By Beatrice Nakibuuka
In the heart of Uganda’s farmlands—from the maize-rich plains of Masindi, Mubende, Kiboga, Kasanda, and Luwero in the Central region, and Kakumiro and Kiryandongo to the matooke fields of Mbarara—farmers are constantly searching for ways to increase crop yields.
With a growing population and demand for food surging, fertilisers have become a key tool in this battle for productivity. But while chemical fertilisers promise higher yields, they also pose long-term risks to the very soil that sustains agriculture. If used improperly or excessively, these synthetic boosters can deplete natural nutrients, disrupt microbial life, and even reduce soil fertility over time.
In this article, we explore why fertilisers are important for productivity, how artificial fertilisers can harm the soil, and what Ugandan farmers can do to balance food security with soil sustainability.
A boost for higher yields
Uganda’s soils were once known for their natural fertility. However, decades of continuous farming, deforestation, erosion, and climate change have degraded many soils, especially in areas with intense cultivation. To cope with this, many farmers turn to fertilisers to replenish nutrients and enhance growth.
Fertilisers supply essential nutrients such as nitrogen (N), phosphorus (P), and potassium (K), often referred to as NPK. These nutrients play crucial roles:
Nitrogen supports leafy growth in crops like maize and cabbage; phosphorus is essential for root development and flowering, and potassium enhances overall plant health and disease resistance.
“When used correctly, fertilisers can double or even triple yields,” says Fanuel Ongua, a soil microbiologist at the National Agricultural Research Laboratories (NARL). “For example, maize yields can go from 1.5 tonnes per hectare to over 4 tonnes with the right application of fertiliser.”
Indeed, Uganda’s agricultural development strategy encourages the use of fertilisers to reduce food imports and improve farmer incomes.
How artificial fertilisers harm soil health
Despite their benefits, Bernard Bwambale, the programme head at Global Consumer Centre (CONSENT) remarks that artificial fertilisers can also degrade the soil if not managed properly. Unlike organic fertilisers, which improve soil structure and biodiversity, chemical fertilisers offer only nutrients and nothing else. When used year after year, they can trigger several problems:
“Repeated use of nitrogen-based fertilisers such as urea and ammonium sulphate can lower the soil’s pH, making it more acidic. Acidic soils hinder the absorption of important nutrients, stunting plant growth,” he says.
It is also important to note that chemical fertilisers do not add organic matter to the soil. Without organic inputs like compost or manure, the soil becomes less spongy and more prone to compaction and erosion.
Soil is alive with billions of microorganisms that help convert organic material into nutrients. Excessive use of artificial fertilisers can kill or suppress these microbes, reducing soil vitality.
Nutrient imbalance
Focusing only on NPK can lead to the neglect of secondary nutrients like calcium, magnesium, and sulphur. Over time, this imbalance can reduce crop quality and resilience.
“We are seeing more farmers with sick soils,” says Mary Atim, a soil scientist based in Lira. “The yields may be high in the short term, but the long-term damage can be catastrophic if we don’t change how we use fertilisers.”
Understanding the root of the problem
One major reason artificial fertilisers become harmful is the lack of soil testing. Many Ugandan farmers apply fertilisers blindly, without knowing what their soils actually need.
According to Ongua, soil testing should not be limited to nitrogen, phosphorus, and potassium (NPK) levels but should also include microbial activity and micronutrient availability.
“Understanding the biological composition of your soil and how it functions provides valuable insights into nutrient cycling and soil health,” Ongua says. “A bountiful harvest is directly linked to the presence of both macro- and micronutrients essential for plant growth. Monitoring soil mineral content throughout the growing season can help farmers make informed decisions to improve soil and crop health.”
Government extension services, NGOs, and private labs across the country are increasingly offering soil testing at affordable rates. Yet uptake remains low due to lack of awareness, costs, and accessibility.
