In the heart of Malawi, a groundbreaking study is challenging conventional wisdom about zinc fertilization in maize production, offering promising insights for farmers and the agriculture sector at large. Researchers have discovered that applying zinc at rates significantly higher than the current national recommendation can boost maize productivity and nutritional quality, with residual benefits that persist into the following growing season.
The study, led by Lester Botoman of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) at Chitedze Agricultural Research Station, evaluated the residual effects of soil-applied zinc on maize grain yield, zinc concentration, and uptake. The findings, published in *Frontiers in Soil Science*, reveal that applying 30 kg of zinc per hectare—30 times the current national recommendation of 1 kg ha⁻¹—resulted in a 24.6% increase in maize grain yield compared to the lowest rate. Moreover, grain zinc concentration and uptake increased by 12.5% and 29.6%, respectively.
“What we found is that there’s a significant residual benefit to applying higher rates of zinc,” Botoman explained. “This means that farmers can potentially improve both their yields and the nutritional quality of their maize with a single application that continues to pay dividends in the following season.”
The study was conducted at two agricultural research stations, Chitedze and Chitala, each with contrasting soil types—Lixisols and Vertisols. Interestingly, the residual benefits of zinc application did not vary between soil types, suggesting that the findings could be widely applicable across different agricultural landscapes in Malawi and potentially other regions with similar soil characteristics.
The implications for the agriculture sector are substantial. By revising zinc fertilizer guidelines to higher but optimized rates, biofortification programs could become more effective without incurring additional environmental or economic costs. “There’s no added advantage to applying even higher rates, like 90 kg ha⁻¹,” Botoman noted. “So, from an economic and environmental perspective, 30 kg ha⁻¹ seems to be the sweet spot.”
This research could shape future developments in sustainable agriculture and biofortification efforts. As the global population continues to grow, the demand for nutrient-rich crops is increasing. Understanding how to maximize the residual value of zinc fertilization can help meet this demand while promoting sustainable farming practices.
The study’s findings offer a compelling case for revisiting and potentially revising current zinc fertilization guidelines. By doing so, farmers can enhance both the productivity and nutritional quality of their maize crops, contributing to food security and improved public health. As the agriculture sector continues to evolve, research like this will be crucial in driving innovation and sustainability.
The study, “Residual soil-applied zinc improves grain zinc nutritional quality of maize grown under contrasting soil types in Malawi,” was published in *Frontiers in Soil Science* and led by Lester Botoman of ICRISAT’s Chitedze Agricultural Research Station in Lilongwe, Malawi.