Zambia: What soil can tell farmers about what to plant (FAO)

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The difference between a successful harvest and a disappointing one is not always visible from the surface.

In Zambia’s Southern Province, maize grown under identical climate conditions and farming practices was found to be unsuitable on one soil type and highly suitable on another. Nothing above ground had changed. The difference lay beneath the farmers’ feet.

This is true far beyond Zambia. Around the world, farmers make decisions about what to plant, how much fertilizer to apply, and where to invest scarce resources. Yet, the soils that support those decisions can vary dramatically across short distances. Two fields may receive the same rainfall and the same management, while producing very different results.

Understanding these differences is becoming increasingly important as countries seek to increase productivity while making more efficient use of limited resources.

Recent fertilizer supply disruptions and rising input costs have further highlighted the need for more targeted agricultural decisions. When fertilizers are expensive or scarce, knowing which crops are best suited to local conditions becomes even more important for improving productivity and avoiding wasted investments.

For much of modern agriculture, decisions have been guided by climate, seed varieties, management practices, and fertilizer recommendations. But soil information is key to this decision – yet it has been harder to obtain, harder to interpret, and less readily available to those making decisions on the ground. Advances in soil mapping and crop suitability analysis are beginning to change that, making it possible to transform soil data into soil intelligence that can help farmers, advisers, and policymakers make better-informed decisions about crop selection and land management.

By combining information on soils, climate, terrain, and crop requirements, researchers can assess which crops are likely to perform well in specific locations and identify factors that may limit productivity. The resulting suitability assessments help indicate where a crop is likely to thrive, where production may be constrained, and where alternative crop choices may offer better opportunities. Such assessments provide a clearer picture of agricultural potential before resources are committed to farming.

The SoilFER CropSuit App is one tool generating these insights. This app allows users to explore how different crops perform under specific soil, climate and management conditions. Rodgers Kabiti works for the Zambia Agriculture Research Institute and is the national focal point for the SoilFER Project. He says, “The CropSuit App offers accessible, science-based crop suitability information that will help farmers, extension officers, researchers and planners make smarter decisions – from choosing the right crops for local agroecological conditions to managing soil fertility and diversifying crop production.”

Using this app in Zambia’s Southern Province, analysts examined how maize would fare under rainfed, low-input conditions where multiple soil types occur within the same area. Leptosols, for example, according to the World Reference Base for Soil Resources, are generally shallow, stony soils that can restrict crop growth, while Luvisols are often more fertile soils with greater agricultural potential.

When Leptosols were identified as the dominant soil, maize was classified as not suitable. When the assessment was repeated using Luvisols at the same location, maize suitability increased to very high, together with a substantial increase in attainable yield.

The comparison suggests that soil characteristics alone can have a profound influence on agricultural outcomes. So while a decision may appear sound when viewed through the lens of climate alone, it looks very different once soil conditions are taken into account.

Mr. Kabiti adds, “This tool has strong potential to support Zambia’s agricultural transformation by reducing crop failure risks and promoting more sustainable land use.”

The SoilFER CropSuit App was developed as part of the Soil Mapping for Resilient Agrifood Systems program, or SoilFER, an initiative of the Food and Agriculture Organization of the United Nations. SoilFER is implemented with the financial support of the Government of the United States of America and the Government of Japan. Drawing on soil information, environmental data and crop suitability modelling, the program supports efforts to better understand soil fertility and land suitability, guiding management decisions and practices across different landscapes.

The analysis in Zambia also identified alternative crops that may perform well under the same conditions. Cassava, cowpea and fonio emerged as highly suitable options in the Luvisol scenario, highlighting opportunities for diversification and adaptation.

The potential value of such information extends beyond a single assessment. In Zambia, where improving productivity and strengthening climate resilience are national priorities, tools that help match crops to local conditions can support more informed agricultural decisions.

The lesson from Zambia is straightforward. Before questions about fertiliser, irrigation or seed varieties can be answered, there is another question that comes first: is this the right crop for this soil?

The answer may determine far more than farmers once realised.

This story is based on an article by the FAO titled “Right crop, right place: What soil can tell us about the future of farming.” To read the full story, go to: https://www.fao.org/newsroom/story/right-crop-right-place/en

And to use the CropSuit App, go to: https://data.apps.fao.org/soilfer/cropsuit