Holistic analysis of sustainable waste streams used as lettuce fertilizers applied individually and in combinations

Sustainable nutrient management is essential for agriculture in arid regions such as Yuma, Arizona, which produces over 90% of US. winter leafy greens. Nutrient-rich waste streams, including biosolids, manure, and source-separated urine, can reduce reliance on synthetic fertilizers but may introduce chemical and microbiological contaminants. In a controlled pot experiment, we compared individual and combined waste-derived fertilizers with a chemical fertilizer control. Chemical fertilizer produced the largest plants and highest chlorophyll levels. Urine and urine-based combinations yielded moderate growth with lower uptake of metals, antibiotics, and per- and polyfluoroalkyl substances than other waste streams. Biosolid treatments had the highest per- and polyfluoroalkyl substances and antimicrobial resistance gene (sul1 and intI1) concentrations in soil, while manure and biosolid-manure mixtures were associated with elevated levels of certain antibiotics. Findings highlight opportunities and tradeoffs in recycling waste nutrients, informing strategies for sustainable agriculture and environmental health protection.