This archive report was first published on 5 June 2020.
Native to Asian countries such as India, Sri Lanka, Malaysia, Indonesia, and the Philippines, Sesbania sesban has also spread to Africa, where it grows from Senegal in the west to Somalia, Egypt, and South Africa.
Its adaptability to various ecological zones in Kenya, ranging from altitudes of 350m to 1,900m above sea level and annual rainfalls of between 400mm and more than 1,400mm, makes it a valuable tree species.
Commonly found in riverine vegetation and the margins of fresh water lakes like Naivasha and Baringo, Sesbania sesban also thrives in many seasonal swamps.
Before discovering that Acacia xanthophloea can withstand waterlogging, Sesbania sesban was the only tree that grew on the swampy part of my farm in Soy.
According to A Guide to Tree Planting in Kenya, a publication of the Kenya Forestry Research Institute, any tree species selected for planting must be able to fulfill specific objectives, including soil and water conservation, improvement of soil fertility, animal fodder, shade, and saleable products.
Sesbania sesban ticks many of these boxes, although its potential has not been fully exploited in Kenya, unlike in its native Asian lands.
The tree improves soils by fixing nitrogen and its leaves form green manure, making it an ideal cover crop for crops such as turmeric, ginger, and vines.
Studies have shown that one-year fallow with Sesbania sesban can increase maize yields from two to four tonnes per hectare without the application of nitrogen fertilizer.
However, according to Useful Trees and Shrubs for Kenya by P. Maundu and B. Tengnas (World Agroforestry Centre), Sesbania sesban harbors root-knot nematodes, making it unsuitable for combination with crops sensitive to nematodes like bananas and potatoes.
As a food source, Sesbania sesban is rich in vitamins B1, C, phosphorous, and iron, making it an essential constituent of any diet.
Its young leaves, flowers, and pods are used in curries and soups, lightly fried, steamed, or boiled, while its seeds are high in protein (33.7 per cent).
Sesbania sesban foliage is used as fodder for cattle, goats, and sheep, and a study published in Livestock Science attests to its suitability for animals.
Introduced in the Ethiopian highlands for livestock feed and soil conservation, Sesbania sesban supplementation improved intake and digestibility of basal diet and growth rate of animals.
Its various parts, including bark, roots, leaves, gum, and flowers, are used in traditional medicine to treat illnesses like rheumatism, leprosy, gout, and liver disorders.
A tea made from its leaves is believed to have antibiotic properties, and many herbalists have come to my Soy farm to harvest parts of this tree.
As a source of firewood, Sesbania sesban trunks may be used for light construction and have been used as poles for temporary shelters and sheds.
However, they do not last long as they are vulnerable to insect attacks.
Propagation is by direct sowing at site or wilding, and seeds cost Sh1,500 a kilogramme at Kenya Forest Research Institute seed shops.
They require pre-sowing treatment to soften the hard coat for faster germination, which is done by soaking in hot water for 12 - 24 hours.
