Zinc fertilisers address critical soil deficiencies, enhancing crop yields, and contributing to food security. Simon Norton, Director of the International Zinc Association (Africa), explains the intricate process of manufacturing zinc fertilisers, their application in soil, and the wide array of crops that benefit from their use.

“Zinc is a vital micronutrient that plays an indispensable role in crop growth and development,” says Norton. “In Africa, where nutrient-poor soils are a common challenge, zinc fertilisers are a powerful tool to improve agricultural productivity and ensure the sustainability of our food systems.”

The journey of zinc fertilisers begins with raw materials such as zinc sulphate, zinc oxide, and chelated zinc compounds. These are derived from mined zinc ores or recycled industrial by-products. The manufacturing process involves blending zinc with other nutrients, granulating the mixture into uniform pellets, and drying and packaging the final product.

“Zinc fertilisers are carefully engineered to maximise their efficiency and ease of use,” explains Norton. “The granules are designed for even distribution and optimal absorption, ensuring that plants get the nutrients they need to thrive.” Surfactants ensure that the zinc ion reaches the right place in the soil to enhance crop growth.

Zinc fertilisers can be applied using several techniques, each tailored to specific farming needs. Broadcast application is ideal for large fields, ensuring uniform distribution but requiring careful management to minimise nutrient loss. Band application is placing zinc fertilisers near plant roots to increase availability and reduce the quantity required.

Quick and effective foliar sprays are often used to address zinc deficiencies in crops showing visible symptoms. Seed coating involves treating seeds with zinc before planting to ensure seedlings have immediate access to this crucial nutrient. Fertigation delivers zinc through irrigation systems for precise control over nutrient delivery.

“Each method has its advantages,” notes Norton. “The choice depends on the crop, soil conditions, and the farmer’s specific goals.” Zinc fertilisers are particularly effective in improving the growth and yield of a range of crops:

• Cereals: Wheat, rice, and maize benefit from zinc’s role in grain filling and root development.
• Legumes: Beans and lentils see enhanced nitrogen fixation and seed quality.
• Vegetables and Fruits: From tomatoes to citrus, zinc improves yield, quality, and disease resistance.
• Oilseeds and Tubers: Crops like soybeans and potatoes gain better growth and resilience.

“Zinc is not just about increasing yield; it is about ensuring the nutritional quality of our food,” stresses Norton. “This is critical in Africa, where zinc deficiency in soils can directly impact human health.”

Addressing zinc deficiencies in African soils has implications beyond agriculture. “Zinc is essential for human nutrition. Ensuring our crops have adequate zinc levels contributes to healthier communities and combats issues like malnutrition and stunted growth.”

Norton also highlights the role of zinc fertilisers in building resilience against climate change. “Healthy, zinc-enriched crops are more resistant to stresses like drought and pests, making zinc a cornerstone of sustainable farming,” he concludes.

IZA