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Loam for the beds.

In growing mushrooms we need loam for casing the beds after they are spawned, topdressing the bearing beds when they first show signs of exhaustion, filling up the cavities in the surface of the beds caused by the removal of the mushroom stumps, and for mixing with manure to form the beds. The selection of soil depends a good deal on what kind of soil we have at hand, or can readily obtain.

The best kind of loam for every purpose in connection with mushroom-growing is rich, fresh, mellow soil, such as florists eagerly seek for potting and other greenhouse purposes. In early fall I get together a pile of fresh sod loam, that is, the top spit from a pasture field, but do not add any manure to it. Of course, while this contains a good deal of grassy sod there is much fine soil among it, and this is what I use for mushrooms. Before using it I break up the sods with a spade or fork, throw aside the very toughest parts of them, and use the finer earthy portion, but always in its rough state, and never sifted. The green, soddy parts that are not too rough are allowed to remain in the soil, for they do no harm whatever, either in arresting the mycelium or checking the mushrooms, and there is no danger that the grass would grow up and smother the mushrooms.

Common loam from an open, well-drained fallow field is good, and, if the soil is naturally rich, excellent for any purpose. But do not take it from the wet parts of the fields. Reject all stones, rough clods, tussocks, and the like. Such loam may be used at once.

Ordinary garden soil is used more frequently than any other sort, and altogether with highly satisfactory results. The greatest objection I have to it is the amount of insects it is apt to contain on account of its often repeated heavy manurings.

Roadside dirt, whether loamy or gritty, may also be used with good results. If free from weeds, sticks, stones and rough drift, it may be used at once, but it is much better to stack it in a pile to rot for a few months before using.

Sandy soil, such as occurs in the water-shed drifts along the roads and where it has been washed into the fields, is much inferior to stiffer and more fibrous earth.

I have used the rich dark colored soil from slopes and dry hollows in woods, and, odd though it may appear, as mushrooms do not naturally grow in woods, with success. But it is not as good as loam from the open field.

Peat soil or swamp muck that has been composted for two or three years has failed to give me good returns. The mushrooms will come up through it all right, but they do not take kindly to it.

Heavy, clayey loam is, in one way, excellent, in another, not so good. So long as we can keep it equably moist without making it muddy it is all right, but if we let it get a little too dry it cracks, and in this way breaks the threads of the spawn and ruins the mushrooms that were fed through them.

Loam Containing Old Manure.- Loam in which there is a good deal of old, undecomposed manure, such as the rich soil of our vegetable gardens, is unqualifiedly condemned by some writers because of the quantity of spurious and noxious fungi it is supposed to produce when used in mushroom beds. But I can not join in this denunciation because my experience does not justify it. This earth is the only kind used by many market gardeners, as they have no other, and certainly without apparent injurious effect. When I was connected with the London market gardens, some twenty years ago, Steele, Bagley, Broadbent, and the other large mushroom growers in the Fulham Fields cased all of their beds with the common garden soil perhaps the most manure-filled soil on the face of the earth and spurious fungi never troubled them. Indeed, I can not understand why it should produce baneful crops of toadstools when used in mushroom beds, and no toadstools when used for other horticultural purposes, as on our carnation benches in greenhouses, in our lettuce or cucumber beds, or in the case of potted plants. True, spurious fungi may appear in the earth on our greenhouse benches or frame beds or mushroom beds at any time and in more or less quantity, but I am convinced that the rich earth of the vegetable garden has no more to do with producing toadstools than has any other good soil, and old manure has far less to do with it than has fresh manure.

All practical gardeners know how apt hotbeds, in spring when their heat is on the decline, are to produce a number of toadstools; and, also, that when the bed is “spent,” that is, when the heat is altogether gone, the tendency to bear toadstools has gone too. This peculiarity is more apparent in spring than in fall. All mushroom growers know that spurious fungi, when they appear at all, are most numerous three to two weeks before it is time for the mushrooms to come in sight. The same growth appears in the manure piles out in the yard; a few weeks after the strong heat of the manure has gone lots of toadstools may be observed on and about the heaps, but on the piles of well-rotted cold manure we seldom find toadstools at all.

The fresh, clean stable manure used in mushroom-growing is not apt to be charged with the spores of pernicious toadstools; their presence is always most marked in the case of mixed manures.

And there is a current idea that mushrooms will not thrive in beds in which old manure abounds, either in the loam or fermenting material; that it kills the mycelium. This, too, I must refute. I have seen heavy crops of spontaneous mushrooms come up in violet and carnation beds in winter, and where the soil consisted of at least one-fourth of rotted manure well mixed with the earth. In cucumber and lettuce beds the same thing has taken place. And in similar beds that have been planted artificially with spawn, good crops of mushrooms have also been raised, and the mycelium, instead of evading the lumps of old manure in the soil often forms a white web right through them.