Summary
This spatially representative survey of 1,600 locations in Malawi identified soil properties and environmental factors explaining geospatial variation in maize grain zinc concentration, a critical dietary micronutrient source in sub-Saharan Africa. Soil pH, labile zinc forms (measured via isotopic dilution), and available zinc (DTPA-extractable) emerged as significant predictors within a linear mixed model framework, whilst temperature also contributed to spatial variation. The findings provide a basis for spatially targeted interventions to improve dietary zinc intake through staple crop biofortification.
UK applicability
The mechanistic understanding of soil factors controlling grain zinc concentration may have limited direct application to UK cereal production, where zinc deficiency is not a public health priority and soil zinc status is generally adequate. However, the methodology combining isotopic dilution with spatial modelling could inform UK soil-testing protocols or precision agriculture applications.
Key measures
Maize grain zinc concentration (mg/kg); soil pH (water); isotopically exchangeable zinc (Zn_E); DTPA-extractable zinc (Zn_DTPA); downscaled mean annual temperature
Outcomes reported
The study identified soil pH, isotopically exchangeable zinc, and DTPA-extractable zinc as significant predictors of maize grain zinc concentration across 1,600 surveyed locations in Malawi. Mean grain zinc concentration was 21.8 mg/kg with robust spatial variation demonstrated at distances up to approximately 100 km.
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