Spent mushroom compost enhances plant response and phytoremediation of heavy metal polluted soil

Abstract Background: Stimulatory efficacy of spent mushroom compost (SMC) cannot be overemphasized. Aims: In this study, the effect of SMC on phytoremediation and plant's response to heavy metal polluted soil was investigated and suggested for the establishment of feasible soil remediation. Methods: Heavy metal polluted soil (80 kg) was sterilized at 121°C in soil sterilizer for 30 min and repeated four more times to remove microbial interference. Five kg of soil was packed into pots supplemented with SMC of Pleurotus ostreatus at different concentrations of 10, 20, 30, and 40%, and control (no SMC), and used to grow the test plant ( Megathyrsus maximus commonly known as Guinea grass) for 90 d. Effect of SMC treatments on chemical characteristics of the soil was determined through soil analysis before and after the experiment. Plant response to SMC in polluted soils was studied by observing root proliferation, plant growth, and biomass. Results: The results suggest that SMC treatment modified soil chemical characteristics, the germination index (GI), plant growth, and phytoremediation potential. The soil's pH increased from 4.3 in control to 6.8 both in 40 and 30% SMC treatments; also the soil's nutrients, cation exchange capacity (CEC), and GI improved with incremental increase in SMC treatments, while the heavy metal removal was best observed at 40 and 30% treatments. In addition, the bio‐stimulatory effect of SMC was confirmed on guinea grass root proliferation, growth, phytomass and its phytoremediation potentials on heavy metals. Conclusions: The SMC is therefore suggested for soil stimulation to improve plant's growth and phytoremediation.