From degraded soil to thriving farms
Kenyan farmer George Muturi says the stinky wooden shack teeming with redworms has helped rescue his land from the soil degradation caused by chemical fertilizers. Agriculture is vital to east Africa's economy, but a 2025 soil report by the Heinrich Boll Foundation, a German think tank, found that more than 40% of the region's soils were degraded — in part by overuse of chemical fertilizers — costing more than US$65 billion a year in lost productivity.
Fertilizer prices have also increased this year due to the war in the Middle East, driving a search for alternatives. In Kenya, 32% of cropland was classified as strongly acidic in the soil report, with changing climatic conditions and intensive farming practices also to blame.
Muturi, a 31-year-old farmer in Lari, about 50 kilometers from the capital Nairobi, switched to "vermicompost" — using redworms that turn food and crop waste into a natural, nutrient-rich form of fertilizer. He says moving away from chemical fertilizers has boosted his harvests.
"Vermicomposting was a breakthrough for us... our soil is much better in a way that we can be able to plant and sustain the crop even during dry season," he told AFP during a visit to his farm.
About 70 beds, each filled with at least 5,000 redworms, hold layers of food and crop waste mixed with cow dung that the worms break down over six weeks to create vermicompost. Multiple studies have shown that vermicompost can improve soil structure, organic matter, and water retention.
Muturi acknowledges that it is some way off being used on an industrial scale, since very large quantities are needed to match the effects of synthetic fertilizers. But he says he has seen positive results on his vegetables and has started selling the compost to other farmers around the country.
Bugs as allies
About 200 km away in Nakuru County, Robert Mwangi, founder of Nawiri Organics, uses black soldier fly larvae to break down organic waste. Mwangi collects waste from the city's main market in Njoro constituency and feeds it to the larvae. The larvae break down the waste into frass, an organic fertilizer, and the mature larvae are dried and used as animal feed.
Mwangi processes about 10 tonnes of food waste per week, roughly 40 tonnes per month. He says conventional fertilizers create an acidic environment harmful to soil microbes, while organic fertilizer improves soil productivity and fertility and reduces production costs.
"Demand has overwhelmed what we can produce," Mwangi said, reflecting the growing interest in organic alternatives.
Expert perspective
Agroecologist Harun Warui says chemical fertilizers address only one aspect of soil nutrition. He argues that farmers need to adopt a more holistic approach to soil health.
"Farmers are going to realize that year in, year out dependence on chemical fertilizer is not the solution," Warui said.
As fertilizer prices remain elevated and soil degradation continues, these insect-based methods are gaining traction among Kenyan farmers seeking sustainable and cost-effective ways to restore their land.