EARTHING OVER THE BEDS.
This is an important operation in mushroom-growing, and the one for
which loam is indispensable. It consists in covering the manure beds,
after they have been spawned, with a coating, or casing as it is more
commonly called, of loam. The spawn spreads in the manure and rises up
into the casing, where most of the young mushrooms develop, and all find
a firm foothold. The loam also contributes to their sustenance. And it
protects the manure, hence the spawn, from sudden fluctuations of
temperature, and preserves it from undue wetting or drying.
The best soil to use for this purpose is rich, fibrous, mellow loam,
such as is described, page 100.
If the manure is fresh and in good condition and the beds are in a snug
cellar or closed mushroom house, I would not case them until the second
week after spawning, say about the eighth or tenth day; but were these
same beds in an open, airy shed or other building I would case them over
some days earlier, say the fourth or fifth day. A fear is often
expressed that when beds are cased within three or four days after being
spawned the close exclusion of the manure from the air is apt to raise
the heat of the manure in the bed, and thereby destroy the spawn; but I
have never known of any truth in this theory, and with well-prepared
manure I am satisfied no brisk reheating takes place, at least the
thermometer does not indicate it. The great danger of early casing is in
killing the spawn by burying it too deep in damp material and before it
has begun to run through the manure.
I have conducted several experiments in order to satisfy myself
regarding when is the proper time to case the beds, and have found no
difference in results between beds that were cased over as soon as they
were spawned and others that were not cased over until the fourth,
seventh, tenth, or fourteenth day after spawning. The good or bad
results in the time of casing depend on the condition of the manure in
the beds, the depth at which the spawn has been inserted, the openness
or closeness of the place in which the beds are situated, and other
cultural conditions. But to delay casing as late as the fifteenth or
sixteenth day after spawning is injurious to the crop, because in
applying the covering of soil we are sure to break many of the mycelium
threads that have by this time so freely permeated the surface of the
manure. After the fourth week little white knots may be observed here
and there on the spawn threads; these are forming mushrooms, and to
delay casing the bed until this time would smother these little
pinheads, and greatly mar our prospects of a good crop.
Peter Henderson, in his invaluable work, "Gardening for Profit," has
given rise to a deep seated prejudice against molding over mushroom
beds as soon as they are spawned by telling us that in his first attempt
at mushroom-growing he had labored for two years without being able to
produce a single mushroom, and all because he molded over his beds with
a two-inch casing of loam just as soon as he had spawned them. Then he
changed his tactics, and did not mold over the beds until the tenth or
twelfth day after spawning, and was rewarded with good crops of
mushrooms. Now, notwithstanding Mr. Henderson's experience, it is a fact
that many excellent growers spawn and mold their beds the same day, and
with success. But Mr. H. has done much good in displaying a rock against
which many might be wrecked, so much depends upon other cultural
conditions. The old practice of inserting the spawn three or more inches
deep into the manure bed and then molding it at once with two inches
deep of loam was enough to destroy the most potent spawn; nowadays we
barely cover the spawn with the manure, and this is how molding over at
once is so successful.
All the preparation necessary is to have the loam in medium dry, mellow
condition, well broken up with the spade or digging fork, and freed from
sticks, stones, big roots, clods, chunks of old manure, and the like.
Sifting the soil for casing the beds is labor lost. Sifted soil has no
advantage over unsifted earth, except when it is to be used for
topdressing the bearing beds or filling up the holes in their surface.
The condition of the soil should be mellow but inclined to moist. If wet
it can only be used clumsily and spread with difficulty; if dry it can
be spread easily but not made firm, and on ridge beds can not be put on
evenly. But when moderately moist it can be spread easily and evenly on
flat or rounded surfaces, and made firm and smooth.
How deep the mold shall be put upon the bed is also an unsettled
question. Some growers recommend three-fourths of an inch, others one,
one and one-half, two, or two and one-half inches, and some of our best
growers of fifty or seventy-five years ago were emphatic in asserting
three inches as the proper depth, but among recent writers I do not find
any who go beyond two and one-half inches. My own experience is in favor
of a heavy covering, say one and one-half to two inches. In the case of
a thin covering the mushrooms come up all right but their texture is not
as solid as it is in the case of a heavy covering, nor do the beds
continue as long in bearing; besides, "fogging off" is much more
prevalent under thinly covered than under heavily covered beds; also,
when the coating of loam is heavy a great many more of the "pinheads"
develop into full sized mushrooms than in the case of thinly molded
beds.
Opinions differ as to firming the soil. I am in favor of packing the
soil quite firm, and have never seen good mushrooms that could not come
through a well firmed casing of loam, and I never knew of an instance
where firm casing stopped or checked the spreading of the mycelium or
the development of the mushrooms. In the case of flat beds,--for
instance, those made on shelves and floors,--a slightly compacted
coating (and this is all Mr. J. G. Gardner uses) may be all right, but
in the case of alongside-of-walls, ridge, and other rounded beds I much
prefer and always use solidly compacted casings.
Mr. Henshaw has for several years used green sods about two inches
thick, put all over the bed, grass side down, and beaten firmly. The
advantage of using sods instead of soil, he thinks, is that the young
clusters of mushrooms never damp or "fogg off" as they are apt to do
when soil is used.
I have given this green sods method repeated and careful trials, and am
satisfied that it has no advantages, in any way, over common fibrous
loam; indeed, it is not as good. No matter how firmly a sod, having its
green side down, may be beaten on to a bed of manure, there is barely
any union between the two; the sod merely rests upon the dung, but so
closely that the mycelium enters it freely. A slight movement or
displacement of the sod after the spawn enters it will break the threads
of mycelium between the manure and the sod, and this will destroy the
immature mushrooms forming in the sod. This gave me a good deal of
trouble. Stepping on the sod would disturb it. A clump of strong
mushrooms formed under it sometimes displaces it in forcing their way to
the surface.
Sods are only fit for use on flat beds where they can lie solid; on
rounded or ridge beds they are too liable to be disturbed. And the
trouble and expense of procuring sods are too great to warrant their
use, even if they had any advantages.