Extraction and use of nutrients from composted wheat and potato plants.

Human survival on extended-duration space missions will require reliable regenerative life support systems. Biological systems using higher plants could be incorporated into life support systems; however, substantial quantities of inedible crop residues will also be produced. Composting can reduce the volume of crop residues and provide an end product that may be leached to remove soluble nutrients for use in hydroponic plant growth systems. Solubilization can be affected by physical conditions; we investigated several treatments (pH, temperature, agitation, or pretreatment sonication) for aqueous extraction of nutrients from composted inedible potato and wheat biomass. No significant differences were noted in electrical conductivity data. Chemical analyses indicated highly significant differences. Wheat seeds (Triticum aestivum L. cv. Apogee) were germinated in each extract to monitor for potentially inhibitory compounds. Seeds germinated in each extract, but total mean root lengths were affected negatively by sonication before extraction. Aqueous extracts may also support plant growth.