Circular alternatives to peat in growing media: A microbiome perspective

T. Taparia*, E.A.H.J. Hendrix, E.H. Nijhuis, W. de Boer, J.M. van der Wolf*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Peat use in horticulture is associated with a large ecological footprint. Peat is the predominant growing media in Europe. Modern cropping systems rely heavily on dynamic interactions of the crop with the microorganisms in the growing media and yet, in the search for sustainable peat-alternatives, the microbiome of the growing media has often been ignored. In mushroom cultivation, peat is a prime determinant of productivity, in the form of a casing soil which supplies beneficial microbes. In this study we describe the microbial composition, interactions, and activity of four circular substrates used to proportionally replace peat in mushroom growing media. We also evaluate various physico-chemical characteristics of the peat-alternatives. We characterize the impact of sanitary pre-treatments such as steaming and acidification on the microbiome as well as the agronomical performance of the peat-reduced growing media. We found that grass fibres from agricultural residue streams, peat-moss farmed in degraded peatlands, and spent casing soil recycled from previous cultivation cycles can be used to successfully replace peat in mushroom growing media. Peat moss and spent casing were expectedly similar to peat in physical, chemical, and microbiological properties. However, the grass fibres had unique characteristics, such as high organic matter content, low water holding capacity and a diverse and competitive microbiome. Pretreatment of the substrates by acidification and steaming significantly affected the microbiome, and reduced the presence of pests, pathogens and competitive fungi in the peat-reduced media. Strong trade-offs existed between the productivity and disease pressure in the circular cropping system, which are also governed by the microbial composition of the growing media. Knowledge on the accessibility, sustainability, and economic viability of these peat-alternatives will further determine the transition away from peat use and towards sustainable growing media.
Original languageEnglish
Article number129375
JournalJournal of Cleaner Production
Volume327
DOIs
Publication statusPublished - 10 Dec 2021

Keywords

  • Circular agriculture
  • Peat-alternative
  • Physico-chemical properties
  • Microbial composition
  • Mushroom cultivation
  • Casing soil

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