While human waste has historically been used as a fertilizer, its use in soiless systems is a recent field or research.
Since then, other researchers have explored both human mixed waste and human urine as nutrient sources for hydroponic cultivation, studying the potential of such waste,[REF] comparisons to traditional fertilizers,[REF] both in the context of wastewater treatment,[REF][REF] agriculture,[REF] and even space exploration [REF].