Used extensively in human and livestock healthcare and growth promotion, antibiotics can enter the agricultural environment through animal waste and wastewater, polluting soil and crops. The escalating use of antibiotics has raised concerns about potential environmental contamination and the associated antibiotic resistance genes (ARGs). These can affect crop growth and productivity, and cause antibiotic bioaccumulation in crops. Additionally, soil pathogens may gain antibiotic resistance and enter the food chain, negatively affecting human health and ecosystem safety.
To mitigate the environmental contamination caused by antibiotics and ARGs, Dr Livia Pan Min, Senior Lecturer from the School of Science and Technology, and her team have developed a “3-in-1” soil-plant system amendment method. This method involves the application of three waste-derived materials to soil: sewage sludge, Chinese medicinal herbal residues and biochar. Sewage sludge, being rich in organic matter and nutrients, must first be treated to remove pathogens and toxic elements. Chinese medicinal herbal residues, which are derived from carbon-rich fibrous plant materials, possess antipathogenic properties and can positively alter soil microbial communities. Biochar has been proven to effectively reduce the bioavailability of antibiotics in the soil-plant system. “Previous studies have explored soil amendment with sludge or biochar, but none had focused on their combined effectiveness with antipathogenic Chinese medicinal herbal residues in reducing antibiotics and ARGs in soil. We wanted to investigate how these three waste-derived materials could work together to reduce antibiotics and ARGs in soil and crops, while also improving soil quality,” explains Dr Pan.
To find out the optimal formula, the research team conducted multiple trials on the growth of different plants with different formulations. The findings revealed that adding 20% of the “3-in-1” formulation to soil was the most effective in increasing the soil nutrient content and reducing the amount of antibiotics and ARGs.
The research was supported by the Faculty Development Scheme of the Research Grants Council and has been granted a short-term patent in Hong Kong. Dr Pan and her team will continue to optimise the formula to further improve its effectiveness.
