GROWING GOURMET - Anto2ni.it

move debris from the feet and enhances the
effectiveness of the foot bath.
7) Rate of air exchange Air exchanges control
the availability of fresh oxygen and the purging of
carbon dioxide from the respiring mushroom
mycelium. High air exchange rates may adversely
affect humidity, especially prior to and at primordia
formation when there aerial mycelium
abounds. Should aerial mycelial die back, or
"pan", potential yields are substantially depressed.
On the other hand, to prevent
malformation of the fruitbody, bacterial blotch,
and mold infestation, the movement of air—turbidity—is
a substantial factor in preventing
disease vectors.
The need for adequate air exchange is a direct
reflection of the species being grown, its
rate of metabolism (as measured by CO2
generation), and the "density of fill". Fastgrowing,
tropical strains generate more CO2
than cold weather strains due to their higher
rate of metabolism. The density of fill is the
fraction of space occupied by substrate vs. the
total volume of the growing room. Button
mushrooms growers often fill up to 1/4 of the
growing room space with substrate. This high
rate of fill is impractical with most gourmet
mushrooms. I recommend filling the growing
rooms to no more than 1/6th, and preferably 1/8th
of capacity.
At 1000 cubic feet per minute (cfm) of free air
delivery, an empty 10,000 cubic foot room, will
be exchanged every 10 minutes, equivalent to 6
air exchanges per hour. This rate of air exchange
is near to the minimum required for gourmet
mushroom cultivation. At 2000 cfm, this same
room will be exchanged every 5 minutes, or 12
air exchanges per hour. I recommend designing
growing rooms which can operate within this
rate of air exchange, i. e. between 6-12 air exchanges
per hour. The actual rate of air exchange
THE GROWING ROOM 475
will be affected by the rate of fill and limited by
the avenues of exhaust. The growing rooms
should always remain positive-pressurized to
limit contamination vectors from the outside. A
strip of cloth or plastic above the door jam works
well as a simple, visual indicator of positive
pressurization.
A 400-600 cfm thermal exhaust fan is recommended
for a growing room of the
above-described dimensions. This fan is typically
located at the apex of the growing room,
opposite the incoming air. A thermostat, preset
by the cultivator to skim off excess heat,
activates this fan. Another fan, which I call a
"vortex fan" having a 200-400 cfm capacity,
is located below the thermal exhaust fan, usually
at head level, above the exit door. The
vortex fan helps enhance the cyclonic entrainment
of the air as it moves down the
growing room. Both fans should be covered,
from the inside, with a bug-proof, non-mudewing
cloth. This cloth will prevent the entry
of insects when the fans are not in operation.
Furthermore, the thermal exhaust and
vortex fan should have louvered shutters that
close when not in use.
This is but one configuration of a growing
room. Ideally, the growing room environment
acts as a giant wind tunnel, providing a homogeneously
mixed atmosphere. Simplicity of
design makes operation easy. Each growing
room should be independently controlled so
that crops can be cycled and managed according
to their stage of development.
8) Filtration of fresh air supply Fresh air is
brought in from the outside and passed through
a series of ifiters. The growing rooms do not require
the degree of filtration that is necessary for
the laboratory. Since the growing room will, at
times, have full air exchanges of 4-10 times per
hour, the filters must have sufficient canying ca-
PDF compression, OCR, web-optimization with CVISION's PdfCompressor