Fertilisers are an essential part of modern agriculture, offering plants the necessary nutrients for growth and development. When used correctly, they contribute to global food security, thereby helping to alleviate poverty. However, their use can also have unintended negative consequences. For example, over-application can lead to nutrient runoff, which can cause eutrophication. Likewise, many fertilisers contain more than just nutrients, with unwanted or potentially harmful impurities including heavy metals (“HMs”).