Contaminants and Nutrient Transfer in Organic Farming Systems: a review of risks and food safety implications in vegetable crops

As one way to achieve sustainable agriculture, organic farming is increasingly being adopted by farmers to reduce reliance on synthetic inputs, enhance soil fertility and conserve biodiversity. Although organic farming offers a lot of benefits in agriculture production, it is however, not free from contamination risks. Heavy metals, pathogens and organic contaminants originating from soil, atmospheric air and water can be transferred into crops especially vegetables. This review aims at synthesizing documented studies on the sources of contaminants in organic farming such as manure, biochar, copper-based fungicides and contaminated irrigation water and link with their uptake mechanisms by plants via root and foliar transfer; finally, showing how these contaminants disrupt nutrient uptake, reduce crop quality, and lower nutritional value. Regulations of organic inputs, improved monitoring and promoting water management practices are needed to address contamination risks in organic farming systems. This review provides some insights into the potential risks in organic farming systems by combining existing studies on contaminants in organic farming systems with a focus on vegetable crops.