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Location: Coastal Washington

Mushroom compost

A few miles from where I live there is a small 'cottage-industry' type operation that grows gourmet mushrooms. Their growing medium is heat-sterilized sawdust packed in relatively small plastic bags. Size-wise they resemble presto-logs, but unlike presto-logs the sawdust is just hand packed in the bags, holes are punched in the bags and the mushrooms grow out through the holes. Twice a year they replace all the growing medium and the 'spent' medium is available, free for the asking, in large quantities. The soil on my property is quite sandy. Would this material be a good addition, dug into my gardening plots??
Note; This stuff is not mushroom 'manure' as I know it, with soil, fertilizer and other additions.

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Greener Thumb
Posts: 1899
Joined: Tue Apr 14, 2009 6:13 pm
Location: wnc - zones 6/7 line

without seeing a layout of what's in it, the answer is 'maybe'. spent mushroom growing medium sometimes has a bunch of salts in it, like a by-product.

it would definitely add a a lot of organic matter, which it sounds like your soil could use, but you may be better off mixing it with something else before mixing it into the soil, growing-stuff-wise.

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Super Green Thumb
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Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

Never turn down free organic materials :) , but I'd think about it as a good "brown" to add to your compost pile, rather than directly adding it to the soil. Any salts in it would get broken down and it would get better balanced.

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Super Green Thumb
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Joined: Fri Jun 26, 2009 9:42 pm
Location: Wentzville, MO (Just West oF St. Louis) Zone 5B

I would use it. Unless you are putting mass quantity on I wouldn't worry too much about the salts especially since this season is winding down for the most part. Maybe find some horse manure around or cow and add both together.

Since it's a "Brown" I would add grass clippings to even things out as well. I'm not a big compost pile person, I compost in the bed just like mom nature does. :D

Greener Thumb
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Joined: Wed Sep 24, 2008 5:15 am
Location: Ventura County, CA, Sunset 23

Go with it

I'm sure it's usable.

What you'll find though is it's kind of a monoculture and will only help so much. I wouldn't expect it to be anything you could rely on to support a diverse bunch of plants.

Some folks use mushroom compost to bulk up their regular compost. Works great if you want to generate a lot of compost.

Be prepared to add to it as time goes by.

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