UK mushroom rising makes use of 100,000 m³ of peat a yr – can we do higher?

Peat bogs are an essential carbon retailer, so mushroom growers are looking for a method to develop their produce on different substrates

By Adam Vaughan

The next is an extract from our Repair the Planet e-newsletter, a weekly electronic mail about options to the local weather disaster.

In an enormous industrial shed on Leckford Property, a farm owned by the grocery store Waitrose in a fantastic a part of southern England, a revolution is stirring on the earth of mushroom rising. UK manufacturing of this crop depends on peat, the extremely carbon-rich natural matter present in bogs and fens throughout the nation. Peatland comprises a lot carbon, it’s generally described as “the UK’s rainforests”. That’s the reason the UK authorities has promised to revive 280,000 hectares of peatland in England alone by 2050, to assist meet its local weather change targets.

Why are we utilizing peat to develop mushrooms?

Round 60 years in the past, UK growers realised that utilizing peat as a substitute of soil to develop mushrooms “massively improved” their yield, says Ralph Noble of horticulture firm Microbiotech. Most button mushrooms are grown on a substrate of composted straw and animal manure, however to truly get the bit that we harvest and eat, the cap and stalk that comprise the fruiting physique of the mushroom, you want a so-called casing layer on high of the substrate to make these fruiting our bodies type. That’s what the peat is used for. It is vitally good for the duty as a result of it holds quite a lot of water and has the perfect bodily and organic properties that result in fruiting our bodies.

Why is that an issue?

Just about all of the mushrooms produced within the UK for consumption are grown this fashion. Noble says that the UK makes use of within the area of 100,000 cubic metres of peat a yr for this goal, or roughly a ninth of the peat extracted from UK landscapes yearly. “It’s fairly a big use of peat,” says Noble. Pete Smith on the College of Aberdeen within the UK says the peat used would launch round 11,000 tonnes of CO2, after making some assumptions in regards to the density of the fabric. Primarily based on a mean household automotive’s annual emissions, he says which means rising mushrooms within the UK is equal to the emissions of greater than 2600 vehicles.

I nonetheless need mushrooms. What are the alternate options to peat?

“The problem is discovering a fabric that offers the identical [mushroom] yield and high quality as peat,” says Noble. His firm is main a consortium together with Waitrose engaged on a £108,000 government-funded analysis challenge into peat-free casing supplies. A number one contender is coir, a fibre from coconut husks. Different choices being examined are powdered bark and composted plant materials. A Dutch analysis staff, led by Jan van der Wolf at Wageningen College and Analysis, discovered final yr that grass fibres made with a patented course of involving agricultural waste could possibly be used.

What progress is being made?

Van der Wolf and his staff have been in a position to develop mushrooms within the grass fibres, and the ensuing mushrooms appeared no completely different to ones grown in peat. At Leckford Property, the workers say they’ve efficiently used coir in small exams to create mushroom spores, and this week they’re within the technique of placing it down throughout a complete mattress to supply complete mushrooms. They are saying the large query that continues to be is yield, and whether or not swapping peat for coir would imply they will develop fewer mushrooms in the identical shed. Noble is tight-lipped on the official outcomes of the challenge, funded by Innovate UK, the nation’s government-backed innovation company, as he says they received’t be revealed till subsequent yr on the earliest.

The Nationwide Belief, a UK heritage and conservation charity, says that as a part of its efforts to part out peat, it has been looking for a provider that may present closed-cup mushrooms grown with out peat. However up to now it hasn’t discovered one that may accomplish that on the scale required. Within the meantime, the belief says it has determined to scale back using mushrooms at its 280 cafes.

What are the challenges for peat-free alternate options? 

Scale goes to be a problem, judging from the Nationwide Belief’s expertise. “It needs to be one thing in abundance,” says Noble, and it’s unclear whether or not there’s sufficient coconut husks to fill that peat-shaped gap. The Leckford Property workers, for his or her half, do suppose there’s sufficient coir to go spherical. One other massive problem is water retention: peat is superb at holding water, and plant-based compost and coir received’t maintain as a lot. Mushrooms are about 95 per cent water, says Noble, and most of that moisture comes from the casing materials. One other stumbling block is that peat doesn’t differ very a lot, so alternate options might want to mimic that uniformity to maintain mushroom yields up.

Can’t we simply keep it up as we’re? 

The workers at Leckford Property don’t suppose so: their seek for peat-free mushroom manufacturing is a part of a far wider dedication to shift the farm’s strategies to restrict its environmental impression. Furthermore, regulation is coming. The UK authorities lately consulted on the thought of phasing out peat use in industrial horticulture by 2028, which might put an finish date on how mushrooms are grown right this moment, if adopted. That’s nonetheless a giant if till a remaining authorities determination. One worry Noble has is that mushroom manufacturing merely will get shifted to different nations which are much less apprehensive in regards to the environmental impression, which is why growing alternate options is important. “Utilizing peat basically as a horticulture rising medium most likely isn’t sustainable. There’s quite a lot of strain on peat bogs,” he says. Smith salutes these researching peat-free alternate options. “Peatland is simply too treasured to make use of for horticulture,” he says.