Kenya's soils are losing fertility, and farmers are paying the price in lower harvests and higher costs. A new mapping programme aims to tell them what their land actually needs.
Soil scientist Dr Caroline Kundu of the Kenya Agricultural and Livestock Research Organization (KALRO) told the Daily Nation that 63 per cent of soils in Kenya's farming areas are acidic. About 70 per cent of soils nationally have low organic carbon, which helps crops take up nutrients.
The causes differ by region. In high-rainfall areas, including parts of Kakamega and Kericho, heavy rain washes nutrients out of the soil and makes it more acidic. Kundu said that in some places the pH falls below five, a level at which many crops struggle to take up nutrients. In dry areas, water loss and salt build-up make farming harder.
Farming practices add to the problem. Kundu pointed to "nutrient mining," where harvests remove nutrients that are never put back. Maize farmers, for example, often take away the stalks and leaves for animal feed, leaving little to rot back into the soil.
The result is higher costs and weaker yields. Kundu warned that farmers who apply fertiliser without testing their soil may use the wrong product, or make existing problems worse.
That is the gap SoilFER, the Soil Mapping for Resilient Agrifood Systems programme, aims to close. The United Nations reported on October 27 that more than 3,600 soil samples have been collected and mapped across 45 counties. The programme is run by the Food and Agriculture Organization (FAO) and KALRO, with funding from the United States Department of State and Japan. Results are sent to farmers' phones, and selected farmers are trained as "soil doctors" to teach others.
Kakamega farmer Agness Munialo, a trained soil doctor, said farmers used to pile on fertiliser to chase higher yields. "Now we know better," she said.
Kenya is one of seven countries in the programme. The Nation reports that Kenya has collected over 3,600 of the 40,000 samples targeted across all seven.
Agriculture Cabinet Secretary Mutahi Kagwe says mapping should guide government spending as well as farm decisions. "Subsidy without a soil test is sympathy. It is not strategy," he said.
Kundu cautions that a map does not solve the problem on its own. Sampling every farm is costly, she said, so the work must continue, and farmers must be able to use what it finds. Her advice is simple: leave some crop residue on the field, or return manure to it, to rebuild organic matter.
