the fourth year of the experiment, composite Eucalyptus camaldulensis (18.33cm), Acacia Senegal surface (0-15cm) soil samples taken and mixed from 5 (17.14cm), and Prosopis juliflora (16.25cm). stratified random locations under each of the tree species Current annual and mean (estimated by regression plantations were analysed for some of their physical and analysis) growth rates are presented in Table 2. It indicates chemical properties. Soil samples similarly taken and that very rapid current annual growth occurred in the first analyzed from the surrounding natural fallow field were the two years, decreasing from 10.42cm in the first year to control against which the soils from the forest plantations 9.35cm in the second one. This was probably aided by the were compared. Soil samples similarly taken were used to supplementary dry season irrigation in the first year and grow a local variety of Sorghum (Sorghum vulgare) in pots, intercropping with beans (Vigna unguiculata) during the two under nursery conditions. The soil from each tree species years. Cessations of intercropping and lower rainfall were plantation (and the control) was replicated in 10 pots. The associated with further decline in tree growth rates in the pots from all the tree plantations, including the control, were third and fourth years respectively. With improved rainfall in randomly arranged and similarly managed. After eight weeks the final year and possibly recovery from shock due to growth, total aerial dry biomass yields as well as nutrient cessation of irrigation and intercropping, tree growth rates content of the sorghum crops were determined. Variability of improve but were still lower than those of the first two years. the crop yield data among the tree species and control was The differences between the third, second and first year finally tested using the analysis of variance and Duncan’s growths respectively, gives some indication of the effects of multiple range tests. intercropping and irrigation as well as age. Table 1. Girth development (cm/tree) of tree species, at different ages (months), on entisols in the Sudan Sahel region of Nigeria. Mean tree girth (cm/tree) at various ages (months): Tree Species Tree Survival (%) 3 15 33 45 66 L. Leucocephala 3.21 11.69 18.56 19.65 22.58 87 A. Senegal 2.29 11.81 16.43 16.51 17.14 97 P. Juliflora 2.66 11.84 14.47 14.84 16.24 93 K. Senegalensis 1.96 13.81 16.62 16.69 18.88 76 A. Nilotica 2.95 13.84 16.62 18.64 24.42 99 E. Camaldulensis 1.88 8.5 11.14 11.88 18.33 59 A. Indica 3.29 12.13 14.43 16.15 21.17 81 Mean 2.61 11.69 15.48 16.34 19.82 84.57 Environment and Ecology Research 5(2): 161-166, 2017 163 Table 2. Current annual growth (cm/tree) of tree species, at different ages (months), on entisols in the Sudan Sahel region of Nigeria. Mean tree girth (cm/tree) at various ages (months): Tree Species Mean L. Reg slope 3 15 33 45 66 L. Leucocephala 12.84 8.48 4.64 1.00 1.67 5.73 3.65 A. Senegal 9.16 9.52 3.08 0.08 0.63 4.49 2.55 P.