Nitrogen Supplement For Mushroom Substrate

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Overcup Oak Swamp Chestnut Oak

Water Oak

Pin Oak Willow Oak

Northern Red Oak

Live Oak Sumac

Black Locust

New Mexico Black

Locust Black Locust Willows

Peachleaf Willow Sandbar or Coyote Willow Crack Willow Geyer Willow Pacific Willow Arrow Willow Black Willow Scouler Willow


Pacific Yew Elms

American Elm English Elm Fluttering Elm Mountain Elm

Figure 38. Oyster mushrooms growing from my previous book, The Mushroom Cultivator.

Cereal Straws For the cultivation of Oyster mushrooms, cereal straws rank as the most usable base material. Wheat, rye, oat and rice straw perform the best. Of all the straws, I pre fer wheat. Inexpensive, readily available, preserving well under dry storage conditions, wheat straw admits few competitors. Furthermore, wheat straw has a nearly ideal shaft diameter which selec'" rely favors the filamen tous cells of most mushrooms. Chopped into 1 -4 inch lengths, the wheat straw needs only to be pasteurized by any one of several methods. The approach most eas" y used by home cultivators is to submerge the chopped straw into hot water (160° F„ 710 C.) for 1 -2 hours, drain, and inoculate. First, fill a metal barrel w:'h hot tap water and place a propane burner underneath. (Diums should be food grade quality. Do not use those that have stored chemicals.) A sec ond method calls for the laying of straw onto a cement slab or plast'c sheeting to a depth of no more than 24 inches.The strav- is wetted and turned for 2-4 days, and then loaded into a highly insulated box or room. Steam is intro duced, heating the mass to 160° F. (71° C.) for 2-4 hours. (See Chapter 18 for these methods.)

The semi-selectivity of wheat straw, especially after pasteurization, gives the cuif'vator a two-week "window of opportunity" to estab lish the gourmet mushroom mycelium. Wheat straw is one of the most forgoing substrates with which to work. Outdoor inoculations of pasteurized wheat straw with grain spawn, even when the inoculations take place in the open-air, have a surprisingly high rate of success for home cu'tivators

Rye straw is similar to wheat, but coarser. Oat and rice straw are finer than both wheat and rye. The final structure of the substrate depends upon the diameter and the length of each straw shaft. Coarser straws result in a

Figure 38. Oyster mushrooms growing from my previous book, The Mushroom Cultivator.

looser substrate whereas finer straws create a denser or "closed" substrate. A cubic foot of wetted straw snould weigh around 20-25 lbs. Substrates with lower densities tend to perform poorly. The cultivator must design a substrate which allows air-exchange to the core. Substrate dynamics are determined by a combination of all these variables.

Paper Products (Newsoaper, Cardboard, Books, etc ) Using paper products as a substrate base is particularly attractive to those wishing to grow mushrooms where sawdust supplies are limited. Tropical islands and desert communities are two examples. Paper products are made of pulped wood, (lignin-cellulose fibers), and therefore support most wood-decomposing mushrooms. In recent years, most printing companies have switched co soybean-based inks, reducing or almost eliminating toxic residues. S'nce many large newspapers are recycling, data on toxin residues is readily available. (If the data can not be validated, or is outdated, the use of such newsprint is not recommended.) Since the use of processed wood fiber may disqualify a grower for state organic certification, cultivators in the United States should check with their Organic Certification Director or with their State Department of Agriculture before venturing into the commercial cultivation of gourmet mushrooms on paper-based waste products. If these preconditions can be satisfied, the would-be cultivator can tap into an enormous stream of cheap materials suitable for substrate composition.

Corncobs & cornstalks Corncobs (sans kernels) and cornstalks are conveniently structured for rapid permeation by mycelium. Their cell walls and seed cavities provide a uniquely attractive environment for mycelium. Although whole corncobs can be used directly, a more uniform substrate is created by grinding of corncobs to 1-3 inch particles using hammer-mill type chipper-shredders. After moistening, the corn roughage can be cooked for 2-4 hours at 160-180° F. to achieve pasteurization. If the kernels are still on the cob, sterilization may be necessary. Cornstalks, having a lower nutritional content, are "ess likely to contaminate.

Coffee & banana plants In the subtropical and tropical regions of Central and South America, the abundance of coffee and banana leaves has spurred mycologists to examine their usefulness in growing gourmet mushrooms. The difficulty in selecting any single plant material from warm, humid regions is the speed of natural decomposition due to competitors. The combination of high humidity and heat accelerates decomposition ot everything biodegradable. Leaves must be dried, shredded, and stored in a manner not to encourage composting. Once weec I fungi, especially black and green molds, begin to proliferate the suitability of these base materials is jeopardized. Ar present, the only mushrooms demonstrating commercial yield efficiencies on banana and coffee pulp are warm-weather strains of Oyster mushrooms, particularly Pleurotus citrinopileatus Pleurotuscystidiosus, Pleurotus djamor, Pleurotus ostreatus and Pleurotus pulmonarius. For more information on the cultivation of Oyster mushrooms on coffee waste, please refer to Thielke (1989), or Martinez-Carrera (1987).

Sugar cane bagasse Sugar cane bagasse is the major waste product recovered from sugar cane harvesting and processing. Widely used in Hawaii and the Phillipines by Oyster growers, sugar cane bagasse needs only pasteurization for cultivating Oyster mushrooms. Some Shiitake strains will produce on sugar cane residue, but yield efficiencies are low compared to wood-based substrates. Since the residual sugar stimulates mycelial growth and is a known trigger to fruiting, sugar cane residues are good complements to wood-based substrates.

Seed hulls Seed hulls, particularly cottonseed hulls, are perfect for their particle size and their ability to retain water. Buffered with 5-7% calcium sulfate and calcium carbonate, cottonseed hulls simply need wetting, pasteurization and inoculation. Cottonseed hulls, on a dry weight basis, are richer in nitrogen than most cereal straws. Many Button cultivators consider cottonseed hulls a supplement to their manure-based composts. On unamended seed hulls, Oyster and Paddy Straw are the best mushrooms to grow.

Peanut shells have had little or no value except, until now, to mushroom growers. The peanut hulls are rich in oils and starch which stimulate mushroom growth.The shells must be chipped into 1/4 to 3/4 inch pieces, wetted, and pasteurized for several hours. Because peanut shells form subterraneously and are in ground contact, they should be thoroughly washed before pasteurization. Sterilization may be required if pasteurization is insufficient. The addition of 5% gypsum (calcium sulfate)helps keep the substrate loose and aerated. Oyster mushrooms, in particular, thrive on this material.

Soybean roughage (Okara) Okara is the main by-product of tofu and tempeh production. Essentially the extracted roughage of boiled soybean mash, Okara is perfectly suited for quick colonization by a wide variety of mushrooms, from the Pleurotus species to Ganoderma lucidum, even Morels. Several companies currently use Okara for generating mycelium for extraction and/or for flavorings.

All of the above-mentioned materials can be used to construct a base formushroom production, outdoors or indoors. A more expansive list could include every primary by-product from agricultural and forestry practices. To the imaginative cultivator, the resources seem almost limitiess.

Supplementing the substrate can boost yields. A wide variety of protein-rich (nitrogenous) materials can be used to enhance the base substrate. Many of these are grains or their derivatives, like rice, wheat or oat bran, ground corn, etc. Supplementing a substrate, such as straw or sawdust, changes the number and the type of organisms that can ne supported. Most of the raw materials used for growing the mushrooms listed in this book favor mushroom mycelium and are nitrogen-poor. Semi-selectivity is lost after nitrogen supplements are added, but ultimately mushroom yields improve. Therefore, when supplements are usea, extra care is required to discourage contamination and insure success. Here good hygiene and good flow pat terns to, from and within the growing rooms are crucial. Supplementation of outdoor beds risks competition from contaminants and insects.

If supplementing a substrate, the sterilization cycle should be prolonged. Sterilization must be extended from 2 hours for plain sawdust at 15 psi to 4 hours for the same sawdust supplemented with 20% rice bran

Supplemented sawdust, straw and compost substrates undergo thermogenesis, a spontaneous temperature increase as the mycelium and ()ther organisms grow. If this naturally occurring biological combustion is not held in check, a plethora of molds awaken as the substrate temperature approaches 100° F. (38° C.). Below this threshold level, these organisms rem? n dormant, soon being consumed by the mushroom mycelium. Although true sterilization has not been achieved, full colonization is often times successful because the cultivator offsets the upward spiral of temperature. Simply spacing spawn bags or jars apart from one another, and lowering spawn room temperatures as thermogenesis begins, can stop this catalytic climb. For many of the gourmet wood decomposers, a tempera ture plateau of 75-85° F. (24-29° C.) is ideal

The following supplements can be added at various percentages of total dry mass of the bulk substrate to enhance yields. corn meal cottonseed meal or flour oat bran, oat meal rice bran rye grain soybean meal & oil spent grains from beer fermentation

(barley & wheat) vegetable oils wheat grain, wheat bran nutritional yeast The nutritional composition of these supple 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 approximately 12. 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 pelletized cattle feed, which also work well as inexpensive substitutes for many of the additives listed above.

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