THE MANAGEMENT OF MANURES.--Continued.
WHY DO WE FERMENT MANURE?
However much farmers may differ in regard to the advantages or
disadvantages of fermenting manure, I have never met with one who
contended that it was good, either in theory or practice, to leave
manure for months, scattered over a barn-yard, exposed to the spring and
autumn rains, and to the summer’s sun and wind. All admit that, if it is
necessary to leave manure in the yards, it should be either thrown into
a basin, or put into a pile or heap, where it will be compact, and not
much exposed.
We did not need the experiments of Dr. Vœlcker to convince us that there
was great waste in leaving manure exposed to the leaching action of our
heavy rains. We did not know exactly how much we lost, but we knew it
must be considerable. No one advocates the practice of exposing manure,
and it is of no use to discuss the matter. All will admit that it is
unwise and wasteful to allow manure to lie scattered and exposed over
the barn-yards any longer than is absolutely necessary.
We should either draw it directly to the field and use it, or we should
make it into a compact heap, where it will not receive more rain than is
needed to keep it moist.
One reason for piling manure, therefore, is to preserve it from loss,
until we wish to use it on the land.
“We all admit that,” said the Deacon, “but is there anything actually
gained by fermenting it in the heap?”--In one sense, no; but in another,
and very important sense, yes. When we cook corn-meal for our little
pigs, we add nothing to it. We have no more meal after it is cooked than
before. There are no more starch, or oil, or nitrogenous matters in the
meal, but we think the pigs can digest the food more readily. And so, in
fermenting manure, we add nothing to it; there is no more actual
nitrogen, or phosphoric acid, or potash, or any other ingredient after
fermentation than there was before, but these ingredients are rendered
more soluble, and can be more rapidly taken up by the plants. In this
sense, therefore, there is a great gain.
One thing is certain, we do not, in many cases, get anything like as
much benefit from our manure as the ingredients it contains would lead
us to expect.
Mr. Lawes, on his clayey soil at Rothamsted, England, has grown over
thirty crops of wheat, year after year, on the same land. One plot has
received 14 tons of barn-yard manure per acre every year, and yet the
produce from this plot is no larger, and, in fact, is frequently much
less, than from a few hundred pounds of artificial manure containing far
less nitrogen.
For nineteen years, 1852 to 1870, some of the plots have received the
same manure year after year. The following shows the _average_ yield for
the nineteen years:
_Wheat _Straw
per acre._ per acre._
Plot 5.--Mixed mineral manure, alone 17 bus. 15 cwt.
” 6.--Mixed mineral manure, and 200
lbs. ammoniacal salts 27 bus. 25 cwt.
” 7.--Mixed mineral manure, and 400
lbs. ammoniacal salts 36 bus. 36 cwt.
” 9.--Mixed mineral manure, and 550
lbs. nitrate of soda 37 bus. 41 cwt.
” 2.--14 tons farm-yard dung 36 bus. 34 cwt.
The 14 tons (31,360 lbs.) of farm-yard manure contained about 8,540 lbs.
organic matter, 868 lbs. mineral matter, and 200 lbs. nitrogen. The 400
lbs. of ammoniacal salts, and the 550 lbs. nitrate of soda, each
contained 82 lbs. of nitrogen; and it will be seen that this 82 lbs. of
nitrogen produced as great an effect as the 200 lbs. of nitrogen in
barn-yard manure.
Similar experiments have been made on barley, with even more striking
results. The plot dressed with 300 lbs. superphosphate of lime, and 200
lbs. ammoniacal salts per acre, produced as large a crop as 14 tons of
farm-yard manure. The average yield of barley for nineteen crops grown
on the same land each year was 48 bus. and 28 cwt. of straw per acre on
both plots. In other words, 41 lbs. of nitrogen, in ammoniacal salts,
produced as great an effect as 200 lbs. of nitrogen in farm-yard manure!
During the nineteen years, one plot had received 162,260 lbs. of organic
matter, 16,492 lbs. of mineral matter, and 3,800 lbs. of nitrogen; while
the other had received only 5,700 lbs. mineral matter, and 779 lbs. of
nitrogen--and yet one has produced as large a crop as the other.
Why this difference? It will not do to say that more nitrogen was
applied in the farm-yard manure than was needed. Mr. Lawes says: “For
some years, an amount of ammonia-salts, containing 82 lbs. of nitrogen,
was applied to one series of plots (of barley), but this was found to be
too much, the crop generally being too heavy and laid. Yet probably
about 200 lbs. of nitrogen was annually supplied in the dung, but with
it there was no over-luxuriance, and no more crop, than where 41 lbs. of
nitrogen was supplied in the form of ammonia or nitric acid.”
It would seem that there can be but one explanation of these
accurately-ascertained facts. The nitrogenous matter in the manure is
not in an available condition. It is in the manure, but the plants can
not take it up until it is decomposed and rendered soluble. Dr. Vœlcker
analyzed “perfectly fresh horse-dung,” and found that of _free_ ammonia
there was not more than one pound in 15 tons! And yet these 15 tons
contained nitrogen enough to furnish 140 lbs. of ammonia.
“But,” it may be asked, “will not this fresh manure decompose in the
soil, and furnish ammonia?” In light, sandy soil, I presume it will do
so to a considerable extent. We know that clay mixed with manure retards
fermentation, but sand mixed with manure accelerates fermentation. This,
at any rate, is the case when sand is added in small quantities to a
heap of fermenting manure. But I do not suppose it would have the same
effect when a small quantity of manure is mixed with a large amount of
sand, as is the case when manure is applied to land, and plowed under.
At any rate, practical farmers, with almost entire unanimity, think
well-rotted manure is better for sandy land than fresh manure.
As to how rapidly, or rather how slowly, manure decomposes in a rather
heavy loamy soil, the above experiments of Mr. Lawes afford very
conclusive, but at the same time very discouraging evidence. During the
19 years, 3,800 lbs. of nitrogen, and 16,492 lbs. of mineral matter, in
the form of farm-yard manure, were applied to an acre of land, and the
19 crops of barley in grain and straw removed only 3,724 lbs. of mineral
matter, and 1,064 lbs. of nitrogen. The soil now contains, unless it has
drained away, 1,736 lbs. more nitrogen per acre than it did when the
experiments commenced. And yet 41 lbs. of nitrogen in an _available
condition_ is sufficient to produce a good large crop of barley, and 82
lbs. per acre furnished more than the plants could organize.
“Those are very interesting experiments,” said the Doctor, “and show why
it is that our farmers can afford to pay a higher price for nitrogen and
phosphoric acid in superphosphate, and other artificial manures, than
for the same amount of nitrogen and phosphoric acid in stable-manure.”
We will not discuss this point at present. What I want to ascertain is,
whether we can not find some method of making our farm-yard manure more
readily available. Piling it up, and letting it ferment, is one method
of doing this, though I think other methods will yet be discovered.
Possibly it will be found that spreading well-rotted manure on the
surface of the land will be one of the most practical and simplest
methods of accomplishing this object.
“We pile the manure, therefore,” said Charley, “first, because we do not
wish it to lie exposed to the rain in the yards, and, second, because
fermenting it in the heap renders it more soluble, and otherwise more
available for the crops, when applied to the land.”
That is it exactly, and another reason for piling manure is, that the
fermentation greatly reduces its bulk, and we have less labor to perform
in drawing it out and spreading it. Ellwanger & Barry, who draw several
thousand loads of stable-manure every year, and pile it up to ferment,
tell me that it takes three loads of fresh manure to make one load of
rotted manure. This, of course, has reference to bulk, and not weight.
Three tons of fresh barn-yard manure, according to the experiments of
Dr. Vœlcker, will make about two tons when well rotted. Even this is a
great saving of labor, and the rotted manure can be more easily spread,
and mixed more thoroughly with the soil--a point of great importance.
“Another reason for fermenting manure,” said the Squire, “is the
destruction of weed-seeds.”
“That is true,” said I, “and a very important reason; but I try not to
think about this method of killing weed-seeds. It is a great deal better
to kill the weeds. There can be no doubt that a fermenting manure-heap
will kill many of the weed-seeds, but enough will usually escape to
re-seed the land.”
It is fortunate, however, that the best means to kill weed-seeds in the
manure, are also the best for rendering the manure most efficient. I was
talking to John Johnston on this subject a few days ago. He told me how
he piled manure in his yards.
“I commence,” he said, “where the heap is intended to be, and throw the
manure on one side, until the bare ground is reached.”
“What is the use of that?” I asked.
“If you do not do so,” he replied, “there will be some portion of the
manure under the heap that will be so compact that it will not ferment,
and the weed-seeds will not be killed.”
“You think,” said I, “that weed-seeds can be killed in this way?”
“I know they can,” he replied, “but the heap must be carefully made, so
that it will ferment evenly, and when the pile is turned, the bottom and
sides should be thrown into the center of the heap.”
LOSS OF AMMONIA BY FERMENTING MANURE.
If you throw a quantity of fresh horse-manure into a loose heap,
fermentation proceeds with great rapidity. Much heat is produced, and if
the manure is under cover, or there is not rain enough to keep the heap
moist, the manure will “fire-fang” and a large proportion of the
carbonate of ammonia produced by the fermentation will escape into the
atmosphere and be lost.
As I have said before, we use our horse-manure for bedding the store and
fattening pigs. We throw the manure every morning and evening, when the
stable is cleaned out, into an empty stall near the door of the stable,
and there it remains until wanted to bed the pigs. We find it is
necessary to remove it frequently, especially in the summer, as
fermentation soon sets in, and the escape of the ammonia is detected by
its well known pungent smell. Throw this manure into the pig-cellar and
let the pigs trample it down, and there is no longer any escape of
ammonia. At any rate, I have never perceived any. Litmus paper will
detect ammonia in an atmosphere containing only one seventy-five
thousandth part of it; and, as Prof. S. W. Johnson once remarked, “It is
certain that a healthy nose is not far inferior in delicacy to litmus
paper.” I feel sure that no ammonia escapes from this horse-manure after
it is trampled down by the pigs, although it contains an additional
quantity of “potential ammonia” from the liquid and solid droppings of
these animals.
Water has a strong attraction for ammonia. One gallon of ice-cold water
will absorb 1,150 gallons of ammonia.
If the manure, therefore, is moderately moist, the ammonia is not likely
to escape. Furthermore, as Dr. Vœlcker has shown us, during the
fermentation of the manure in a heap, ulmic and humic, crenic and
apocrenic acids are produced, and these unite with the ammonia and “fix”
it--in other words, they change it from a volatile gas into a
non-volatile salt.
If the heap of manure, therefore, is moist enough and large enough, all
the evidence goes to show, that there is little or no loss of ammonia.
If the centre of the heap gets so hot and so dry that the ammonia is not
retained, there is still no necessity for loss.
The sides of the heap are cool and moist, and will retain the carbonate
of ammonia, the acids mentioned also coming into play.
The ammonia is much more likely to escape from the top of the heap than
from the sides. The heat and steam form little chimneys, and when a
fermenting manure-heap is covered with snow, these little chimneys are
readily seen. If you think the manure is fermenting too rapidly, and
that the ammonia is escaping, trample the manure down firmly about the
chimneys, thus closing them up, and if need be, or if convenient, throw
more manure on top, or throw on a few pailfuls of water.
It is a good plan, too, where convenient, to cover the heap with soil.
I sometimes do this when piling manure in the field, not from fear of
losing ammonia, but in order to retain moisture in the heap. With proper
precautions, I think we may safely dismiss the idea of any serious loss
of ammonia from fermenting manure.
THE WASTE OF MANURE FROM LEACHING.
As we have endeavored to show, there is little danger of losing ammonia
by keeping and fermenting manure. But this is not the only question to
be considered. We have seen that in 10,000 lbs. of fresh farm-yard
manure, there is about 64 lbs. of nitrogen. Of this, about 15 lbs. are
soluble, and 49 lbs. insoluble. Of mineral matter, we have in this
quantity of manure, 559 lbs., of which 154 lbs. are soluble in water,
and 405 lbs. insoluble. If we had a heap of five tons of fermenting
manure in a stable, the escape of half an ounce of carbonate of ammonia
would make a tremendous smell, and we should at once use means to check
the escape of this precious substance. But it will be seen that we have
in this five tons of fresh manure, nitrogenous matter, capable of
forming over 180 lbs. of carbonate of ammonia, over 42 lbs. of which is
in a soluble condition. This may be leached day after day, slowly and
imperceptibly, with no heat, or smell, to attract attention.
How often do we see manure lying under the eaves of an unspouted shed or
barn, where one of our heavy showers will saturate it in a few minutes,
and yet where it will lie for hours, and days, and weeks, until it would
seem that a large proportion of its soluble matter would be washed out
of it! The loss is unquestionably very great, and would be greater if it
were not for the coarse nature of the material, which allows the water
to pass through it rapidly and without coming in direct contact with
only the outside portions of the particles of hay, straw, etc., of which
the manure is largely composed. If the manure was ground up very fine,
as it would be when prepared for analysis, the loss of soluble matter
would be still more serious. Or, if the manure was first fermented, so
that the particles of matter would be more or less decomposed and broken
up fine, the rain would wash out a large amount of soluble matter, and
prove much more injurious than if the manure was fresh and unfermented.
“That is an argument,” said the Deacon, “against your plan of piling and
fermenting manure.”
“Not at all,” I replied; “it is a strong reason for not letting manure
lie under the eaves of an unspouted building--especially _good_ manure,
that is made from rich food. The better the manure, the more it will
lose from bad management. I have never recommended any one to pile their
manure where it would receive from ten to twenty times as much water as
would fall on the surface of the heap.”
“But you do recommend piling manure and fermenting it in the open air
and keeping the top flat, so that it will catch all the rain, and I
think your heaps must sometimes get pretty well soaked.”
“Soaking the heap of manure,” I replied, “does not wash out any of its
soluble matter, _provided_ you carry the matter no further than the
point of saturation. The water may, and doubtless does, wash out the
soluble matter from some portions of the manure, but if the water does
not filter through the heap, but is all absorbed by the manure, there is
no loss. It is when the water passes through the heap that it runs away
with our soluble nitrogenous and mineral matter, and with any ready
formed ammonia it may find in the manure.”
How to keep cows tied up in the barn, and at the same time save all the
urine, is one of the most difficult problems I have to deal with in the
management of manure on my farm. The best plan I have yet tried is, to
throw horse-manure, or sheep-manure, back of the cows, where it will
receive and absorb the urine. The plan works well, but it is a question
of labor, and the answer will depend on the arrangement of the
buildings. If the horses are kept near the cows, it will be little
trouble to throw the horse-litter, every day, under or back of the cows.
In my own case, my cows are kept in a basement, with a tight barn-floor
overhead. When this barn-floor is occupied with sheep, we keep them
well-bedded with straw, and it is an easy matter to throw this soiled
bedding down to the cow-stable below, where it is used to absorb the
urine of the cows, and is then wheeled out to the manure-heap in the
yard.
At other times, we use dry earth as an absorbent.