Improving Soil Resilience and Crop Productivity Through Recycling of Spent Mushroom Substrate: A Transition Towards Circular Economy in Hill Agriculture

Abstract

Unlike make–use–dispose practice in the linear economy, the circular economy aims to achieve make–use–recycle–reuse to realize higher environmental gains with minimum costs. In the present study, cultivation of Agaricus bisporus was attempted, and 20.4 kg of fresh mushroom yield was harvested per 100 kg of compost. The leftover spent mushroom substrate (SMS) after harvesting the mushrooms was further re-composted to convert it into spent mushroom compost (SMC). French beans were raised in a field trial with SMC prepared by different methods, and a maximum yield of 11.15 t ha⁻¹ was recorded with the application of SMC enriched with rock phosphate at 2% w/w. SMC had exhibited a strong de-acidifying effect in the soils of the high-rainfall temperate region of the Western Ghats, India. The soil organic carbon increased significantly by 29% than the untreated control, and the soil micro-aggregates increased significantly from 6.72% in the pre-treated soil to 37.39% in SMC-treated soil. Soil CO₂ efflux at the field conditions was found to be 26.5% lower in SMC-treated soil (0.47 µmol m⁻² s⁻¹) than the recommended practice of application of farmyard manure (0.64 µmol m⁻² s⁻¹) in the study area. High-throughput sequencing to study the fungal biota revealed that SMC-applied soils were dominated by the genus Mortierella. Adopting circular economy practices in hill agriculture can lead to more resilient, sustainable, and environmentally friendly agricultural systems, which are essential for the long-term viability of agriculture in these regions.