Developing a database of bio-markers for compost quality control to maximise mushroom production yield (MU17006)
What’s it all about?
The quality and yield of button mushroom crops is critically dependent on the quality of compost used. Beginning in June 2019, this investment is exploring how microbial populations within compost can be used to understand, measure and manipulate compost quality.
The project team’s work involves investigating microbial populations across a range of mushroom composting facilities. This includes looking at the microbial population dynamics at different points along the composting timeline, how they align with other compost quality indicators, and correlating everything back to mushroom crop yield and quality.
The research will culminate in a database of compost ‘bio-markers’ (microbe indicators) for the industry, which will be able to be used to assist in maximising productivity and crop outcomes.
The feasibility of the project was confirmed over the past six months, using a preliminary survey of three successive compost crops from multiple Australian composting facilities. The major sampling program (26 successive crops obtained from composters in four Australian states) commenced in October 2022, taking samples from four timepoints at every second compost crop. So far 86 samples have been received and processed (mixing, sub sampling, drying, grinding), making up 16 per cent of the total samples for the project. On site sampling by composters has been fairly reliable, and only four samples were not collected for operational reasons. This suggests that the overall database will be able to achieve the anticipated data resolution. DNA purification from the received samples is ongoing, and generation of microbial diversity data will commence once 50% per cent of the total samples have been processed. Work is ongoing to obtain mushroom crop yield and quality data from growers for the composts that have already been sampled.
The feasibility of the project was tested in a testing program using samples collected from three successive crops at four independent mushroom composting facilities across New South Wales, Victoria and South Australia.
Chemical compost quality markers in these samples (pH, moisture, total C and N, soluble C and N, microbial biomass, humification index, nitrification index) were compared with microbial diversity at four composting timepoints. Close chemical and biological reproducibility between successive crops at individual yards was confirmed.
There was more overall variation observed between yards, presumably due to differing feedstocks at widely different locations and differing process parameters used by individual computers, especially during Phase 1. Both biological and physicochemical variation was highest at bunker fill, but much less by the end of phase 2, especially for the microbial markers tested.
The results confirm the feasibility of developing biological indicators as a predictor of crop yield/quality, and a 12-month sampling effort has commenced to provide the depth of data needed to support this.
Since project commencement, progress has been severely impacted by COVID-19 travel restrictions, leading to a temporary pause in research activites.
Restarting in January 2021, the team focused on developing effective and reproducible compost sampling strategies.
The initial phase worked to assess changes in microbial diversity and other compost quality parameters in three successive compost crops from yards in three different States. With sampling almost complete, the analytical methods required for analysis have been optimised.
The results from this study are now being used to prepare methods for a much larger one-year study.
This project is a strategic levy investment in the Hort Innovation Mushroom Fund