Emerging trends in algae farming on non-arable lands for resource reclamation, recycling, and mitigation of climate change-driven food security challenges

The current agri-food systems are unable to fulfill global demand and account for 33% of all greenhouse gas emissions. Conventional agriculture cannot produce more food because of the scarcity of arable land, the depletion of freshwater resources, and the increase in greenhouse gas emissions. Thus, it is important to investigate alternate farming methods. Algae farming is a feasible alternative that produces food, feed, and feedstock using wastelands and unconventional agricultural settings such as coastal regions, salt-affected soils, and urban/peri-urban environments. This review focuses on three emerging scenarios. First is seawater, which makes up 97.5% of the water on Earth. However, it is nevertheless used less often than freshwater. Second is a growing trend of people moving from rural to urban regions for improved employment prospects, living standards, and business chances. However, most rural migrants are essentially skilled in agriculture, which limits their applicability in metropolitan environments. The third scenario focuses on excellent crop yields and soil fertility; it is essential to maintain appropriate levels of organic matter and soil structure. In this case, algae have remarkable potential for osmoregulation-based salt tolerance and may provide valuable metabolites when cultivated in brackish or saltwater. Using brackish water, treated wastewater, and saltwater, algal culture systems may be established in arid/semi-arid, urban/peri-urban, and coastal areas to fulfill the increasing need for food, feed, and industrial feedstocks. It may also provide migrants from rural areas with work possibilities, which would allay environmental footprints.