Cultivation Quarters

Ken Litchfield

Last month we looked at the biology of mushroom cultivation lifestyles in general and specifically at saprobic mushrooms, those that live on dead raw tree trunk heartwood, or raw cellulose. The heartwood cell walls are made up of not just cellulose but also of lignin and a few other things like pectin and hemicellulose. Though cellulose is common to all plant cells and composes 35-50% of the cell wall, lignin is mostly found in the xylem or woody tissue of Gymnosperms and Angiosperms and specifically mostly in the “softwood” conifers and “hardwood” dicots where it composes about 10-25% of the wood.

There aren’t as many mushrooms that will break down lignins as will decay the much more common cellulose. Lignin decay fungi are called white rot fungi because they leave the lighter colored cellulose “white rot” alone, while the “brown rot” cellulose feeders leave the brown lignin behind. Because the lignin isn’t as readily broken down as the cellulose it provides “bulk” or spongy tilth to the soil organic matter, a good thing. For practical mushroom cultivation purposes it isn’t necessary to be concerned about lignin eating mushrooms; just feed all your wood source materials to your raw cellulose feeders. Because cellulose is the much more common component for most raw saprobic fungi to eat I usually refer to them as “raw cellulose feeders” as compared to the mushrooms that like broken down cellulose or “compost feeders.”

So last month we looked at the tree trunk heartwood or raw cellulose feeders. Those that feed on the raw heartwood can also feed on cellulose rich ag or forest product materials that can be bagged or mulched for commercial growing of saprobic mushrooms. Straw, wood chips, cardboard, etc that will metabolically “burn” faster than the slow burning dense heartwood will produce a quicker crop of mushrooms for harvest. The recycle pile at Far West Farm is loaded with plenty of undecayed sawdust loaves that will still produce more mushrooms but there is also plenty of broken down sawdust or “mushroom compost” for the taking. Far West is even considering using it in a button mushroom growing operation (in 2022 - may be restricted due to Covid, contact Far West prior to visiting).

Once the raw cellulose is decayed or spent by the raw cellulose feeders, the remaining decomposed cellulose or compost can be fed to plants or compost feeding mushrooms. Compost feeding mushrooms are those like Shaggy Parasol, Shaggy Mane, and the Agaricus genus of Button Mushrooms. Shaggies and Buttons will eat the leftovers from raw cellulose feeders but often like a richer compost or manure mix that you can make at home.

To make a rich compost for compost feeding mushrooms and/or your regular garden plants, there are several methods. The simplest is maintaining a thick mulch of chippy wood chips throughout the garden, but especially in the pathways. The wood chips decay from microorganisms, fungi, and worms into rich compost over 2-4 years. The thick mulch can be inoculated with mushroom mycelial spawn of Garden Giant or Stinky Whiffle Ball, two of the easiest edible mulch mushrooms to grow in your fresh mulched garden. Masses of mycelium can be produced on chippy wood chip mulch this way that can be used as mother spawn beds to inoculate other areas of the garden. The compost produced in the pathways can be dug out and put into the garden beds and replaced with more chips to generate more compost. Burying kitchen scraps, garden waste, tree leaves, and other organic matter under thick garden mulches is a quick and simple method for producing compost where you need it. A passive slow decay compost bin that regularly takes kitchen scraps and miscellaneous organic material is a simple easy place to transplant bases of wild or garden collected compost feeding mushrooms or the spore rich slurries of the mushroom tops mushed up in a bucket of water.

However, the coolest composting method is hot composting in 14 days, though it is more labor intensive than other methods. This simple method was originated, or at least promulgated for decades, back in the 60s and 70s by the Rodales in Organic Gardening magazine. There is another method, sometimes called the 18 day method, claimed to be originated at UC Berkeley, more commonly known and promulgated by folks trained in the more current urban ag and permaculture movements. It overemphasizes the proper 30:1 proportions of carbon and nitrogen and dry and green materials and how to calculate that based upon complex compositional analyses of multitudes of ingredients. And then after belaboring how to do the calculations it usually recommends resorting to a simplification that emulates the original Rodale method anyway. I have compared methods several times with C:N proponents and not seen any advantages to the C:N method. It is overly complicated to explain for its own proponents and has too many recommendations for how to correct the formula when it isn’t working. You can look up the C:N method online if you want to use that but I’ll describe the simpler and more effective Rodale method here, since it is apparently not so well known anymore.

For rich black compost in 14 days you only need to remember 4 components.

1. Maximize particle surface area - Shred all the ingredients.
2. N - Provide high Nitrogen ingredients to compose at least 1/3 of the pile
3. H2O - Keep all the ingredients uniformly damp and mixed.
4. O2 - Turn the pile daily to aerate it.

1) The raw ingredients will compost down much faster if their chunkiness is broken down to an ideal size range of little fingernail size to thumbnail size. Some could be bigger and some smaller but that range is ideal for microbial digestion, aeration, drainage, and turnability during the composting process, and the friable texture of the final usable compost. If the particle size is too small, like, say, sawdust, then the compost will too easily cake and clump and not mix well. If it is too chunky like, say, thumb sized wood chips, then the internal volume of the chunks doesn’t get broken down as quickly as the rest of the materials. Caked sawdust, chunky wood chips, and long stringy grass or twigs are difficult to turn and often their fibers are still too long and tangly for friable finished compost texture.

2) Rather than the complicated calculations of the C:N method needed to figure out how much of each Nitrogen rich material to add in comparison to each Carbon rich material, you only need to remember to use 1/3 of the mass of the pile as high N materials. High N materials might be green grass clippings or horse, cow, or sheep manure at 1-2% N. Richer N materials like goat, rabbit, or chicken manure or blood or cottonseed meal can be used as supplemental high N enrichments to stimulate full metabolic heat production in the pile. You can find the N and C analyses of lists of compostable materials online

3) Like all living organisms, microbes need water to live and carry on their metabolic processes. If the compost ingredients used to build a new pile are dry they need to be wetted to break their surface tension and soak water into the material so the microbes can devour them. When the compost pile heats up the materials will dry out faster and the moisture needs to be replenished regularly. Some folks express concern about the pile getting too wet but, since it should be resting on open ground, if there is “too much” water it will simply drain away by gravity. Because the pile will be turned daily, the turning will aerate any pockets of “too wet” material and prevent it from going stagnant.

4) Like all aerobic organisms composting microbes need oxygen to carry on their metabolic processes. Turning the pile daily gets any wet soggy spots broken up, drained, and aerated and any dry spots remixed with the the rest of the moist pile materials. It also feeds oxygen back into the pile preventing carbon dioxide and other metabolic waste products from building up in pockets.

Building the compost pile entails mounding all the well mixed ingredients into an easy to turn human labor-convenient pile about 5’ x 5’ and 4-5’ high. This is plenty large enough to heat up and small enough so the average person can turn it in 5-10 minutes. The pile should be built on one half of a 5’ x 10’ area so the pile can be turned easily from one half of the rectangle to the other half and back again daily. It should not be enclosed in a bin or boxed in area whether with a container or with wooden pallets. Containing the pile prevents quick easy turning and makes it more difficult to get full access to all parts of the pile. For aesthetic purposes the composting area can be located behind a vine covered pallet wall or wire or string fence while still giving full accessibility to all parts of the pile.

For folks with larger gardening or farming territories that need and can use more compost and also generate more composting materials, you can build your composting area in the back 40 somewhere on a 5’ x 70’ row. This allows 14 compost piles to be built side by side, one for each day of the two week process. To start the process, the first pile is built on the first day in the first 5’ end position. Then the next day that pile is turned to the second adjacent 5’ position and another pile is built on the first position. The third day the first pile is moved from the second position to the third position, the second pile is moved from the first position to the second position, and a new pile is built again on the first position. This progression is repeated each day until all 14 positions in the 70’ row are filled and the first pile that has reached the end of the line is carted away for use, then all the rest of the piles are turned in series, and another new pile is built at the beginning. In a setup like this it helps to arrange the composting area on parallel contour with the highest elevation of the garden or farming area so that finished materials are easier to cart downhill and any runoff from the composting process is slowed and captured by thick wood chip mulches and the rich water feeds the downhill garden area. Uphill road access to the beginning of the compost area allows easy dumping of raw materials like free delivery of tree trimmer wood chips and neighbors’ stable manure.