What is SMS?
Spent Mushroom Substrate (SMS) is a composted, growing medium that results
from the mushroom growing process.
SMS is made from agricultural materials, such as wheat-straw bedded horse
manure, hay, poultry manure, cottonseed meal, cocoa shells and gypsum. Mushroom
production takes place in specialized, climate-controlled rooms and lasts for
approximately 70 days before new compost is required.
When new compost is needed, the SMS remaining from the old compost is steam
pasteurized to reduce hygiene problems for the next mushroom crop and then removed
from the growing rooms. SMS can be used for other agricultural crops and products
since it is an ideal soil amendment with important nutrients.
To download an SMS brochure, click here. To download an SMS booklet that contains more detailed information about what SMS is and how it can be used, including scientific research and practical applications, click here.
Mushroom Crop Production
Because sterile conditions are required to begin the life of a cultivated mushroom,
the entire operation begins in a laboratory. The spores, or natural seeds of the
mushroom, are so minuscule that the mushroom grower cannot handle them. Laboratory
personnel inoculate sterile cereal grains with the spores and incubate them until
a viable product is developed. These grains become "spawn" which can
then be sown like seed.
At the farm, the grower carefully prepares the compost, the basic growing medium
for mushroom production. Two types of starting material are generally used for
mushroom compost: synthetic compost consisting of wheat or rye straw, hay and/or
crushed corn cobs or manure-based compost made from stable bedding from local
race tracks and horse stables. Both types of compost require the addition of
other supplements.
The compost is produced outdoors on a concrete slab, commonly referred to as
a composting wharf. The ingredients are thoroughly mixed, wetted, and placed
in large piles to initiate the composting process. As the starting materials
degrade, the compost continues to be mixed, watered and supplemented for about
15-25 days. The outdoor process is followed by an indoor pasteurization cycle
to kill any pests that are present in the compost.
Inside the growing houses, the pasteurized compost is placed in stacked, wooden
trays or beds, the spawn is mixed in and a top layer (usually of peat moss)
is applied. From this point, it takes about a month to produce the first mushrooms
for harvest. Throughout the growing period, temperature and humidity are carefully
controlled.
Mushrooms mature at varying times, so picking by hand is continuous for 6 to
10 weeks. The tray or bed is then completely emptied and the entire growing
area is pasteurized with steam before a new crop is started. The composted material
or “spent” material from the growing process is called spent mushroom
substrate.
Mushrooms are one of the most difficult commodities to grow. Intensive labor is
required to produce a consistent, high-quality crop. Also, mushroom farms today
are highly technical operations, complete with extensive computerized systems
to monitor each point in production.
Mushroom Compost
Commercial mushrooms grow in a specially formulated and processed compost made
from wheat straw, hay, corncobs, cottonseed hulls, gypsum and chicken manure.
The three to four week long composting period is closely supervised and managed
to assure that the composting temperatures exceed 160°F for a few days in
addition to a steam pasteurization which occurs about one week before mushroom
spawn is mixed with the compost. Finally, a layer of sphagnum peat moss mixed
with ground limestone is top dressed onto the compost, and mushrooms grow on the
peat.
Complete Growing Methods
For a detailed look at the growing methods for White mushrooms, Agaricus
bisporus, go to www.americanmushroom.org and click on Growing Agaricus Mushrooms.
ACRE Legislation
For details on the Agriculture, Communities and the Rural Environment
ACT 38 of 2005, click here.
For questions or more information on SMS, email mushroomnews@kennett.net
Web site produced with a grant from the Pennsylvania Department of Agriculture.