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Acacia nilotica (L.) Willd ex Del.
Common Names “Motse,” Egyptian Mimosa, Egyptian thorn, red-heat, kudupod, “sweet smell,” babul (India), prickly acacia, black thorn, Nile acacia, algaroba, gum arabic tree, babar (Pakistan), sunt (Arabic)1, 2, 4
Native Range / Natural Occurrence Among several varieties, two most widely grown for fuel are: Acacia nilotica subsp. indica: is native to Sind, Punjab, and Deccan areas of Pakistan and India1.Acacia nilotica subsp. nilotica: is native to Africa including Egypt, Mozambique, Sudan, Natal, Zambia and Botswana1, 2. Drier areas of Africa – Senegal, Egypt, South Africa. Asia – from Arabia to India, Burma, Sri Lanka3
Introduced Range / Presence and Distribution Australia, Cape Verde islands, Indonesia, Iran, Iraq, Nepal, Vietnam3; West Indies – naturalized there.
Native Habitat / Ecology General Optimal Condition: Moderate-sized tree that can withstand extreme environment. Favors steams in semi-arid areas. Can survive very arid sites, thrives under irrigation and endures floods2. Some African subspecies occur in wooded grassland, savanna and dry shrub forests. Other African subspecies are restricted to riverine habitats and seasonally flooded areas3. Subspecies nilotica is adapted to periodic flooding followed by extended droughts1. Elevation: up to 500 m (in Himalayas)1; sea level to over 2000 m3 Mean Annual Rainfall: 250-1500 mm, 380-2280 mm (reported to tolerate)2 Mean Annual Temperature: 18 to 28 °C 2, -1 to 50 °C 3 pH range: 5.0-8.02 Soil: Grows on variety of soils even poor ones. Prefers alluvium but also grows well on heavy, clay soils. Tolerance: Seedlings are shade intolerant and require full sun. Frost tender when young1.
Species Descriptions General: Varies from a shrubby tree with wide spreading flat crowns in savanna habitats to a 20 m tree in riverine situations3. Generally deciduous during dry season, though riverine subspecies can be almost evergreen. Easily recognized by its bright yellow, sweet-scented flower heads and sweet-smelling pods1. Height: 2.5-14 m, til 20 m (when favorable, moist condition) Diameter: Adds 2-3 cm each year; 16.5 cm (25 year old)7 Mature Age: Maturation takes 8 months (ideal) to 12 years (harsh condition). 5-7 years are typical6. Rotation Age: 20-30 year rotation1. Growth: Growth rates are highly variable. Fast growing tree under favorable soil irrigation.
Seed Handling Seed Harvest: The pods are mature after turning from green to black. The pods do not break open (indehiscent*) but disintegrate on the ground. Seeds are hard coated. Collect seed pods from 5-7 year old trees and dry in the sun. Extract seeds by beating or pounding the pods or collected from animal pens after the pods have been eaten. Clean by winnowing. Separate also through immersion in water3,8. Seed Storage: Store in cool and dry place with good air circulation. If stored in air tight containers there is little loss in germination for up to 3 years8. Can remain dormant in the soil for long periods4.
Cultivation / Nursery Establishment Propagation: Generally by seeds1 but can also be established by seedling3. Direct seeding is common practice but need to watch for browsing animals, inadequate soil moisture or weed competition. Fresh seeds can be planted directly but stored seeds need pre-germination. Pre-germination treatment: Seeds need to be scarified for good germination. There are several ways: a) Mechanical scarification – works best for small seed lots. Nick* the seed coat with nail clippers or sandpaper5. b) Acid scarification – from 60-120 minutes. c) Pour boiling water over seeds and allow them to soak 24 hours. d) Pods are fed to animals (cattle, goats) and scarified seeds are recovered or confine the animals in the area that is to be reseeded1. Germination Time: 1-3 weeks7; 7 days8 Germination Rate: varies from 5-97% 7; 75-95% 8 Sowing and Planting: Seeds can be naturally sown when they are eaten and scarified through animal’s gut. The seeds are then subsequently deposited in dung pats6. Seeds also can be scattered by hand. Growth and Development: Sow 10-15 seeds at 2x3 m space. Thin to 3-4 seedlings after 3-4 months. Seedlings are shade intolerant. Seedlings require full sun and frequent weeding. Further thinning occurs at 5 year intervals. A spacing of 3 x 3 m between trees is common. Rotations are 20-25, 30 years1, 3.
Yields Mean Annual Increment: 10.5-13 m3/ha 3 Annual Biomass Production (bark): 12 tons/ha (at 600 plants/ha, 15 year rotation) Calorific Value: 4,800 kcal/kg (sapwood); 4,950 kcal/kg (heartwood) Specific Gravity: 0.67-0.68 (heavy) 1 Basic Density: 650-830 kg/m3 Number of Seeds by weight: 5,000-16,000 seeds/kg Number of Seeds per pod: 8-16 seeds/pod3; 10-15 seeds/pod8
Uses Firewood / Charcoal: Excellent firewood and charcoal. Used to fuel locomotives, river steamers and boilers in some small industries. Timber / Wood: Hard, tough wood. Resistant to termites, water. Popular for railroad, tool handles, carts, oars, posts, buildings. Attractive wood good for carving, turnery and boatbuilding1. Pulp and Paper: Wood is good for paper and pulp making7. Forage / Fodder: Leaves, tender pods and shoots used as forage for goats, sheep, camels. Seeds are also a valuable cattle food2. Pods contain 12-15% crude protein1. Rich in mineral. Agroforestry: Makes an ideal windbreak. Nodulates and fixes nitrogen. Land Rehabilitaiton: Used on degraded saline/alkaline soils as well as flooded areas2, 3. Tannins: Bark has high levels of tannin (12-20% for subspecies indica). Used for tanning and dyeing leathers. Pods of subspecies nilotica used for tanning. Gum Arabic: Tapped for gum Arabic by removing bark. Used in making candles, inks, matches, paints2. Medicinal Use: Extract of the fruit, rich in tannin (18-23%) has medicinal use as a powerful astringent, molluscicide and algicide2,3. The gum is also used in medicines3.
Limitations/Concerns/Comments/Additional information Trees are extremely thorny and could become a major problem when introduced to areas where people do not traditionally use thorn trees3. Introduce to arid areas where need for firewood is absolutely critical1. Can become weedy when introduced out of its native range, especially in more humid zones. It is one of Australia's worst environmental weeds4. Trees coppice occasionally1.
References 1. Firewood Crops: Shrub and Tree Species for Energy Production, National Academy of Sciences, 1980. pp.98-99. 2. Duke, James, A. Handbook of Energy Crops. Unpublished. 1983. http://www.hort.purdue.edu/newcrop/duke_energy/Acacia_nilotica.html 3. Fagg, Christopher W. FACT Sheet: A quick guide to multipurpose trees from around the world: Acacia nilotica – Pioneer for Dry Land. FACT NET (formerly NFTA), c/o Winrock International. June 1992. 2p. Or on the web at: http://www.winrock.org/forestry/FACTPUB/FACTSH/A_nilotica.html 4. Pacific Island Ecosystems at Risk (PIER): Acacia nilotica. On-line: http://www.hear.org/pier/acnil.htm 5. http://tree.cabweb.org/Compendium/Acacia_nilotica.htm 6. Kriticos, D., Brown, J., Radford, I., Nicholas, M. Plant population ecology and biological control: Acacia nilotica as a case study. Biological Control. Orlando, Fla.: Academic Press. Oct 1999. v.16 (2) pp.230-239. 7. Dwivedi, A.P. Babul (Acacia nilotica): a multipurpose tree of dry areas. Jodhpur: Arid Forest Research Institute; Dehra Dun: Indian Council of Forestry Research & Education. 1993. 226p. 8. Hines, Deborah A.; Eckman, Karlyn. Indigenous multipurpose trees of Tanzania: Uses and economic benefits for people: Acacia tortilis. Ottawa, Ontario, Canada. 1993. Or at: http://www.fao.org/docrep/X5327e/x5327e0e.htm#acacia%20nilotica*
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