Recycling of ferrous slag in agriculture: Potentials and challenges

A large volume of slag is generated as a by-product during steel manufacturing. In order to ensure environmental and economic sustainability, it is imperative to find innovative solutions for the efficient recycling of slag. This review broadly and critically explores the available information concerning the effective recycling of slag in agriculture and its potentials in crop yield, soil conditioning, greenhouse gas (GHG) emissions, soil carbon sequestration, and heavy metal stabilization in contaminated soils. An agronomic assessment of GHG emissions and environmental concerns related to potential contamination of heavy metals in the food chain have also been evaluated. Existing literatures documents a range of impacts that slag fertilization can be effective in increasing crop yield, mitigating GHG emissions, and decreasing yield-scaled global warming potential. Heavy metal accumulation in soil and their uptake by the plant are not consistent with the application of slag, mostly accumulated in roots, and very low translocation level in grains/fruits. In order to secure the reliability of recycling slag in agriculture, regulatory compliance related to environmental problems, novel technological solutions to improve the quality of slag, and strategic planning to expand its market value need great attention.