Though shea nut trees typically grow wild, crop scientists at National Agricultural Research Organisation (Naro) have researched on the tree for more than a decade and unleashed a stunning result that it really does well under domestication. The good news now mean that the tree currently feared be facing extinction could be saved once farmers pick up efforts to invest in its husbandry.
Shea tree (Vitellaria paradoxa) is an important indigenous fruit tree in Uganda that takes about 25 years to mature. The fruits resemble plums and take about four to six months to fully ripen (bear fruits once a year). However, when faced with adverse environmental factors such as bush fires, the shea nut tree may become stunted and take up to 15 years to bear fruit.
The shea tree grows within the shea belt about 5,000 kilometres long through 21 countries in Africa (from Senegal to Ethiopia). In Uganda, the trees grow in Karamoja, West Nile, Nakasongola, Teso, Lango and Acholi regions.
Hundreds of farmers who thronged the Zonal Agricultural Research and Development Institute at Ngetta in Lira District recently for the 17th Seeds of Gold Farm Clinic were surprised by the ease with which the plant can be domesticated.
Moses Okao, an agroforestry scientist at Ngetta ZARDI coached the farmers through the process of raising the plant untill harvest time. “It is one of the most economically-valuable trees that a farmer needs to plant because it brings in a lot of cash. All of us have the land and the energy except that we now need to learn how it is raised,” Okao told farmers.
How to plant
Seeds meant for planting should not be dried but sown as soon as possible because their viability is very short, when fresh seed is used, germination is 90 per cent at 25°C and 30°C. Seed can be planted directly in the field or in the nursery. Seed-beds are made of a mixture of organic compost and sand. After one year, seedlings are transplanted in the nursery or planted directly in the field. Those grown in containers are transplanted after one to two years.
According to Okao, planting the tree begins with the selection of vigorous seedlings from the nursery for field planting just at the onset of the rains.
It does well in light (sandy), medium (loamy) and heavy (clay) soils, but prefers well-drained soil with acidic, neutral and basic (alkaline) soils although it can also
grow in nutritionally poor soil. An area of well drained soils preferably sandy or clay makes a great deal.
However the plants should be watered in the early stages to ease absorption of nutrients from the soil and to protect the soil from other dry conditions.
“Upon field preparation, the seedlings are planted with a spacing of at least eight metres between each tree. We recommend that you use organic fertilisers because inorganic fertilisers destroy soil quality,” he told farmers. “Ensure that the young trees are not covered with weeds by carrying out spot or line weeding. Where necessary, dig fire lines or carry out bush clearing to minimise damages by wild fires,” he added.
He said that grafting is highly recommended to enhance early maturity of shea trees: “Well established and maintained trees can be grafted with mature scions when they reach knee height, approximately three years after planting.”
“It takes approximately 20 to 25 years for a shea tree to mature and begin fruiting. Late maturity in exceptional cases can be associated with wild fires which keep destroying young trees, animal herding and damages to the trees during land preparation and farming.”
To produce quality shea nut kernels, Okao says that a farmer has to collect only fruits that are fully matured and are usually soft and sweet in taste. “The pulp (flesh) is then removed immediately to avoid fermentation and dry in the sun on a clean tarpaulin or solar drier for about four to six days. It is then shelled immediately after they are dry to avoid the nuts from getting dump,” he said.
He adds that the nuts are then sorted and graded according to quality to be packed in bags.
Although modern methods of cold compress is taking prominence currently, traditional methods where the nuts are roasted and grinded to realise a paste that it then boiled in hot water or kneaded by hand to separate out the butter oils is still in practice.
Shea nut butter is one of the many products one can get from the shea nut. The shea butter is categorised in five grades: A (raw or unrefined, extracted using water), B (refined), C (highly refined and extracted with solvents such as hexane), D (lowest uncontaminated grade) and E (with contaminants). Commercial grades are A, B, and C. The colour of raw (grade A) butter ranges from cream (such as whipped butter) to greyish yellow. It has a nutty aroma which is removed in the other grades.
Grade C is pure white. While the level of vitamin content can be affected by refining, up to 95 per cent of vitamin content can be removed from refined grades (i.e., grade C) of shea butter while reducing contamination levels to undetectable levels.
Although it is largely consumed in northern Uganda as cooking oil for frying and making stew, the butter has gained commercial values where artisan soap makers apply the butter, besides using it as waterproofing wax, for hairdressing, and candle-making.
“The extract is also used to make numerous products such as medicinal creams, cooking oil and chocolates,” said Okao. In apiculture, the tree is exceptionally good for bee forage and produces high quality honey which is golden brown in colour.
Shea nut benefits
Fodder. Shea nut cake, a residue that remains after shea butter extraction is a good supplement for animals and poultry feeds.
Timber. Wood is traditionally used for making house posts and support poles, stakes and fencing, joinery, seats, household utensils, durable platters and bowls, pestles and mortars and tool handles.