Biochar–Compost blends modulate trace element and nutrient dynamics in rooftop farming systems under Mediterranean conditions
Medina Veliu, Hugo López-Romano, Giuseppe Picca, Marco Panettieri, Eduardo Moreno‐Jiménez, Denis Courtier‐Murias, Liliane Jean‐Soro, Johnny Gaspéri, Laura L. de Sosa
Ecotoxicology and Environmental Safety
Urban Farm DB summary
This study investigated the impact of biochar-amended composts on trace element and nutrient dynamics in rooftop farming systems by cultivating tomatoes, lettuce, and Swiss chard for three years on a Madrid rooftop. Six substrates derived from spent coffee grounds, coffee silverskin, and seaweeds, with and without biochar, were used. Results showed that biochar reduced plant uptake and leaching of trace elements, lowering arsenic uptake by up to 40% in seaweed-based composts. Biochar also improved nutrient retention, reducing phosphorus and nitrogen losses by 40% and 25% respectively.