Executive summary
This project aims to ensure the sustainability and economic viability of mushroom growing in New Zealand by exploring and implementing alternative casing materials and mitigating the risks associated with peat reliance.
Mushroom farmers around the world have long used peat as a key ingredient in mushroom growing. Due to its unique characteristics, peat makes an excellent casing material as it is:
- Widely available, low cost, contaminant-free, low pH, and highly water-retentive
- Aerated enough to create microclimates perfect for efficient mushroom growing at a commercial scale e.g. maximises yield and minimises harvesting labour costs
This project seeks to explain the characteristics of why peat is such a great medium for growing mushrooms. It is very difficult to get an alternate product that is more sustainable and will deliver the same financial results as peat.
While much work has been done on peat alternatives, there is still no clear pathway from peat. If anything, the problem will only get more significant as demand for peat increases over the coming years. Peat mining is only coming under more pressure, with countries like Germany setting targets of 2030 to ban all peat mining. There is also the diminishing social licence and more pressure from supermarkets, especially in the UK, where they ask for peat- free mushrooms. As it stands, there is little to no pressure from the government or the supermarkets here in New Zealand. From the interaction and interviews conducted for this project, it looks like this is only a matter of time before New Zealand follows in the footsteps of other European countries.
From the research conducted, there is a lot of scepticism around peat alternatives particularly from mushroom growers who view any other medium other than peat used as a casing soil is going to be more expensive, yield less and have lower quality than peat. Farm owners and growers are under more and more pressure to manage costs and see peat replacement as just that.
From the trials conducted wood fibre blended with peat at 30% rate delivers the same results as 100% peat casing.
Wood fibre mixed with peat only makes sense for countries that rely on imported peat. It is here where the efficiency gain in the logistics of the wood fibre make it economically viable over bulk peat.
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