Agro-Based Spent Mushroom Compost Substrates Improve Soil Properties and Microbial Diversity in Greenhouse Tomatoes

Spent mushroom compost (SMC) substrates are commonly used as growth media for greenhouse crops and horticulture production. This study aimed to investigate the responses of physiochemical soil properties, enzyme activities, and microbial community compositions to different cultivation durations and SMC soil treatments on tomatoes. The experiment included the following treatments: SMC substrate and the surrounding soil after planting at 1, 3, and 7 years and comparing control treatments including non-planting SMC substrates and continuous mono-cropping soil. The results revealed that the SMC substrates had higher contents of total N P and organic C nutrients than the surrounding soil treatments. The physicochemical soil properties and soil enzyme activities of the SMC substrates were significantly decreased with longer cultivation duration. Microbial alpha diversity was higher in the SMC substrates regardless of cultivation duration than in the control treatments. It was observed that many beneficial microbes, such as bacteria of the Deinococcus-Thermus, Halanaerobiaeota, and Nitrospirae phyla, and the fungi of the Basidiomycota, Mortierellomycota, and Chytridiomycota phyla were enriched in the SMC substrates. The SMC substrate and surrounding soil had enriched several potentially beneficial microorganism genera such as the bacterial Saccharimonadales, Gaiella, Bacillus, and the fungal Thermomyces, Kernia, and Mortierella. Therefore, the agro-based SMC substrate grooved cultivation system is recommended as an environmentally compatible practice for tomato growth in the greenhouse.