Effects of Spent Mushroom Compost (SMC) as an Ingredient in Phase I Compost on Production of Agaricus bisporus

ABSTRACT

Experiments were performed to determine the effect of using 20% spent mushroom compost (SMC) as an ingredient in phase I compost on mushroom yield. Yields from compost prepared with two 20% SMC formulations (80Ctl, 80LC) were compared to a standard control (Ctl) containing no SMC. The 80LC compost was formulated with a higher level of lignocellulose raw materials, including corn stover, corncobs, cottonseed hulls, and wheat straw. The 80Ctl compost contained 20% SMC plus the same raw materials used to prepare Ctl compost. Yields of 80LC matched or exceeded yields of the Ctl compost in all three crops while yields of 80Ctl were significantly lower. As an additional factor, lignocellulose supplements were added at spawning and were a significant factor in increasing mushroom yields, although not superior to a standard commercial supplement applied at 3.7% (dry compost weight). Compost bulk density was significantly higher (19–20%) in compost formulations containing 20% SMC compared to the non-SMC Ctl. Populations of four prominent phyla of bacteria (Firmicutes, Actinobacteria, Proteobacteria, and Chloroflexi), as determined by pyrosequence analysis, were similar in both compost types and did not appear to influence mushroom yield.

Acknowledgements

We thank Lijun Xu at the Statistical Consulting Center at Penn State University, University Park Campus for assistance with SPSS and creating a model to aid in interpreting cropping data. We also thank Deborah Grove and the Huck Institute's Genomics Core Facility (Penn State University, University Park campus) for running DNA extracts on the pyrosequencer; Michelle T. Carlson and Suzanne Kennedy at MoBio for sharing their expertise with derailing inhibitors for successful DNA extraction; and Doug Keith, Diane Kramer and Kim Paley at the Mushroom Research Center for assistance in compost preparation through harvesting. We also thank Giorgi Mushroom Co. for providing the spent mushroom compost and corncobs for this research.

Funding

We thank the Department of Plant Pathology and Environmental Microbiology for the graduate assistantship that allowed this project to take place.