The effects of spent mushroom substrate on the vegetative growth and yields of cowpea and tomato were determined. Autoclaved and unautoclaved spent mushroom substrates, mixed with loamy soil in ratio 1:9 were utilized with both composted and uncomposted spent mushroom substrates. Composted spent mushroom substrate mixed with loamy soil produced greater vegetative growth and yields of cowpea and tomato than uncomposted spent mushroom substrate, which in turn gave better results than loamy soil controls. Autoclaving was found to be unnecessary in sterilizing the spent substrate; loamy soil mixture as autoclaving caused biodegradation of some of the component nutrients, thus resulting in lower vegetative growth and yields of cowpea and tomato. Oven-drying only of the spent substrate; loamy soil mixture was found to confer enough sterilization.
Key words: Spent mushroom substrate, Lentinus subnudus, loamy soil, cowpea, tomato