Nano-engineering metal-based fertilizers using biopolymers: An innovative strategy for a more sustainable agriculture

Ongoing pandemic has put a strain on food productivity and induced a significant increase in food demands. Even before this scenario, acute hunger has been on the rise in developing countries due to rapid population growth, climate change and socio-economic conditions. In this context, the use of bulky chemically processed fertilizers has been promoted in recent decades to improve agricultural productivity. However, the major concern with these conventional fertilizers is their propensity to advance environmental toxicity, water, air, and soil pollution. The nanoformulation of nutrients has been argued to serve as a valuable strategy that could revolutionize the agricultural sector and provide solutions for current and future concerns surrounding sustainable and climate-sensitive crops. Given these facts, this review opens with an overview of the primary agricultural sector's main challenges, especially in developing countries. Next, the latest progress in synthesizing metal-based nanofertilizers and their encapsulation using biopolymeric materials is systematically presented. Biochemical and physiological effects of these inputs in different plant model systems are also elaborated. In the end, perspectives on major gaps in the literature and the design of multivalent nano-delivery systems for optimum crop production are proposed. Packaging the potentially toxic metal-based nutrients into a biopolymeric nanocarrier offers a means to regulate their dissolution, alleviate nutrient losses, and limit the detrimental effect in plants at elevated concentrations.