Soil Type Drives Maize Performance in Zambia Despite Identical Climate and Farming Practices

Source: Supplied | FAO/ZARI

In Zambia's Southern Province, maize grown under the same climate conditions and farming practices performed very differently depending on the soil type. While one soil type proved unsuitable for maize, another was found to be highly suitable, despite no visible differences above ground.

The findings highlight a challenge faced by farmers around the world. Soil conditions can vary significantly across short distances, meaning neighbouring fields may receive the same rainfall and management while producing very different results.

Understanding these differences is becoming increasingly important as farmers look to improve productivity while making more efficient use of limited resources. Rising fertiliser prices and recent supply disruptions have also reinforced the need to make better-informed decisions about crop selection and input use.

While farming decisions have traditionally been guided by climate, seed varieties, management practices and fertiliser recommendations, advances in soil mapping and crop suitability analysis are making soil information more accessible. By combining soil, climate, terrain and crop data, researchers can identify which crops are most likely to perform well in specific locations and where production constraints may exist before resources are committed.

Source: Supplied | FAO/ZARI

Using soil data to support farming decisions

These insights are being generated through initiatives such as the Soil Mapping for Resilient Agrifood Systems (SoilFER) programme, led by the Food and Agriculture Organization of the United Nations (FAO) with financial support from the governments of the United States and Japan.

Drawing on soil information, environmental data and crop suitability modelling, the programme aims to improve understanding of soil fertility and land suitability to support agricultural management decisions across different landscapes.

One of the tools developed through the programme is the SoilFER CropSuit App, which allows users to assess how different crops are likely to perform under specific soil, climate and management conditions.

Using the app in Zambia's Southern Province, analysts assessed maize production under rainfed, low-input conditions across different soil types. Leptosols, which are generally shallow and stony soils, were classified as unsuitable for maize production, while Luvisols, which are typically more fertile, were rated as highly suitable and offered substantially higher attainable yields.

The assessment also identified cassava, cowpea and fonio as highly suitable alternatives under the Luvisol scenario, demonstrating opportunities for crop diversification and adaptation.

Source: Supplied | FAO/ZARI

Supporting more informed agricultural planning

The findings highlight the potential for soil intelligence to support agricultural planning, particularly in countries such as Zambia where improving productivity and strengthening climate resilience remain priorities.

"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," says Rodgers Kabiti of the Zambia Agriculture Research Institute (ZARI) and National Focal Point for the SoilFER Project.

"This tool has strong potential to support Zambia's agricultural transformation by reducing crop failure risks and promoting more sustainable land use."

"By integrating soil, climate, terrain and crop information into a single platform, we created a system that helps users understand local constraints and identify suitable crops for specific locations" says Rutendo Mukaratirwa, FAO Agro-Ecological Zoning Specialist and one of the developers of the CropSuit App.

The application has also been designed to be adapted to country-specific priorities and agricultural conditions as it is adopted and refined over time.

The Zambia assessment highlights an important consideration for farmers and policymakers alike: before decisions are made about fertiliser, irrigation or seed varieties, understanding whether a crop is suited to the soil may be one of the most important factors in improving agricultural outcomes.