Fig. 20. Bale of German Peat Moss.
Sawdust Stable Manure for Mushroom Beds.—This is the manure obtained from stables where sawdust has been used for bedding for the horses. It is a good absorbent and retains considerable of the stable wettings. Such manure ferments well, makes up nicely into beds, the mycelium runs well in it, and good mushrooms are produced from it. But if I could get any other fairly good manure I wouldn't use it. I remember seeing it at Mr. Henshaw's place some years ago. He had bought a quantity of fresh stable manure from the Brighton coal yards, where sawdust had been used for bedding for the horses, and this he used for his mushroom beds. I went back again in a few months to see the bed in bearing, but it was not a success. At the same time, some European growers record great success with sawdust stable manure. George Bolas, Hopton, Wirkeworth, England, sent specimens of mushrooms that he grew on sawdust manure beds to the editor of the Garden, who pronounced them "in every way excellent." Mr. Bolas says: "In making up the bed I mixed about one-third of burnt earth with the sawdust, sand, and droppings. The mushrooms were longer in coming up than usual, the bed being in a close shed, without any heat whatever. They have, however, far exceeded my expectations."
Richard Gilbert, of Burghley, also wrote to the Garden, April 25, 1885: "There is nothing new in growing mushrooms in sawdust. I have done it here for years past; that is to say, after it had done service as a bed for horses, and got intermixed with their droppings. I have never been able to detect the least difference in size or quality between mushrooms grown in sawdust and those produced in the ordinary way."
Tree Leaves.—Forest tree leaves are often used for mushroom beds, sometimes alone, instead of manure, but more frequently mixed with horse manure to increase the bulk of the fermenting material. Oak tree leaves are the best; quick-rotting leaves, like those of the chestnut, maple, or linden, are not so good, and those of coniferous trees are of no use whatever. As the leaves must be in a condition to heat readily they should be fresh; such are easily secured before winter sets in, but in spring, after lying out under the winter's snow and rain, their "vitality" is mostly gone. But we can secure a large lot of dry leaves in the fall and pile them where they will keep dry until required for use. As needed we can prepare a part of this pile by wetting the leaves, taking them under cover to a warm south-facing shed, and otherwise assisting fermentation just as if we were preparing for a hotbed. While moistening the leaves with clean water will induce a good fermentation, wetting them with liquid from the horse-stable urine tanks will cause a brisk heat, and for mushrooms produce more genial conditions.
Mushroom beds composed in whole or part of fermenting tree leaves should be much deeper than would be necessary were horse manure alone used; for half leaves and half manure, say fifteen inches deep; for all leaves, say twenty to thirty inches deep.
While mushroom spawn will run freely in leaf beds and we can get good mushrooms from them, my experience has satisfied me that we do not get as fine crops from these beds or any modification of them as from the ordinary stable manure beds. And we can not wonder much at this, considering that the wild mushroom is scarcely ever found in the neighborhood of trees or where leaf mold deposits occur.
Spent Hops.—We can make good use of this in one way. If we are short of good materials for a mushroom bed, we can first make up the beds eight or ten inches deep with fermenting spent hops, and above this lay a four or five inch layer of horse manure, or this and loam mixed. The hops will keep up the warmth, and the manure affords a congenial home for the mushroom spawn. But we should never use spent hops alone, nor so near the surface of the beds that the spawn will have to travel through it.
Spent hops can be had for nothing, and our city brewers even pay a premium to the manure agents to take the hops away.