Cold Water Straw Fermentation
Hey, so we’re really stoked to share this easy, fun, DIY technique for treating your straw for cultivation that doesn’t require the needless waste of wood or fossil fuels: Cold water pasteurization!
Simple and scalable, this method is a great technique to have in your toolbox if you’re doing low-tech cultivation. It prevents the cultivator from having to use fossil fuels and emit CO2 and doesn’t require any fancy equipment. Essentially a fermentation process, this method kills off competitors to your spawn by the simple act of submersion in water over a period of days. During the submersion process the anaerobic microorganisms live and grow while all the aerobic (oxygen loving) microorganisms die. When the water is removed after a week, the anaerobic bacteria die as soon as they are out in the open, leaving “clean” straw to use for inoculation. The process is quite simple and goes as follows:
1. Line a garbage can (or any hard, upright container) with a heavy duty (3 mil) trashbag, or find a big barrel that you’ll be able to dump.
2. Fill the bag with dry straw that has (ideally) been chopped with a weed whacker. I don’t personally have a weed whacker so I just break the straw up with my hands. But the increased surface area and smaller pieces provided by the use of this machine will enable better colonization and make handling easier later on.
3. Fill the can with water, covering the straw.
4. Add a weight on top to of the straw to keep it submerged. Big rocks and concrete blocks work well.
5. Put a lid on the can and keep it warm place, ideally in the sun.
6. Wait 7-12 days. If you’re in a warm environment, it’ll go a lot quicker than if you’re in cold environment.
7. At this point the water should be discolored and stinky. This is good, hopefully only anaerobic bacteria are still alive, and these will die when you expose the straw to air. You will now want to extract the straw from the water. If you decided to use a plastic bag inside of the barrel, twist up the top of the bag, poke some holes in it, and let the water drain out.
8. Inoculate your straw with your favorite species of mushroom spawn!
This is a great method! Thank you for sharing.
My tapwater is contaminated with chloramine. When I find a good solution for cleaning up the chloramine I will give this fermentation pasteurization a try.
May 1, 2012 at 8:23 pm
sodium thiosulfate will convert chlorine and chloramine to relatively inert chloride ions.
You can use fish tank water purifier solution as long as it has thiosulfate in it, or just buy it pure at a high grade and use the powdered version.
January 4, 2013 at 3:13 am
Hi. This is very intriguing, thank you for the posting. Could you clarify step 7 a bit more. It says to turn the can upside down and drain, then to twist the bag and turn the can upside down and drain. I didn’t quite follow that.
Is the bag somehow suspended for 2 days to drain the remaining liquid? If so, wouldn’t that be prime time for re-contamination?
Also, How is the contamination rate relative to heat sterilization?
Thanks again for this great info. I hope to make it work on our farm!
May 20, 2012 at 3:18 am
Hello! Thanks for reminding me to clarify this part of it. There will be a new version up soon….
May 20, 2012 at 11:58 pm
Great! Thanks for the updated version. Right now I have my first tests going of a pasteurized sample, a sterilized sample, and a gas free hydrated lime sample. I look forward to trying your version soon. Thanks for spreading the info!
May 28, 2012 at 9:10 pm
Cool! I’d love to hear about the results of your tests, if you’d like to write something up you can email it to armillarianabs@gmail.com and I can post it on this blog.
May 28, 2012 at 10:38 pm
I’m a little concerned with this method, and the implications about burning fossil fuels. The potential drawback is that it produces methane, more potent than the CO2 normally produced by burning but this could possibly be a positive if we were able to harness it. I’m not finding much information on the proper handling of the anaerobic liquid that remains either. Is it reusable, or do I need to aerate it to prep it for compost? If I’m not able to dispose of the liquid in a reasonable time frame this leaves me potentially with large amounts of liquid, and nowhere to store it. It would be interesting to setup an anaerobic fermenter for the straw, capture the methane, and use it to power a heated system…
October 23, 2012 at 10:07 pm
Interesting ideas. The remaining liquid can be used as a natural pesticide, or can be added to compost.
November 6, 2012 at 12:32 am