Kenya: Trees help farmers restore soil fertility and increase crop production

June 24, 2019
A translation for this article is available in French Swahili

Beatrice Wamalwa smiles as she walks around her farm, surrounded by trees. She looks with amazement at the sheer number of trees and remembers vividly how different the farm looked in 2009.

Mrs. Wamalwa says that, because she didn’t plant trees on her farm, rains washed away the soil. Her land became infertile and production from her one-acre field dropped.

To change her fortunes, she started practicing agroforestry, a technique in which farmers plant trees or shrubs around or among crops. She explains: “I dug trenches around my farm and planted the fast-growing Grevillea robusta trees and local indigenous trees. Today, even if it rains heavily, my soil does not get eroded [because] it is protected.”

Mrs. Wamalwa is a mother of six and grandmother who lives in Tembelela village in western Kenya’s Bungoma county. She learned how growing trees conserves land and improves soil fertility from Vi-Agroforestry, a non-governmental organization that trained 51 members of her farming group a decade ago.

She says, “They taught us that cutting down trees caused our farms to get scorched by the sun—and hence it became less productive.”

Mrs. Wamalwa grows beans, indigenous vegetables, peppers (capsicum), maize, and sweet potatoes. She started planting Grevillea robusta trees in 2009 on the perimeter of her field and at specific points in the middle. The trees remain in the field indefinitely but do not compete for nutrients with her crops because their roots go much deeper. She says the trees have helped restore soil fertility and reduce erosion. Their timber is used to build furniture, and their nectar attracts bees.

When they drop their leaves, the trees provide Mrs. Wamalwa with about 30 to 40 centimetres of mulch, which also helps to conserve moisture and protect the soil. When the leaves decompose, they help restore soil fertility.

Albert Luvanda is a researcher at the Kenya Forestry Research Institute. He says farmers should prune their Grevillea robusta trees if they start interfering or competing with crops for food or sunlight.

Ezekiel Odeo is a farmer in the same area who started growing Grevillea robusta trees on his farm after the trainings by Vi-Agroforestry. He says that adopting agroforestry techniques has lifted him from poverty.

To avoid livestock eating or damaging Grevillea robusta trees after harvest, Mr. Odeo prunes the trees, then feeds the leaves to his goats and cows and uses the stems for firewood.

Amos Wekesa is a climate change advisor at Vi-Agroforestry. He says that farmers who practice agroforestry in the area have improved their food, income, and nutrition security. Mr. Wekesa adds, “They are able to feed their families in a better way, and have developed resilience to the impacts of climate change.”

Mr. Odeo says he earns over $2,500 US from farming because of agroforestry techniques. This has helped him educate his children and build a two-bedroom brick house for his family. He says, “Over 70% of my earnings today come from farming.”

This year, Mrs. Wamalwa harvested 60 bags of maize weighing 90 kgs each from her one acre, plus two bags of beans. Before she planted Grevillea robusta trees, she used to harvest three 90-kg bags of maize and about 40 kgs of beans.

She says, “It’s a miracle that my own trees are benefitting me and earning me extra cash.”