When Benson Wanjala began farming in his western Kenya village 25 years ago, his 10-acre plot produced a robust 200 bags of maize. Now, his harvest has dwindled to just 30 bags. He blames the decline on the acidifying fertilizers introduced in Kenya and other African countries in recent years. These fertilizers initially increased his yield but eventually lost their effectiveness. The Kenyan government introduced a fertilizer subsidy in 2008 to make these chemicals more accessible to smaller-scale farmers.
According to the agriculture ministry, 63% of Kenya’s arable land is now acidic. This has contributed to reduced production of staple crops like maize and key exports such as horticulture and tea. In 2022, maize production fell by 4% to 44 million tons, although the Food and Agriculture Organization did not provide specific reasons for this drop.
The agriculture ministry has not responded to inquiries, particularly following a scandal in April involving counterfeit fertilizer. The fake products, which were simply quarry dirt, were distributed through the national subsidy program. President William Ruto announced that about 7,000 farmers who bought the counterfeit fertilizer would receive proper replacements.
Soil health issues are escalating as Africa faces challenges in feeding itself. Despite having 65% of the world’s remaining uncultivated arable land, the continent spends around $60 billion annually on food imports, a figure projected to rise to $110 billion by 2025 due to growing demand and changing consumption patterns, according to the African Development Bank. In May, Kenya hosted an Africa-wide soil health summit to address declining production, climate change, and other factors affecting food security. Agriculture plays a crucial role in Kenya’s economy, contributing over a quarter of its GDP.
At the summit, Stephen Muchiri, executive director of the Eastern Africa Farmers Federation, emphasized the need to return to traditional farming methods to restore depleted soils. He advocated for practices like crop diversity and minimal soil disturbance.
“Inorganic fertilizers were never intended to be the cornerstone of crop production,” Muchiri stated, adding that commercial farming practices have led to soils becoming poor, acidic, and depleted of biomass. He suggested that farmers should implement crop rotation and use compost from livestock, such as goats, to help restore soil fertility. “There must be some kind of transition and adaptation for our soils to regain their fertility,” he said.
Experts indicate that soil acidity contributes to land degradation by reducing the availability of essential nutrients for plants and making the soil more prone to structural decline and erosion.
Bridget Mugambe, program coordinator for the Alliance for Food Sovereignty in Africa, recommended phasing out chemical fertilizers. “Soil health requires more than the temporary solutions offered by chemical fertilizers. In fact, these fertilizers have severely harmed our soils in Africa. We need a more holistic approach to soil management,” she said.
The African Union soil health summit, which in 2006 encouraged the increased use of chemical fertilizers, has now adopted a 10-year plan. This plan aims to boost investment in local production of both organic and chemical fertilizers and to triple their use to enhance agricultural output.
During the summit, AU commissioner for agriculture Josefa Leonel Correia Sacko highlighted that the continent loses over $4 billion worth of soil nutrients annually.
Kenya is heavily dependent on imported fertilizers due to limited local production, with the European Union being the primary supplier, followed by Saudi Arabia and Russia.
John Macharia, Kenya manager for the Alliance for a Green Revolution in Africa, stated that the recent fertilizer scandal should not deter farmers. “It remains crucial that we collaborate with the government to ensure the correct fertilizers are available in stores,” Macharia said. He advocated for the use of both chemical and organic fertilizers, provided they address specific soil issues, and emphasized that soil analysis should guide farmers.
Declining soil quality is a significant food security issue across Africa.
In Zimbabwe, once a major agricultural hub, around 70% of the soil is now acidic, according to the government. Previous attempts to improve soil quality with chemical fertilizers led to a reduction in organic matter due to improper usage.
“Before mineral fertilizers were introduced, our ancestors understood that adding organic manure made the soil fertile and improved crop performance,” said Wonder Ngezimana, a crop science associate professor at Marondera University of Agricultural Sciences and Technology in Zimbabwe. “This practice has been a traditional norm in Zimbabwe and throughout Africa, where people have historically used available organic matter to enrich the soil.”
This includes using animal manure, grass, leaves and twigs, crop residue, ash, and compost. However, many Zimbabwean farmers have lost their cattle due to recent droughts, making it difficult to produce enough organic matter. “Farmers are struggling to maintain soil health because they can’t generate sufficient quantities of organic matter,” said Ngezimana.
AGRA has advised farmers to test their soil’s acidity and use lime to address high acidity levels. However, farmers find both soil testing and lime application to be limited and costly. Soil testing services are offered by government agricultural agencies, public universities, and private organizations, with prices ranging from $20 to $40.
Wanjala, the farmer, mentioned that he cannot even afford cattle for manure, let alone seeds. “I can’t bear additional expenses,” he said.
