Previous Page Table of Contents Next Page


ACACIA NILOTICA*

DISTRIBUTION

Is one of the most widely distributed of the Acacias, and is tolerant of a range of conditions. It prefers savannah sites including wooded grasslands, Miombo woodlands, deciduous woodlands and costar bushland. A. nilotica is found in Dodoma, Tanga, Morogoro, Mbeya, Coast Region and Dar es Salaam (Rulangaranga 1989).

Minimum Attitude (m):

0

Maximum Altitude (m):

500

Minimum Rainfall (mm):

200

Maximum Rainfall (mm):

1500

Maximum Temperature (C):

50

REQUIREMENTS

Soil Requirements: Grows on sandy loam fine-textured soils, coastal sandy, rocky, soils, heavy clays, or black cotton soils (RSCU 1992). It is also found on loamy lateritic or calcareous sites (don Maydell 1986).

Light Requirements: Strongly demanding.

Influential Factors: Susceptible to fire, frost, and browsing by livestock. Tolerates seasonal flooding and thrives with a certain amount of seasonal waterlogging (Teel 1984). Mature trees are killed if flooding lasts more than 8 months. It can withstand drought. Resistant to termites but liable to attack by various wood borers and Bruchid beetles attack seeds (Webb 1984). Can form thickets (Palgrave 1988).

PROPAGATION

Means of Propagation: Direct sowing, cuttings, or nursery seedlings.

Seeds per kg:

5000-10000

Germination Rate (%):

75-95

Germination Length:

7 days

Seed Sources:

1500 TSH per kg - Tanzania: National Seed Centre 1991.

Seed Treatments: Pods are long and pendulous. They are mature after turning from green to black, and have a strong, fruity smell. Each pod contains 10 to 15 seeds. The pods do not break open, but disintegrate on the ground. Collect seed pods from 5 to 7 year old trees and dry in the sun. Separate seed from pods by beating with a stick and clean by winnowing. Separate also through immersion in water. Clean seed may be stored in gunny bags, tins, or baskets in a cool dry place. If stored in air tight containers there is little loss in germination for up to 3 years (Parkash 1991).

Fresh seeds need no pretreatment but older seeds should be nicked and/or soaked for 24 hours in water or in H2SO4 for 5 to 15 minutes (don Carlowitz 1986, Teel 1984). Alternative methods include keeping the seed in a moist cow dung-heap for 2 to 3 days or by feeding the pods to sheep and goats and then collecting the seed from their droppings. Treated seed should be planted promptly, and not allowed to be stored nor become dry (Parkash 1991).

Seedling Management: Requires 14 to 18 weeks in the nursery before outplanting, which should coincide with the rainy season (Weber and Stony 1986). Sow in polyethylene pods in March or April, or preferably, in situ. If direct sowing, place 3 seeds per pit and thin out when 60 cm high.

SILVICULTURE

Planting Types: Afforestation and enrichment planting. It is recommended for agroforestry in arid and semiarid areas and for erosion control.

Growth Factors: Grows vigorously with a wide ranging root system, it may become invasive (Palmer and Pitman 1972). It is medium to fast growing on good sites. Growth is rapid when soil moisture is adequate.

Growth Cycle: Short lived (Webb 1984). Long foliation during dry season (until end of February) indicates that it is desirable to have a high ground water table (don Maydell 1986).

Management Systems: Avoid excessive watering. Seedlings are susceptible to damping off. Shading is necessary to prevent surface drying (Parkash 1991). May be outplanted in pits 30 to 50 cm3 deep, spaced 3×3 m or 4×4 m. Linear spacing is 5 to 10 m, such as along roadsides, using 1 year old seedlings (Parkash 1991). Spacing of 2×2 m is also recommended. When young, this is a good intercropping species.

Regular thinning can be done on a 5 year cycle in the 5th, 10th, and 20th years. Spacing between the trees should be roughly equal to their height (Parkash 1991). Lopping and pollarding are also common management techniques.

Careful weed control in plantations is necessary. Weeding is essential for 2 years since young plants do not compete well with grasses or weeds. Plants should be protected against flood inundations and stagnant water during the early years. Goats can cause damage in young forests so fencing of areas under regeneration is essential. After about 1 year, cattle do not cause much damage, and may even help in keeping vegetation down. The area can be opened to cattle once established.

IMPORTANT USES

Use #1: MEDICINE
The Gogo Tribe consider A. nilotica to be very important for medicinal purposes and various medicinal uses are reported in the literature. Those mentioned specifically for Tanzania include: juice from phloem strands is used for treating sore throats, leaves are boiled in a tea for chest pain and pneumonia, and boiled roots are used for stomach problems (Rulangaranga 1989). Other uses mentioned include using powdered roots mixed with water for toothaches, chest and stomach problems and to cure gonorrhoea. The bark and leaves are also used to treat colds, diarrhoea and dysentery. A drink is prepared from the liquid of boiled bark.

Use #2: FUEL
The heartwood is especially valued for both firewood and charcoal. It has a calorific value of 4950 kcal per kg.

The wood is dense, heavy, termite resistant, and water repellent (Teel 1984). It is used for fencing, tool handles, and boat construction.

Use #3: FODDER
Pods, leaves, and shoots are important sources of fodder. The leaves are reported to contain up to 12% protein and 21% crude fibre (Westman Draft). In some parts of India it is one of the most valuable fodder trees producing up to 80 kg of pods per year (don Maydell 1986).


Previous Page Top of Page Next Page