GROWING GOURMET - Anto2ni.it

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MATERIALS FOR FORMULATING A FRUITING SUBSTRATE
ments and hundreds of others are listed in Appendix
V. Using rice bran as a reference
standard, the substitution of other supplements
should be added according to their relative protein
and nitrogen contents. For instance, rice
bran is approximatelyl2. 5 % protein and 2%
nitrogen. If soybean meal is substituted for rice
bran, with its 44% protein and 7% nitrogen content,
the cultivator should add roughly 1/4 as
much to the same supplemented sawdust formula.
Until performance is established, the
cultivator is better off erring on the conservative
side than risking over-supplementation.
A steady supply of supplements can be cheaply
obtained by recycling bakery waste, especially
stale breads. A number of companies transform
bakery by-products into a peiletized cattle feed,
which also work well as inexpensive substitutes
for many of the additives listed above.
Structure of the Habitat
Whichever materials are chosen for making
up the substrate base, particular attention must
be given to structure. Sawdust is uniform in
particle size but is not ideal for growing mushrooms
by itself. Fine sawdust is "closed" which
means the particle size is so small that air
spaces are soon lost due to compression.
Closed substrates tend to become anaerobic
and encourage weed fungi to grow.
Wood shavings have the opposite problem of
fine sawdust. They are too fluffy. The curls have
large spaces between the wood fibers. Mycelium
will grow on shavings, but too much cellular energy
is needed to generate chains of cells to
bridge the gaps between one wood curl and the
next. The result is a highly dispersed, cushionlike
substrate capable of supporting vegetative
mycelium, but incapable of generating mushrooms
since substrate mass lacks density.
The ideal substrate structure is a mix of fine
and large particles. Fine sawdust particles encourage
mycelia to grow quickly. Interspersed
throughout the fine sawdust should be larger
wood chips (1-4 inches) which figure as concentrated
islands of nutrition. Mycelium running
through sawdust is often wispy in form until it
encounters larger wood chips, whereupon the
mycelium changes and becomes highly aggressive
and rhizomorphic as it penetrates through
the denser woody tissue. The structure of the
substrate affects the design of the mycelium
network as it is projected. From these larger island-like
particles, abundant primordia form
and can enlarge into mushrooms of great mass.
For a good analogy for this phenomenon,
think of a camp fire or a wood stove. When you
add sawdust to a fire, there is a flare of activity
which soon subsides as the fuel bums out.
When you add logs or chunks of wood, the fire
is sustained over the long term. Mycelium behaves
in much the same fashion.
Optimizing the structure of a substrate is essential
for good yields. If you are just using fine
sawdust and wood chips (in the 1-4 inch range)
then mix 2 units of sawdust to every 1 unit of wood
chips (by volume). (Garden shredders are useful
in reducing piles of debris into the 1-4 inch chips.)
Although homogeneity in particle size is important
at all stages leading up to and through
spawn generation, the fniitbody formation period
benefits from having a complex mosaic of substrate
components. A direct relationship prevails
between complexity of habitat structure and
health of the resulting mushroom bed.
A good substrate can be made up of woody
debris, chopped corncobs and cornstalks,
stalks of garden vegetables, vines of berries or
grapes. When the base components are disproportionately
too large or small, without
connective particles, then colonization by the
mushroom mycelium is hindered.
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