COHSTRUCTIOS AH? SERVICE
CONSTRUCTION AND SERVICE
M. L. KING
Formerly Silo Investigation Expert,
Iowa State College
WEBB PUBLISHING COMPANY
During the past few years, I have had occasion to examine
and to study the construction of a large number of silos in a
dozen states, both in the East and in the Middle West. As
the result of this study I have become thoroughly impressed
with the belief that many of the mistakes and difficulties in
the building of silos might be avoided if the builders had a
more thorough knowledge of the fundamental principles of
silo construction and the preservation of silage. There is
no recent American book on silo building and none of any
date which covers the many types of silos now in use and
gives details of their construction. There are a number of
experiment station publications on the subject, but these are
necessarily either brief in their treatment or limited to special
types. It is with the object of presenting to the intending
builder the principles of silo construction and the advantages
and disadvantages of the different types, and more parti-
cularly of giving the actual methods of construction, that
this book is written.
The first part of the volume takes up the fundamentals
of silage preservation, descriptions of the different types of
silos follow, and an explanation of the details and the con-
struction of all the important types. These details and the
p ans and specifications are in nearly all cases from first-
Where the information has occasionally been gleaned from
others, full credit is given. The author wishes to acknowl-
edge his indebtedness to all engineers and mechanics with
whom he has associated in his silo work, as they have all
contributed ideas very helpful in developing silos. Promi-
nent among these should be mentioned C. H. VanZee, E. Y.
Cable, and A. O. Alexander. For careful editing and helpful
suggestions as to methods of presenting the facts contained
in this volume, the author is very grateful to Professor Fred
M. L. KING
I. EARLY DEVELOPMENT . . . 7
II. FUNDAMENTALS OF SILAGE PRESERVATION 11
III. WOOD SILOS
IV. MASONRY SILOS
V. PLANNING THE SILO
VI. ERECTION OF STAVE SILOS . . 52
VII. MONOLITHIC CONCRETE SILOS 60
VIII. THE IOWA SYSTEM OF BUILDING BLOCK SILOS . 65
IX. SAFE STRENGTH OF MATERIALS . . &4
X. BUYING AND CONTRACTING SILOS . . 96
Silos: Construction and Service
Origin. The silo probably originated in the southern
part of Europe somewhat previous to 1845.
Subsequent Development. The first silos used were
simply pits in which green fodders were packed and covered
with earth. Later these pits were made more permanent
by lining with masonry. To keep the upper layer of this
fodder moist and the whole more compact, the top was gen-
erally covered with earth or other heavy material. When
the fodder was used it was found that the silage at the bottom
was better preserved than that at the top, and that the
amount of inferior silage at the top was practically the same,
regardless of the depth of the silo. Thus the deeper pits had
a smaller percentage of inferior silage than the shallow ones.
The logical development, therefore, was to increase the depth
of the silo pit. However, soil waters often limited the depth,
so that it became necessary in many cases to build a super-
structure, or what we now consider a silo.
Under modern conditions we find that in most cases it is
cheaper to build above ground than below, so that today the
silo generally goes into the ground only deep enough to secure
a firm foundation; or in the case of a bank barn, it extends
down to a level with the barn floor. For Northern or North
Central states, the pit extends in the ground 3 or 4 feet, while
the superstructure, or silo proper, in case of wood, is gener-
ally built 30 feet high. Wood sflos should not be built much
' SILOS: 'CONSTRUCTION AND SERVICE
higher than this, unless extra precautions are taken in guying.
With the masonry silo, the practical height is not less than
Development of the Round Silo. The original silos were
built square or rectangular, but upon developing the high
silos it was found that a large amount of silage spoiled in the
corners. This lead to the boarding up of the corners with
straight boards, making an octagonal silo; or bent lumber
was used, making it round. This was a great improvement,
but was only an intermediate step in the development of the
round silo, which, during
the later part of the '80 's,
became quite common.
Improvement of Door
and Door-Frames. At first
the round silo had only
one door at the bottom, or
none at all, all silage being
lifted over the top It was
gradually learned that
doors could be maae as
tight and smooth as the rest of the wall, and then silos be-
came common with doors placed at more or less conven-
ient intervals. In the square silos the doors were made
continuous, just as in a grain bin. Likewise, in the early
'90's, continuous doors became common in what is known
as the Wisconsin or sheeted silo. It was only necessary to
place rods across the doors to prevent the jambs from
spreading. It was not quite such a simple matter to build
continuous doors in the stave silos; therefore they were
seldom used prior to 1896. Later a patent was issued cover-
ing this feature, and the use of continuous doors in stave silos
has been more or less involved in litigation.
Fig. 1. Construction
10 SILOS: CONSTRUCTION AND SERVICE
Development of the Masonry Silo. The use of wood and
masonry in silo construction commenced at about the same
time in the United States, namely, in the '70's. However,
steel is necessary in the construction of masonry silos, and
the lack of this general knowledge, together with the cost of
steel, caused many serious failures. For this reason rapid
advancement in the development of masonry silos has
occurred only since the beginning of the present century.
Masonry silos were originally built with very thick walls,
2 feet or even more being a common thickness. By the use
of a combination of steel and masonry, 3 to 6 inches is suffici-
ent. The establishment of this fact has, of course, been a
great factor in the development of an economical masonry
The general features of the modern silo are greater height,
smaller diameter, and convenience in construction and use.
FUNDAMENTALS OF SILAGE PRESERVATION
Nature of the Process. In the silo the corn or other fod-
der undergoes a slight chemical change quite similar to that
which occurs in making sauerkraut. The latter is such a
well known process and is so similar to the preservation of
silage that the comparison is oftentimes used. In the forma-
tion of silage, the action of two principal kinds of bacteria
determines its quality. These are the bacteria that form
lactic acid and those that form acetic acid.
In the early development of the silo, it was common to
cut the corn quite green, which condition favors the formation
of acetic acid. Acetic acid is very much stronger than lactic
acid, and silage containing much of it is what is ordinarily
considered sour silage.
Time for Cutting. The present practice is to permit the
corn to become as ripe as possible without losing much mois-
ture. That is, the corn should become well dented and glazed,
but should not be given opportunity to harden or dry out.
When a few leaves near the bottom of the stalk have dried
and the same with the husks, that indicates about the proper
time for filling the silo. The silage made from such corn
will be what is known as sweet silage. The acid formed will
be principally lactic. Within a very few hours after the
corn is placed in the silo it begins to heat. Only a certain
percentage of acid can form, as it kills the bacteria and thus
automatically controls acidity. The rise of temperature
also aids in the destruction of the bacteria.
Quality of the Silage at the Wall. At the wall of any
silo the rise in temperature due to fermentation is interfered
12 SILOS: CONSTRUCTION AND SERVICE
with on account of heat passing out through the wall; and
since heat is one of the factors in checking fermentation,
there are different conditions and results at the wall than
in the center. This is noticeable in any kind of silo. In
silage taken from against the wall, a slight difference in odor
can always be detected, no matter how good and tight the
walls are. This does not mean that the silage at the wall
is materially inferior to that elsewhere, nor does it mean that
just because there is a little difference in the odor the silage
is all bad. The writer has never found a silo in which this
difference could not be detected.
With a rise in temperature, any material is certain to
expand. The silage settles very rapidly the first few days,
and this, together with the rise of temperature, is the main
source of the outward pressure; during the first few days
after the silo is filled it is greater than at any other time.
The growth of mold or the decay of the silage can only
occur when air is admitted. If the silage is at all dry and
air is admitted mold results. If, however, the moisture
content runs as high as 65 to 70 per cent, and air enters, the
result is usually rotten silage. It is important to mention
this, as the rotten silage prevents air from reaching the rest
of the silage, so the loss in this case is usually not very great.
In the case of dry silage, however, the admission of air causes
a growth of mold which does not prevent to so great an extent
the entrance of air.
The growth of mold does not effectively prevent air from
reaching adjoining silage. Therefore the loss is often much
more serious than would have been the case with more mois-
ture in the silage. In some cases concrete silos could more
appropriately be called gravel silos, as they allow the air to
filter through and at the same time absorb moisture from the
silage, making the conditions right for the development of
SILAGE PRESERVATION 13
heavy mold near the wall. This is not true of a good con-
crete silo, but has usually been the case where sufficient
cement was not used.
Forage or Mold Poisoning. Some of these silage molds
are poisonous, especially to horses. The following is a state-
ment taken from Press Bulletin No. 30 (Iowa), by C. H.
Stange, head of the Veterinary Department of the Iowa State
College, with reference to this problem:
"Iowa farmers have suffered heavy losses in the past few
months by the death of horses from a disease that affects
these animals almost exclusively. It is usually fatal; it is
not contagious, and it is quite certain that it comes from the
eating of moldy fodder or grain. There is only one safe-
guard against it and that is the rejection of any feed that
shows signs of mold. Ensilage and corn fodder of any kind
and hay from swampy lands need to be inspected with special
care, for they are the most likely to be moldy. Cattle often
seem to eat spoiled plant food without harm, but to horses
it is poisonous.
"This disease has been called by various names: Forage
poisoning, cryptogamic poisoning, enzootic cerebritis, epi-
zootic cerebro-spinal meningitis, leuco-encephalitis, etc.
"It usually appears in isolated outbreaks and generally
the horses on a single farm in a community are affected. In
some cases where horses are not fed alike, only those given
a certain kind of feed are taken sick. In these facts there is
quite conclusive evidence that the disease is associated with
the food eaten and that it is not transmitted from one animal
to another. The outbreaks appear more frequently in low,
swampy districts because conditions there are more favorable
for the development of the molds and the undesirable changes
in plant foods believed to be responsible for the disease. It
is not by any means confined to these districts, however,
14 SILOS: CONSTRUCTION AND SERVICE
nor is it limited to any certain food stuff. It merely occurs
more frequently in some foods than others, due to their
nature and method of storing.
"Causes. Forage poisoning is likely to appear whenever
moldy grain or fodder is fed to horses or mules, but it does
not follow in every case where such food is given. More-
over, it very seldom affects cattle. Horses and mules may
sometimes be fed for a considerable time on fodder contain-
ing more or less mold without sickness while in other cases
a comparatively small amount of such feed will cause death
in a short time. Danger lies in the use of fermented foods,
also, on account of poisons developed in fermentation.
Some plants are likewise poisonous at a certain stage of their
growth or when partially wilted. This is true of sorghum,
particularly the second growth, which in some cases causes
almost instantaneous death.
"There are several molds which grow on food materials
under certain conditions which are more or less injurious.
The most common are the black mold, the blue mold and
the green mold. They are found most frequently in ensilage,
corn, hay, oats and ground feeds. Moisture favors their
development on all food stuffs.
"Ensilage. Ensilage is one of the most important and
valuable foods available to the Iowa farmer, but it is often
responsible for forage poisoning. Sweet ensilage is of proved
worth as a feed for horses as well as for cattle, but speaking
generally ensilage feeding is attended by some dangers that
the owners of silos should know. Ensilage contains the
necessary moisture and, in most cases, the required heat, to
favor the development of molds. On this account it is more
often a cause of forage poisoning than other food stuffs. Per-
haps 80 to 90 per cent of the outbreaks reported to this station
come from feeding moldy ensilage. The quantity of mold
SILAGE PRESERVATION 15
may be so small as to be overlooked and yet be dangerous.
Especially is that true of hay coming from low, marshy
ground ; though the mold in it may not be seen at first glance,
there may be enough of it to produce poisoning and death.
"Moldy corn has been responsible for several outbreaks
of forage poisoning. Ears that have been attacked by the
corn ear worm are particularly liable to be moldy.
"Symptoms. Two forms of the disease are most common,
the acute and sub-acute.
' 'In acute forage poisoning loss of appetite and lack of
thirst, associated with depression and lack of spirit are usu-
ally the first symptoms. Following this usually come un-
steadiness of gait and inability to control the hind quarters,
which become worse until the animal either lies down or
falls and is unable to rise. At the same time there is in prac-
tically all cases a paralysis of the muscles of the throat and
cheeks as a result of which there is slobbering, due to inability
to swallow, and a flabby condition of the cheeks, which appear
swollen and pouched. After the animal is unable to rise it
will sometimes lie quietly for hours, and sometimes it will
struggle or show spasms at frequent intervals. In acute
cases there is usually profuse sweating and many times a
peculiar staring appearance of the eyes. The temperature
is normal or frequently below normal, which is contrary to
the fact in contagious diseases. The breathing is usually
irregular and jerky. The acute cases invariably die after
a course of 12 to 72 hours and are usually the first animals
to be affected after moldy food is eaten.
"In sub-acute cases the symptoms are similar to those in
acute cases but they do not come on so suddenly and are less
violent. The sub-acute cases occur among animals that
have eaten less of the poisonous food and they are the last
to show symptoms. Dullness and difficulty in swallowing,
16 SILOS: CONSTRUCTION AND SERVICE
associated with slobbering and dropping partially chewed
cuds of food into the manger and feed box, are early signs of
the disease. These are followed by increasing paralysis,
especially of the limbs, weakness, and often indications of
delirium. In fatal cases death follows in from several days
to a couple of weeks. A few of the less severe cases may
"The length of time between the feeding and the appear-
ance of the symptoms, the suddenness of the attack and its
duration, depend upon the amount of poisonous food taken.
The course is shorter, from 2 to 4 days, the attack is more
sudden and death soon follows in from 12 to 36 hours
when large quantities are consumed.
"Prevention. Since horses and mules are very liable to
poisoning with moldy foods where cattle may eat the same
foods with little or no danger, the method of preventing the
disease is clear. Under no circumstances feed horses or mules
ensilage that is in the least molded or decayed. In feeding
ensilage to cattle do not put it or scatter it where horses or
mules can get to it, for they will sometimes eat the leavings
in the feed trough after the cattle have picked out the best
food. Do not throw waste ensilage where horses or mules
can reach it. Sweet ensilage is a wholesome food for horses
and of known nutritive value, but unless it is certain that it
is perfectly fresh and free from mold it should not be fed to
horses at all. Moldy silage has already caused such heavy
losses on some farms that it will take all the profits a silo can
bring to make good the cost.
"The hay, corn, oats and other grains fed to horses should
always be of the best quality and the water troughs should
be kept clean and the water pure and fresh. With all these
precautions, forage poisoning can be eliminated."
SILAGE PRESERVATION 17
Settling. As has already been mentioned, the heavy
fodder packed into the silo to a depth of from 30 to 50 feet
settles rapidly for the first few days. In case the silo wall
is smooth and vertical, the silage in settling does not draw
away from the wall perceptibly, and there is no occasion for
spoiled silage against the wall. If, however, the wall is not
smooth, the silage will not come in contract with the surface
of the wall in the recesses. These spaces will, of course, con-
tain air, and the result will be moldy or decayed silage. In
case a silo leans, the silage will settle a little heavier against
one side and draw away from the other, thus allowing the
entrance of air and consequent spoiling of silage.
It is sometimes reasoned that a silo should be built a
little larger at the top than at the bottom in order that the
silage will in all cases crowd the wall. On the other hand,
it is sometimes reasoned that the silo should be smaller at
the top than at the bottom, thus reducing the pressure of the
silage against the wall when settling. Either of these two
practices is poor, as the good of the one increases the danger
that the other is designed to correct. In all cases the prop-
erly built silo is round, smooth, and plumb.
Material of the Walls. The material of the walls must
be such that it will absorb as little moisture as possible. The
wall absorbing no moisture would of course not admit air.
The admission of air or the absorbtion of moisture will cause
Strength and Rigidity. It is almost needless to say that
the silo must have walls sufficiently strong to withstand the
pressure of the silage, and should, of course, likewise be rigid
enough to stand the action of wind.
Fire Exposure. Placing a wood silo among the other
farm buildings reduces the distance a fire would need to jump
in order to connect with other buildings. It is not only
18 SILOS: CONSTRUCTION AND SERVICE
exposed to destruction itself, but it also increases the danger
of fire spreading from one building to another. Ordinarily,
silage is not materially damaged by fire, but it is exposed to
decay after the silo is burned.
On the contrary, a masonry silo built of concrete or clay
blocks is not subject to serious danger of damage by a fire.
Moreover, it does to a certain extent serve as a fire wall be-
tween other buildings, actually interfering with the spread
of fire from one building to another.
Extent of Loss. The problem of reducing the quantity
of frozen silage is very important with every silo user. Froz-
en silage is not necessarily a loss, but it is of ten a serious incon-
venience. When thawed and fed soon after, it is practically
as good a feed as before it was frozen. The loss comes from
allowing it to stand exposed to the air too long after it is
thawed, causing it to rot. Thus the danger of loss depends
upon the amount of frozen silage that is allowed to accumu-
late. In most cases if frozen silage is taken from the wall
each morning and piled in the center of the silo it will be
thawed out by night. This of course depends largely upon the
severity of the weather and whether or not the roof is tight
and the door is kept closed. There is always sufficient heat
in the main mass of silage to thaw the usual amount of silage
frozen over night, provided this heat is not allowed to escape
through a poor roof or open door.
How Heat is Lost. Heat may be lost from a silo in two
ways. One is by conduction away from the silage through
the wall. Plainly the amount of this loss will depend largely
and directly upon the kind of material of which the silo is
SILAGE PRESERVATION 19
Heat is also lost by convection, which is the carrying
away of heat by the circulation of air from the surface.
The best kind of house would be uncomfortably cold
in the winter if it had no roof or if the doors were left open;
it is just as true of the silo. If the doors are open or the chute
poorly constructed, much cold air comes in and warm air
escapes. This is particularly true of a poor roof or no roof
at all. These two losses of heat combine at the surface near
the wall to make the freezing most serious at this point.
Also, it happens that this point is farthest away from the
main body of the silage. Therefore heat reaches it more
slowly, and the result is more serious freezing at that point
Prevention. Generally, a few inches below the surface
there is little, if any, frozen silage near the wall. In view
of these facts, two-thirds of the freezing of silage can be pre-
vented by simply keeping the outer eighteen inches of the
surface of the silage beveled down toward the wall. Thus
the silage most likely to freeze is removed before it has time
to freeze. During warm or moderate weather the silage
surface should always be kept level, but when the silage
begins to freeze, the surface should always be beveled near
the wall. Absolutely no silage should be allowed to cling to
the wall of any silo.
The roof should always be made tight, and the following
pages will show how every roof can be made so. Also, the
doors should be kept closed when practicable. If that is
impossible, it is doubly important that the chute be well built
and kept closed.
The loss of heat from the surface, due to allowing the
silage to stick to the walls, is much greater than the loss of
heat out through the walls themselves. So the difference
in materials of which the wall is made is of very much less
20 SILOS: CONSTRUCTION AND SERVICE
importance than has usually been supposed. As will be seen
in the following paragraphs, air does not conduct heat away
from silage as rapidly as building materials; therefore, as
little material as possible should extend continuously from
the inner to the outer parts of the wall. Air spaces are of
considerable advantage, and the larger the percentage of air
space the better. However, it is very questionable if a man
who must be careful of his dollars can afford to let this ques-
tion of warmth influence his choice of materials to any great
So many conditions enter into the question of freezing
silage, that it is very difficult to form any conclusion without
examining carefully a large number of silos which have been
cared for in a similar way, having similar good roofs, doors,
and chutes, and which are similar in exposure to cold winds,
and are fed down to about the same place, at about the same
rate. It is very doubtful in the mind of the writer whether
or not there is much difference to be found between the loss
of heat through a 2-inch stave wall and through a 6-inch
concrete wall. The hollow wall, such as cement block, clay
block, and monolithic concrete, has some advantage, but it
is questionable if an 8-inch clay block wall is any better in
this respect than a 4-inch. That is, the air spaces are not
separate, and there is more material extending across the
wall in the case of an 8-inch wall than in a 4-inch.
Air Spaces in Walls. It is always a good thing, so far as
warmth is concerned, to prevent the circulation of air in the
wall spaces. To illustrate, suppose the air space is vertical
and the air free to circulate. When the silo is half emptied
and the weather cold, the air is slightly warmed in the lower
part of the wall by contact with the inner side of the wall
next to the silage. This causes it to rise, carrying heat from
the silage up to the colder parts of the walls at the top of the
SILAGE PRESERVATION 21
silo. The cold air falls, thus the circulation continues to
carry away heat from the silage. If the circulation of air
is restricted by horizontal partitions, this circulation and
consequent loss of heat does not occur.
In double-wall wood silos, it is often well to provide for
circulation at times. After the silo is emptied, air can be
allowed to circulate in the walls, thus drying them and pre-
venting rapid decay, which would otherwise occur. This,
however, is not the case with masonry silos. There seems to
be no advantage of air circulation in the walls of masonry
silos, and there certainly are very marked disadvantages.
Influence of Materials. Materials differ in the ease
with which heat passes through them; or, as it is generally
stated, there is a difference in their conductivity. Aside
from this, about the only general law of heat transfer which
need be considered is that, other things being equal, the rate
of heat flow through the wall will vary inversely as the
thickness of the wall or the distance which the heat must
travel. Heat will pass through a 1-inch wall twice as rap-
idly as through a 2-inch wall of the same kind. Also, the
content of moisture increases the conductivity of most
materials, because the pores of the material contain moisture
instead of air, and air is a poor or slow conductor of heat.
Thus it will be seen that while dry wood is a very poor
conductor, wet wood conducts heat very much more rapidly.
Although there are several other features in silo building
more important, it seemed advisable to explain this
matter of freezing in order to correct the misunderstanding
that a 2-inch stave silo is so much warmer, or is so much less
subject to freezing, than a thicker masonry wall. The actual
facts do not bear out any such impression as this. In fact,
about the only way to secure marked improvement in this
respect is to build two walls entirely separate and if possible
22 SILOS: CONSTRUCTION AND SERVICE
restrict circulation. It is, however, very doubtful if the
average man can afford to spend very much money for the
slight advantage to be realized in this way.
In the handling of frozen silage it is always best to
remember that a preventative is better than a cure. Frozen
silage is not a good feed any more than snow is a good drink,
and will cause trouble; therefore silage should not be put in
the troughs during cold weather any length of time before
the stock is turned in to eat, and never should the silage be
put into troughs which are already half filled with snow. The
frozen silage which does occur should always be spread out
in the center of the silo and covered lightly with other silage.
This will usually remove the frost before evening feeding.
The wide distribution and cheapness of lumber during
the early stages of silo development were conducive to its
extensive use. A very large proportion, 80 to 90 per cent,
of all the silos in use are wood. Lumber and its uses have
been more widely known to average mechanics, which also
contributes to making the wood silo the most common type.
It can be secured in convenient forms of good grade, and is
quite durable if used properly. Wood swells quickly when
in contact with the moist silage, which makes it an important
and very useful silo-building material.
Kinds of Wood. Practically all authorities are today
agreed that the various woods related to cedar, such as
cypress, California redwood, and Oregon (Douglass) fir, are
the most desirable kinds for silo purposes. There is room
for choice among these woods, as cypress, while extremely
durable, cannot be secured in as clear and long length
stock as the redwood and fir. The redwood is more expen-
sive than the fir, but it also is considered superior to it. It
can be secured in a very clear quality and in any length
required. The fir can also be secured in good quality and
A good quality of white pine is very difficult to get today.
Hemlock is not used a great deal, but for cheap silos a
yellow pine or tamarack serves very well. The heartwood
of the yellow pine or tamarack is very durable, and whenever
possible clear heartwood should be secured.
Painting Wood Silos. With any kind of wood it is
mportant, at least for the sake of appearances, to paint
SILOS: CONSTRUCTION AND SERVICE
the outside. There is some question whether or not paint
on the outside increases the life of the silo, as the moisture
and heat on the inside cause the inner surface to decay
Some paints, such as creosote, not only protect the wood
from moisture, but also are poisonous to the microscopic
plants which cause decay, thus preventing decay, if
the wood is thoroughly saturated. This is accom-
plished by means of heat and pressure. It will undoubtedly
increase the lasting qualities of the silo if the staves are
merely painted. This should be done, however, after it has
been delivered on the farm, as the farmer can then determine
the quality of the wood
before painting. It is
better to paint the
staves before erecting
the silo, as the joints
can then be thoroughly
Frame Silos. The
first wood silos were
square frame structures
studded vertically and
In the development of
the round silo it was
only natural to follow
the same plan, using
Fig. 3. The construction of the Wisconsin silo. lumber thm OUgh to
bend conveniently. Per-
haps the best known of this type of silo was originated
by F. H. King, of the Wisconsin experiment station, in
the '80's. The lumber extending around the siln has suf-
WOOD SILOS 25
ficient strength to prevent the silage from bursting it. Gen-
erally one thickness of siding was placed outside, and two
or three thicknesses with tar paper between were placed inside.
This construction is plainly shown by Fig. 3, taken from an
early Wisconsin bulletin. H. B. Gurler, of DeKalb, Illinois,
substituted lath and plaster for the inner sheathing of the
Wisconsin silo. It was originally designed for use inside of
the barn and Has been more successful there than outside.
This silo has been quite popular, especially in Illinois. In
recent years the quality of lumber found on the market has
decreased considerable, so that it is now difficult in many
localities to secure at a reasonable cost such quality of lum-
ber as can be bent for circular sheathing.
The Wood Hoop Silo originated in the western part of
New York, and is shown in Fig. 4. The first silo of this
type that the author has been able to learn of was built in
1894, by J. T. Wells, a builder and contractor of Scottsville,
New York, and had a continuous door. This silo has several
advantages over the Wisconsin silo in that the sheathing is
not circular and only enough lumber is bent around to pre-
vent the silo from bursting open. Common flooring is used
for sheathing and is nailed vertically on the inside. Where
better work is desired, it is also sheathed on the outside ; this
gives a hollow wall. The silo is nailed together so that, as
in the case of the Wisconsin and Gurler silos, there is nothing
to tighten or loosen at any time. It is made entirely of
standard lumber. If necessary the hoops can be made of
weather boarding. Braces are placed between the hoops for
jambs, and at the door 2-inch material is placed vertically
between the hoops. The hoops are generally placed 3 feet
apart, and all are of such size that the pressure will be taken
care of. Fir, white pine, or cedar siding may be depended
upon to withstand a pull of from 1400 to 1800 pounds per
5/7,05: CONSTRUCTION A ^D SERVICE
square inch, so that
for a 16x30 silo the
hoops should be ap-
proximately 3 inch-
es square. This size
is necessary at the
bottom in order to
stand the pull, and
the same size should
be used at the top,
so that the hoops
will be large enough
to brace the silo wall.
This silo is not very
widely used, but
seems practicable in
a very wide range of
conditions, and in the
opinion of the writer
is destined to become
one of the very popu-
lar wood silos.
Stave Silos. The
stave silo is common-
ly called the tub silo,
and is ordinarily
made of 2x6 tongued
and grooved staves
held together by
hoops made of steel
rods, joined at the
ends by means of mal-
leable iron lugs and
Fig. 5. The independent door.
SILOS: CONSTRUCTION AND SERVICE
nuts. Originally this form of silo was used only with indi-
vidual doors, that is, doors placed between every other pair
of hoops. At present a great many companies are mak-
ing the continuous-door
stave silo, differing only
in minor features of the
door frame. Several of
these are shown in order
to illustrate the different
kinds. A great advan-
tage of the stave silo is
the rapidity with which it
can be built. It requires
only one or two days for
erection. That it is a
moderate priced silo, port-
able, and has a capacity
to resist wind as success-
fully as some of the other
types, are also advant-
If the silo is secured to
the foundation and the
top guyed by means of
three or four wires, nine-
tenths of the difficulty of
blowing down can be
done away with. It
should be secured at the
bottom to the foundation
s^t four to six places, and the guy wires should extend out
quite a distance or across to the framework of the barn.
They should never be placed close to the foot of the silo and
Fig. G. The Unadilla door.
never steeper than 45
degrees. For silos
twelve feet or over in
diameter, the stave
should be 2 inches
thick and 4 to 8
inches wide, the most
common width being
6 inches. In the case
of silos 12 feet in di-
ameter or less, they
have, in some locali-
ties, been built from
1-inch flooring and
the ends of the floor-
ing joined together by
steel splines. The
1-inch stave is quite
economical, and for
small silos has been
found very successful.
In the care of the
stave silo it is neces-
sary, of course, as it
becomes empty and
dried out, to tighten
up the guys and the
hoops. S u ffi ci e n t
threads are provided
for this so that it can
be accomplished very
easily. One of the
most common mis-
Fig. 7. The Indiana door.
SILOS: CONSTRUCTION AND SERVICE
takes made in caring for the silo is to neglect to loosen
the hoops when the staves swell after the silo has been filled.
This should be attended to; as soon as the silo tightens up the
hoops should be let out
to the same point where
they were when they were
originally erected. The
paint on the ends of the
rods will indicate this
point, or it may be
marked by means of a
punch. If this is not
done the door-jambs will
be crushed together, the
edges of the staves
crushed, and the lugs
broken or at least bent
seriously. It requires only
a few years of neglect in this way to use all the threads on the
hoops. Then the silo can not be further tightened without
washers or short pieces of gas pipe under the nuts.
Advantages and Disadvantages. Masonry and steel
makes a successful and permanent silo when properly used.
The chief advantages are permanence and the slight amount
of care necessary. The disadvantages are the length of
time required to build and the difficulty of getting men prop-
erly skilled in this kind of work. It is necessary, as with any
other silo, to use sufficient material to prevent the pressure of
the silage from bursting the sides. Masonry alone cannot
be depended upon to withstand this pressure, and steel must
be applied in the form of wires and rods to withstand this
tension or outward pressure. In order that the steel may be
as permanent as the masonry, it must be protected from the
air by at least an inch of mortar or concrete.
Quality of Materials. It is necessary, in the use of
masonry, to use only such material as will be practically
air tight; that is, it must not be capable of absorbing water
to the extent of more than one-tenth to one-twentieth of
its own weight. In case the masonry silo is found to be
faulty in this respect, it can be improved by plastering the
inside with good rich plaster, or covering with coal tar,
creosote, or similar substance.
It is a poor plan to make one link of a chain weaker than
the others; it is likewise foolish to build one part of a silo less
permanent than another. Wood door frames are less per-
manent and more expensive than masonry, and often cause
leakage of air between the door frames and the wall. To do
away with this difficulty, it is simply necessary to mold con-
crete door frames to receive the doors. The only logical
32 SILOS: CONSTRUCTION AND SERVICE
roof for the masonry silo is masonry. It is easy to build it
either of concrete or clay products, and then it becomes fully
as permanent as any other part of the silo.
Stone Silos. The use of stone silos is naturally confined
to localities where stone is plentiful; and probably the great-
est number of these stone silos are to be found in Wisconsin.
The cost of material under favorable circumstances is very
slight, in fact almost nothing when it must be gathered from
the field to permit cultivation. The labor feature is an
important factor, and as the cost of labor increases, the
building of stone silos decreases.
It was common to depend upon very thick walls to with-
stand the outward pressure, but, as already stated, it is never
safe to depend upon masonry to withstand any force which
tends to pull it apart. Where liberal amounts of steel have
been placed in the wall they have not cracked, and where
they have been plastered inside with a good cement plaster
they have made very satisfactory silos.
Concrete Silos. With the advent of concrete, and
especially reinforced concrete, it was only natural that it
should be tried for silos. It has been used in many different
ways in monolithic construction (molded in place in forms)
with both single and double wall, and is also made into silo
blocks of different kinds. It is difficult to say just who was
the first to use concrete for silos, or even in which section of
the country this use of concrete originated. But today it is
successfully and very widely used.
Like the stone silo, the advisability of using it depends
very largely upon the supply of material; that is, gravel or
crushed stone. It has been found durable for all climates,
is storm proof and fire proof, in fact it is difficult to see how
anything could be built more permanently. Double walls
are advantageous in resisting frost. This form of construe-
tion can be made to embody all of the essentials of silo con-
struction. The precautions to be taken are to secure
competent workmen, thorough reinforcement, and properly
Fig 9. The stone silo.
SILOS: CONSTRUCTION AND SERVICE
A concrete silo, constructed under the supervision of the Nebraska
Plastered Silos. A modification of the concrete silo that
has come into more or less prominence in some localities in
the last few years is the plastered silo. Its essential feature
is simply a skeleton of expanded steel used as reinforcing.
This steel is covered with two or three coats of plaster on each
side, so that when complete it is 2 or 3 inches thick. It is
necessary to use as much steel, or more, in this construction
than is indicated in the reinforcing plate shown on page 78,
and in addition a scaffold for temporarily holding the steel
in position is required.
Clay-Product Silos. The economical masonry building
materials of the present time may be divided into two general
classes, concrete or stone, and clay products.
Either of these classes furnish excellent building materials
for silos. Therefore it is only natural that in many places
brick was used in the early development of the silo. As in
Fig. 11. The cement block silo.
36 SILOS: CONSTRUCTION AND SERVICE
any other masonry material, the outward pressure must be
taken care of or resisted by steel placed in or around the wall,
preferably in the wall, as it is then protected from rust. In
the earlier forms of this silo, as in the concrete and stone
silos, wooden door frames were used.
As already suggested, the choice between clay products
and concrete will usually depend upon the local conditions
and the supply of these materials. Therefore, it was only
natural, while collecting material for the publication of
Bulletin 100 of the Iowa Agricultural experiment station,
that the author put forth an effort to design a successful,
economical, and durable silo for localities in which materials
for concrete construction were scarce and expensive. From
this effort has resulted the Iowa silo, described in Bulletin
117, the distinguishing features of which are a reinforcing
system and a door-frame design for bricks or blocks, either
clay or cement. The fact that it was developed in portions
of the state where concrete material was scarce, resulted
in almost exclusive use of hollow clay blocks or building
The door frame was built of reinforced concrete, molded in
the form of either individual or continuous doors. A
special and simple reinforcing system was designed. The
door jambs are reinforced vertically and are tied together
across the door opening by a half more steel than is used in
the same height of the wall. Heavy wire is used in the mor-
tar joints extending around the silo and secured to the ver-
tical steel in the door jambs. Considerable time and effort
were spent upon the development of a convenient scaffold,
modifications of which are used by most of the Iowa silo
builders. At present this silo has established itself as one of
the economical and practical types of silo in use. Like any
other silo the general precautions to be taken are to
Fig. 12. The old brick silo.
38 SILOS: CONSTRUCTION AND SERVICE
secure good material and have it put together in a work-
manlike manner, as in any other masonry silo the work-
manship is very important, even more so than in a wooden
Interlocking Block Silos. There are on the market
several kinds of interlocking devices for silo building blocks.
In general this depends, in one way or another, upon the
tensile strength of the blocks taking care of the outward
pressure of the silage. If the proper amount of steel is used,
these silos become safe; otherwise, too large a percentage of
them burst, as masonry can not be depended upon to with-
stand a pull. If a sufficient amount of steel is used the inter-
locking devices become an unnecessary expense.
PLANNING THE SILO
Selecting the Location. One of the first questions con-
cerning location is, Shall the silo be placed inside the barn,
or not? It is very seldom that there is an occasion for placing
the silo inside the barn. There are good reasons for this :
First, the silo, with the exception of a few types, is of such
construction that it does not need the protection of a covered
Second, it is not economical to place a silo in a building
where it will occupy space which may be put to other use.
Third, a silo located inside of a building is often unhandy
to fill. The forage cannot be delivered to the cutter con-
Fourth, by locating a silo outside of the building and
connecting it thereto with a passage provided with doors,
-the objectionable odor of the silage may be kept out of the
In general, it seems that there are few advantages in
building a silo inside of a barn, and many in building it out-
side. There are types of barns, however, the large round
barn for instance, which make it possible for a silo to be con-
veniently located at the center.
There are other considerations concerning the location of
the silo which should be taken into account. The conven-
ience in feeding is one of the most important. It is ordinarily
most convenient to place the silo just outside the barn and
directly connected to one end of the feed-way or feed room.
Thus a cart or litter carrier may be loaded with silage and
40 SILOS: CONSTRUCTION AND SERVICE
pushed along the aisle, making a convenient method of dis-
tribution. If yard feeding is practiced, the carrier can be
arranged to run over a line of bunks. In this case the silo
would probably not be placed facing the barn. If silage is
fed both inside and outside, the carrier can be arranged to run
both ways. Sometimes part of the silage will be fed in the
barn and the rest carried in a wagon to the feed boxes. This
is the case on many general stock farms. Then the silo
should be placed far enough from the barn to allow a wagon
to be driven under the chute, thus loading it conveniently.
Large doors can be provided on each side of the passage, so
that while feeding in the barn one does not need to go out
doors to get the silage.
Often, after giving these matters thorough consideration,
there is still an opportunity for choice with reference to expos-
ure to weather or the location of the silo in relation to the
general group of buildings. Other things being equal, it is
well to place the silo where it will be protected as much as
possible from the north and northwest winds and from expos-
ure to the sun. In the case of light wood or stave silos, it is
often of the utmost importance to place the structure so that
it will be protected from the stronger summer winds. This
can often be done by locating it back of groves or in the L of
The question of general appearance of the farm buildings
is too often neglected. This should be only of second con-
sideration, as there is beauty in utility. Often the upper
portion of a well-built silo showing above the sloping roof of
some of the other buildings adds very materially to the
general appearance of the group of buildings. Also the
side near the top often affords the best place for the farm
PLANNING THE SILO 41
Cost Considerations. The question of cost must be
viewed from every possible angle. First, perhaps, is a con-
sideration of the financial affairs of the prospective builder
or purchaser. Lack of money should never be a reason for
going without a silo. Properly used, it will put a farmer in
far better condition to meet his financial obligations than
before. It does, however, often happen that a man is
loaded so heavily with financial obligations that it does not
seem advisable to assume more debts. Yet under these
circumstances it might also happen that labor and help
could be secured from the neighbors, with the understanding
to repay it in labor in the future. In such circumstances it
is clear that the cash outlay for material becomes of the first
importance, and cost of labor becomes second. To illus-
trate, a man in such circumstances might have gravel on
his farm. Also, he might have lumber which he could use tem-
porarily for the scaffold. The cost of cement block molds is
slight, and if this man were somewhat of a mechanic he would
find it advantageous to secure a mold or molds and make his
own cement blocks at odd times. In this way a cement
block silo could be built with less cash outlay than any other
form of silo. In most cases, however, it would be necessary,
in considering cost, to figure the cost of the labor of making
the blocks, etc., so that for the man who must consider time
as money, or who would realize immediate cash returns for
his time, some other type would be a better investment for
him. In such a case the cash outlay might not exceed $150
for a 16x40 silo, while the cost of all material and labor might
In considering the cost of material it is evidently impor-
tant to take into account the amount of material that must
be purchased, also the amount of material that may be fur-
nished from the farm itself. In furnishing such material,
42 SILOS: CONSTRUCTION AND SERVICE
however, it should not be figured as costing nothing simply
because there is no cash outlay, but it should be considered
at its market value. The same is true of labor, which many
times is not figured in because money has not been paid.
This is not only a poor way of figuring, but it is extremely
misleading when costs figured in this way are reported to the
press or in any other way to the public.
Two classes of material are required in building a silo;
namely, that which becomes permanently a part of the silo,
and .he falsework and other equipment, scaffold, forms,
hoisting apparatus, etc. If these are furnished by the con-
tractor or can be sold or rented subsequently, this cost should
not, of course, be charged to the silo.
In regard to the quantity and cost of labor, it is important
to remember that labor can not be figured on definitely for
several reasons, unless it is contracted. Then the con-
tractor assumes the responsibility, and the farmer pays for
being relieved of the same.
The question of the efficiency or perfection of the silo is
of course primarily important. However, each type shown
in this book, is, when properly built, very efficient. Any of
them properly built and filled will preserve silage with prac-
tically no unnecessary loss, so that it becomes a question of
first cost, durability, and probably cost of repair and care.
The silos requiring paint or other attention should be charged
up with that item. In any building the cost of repair
becomes important, and one should consider the cost of
repairing different parts, and the probable length of time
before such repair will be necessary. Finally, the rate of
depreciation must always be considered.
The amount of investment may be considered as the sum
necessary not only to cover the first cost, but also to provide
a sinking fund of enough money put at interest to furnish
PLANNING THE SILO
cost of care and repair permanently, and to have accumu-
lated enough by the time the original building ceases to be
useful, to replace it. In order that such an investment shall
be good, it must produce not only interest but profit upon
this original cost and so-called sinking fund.
Planning the Size of the Silo. The best general advice
as to the dimensions of silos is to build them small in diameter
and great in height. The diameter must be such that at
least 2 inches can be fed from the silo each day. The follow-
ing tables will serve as the basis from which the amount of
Table 7. Capacity of round silos.
Amt. to be
Amt. to be
SILOS: CONSTRUCTION AND SERVICE
feed used daily, and the amount which should be used from
a silo of any size, may be estimated. These tables are taken
from Bulletin 100, Iowa agricultural experiment station,
Table II being furnished by the Animal Husbandry Depart-
ment of the Iowa State College.
Table II. Amounts of silage required per day for various kinds
Kind of stock
Wintering calves, 8 months old
15 to 25
Wintering breeding cows
30 to 50
Fattening beef cattle, 18-22 months old
First stage of fattening
20 to 30
Latter stage of fattening
12 to 20
30 to 50
Wintering breeding sheep
3 to 5
2 to 3
3 to 4
Table I may be used in connection with Table II to
determine the size of silo needed to fulfil various conditions.
For instance, if the silage is to be fed to a herd of 40 dairy
cattle, at the rate of 40 pounds per head per day, a silo 16 or
18 feet in diameter will be satisfactory. In case a smaller
type of cattle were kept, they would eat about 30 pounds each
amounting to 1200 pounds per day. As seen from the right-
hand column of Table I, this is not sufficient for a 16-foot
silo; therefore a 14-foot silo should be used, unless some
young stock is kept in addition to the 40 mentioned.
It should be borne in mind that if the size of the herd is
likely to vary from year to year, the diameter should be
such that the smallest probable herd would still use 2 inches
PLANNING THE SILO 45
from the surface each day. In calculating the height, one
must remember that the height should be such as to furnish
the feed capacity for the maximum size of the herd during
the required feeding season.
The feeding season will vary. In many cases the silo is
not opened until Christmas time, and silage is fed as needed
until grass, which is usually early in May. Oftentimes it is
desirable to feed silage from filling time, the middle of Sep-
tember, until May 1. In many cases silage is fed every day
in the year, and in most every case it is desirable to have
silage to depend upon during the dry summer weather in
August and September. Thus the feeding season varies
from 130 to 365 days, and since at least 2 inches should be fed
per day, for a 130-day season 22 feet or more (usually more)
of silage will be consumed. The silage will settle at least one-
sixth, or approximately 16 per cent, depending upon the time
spent in filling. This indicates that a silo should seldom,
if ever, be built less than 30 feet in height. If any silage is
not used at the end of the winter season, no harm is done, as it
will keep and will be found very advantageous during the
dry summer months. In case the herd is larger than usual
or the feeding season longer, a silo 40 feet in height above the
ground is not too large. Blowers of the ordinary kinds will
handle corn for silos 40 or 50 feet in height without any
The amount to be fed daily from the surface will vary
somewhat with the condition of the silage and the time of
year. The point is that no silage should be left exposed to
the air long enough to permit the growth of mold. The air
penetrates dry and poorly packed silage more rapidly than
more moist and well packed silage. During the summer
mold grows more rapidly than during the winter, so that the
summer silo should be made small in diameter. In addition
46 SILOS: CONSTRUCTION AND SERVICE
to the rapid growth of mold, if the cattle have some pasture
they will not eat as much of the silage as they otherwise
At all times it is important to remove the feed evenly
from the surface of the silage in order that no portion will
be exposed to the air longer than necessary, not longer than
a few days in winter nor longer than one day in summer.
Excavations and Foundations. Every building should
rest upon a foundation broad enough to prevent appreciable
settling, and deep enough to rest upon earth which is never
disturbed by frost. Excavating all the earth to the depth
of the foundation increases the capacity of the silo. This
space, however, costs somewhat more than equal space in
other parts of the silo, on account of the additional labor of
excavation. Thus it will be seen that it is not economical
to extend the foundation deeper than necessary to get
below the frost.
In pits 14 feet or more in diameter, it is usually most
economical to use a team and scraper in removing most of
the dirt. In the case of monolithic concrete silos, the sides of
the pit should be left smooth enough to serve as an outer
form, if the soil is of such a nature as to permit it. For
block silos the diameter of the pit should be such
that the outer part of the silo wall will come within
about 3 inches of the sides of the pit. This space gives room
to work with the trowel, and should afterwards be filled in
with concrete in order to protect the pit from soil water. It
improves the appearance of the silo to carry this concrete
up 8 or 12 inches above the level of the ground. This can be
done very well by laying up blocks temporarily about three
inches from the silo wall. These blocks make a very con-
venient form for the concrete and may be removed before the
concrete is set thoroughly. In the case of a stave silo, it is
PLANNING THE SILO 47
questionable whether or not a pit should be used, as the
concrete wall forms a shoulder inside of the staves,causing the
silage to draw away from the staves as it settles. Also, there
is usually a leakage of air between the staves and the founda-
The foundation of the stave silo can usually be made
most economically by simply digging a trench to the depth of
2 or 3 feet. This trench need not be wider than 6 or 8 inches
but the foundation should be extended above the ground 8
inches or a foot. Usually thin lumber is bent around and
secured to stakes set in a circle to make a form; but the
stakes must not be driven into the ground until the pit is full
of concrete, or the soil will be caved in.
In case a pit is deemed advisable, the earth should be
dug out as soon as the hardening of the concrete will per-
mit, as the inner part of the foundation may then be
trimmed smooth with a spade and plastered, if desired.
Whether this pit is excavated or not, the foundation
should be reinforced with considerable wire or enough steel
rods to be the equivalent of at least a J^-inch rod. The
amount of steel necessary for this, of course, depends entirely
upon the size of the silo and the distance which the founda-
tion projects above the ground. If there is any question as
to the quantity to use, the reinforcing table shown for
masonry silos should be consulted, using the quantity that
is called for in this table.
Drainage is important and should receive more consider-
ation than is usually given in the construction of farm
buildings, and especially of masonry silos. Any soil will
support a greater load when dry than when wet. This is
especially true of clay. The heaving motion of frost is due
entirely to the moisture contained in the soil, which expands
with an almost irresistible force upon freezing. Therefore,
48 SILOS: CONSTRUCTION AND SERVICE
unless the foundation lies in dry, well drained soil, a drain tile
should be used to remove the ground water. The tile may
be located around the lower edge of the wall. If gravel or
cinders are used, they should be well tamped before the
foundation is put in place.
In the case of the wood hoop silo, the walls may be set
flush with the inner part of the foundation of the silo pit,
using a heavy coat of asphalt or tar on top of the foundation.
The wood will then be protected from moisture of the foun-
dation, also the joint between the wall and the foundation
will be made perfectly air tight. In this case the pit is advis-
In case gravel is expensive or scarce it may sometimes be
economical to use brick or clay blocks for the foundation.
If they are used exclusively for the foundation of a clay
block silo, two 8-inch blocks may be laid side by side, making
the first course 16 inches wide. The next may be laid
crossways, making a 12-inch course. The third may then be
laid on edge, starting the 4-inch wall.
Details of Doors. In stave silos found on the market,
very convenient doors are usually provided, so that little need
be said concerning their construction. There will be found
some difference in them, in that some are more nearly air
tight, stionger, and less liable to stick than others.
For masonry silos, a cheap and very good door is shown
in Fig. 28. This door as shown is made of two thicknesses of
ship-lap that lap onto each other about two inches, and are
not beveled at the ends. The boards on the outer side are
shorter than those on the inside. A wide cleat with beveled
edges is nailed to the inner side of the door, on which the
different doors meet end to end, thus offering little obstruction
to the free settling of the silage.
PLANNING THE SILO 49
In order that any silo may fulfil its purpose, it is neces-
sary that the joints between the doors and the door frames be
air tight. It is difficult to obtain air-tight joints between
doors and masonry drawn out of shape, thus causing the loss
of as much as 4 or 5 cubic feet of silage at one door. Sealing
with clay was found to be satisfactory where reasonable care
was exercised in its use. This becomes a very simple matter
by taking a quantity of fine clay or other fine soil, wetting it
until sticky but quite stiff, and filling the shoulder of the
door frame with it before pressing the door into place. If
the mud is rather stiff it will hold the door to place until the
silage is up high enough to secure it permanently. The
moisture of the silage keeps the clay damp on the inside, thus
making it air tight. This is one of the oldest and best meth-
ods of sealing doors. It has been thoroughly tried and found
to be very satisfactory.
Roof Plans. There is in some localities a general impres-
sion that a silo does not need a roof. In reality a roof is not
absolutely necessary but is very desirable. It aids very
materially in preserving the shape of a wood silo, and in any
silo it is important to reduce the amount of frozen silage and
to protect the feed from bad weather. Otherwise, with
changes of weather the character of the feed will change.
In building a roof it is desirable to make as rigid a struc-
ture as is practical, at the same time obstructing the head
room as little as possible. It is quite common to use timbers
extending across stave silos from one side to the other. This
is entirely dispensed with in the drawing shown in Fig. 4. A
most economical roof for the wooden silo is generally made of
rafters placed about 7 feet apart at the cornice and extending
in to the center of the roof. Headers should be placed about
three feet apart between these rafters. On a 16-foot silo roof
with }/$ to J4 pitch, the rafter will be not far from 9 feet in
50 SILOS: CONSTRUCTION AND SERVICE
length, and two headers should be placed between each pair
of rafters about equally spaced along the length of the rafter.
These headers should be made of 2-inch material, and curved.
To determine the curvature of these headers, take a radius
equal to the distance from the rafter to the center line of the
silo, measured on the line extending at right angles to the
rafter at the point where the header is nailed to it. Then
lumber should be bent around the silo for a frieze and the
sheeting nailed securely to this, thus preventing the cold
air from coming in.
The sheathing is most conveniently made from sound 12-
or 14-inch barn boards ripped diagonally. These should be
nailed to the headers and to the top of the silo wall, so that
only the sheathing boards project from the cornice. By
covering this with a good grade of prepared roofing, a good
roof is secured. Dormer windows in the roof are quite
popular and perhaps add something to the appearance of
the roof, but are more expensive than the trap door and do
not serve so well. A glazed sash used as a trap door will let
in more light than the same sash used as a dormer window.
It should be covered with quarter-inch meshed galvanized
screen in order to protect it from hail.
The Chute. In order that the silage may be removed
from the silo conveniently, it is essential that a chute or
vestibule 3}^ to 4 feet square be built in front of the doors.
In case of a wooden silo, the framework of the chute is
nailed directly to the silo; in case of masonry, bolts should
be placed in the wall so that 2x4's may be bolted to the wall,
thus serving to connect the chute to the silo. The wood
chute is more common than masonry, but masonry is some-
times desired on account of its fire-proof qualities, being
more permanent and warmer than the ordinary wood chute.
If a monolithic concrete chute is to be attached to a mono-
PLANNING THE SILO 51
iitmc concrete silo, the two should be built up at the same
time and securely tied together. Some reinforcing should
be used in such a chute.
If the chute is to be of clay blocks, it need not be built up
at the same time as the silo, though it is usually found more
convenient to do so. The chute must have a trap door or a
dormer window in the roof extending out over the chute.
At the bottom the chute should be connected to the feedway
of the barn; sometimes, if considerable silage is fed outside
the barn, it will be found advantageous to set the silo far
enough from the barn so that a wagon can be driven under
the chute between the barn and the silo, when large doors
may be put in the bottom of the chute.
Points on Floors. In many localities a special silo floor
is not considered essential or even advisable. Every one
agrees that the floor may be more often dispensed with than
the roof. The floor, however, is a considerable advantage.
It helps prevent water from seeping into the silo, and reduces
the difficulty of cleaning out the silo before refilling. Con-
crete is usually used for this, but it need not be made thick nor
expensive. A three-inch floor is thick enough, but it should
be made quite dense, generally 1 to 4, unless the gravel is
In some cases where gravel is expensive, paving blocks
or even good hollow blocks may be used to advantage as
flooring by simply plastering them with cement mortar. The
floor should generally be slightly dished in the center, 6 to 10
inches being common.
ERECTION OF STAVE SILOS
ERECTING WITH SCAFFOLD
Inside and Outside Scaffolds. In the use of the scaffold
two quite different methods have been followed. In one,
the scaffold is built inside and in the other, outside of the silo.
The former method is not common and is of questionable
success, as an outside scaffold is most necessary for putting
on the steel. The inside scaffold uses a little less lumber
than the outside, but it is about as much trouble to build
and does not have the advantage of being out where it is*
needed for conveniently putting on the steel or hoops.
Construction. As seen from Fig. 13, in building the out-
side scaffold, place 2x6 uprights a short distance from the
foundation and about 8 or 9 feet apart. Thus the number
of the uprights will depend upon the size of the silo that is
being built. Usually the scaffold is built 16 feet high, thor-
oughly braced, and with brackets placed near the top of the
uprights and extending in toward the silo. The uprights
must be thoroughly braced, not only to one another, but to
stakes in the ground, farther out from the foundation.
Before building the scaffold, the door frame should be
upended in place and thoroughly plumbed and guyed in
If the silo is to be built in two sections with the lap only 2
feet, it is convenient to build the silo to the height of the
scaffold before extending the scaffold any further. A few of
the lower hoops can be then put in place and the silo made
fairly stable before extending it any higher. If the staves
ERECTION OF STAVE SILOS 53
are lapped more than 2 feet, or full-length staves are used, it
will be necessary to build the scaffold full height before erect-
ing any of the staves. The first thing to do is to erect the
The uprights are then spliced to the lower ones and the
scaffold built another section higher in much the same manner
as at first. In securing the staves in place, it is necessary to
have common plastering lath, 3-inch bats, or salt or lime
barrel staves which have been soaked over night in order to
get them to bend easily. As the staves are put in place nail
these strips of lumber to them to hold them together.
Handling the Staves. In any method of erecting it will
be found most convenient to clamp three staves together
before raising. A convenient method of doing this is to set
saw horses upon reasonably level ground and match the silo
staves together upon them. Then nail the convex or outside
surface of the barrel staves fast to the inner surface of the
silo staves, after the staves have been drawn reasonably
close together. The barrel staves ought to be long enough
to project 6 or 8 inches beyond the edges of the two outer
staves so that as each section of these staves is upended,
the projecting ends of the barrel staves may be nailed to the
portion of the silo which is already erected. In this way
crooked or warped staves do not give as much trouble as when
set up singly; also clamping the staves together holds them
The difficulty of lifting a heavy section is overcome by
the use of a rope and pulley. The pulley may be attached to
one branch of a "U" doubletree clevis, which is then hooked
over the top of the last stave set up; by passing the rope
through this pulley and taking a timber hitch around the
three staves they can be easily raised by a man on the ground.
The rope should of course be hitched a few feet from the end,
SILOS: CONSTRUCTION AND SERVICE
Fig. 13. Erecting with outside scaffold.
ERECTION OF STAVE SILOS 55
but not so far that the man at the top will have difficulty in
reaching down to unfasten it.
ERECTING WITHOUT A SCAFFOLD
While the most common practice is to use a scaffold, the
author has had better success with no scaffold at all, and he
very much prefers that method. This has been his experi-
ence with silos of various sizes.
The first step, as in the other methods, is to secure the
door frame firmly in place. This makes it perfectly safe for
one man who can work handily some distance from the
ground, to go to the top of the door frame and manipulate the
clevis and pulley, secure the top end of the sections when they
are raised, and loosen the rope and pass it back down to the
men below. As in the previous method, the staves are
clamped together with three barrel staves if the silo staves
are full length; if not, it will be necessary to use four barrel
staves, one at the top, one at the bottom, and one at each
joint. No scaffold is in the way to interfere with the raising
of the sections. The clevis is simply hooked over the top of
the door frame and a section drawn up.
After the bottom of the section is put in place it is a very
simple matter for the man above to loosen the rope, draw the
section over and place one end of the barrel stave to the door
frame for nailing. Nails should be set in the end of the barrel
staves before raising, as it is sometimes difficult for the man
at the top to get more than one hand free at a time. If there
happens to be much of a wind blowing it is well to nail a
scrap of 1-inch lumber on the ends of the staves and the top
of the door frame so as to hold the two together more
securely. The 1-inch pieces should extend pretty well across
the door frame so that two or more nails may be placed well
apart, thus stiffening the entire part that is already up.
SILOS: CONSTRUCTION AND SERVICE
Fig. 14. Erecting the silo without a scaffold.
ERECTION OF STAVE SILOS 57
The second section may next be raised and secured to
place with the barrel staves. After this is done, ordinarily,
it is best to take the pulley and clevis to the other side of the
door frame and set up two sections there in exactly the same
manner. Next, a 2x6 or 2x8 (nearest door in Fig. 15) is
placed across the silo and nailed to the top of the last stave
on each side. If the wind is blowing seriously it will be advis-
able to stretch No. 9 wires from the ends of these 2x6 's out
to stakes driven in the ground some distance away and
approximately in line with the 2x6's. Now two more sec-
tions may be raised, and secured by means of one-inch scraps
of lumber and nailed to the 2x6 in the same manner as the
first section was secured to the door frame. These two sec-
tions should be placed on opposite sides of the door frame,
and another piece of 2x6 lumber placed across the silo as
before shown in Fig. 15.
Closing the Circle. It is usually rather difficult to decide
just what size of circle to set the staves on* It is necessary
to allow for the staves going together rather loosely, yet it is
difficult to know just how much allowance to make. For
this reason, when the silo is about half erected, some meas-
urements should be taken to find out whether or not the
staves remaining to be used will close the circle properly.
If not, the staves must be set a little further out, or a little
closer in, as the case may require. After the circle is closed
by raising sections alternately on each side of the door frame,
nail another scrap of lumber on top of the last staves erected,
tying both sides securely together. This system of bracing
is shown in Fig. 15. No. 9 guy wires should be used as
needed, depending, of course, upon the weather.
Putting on the Hoops. The staves are now ready for the
hoops. Put them on, commencing with the second from the
bottom. A short piece of hoop is always provided to use
SILOS: CONSTRUCTION AND SERVICE
with the first, in order that it will reach around the first time.
All nuts are then turned up, drawing the silo together
snugly. The first and third hoops can then be connected
Fig. 15. Erecting the silo without a scaffold.
ERECTION OF STAVE SILOS 59
without the use of the extra section. Put on each successive
hoop up to as high as can be reached from ladders resting on
the ground, being sure to mark the spacing of the hoops
If a scaffold is used it is a comparatively simple matter to
stand on the scaffold and put on the successive hoops, tight-
ening them enough to hold the silo firmly in place.
If a scaffold is not used, the steel may be put on in the
following manner: Drive two spikes into the silo in such a
manner that the hoops, which should first be properly bent
to fit the silo, may rest upon these nails. The nails should be
placed about J4 the length of the hoop from each end of it.
Then place a ladder convenient to each nail and let a man on
each ladder carry one end of the hoop section and place it on
the nails. The entire hoop is put in place in this way, and
then each man may go to a joint and put on the lugs and bars.
In this way the lower half of the steel can be placed upon a
30- or 32-foot silo. It is then a simple matter to hook the
ladders to the top of the silo and finish putting on the steel.
The permanent guy wires should be placed and the silo
plumbed before thoroughly tightening the hoops or putting
on the roof. It must of course be borne in mind that the
lugs must not all be placed on one stave; they must be
"staggered" around the silo.
MONOLITHIC CONCRETE SILOS
In the building of silos in which the concrete walls are
moulded or as we generally say, monolithic silos, the common
thickness of wall is 6 inches. This is plenty heavy enough
for any reasonable size, up to a diameter of 25 feet and a
height of 50 to 60 feet. The mixtures used will of course
depend very largely upon the grade of gravel or other aggre-
gate. Mixtures of 1 to 4 and 1 to -3^ are, however, usually
found in the best silos. Stones should never be found in the
wall larger than one-third the thickness of the wall.
Reinforcement. Vertical reinforcement is commonly
recommended for concrete silos, but it is of little or no impor-
tance, as there has never been a failure due to lack of vertical
reinforcement in any masonry silo, except where a very thin
wall has " en built or the horizontal steel placed over 3 feet
The horizontal reinforcements may be determined from
the table on page 78. If other sizes of steel are used than
those shown in the table it will be a simple matter to
determine the equivalent amounts. One 5/g-inch rod is equal
to two ^-inch rods, while one J^-inch rod is equal to four ]/-
Forms. In the building of a concrete silo a scaffold may
be arranged similar to that described in the building of block
silos, but in addition to this equipment, forms will be neces-
sary. Several kinds are on the market at present, and
usually reliable information may be secured concerning them.
The author has not had wide enough experience in their
MONOLITHIC CONCRETE SILOS
COMPLETE FORMS IN PLACE
Inner hoops qre made
in one piece
FORM FOR DOOR
^^ IN PLACE
rC-| Bolt with long thread
PLAN OF FORMS
DETAIL OF HOOP CLAMP
DETAIL OF HOOPS
Fig. 16. Wooden forms for concrete silos.
62 SILOS: CONSTRUCTION AND SERVICE
actual use to compare them intelligently. In addition to
this there are several types of homemade forms, all of which
have been quite thoroughly tried out. The first is taken
from Bulletin 100 of the Iowa agricultural experiment station.
Illustrations of these forms are shown in Fig. 16; the descrip-
tions are taken from the bulletin.
"These forms resemble those used by R. L. Sollet, of
Goldfield, Iowa, in the construction of his silos. Two sec-
tions of staves 30 inches long are held in place by wooden
hoops made of ^ to J^-inch lumber bent to the proper circle
and nailed firmly together.
"The staves rest on %-inch square cleats nailed to the
hoops. The inner hoops are made solid ; and to remove them,
one side is driven down and the hoops sprung out of round.
The outside hoops are made with clamps by which they may
be opened for removal as shown. Three outside and three
inside hoops are required. The purpose of having two sec-
tions of forms is twofold. First, the second set of forms is
accurately located by the first before the second is moved,
and also by using 30-inch staves 5 feet of wall may be built
each day and the form need not be disturbed until the con-
tained wall is at least 18 hours old. Second, no tamping of
fresh concrete occurs on the unsupported wall, as there is
always a section of the forms below the one being filled. The
30-inch stave length was chosen because longer staves are
likely to bend, and the length is handy for fitting the doors,
which are 30 inches high inside and placed 30 inches apart."
The same staves will serve for any diameter of silo and
the hoops can be made adjustable within a limited range, so
that a few sets of hoops will equip a contractor for any diam-
eter of silo. This system of forms has been found to be fully
as cheap as any.
MONOLITHIC CONCRETE SILOS. 63
With this type it is convenient to use scaffolding of the
same plan as shown in the article on clay block silo con-
struction. There are several patented systems embodying
scaffold and forms. They are quite generally advertised and
may be learned of in that way. There are several systems not
In some cases it will be found convenient to use thin sheet
metal for outer forms, but the inner forms must be either of
wood or quite heavy steel on account of the danger of collap-
sing. If, however, a rigid inner form is used, the outer
may be of light material and may be spaced accurately from
the inner form. This secures a properly shaped wall of uni-
form thickness. Any forms should be cleaned every time
they are used, and usually it is well to coat them with grease
or oil. This, however, leaves some grease upon the surface
of the concrete and interferes with plastering in case it is
It is ordinarily advantageous to use two forms, the second
being put in place and filled before the first is removed. With
any system there should be separate forms for the door frame,
that is, it should never be necessary to use a wooden frame in
a concrete silo. After setting the forms they should be filled
around evenly about six inches at a time. Concrete should
not be dropped a great distance into them or any other rough
handling done with them, as it is not advisable to go to the
trouble of making forms that will stand much abuse. The
concrete should be thoroughly tamped or rammed with a
light rammer, and there should be sufficient water in the con-
crete to work to the surface by this process. The concrete
should be thoroughly spaded near the walls, in order to give
it a smooth and even surface.
In putting steel into the concrete, place it at a reasonably
uniform distance apart and about half way between the inner
64 SILOS: CONSTRUCTION AND SERVICE '
and the outer forms, but in no case put any reinforcing
material closer than 1 inch from the surface of the concrete,
also avoid any reverse curves in the steel. Where two pieces
of reinforcing steel join they should lap at least 2 feet, to pre-
vent slipping. Usually, good concrete need only to set over
night, when the form may be removed and raised.
One advantage of using two sets of forms is that in no case
is it necessary to remove them until 18 hours after they have
been filled. The common depth of a set of forms is 2J^ to 3J/
feet, but by using two sets, 5 or 6 feet can be added to the
silo each day.
Vertical reinforcement should be used on each side of the
doorway. In any silo more steel should extend across the
doorways than is found in other parts of the wall. Wall
reinforcement ending at the doorway should be hooked to the
Plastering. In case it is necessary to plaster this silo it
is most conveniently accomplished on the outside from a
swinging scaffold either suspended from the forms, or, if the
silo is completed, the scaffold may be supported from the
cornice. On the inside, it is usually most convenient to
remove the forms and plaster from the scaffold as it is low-
ered. It is better, however, to plaster the silo if possible
before it has thoroughly dried, as there is not much danger
then of the plaster drying too rapidly.
Methods of hoisting material will vary with different
systems of forms, etc. In most outfits on the market a con-
venient method of hoisting is provided. If, however, other
means are not available, a gin-pole, shown in connection with
block silos, Fig 22, will be found very convenient and
strong enough to hoist at least 100-pound loads.
THE IOWA SYSTEM OF BUILDING BLOCK SILOS
Construction of the Wall. The first course of blocks in
an Iowa silo should be a trial course, the blocks spaced J/g
to % of an inch apart, without mortar, in order to determine
the proper diameter of the silo and the length of the guide.
This will overcome the necessity of cutting blocks. Steel
should be placed upon the outer half of the mortar course,
in order that there shall be enough mortar inside to bear
against the wire and hold the blocks. In case of a double
wall the steel should, of course, be on the inner wall.
Loose blocks may be placed temporarily upon the wall to
hold the steel in place at intervals of 6 or 8 feet, as occasion
requires. Steel reinforcement in the joints below and above
the doorways should be long enough to lap past each other
and be hooked, as shown in Fig. 19.
The horizontal or bed joints should be thoroughly bedded
to cover the steel reinforcement. The vertical joints at the
block end should be made with care in order to insure per-
fectly air- and water-tight joints. In order to do this the
ends of both blocks should be mortared before pressing
together. The outside joints should, for the sake of appear-
ance, be struck neatly with the trowel as the work progresses,
and for warmth they should of course be air tight. On the
inside, however, this is scarcely sufficient, as there might still
be an occasional opening left between the ends of the blocks,
which would permit the air to enter.
The Cement Wash. In order to close all such openings,
leave the mortar hanging on the inside or cut it roughly; then,
SILOS: CONSTRUCTION AND SERVICE
while still green, wash with a cement wash before the scaffold
is raised or the work left for the night. This wash naturally
brings to view any crevices which may exist. These may be
then filled with mortar and thoroughly sealed on the inside
of the wall. This wash is composed of cement and water
Fig. 17. The clay block silo.
THE IOWA SILO
mixed to about the consistency of good paint, and can be
applied with a broom. The wash should be applied vigor-
ously, in order to smooth
down and fill the irregu-
Scaffolding. It is
difficult to overestimate
the advantage of con-
venient, safe, and simple
scaffold for any masonry
construction. Three dis-
tinct types have been
tried by the author, and
the one which is shown
here was found to be
superior to any other
type tried. This and
various modifications of
it are in common use.
This scaffold is shown in
the drawing; all parts
are lettered for^the sake
of a clear description.
The top side of the scaf-
fold is shown in Fig. 20.
This scaffold differs
from most building scaf-
folds in that the platform
is movable. The plat-
form itself consists essen-
tially of a square frame-
work of 2x8's or 2x6's
for a small silo, of a rea- Fig. is. The clay block
SILOS: CONSTRUCTION AND SERVICE
THE IOWA SILO 69
sonably clear, stiff lumber. These are shown by the dotted
line A. At the ends of these and flush with the bottom
of each are securely nailed 2-inch pieces, B, of convenient
length. Thus the bevel at the end extends through three
2-inch pieces instead of one, and furnishes ample bearing upon
the supporting pins, N. Instead of resting upon pins, the
scaffold is sometimes hung by means of clevises and short
chains. There should be at least 34 mc h of clearance all
around the post, M . This framework is held together at the
corners by an eye bolt passing through a 2x6, four feet long,
approximately (L shown beneath at the right-hand corner)
and by the outer planks above. The eye bolts should be
made of % inch metal with a washer at each end. The diam-
eter of the eye should be 1 inch inside. Four are required.
A 2x8 or 2x6, F, is bolted at each end to blocks which in
turn are nailed to the middle of the two opposite members, A.
Upon this framework is placed a 2x10, indicated by (r, lying
flat across the center of F and the two members, A. - Extend-
ing at right angles from G and lengthwise but not central
upon F are two 2xlO's, indicated by H. A block is nailed
under the longer 2x10 not supported by F, and nailed to the
inner end of these timbers, H, are blocks which extend two
inches under G. By placing these blocks on each side of F,
it is not necessary to nail H to F. It is highly desirable in a
scaffold which must be used repeatedly that no nails should
be drawn when taking it apart. Upon the corners of and
diagonally to this frame are laid, inside of D, two widths of
2x12 planks, lettered /; and connecting the ends of these and
resting upon the ends of G and H are three 1x12 boards, five
feet long, lettered J, beveled at the corners to fit the circle;
also five 1x12 boards, lettered K, which are not beveled.
The four 1x12 boards, lettered R, complete the upper part of
SILOS: CONSTRUCTION AND SERVICE
If strong 1-inch hardwood lumber is at hand, it may be
substituted for the 2-inch upper foot planks shown in the
drawing. In fact, this plan may often be changed to suit
the materials at hand, but in case all new materials are to be
bought, the plan shown will be found to give general satis-
Fig. 20. A scaffold for the Iowa silo.
faction since all parts, having been used repeatedly, are
known to be sufficiently strong. Four upright posts, M,
secured to the wall at points approximately equally spaced,
support the scaffold platform by means of %-inch round
THE IOWA SILO 71
steel pins 16 inches long, N, extending through 1-inch holes
in the uprights. Eight of these are required, as one set
should not be removed from a lower hole until the other pins
are placed to support the scaffold in case any of the hoisting
parts should break. As already noted devices and short
chains may be used to suspend the scaffold instead of support-
ing it from below.
Each upright consists at first of a 2x6 eight feet long and a
2x6 sixteen feet long screwed together with three 2^-inch No.
14 or No. 16 flat-headed screws. It is necessary to use flat-
headed screws in order that the head will countersink itself
into the wood, thus not interfering with the raising of the
scaffold platform. One of the bottom members of the up-
right is 8 feet long and the other 16 feet long in order that the
post may be added to as needed by simply screwing 16-foot
2x6's on alternate sides. These upright posts are secured to
the wall by means of light wires, P, which are placed about
3 feet apart vertically. Every alternate time the scaffold is
moved, 2-inch blocks, 0, should be placed snugly between
the post and the wall and nailed to the wall. This places the
post about three inches from the wall. Then it should be
toenailed to the block, and the wires passing through the wall
drawn tight. This holds the scaffold support rigid in all
directions and enables the builder to keep them plumb. The
distance between the holes in the upright will depend upon
the kind of hoisting apparatus used, but usually 18 inches is
most convenient. The most convenient device for raising
the scaffold are ^-inch triple blocks.
METHOD OF BUILDING
The Guide Device. It is essentially important, for the
sake of appearance, preservation of silage, and strength of
wall that the silo be circular and plumb. It is highly desir-
SILOS: CONSTRUCTION AND SERVICE
able that the guide be simple, easily used, and in the way as
little as possible when not in use. A common board about 6
feet long and cut to proper curvature also aids in getting a
good, smooth, round wall. It is of course possible to build
a circular wall by starting the circle, then using the plumb at
intervals on the wall. However, the guide devised has been
Nail to scaffold
for laying wall plumb and to true circle.
Fig. 21. A guide device used in constructing the wall.
found better for this purpose by men who have tried both
ways. It is also advantageous, since, by means of ifc, the
owner of the silo may in a very few minutes detect any
faulty shape of wall. It is merely necessary to determine the
proper position of the center-pipe by means of the plumb-bob;
THE IOWA SILO 73
then follow the end of the guide around the wall. All blocks
should be within less than J^ or % inch of the guide, and even
these variations should be gradual so as not to form shoulders
in the wall.
The device is shown in Fig. 21. A piece of 1-inch, or
larger, straight gas pipe, indicated by A, 7 or 8 feet long may
be secured as a center about which to revolve a light arm, B.
The outer extremities of this arm, X, are hinged, in order that
it may not interfere with walking around the scaffold. Also,
when not in use, C may be placed in the position shown in the
figure. It is not necessary to use the guide for each block,
but it is convenient for determining whether or not the blocks
are properly placed by means of this guide, before the mortar
joints are pointed.
The stand, D, is made of 2x4's or any convenient lumber
by means of which the gas pipe may be held in a vertical
position in the center of the scaffold. The collar and set
screw, E, are used to raise the revolving arm to a level with
the top of the course being laid. The upright, F, and two
laths, G, serve the purpose of holding B in a horizontal posi-
It will be readily seen that this guide at once becomes use-
ful not only in securing a circular wall but in making the
course level, as the end of the arm, of course, revolves in a
horizontal plane. This device has proven itself to be very
convenient. In order that the pipe A may be in the center of
the silo after each raising of the scaffold, it is only necessary
to pass a plumb line from the center of the pipe through the
board supporting the pipe to a nail in a stake in the bottom
of the silo. With this as an indication of the proper location
of the guide stand, the latter may be moved to place and
nailed lightly. After raising the scaffold, the first thing to
do, of course, is to drop wedges between scaffold and wall or
74 SILOS: CONSTRUCTION AND SERVICE
secure a scrap of lumber to the scaffold by one nail so the
end, in turning about the nail, will strike the wall.
Hoisting. Two general methods have been followed in
hoisting materials to the scaffold. In one method a pulley is
secured to the outer end of a 2x6 projecting over the wall and
the material is hoisted by a horse. This method is found to
interfere with the use of the guide of Fig. 22; therefore a der-
rick after the plan of Fig. 22 has been devised.
This derrick, 48 feet high, is built of three 2x6's 16 feet
long, A, and six Ix6's 16 feet long, B, besides the pieces neces-
sary for the arm at the top. As seen in the cross-sectional
view in the center, the 1x6 V are nailed flatwise upon the
edges of the 2x6's, thus forming an I beam. All of the mem-
bers are so placed that no joints are closer than 5 feet 4 inches.
Two short 1x6 struts, E, supports each end of the 1x6 pieces,
C. Two No. 9 guy wires, F, are secured to the end of C
toward the silo and fastened to stakes driven into the ground
a considerable distance away from the bottom of the derrick.
These prevent any side motion of the arm where the pulley
is attached, while a third guy wire is fastened to the other
end of C and secures the derrick in the other direction. This
derrick has been thoroughly tried out with loads up to 400
pounds. With the usual loads of less than 100 pounds it is
entirely safe. The derrick itself is most easily raised by
being constructed on the ground and raised after the guy
wires, pulley and rope have been attached.
Reinforcement. The door frames are reinforced both
vertically and horizontally with steel having a cross-sectional
area equivalent to J4 square inch, or a square reinforcing
bar % inch by y% inch.
THE IOWA SILO
L ~^- _|
Fig. 22. An efficient derrick.
SILOS: CONSTRUCTION AND SERVICE
The vertical reinforcing is bent as shown in Fig. 19, and
wired in place,
steel is placed in
the wall. The
steel used for
ing is cut in
lengths of 7 and
11 feet and one of
each length is
placed in each
half of the cross-
then into the wall
on each side, ex-
cept when ce-
ment blocks are
used. The No, 3
wire used for
forcement of the
wall is hooked
around the verti-
ment of the door
shown in Fig. 23,
tially of a contin-
uous door jamb
Bolts for uooder :
chute, or wall
hes ir? each
4"Droir? tile if needed-
Elevation of the doorway.
THE IOWA SILO 77
on each side of the opening. These jambs are
made of reinforced concrete and may be used with
either clay or cement blocks. The horizontal reinforce-
ments of the wall hook into the vertical reinforcements of the
jamb. The jambs are tied together at intervals of 4 or 5 feet
by steel within the crosstie block. This steel not only extends
into the vertical jamb, but, in order to be more secure,
extends several feet into the wall on either side of the jamb.
As shown in Fig. 19, these crossties may be of steel and pro-
tected from rust by being incased within the clay blocks
filled with concrete or within the concrete alone. When the
wall has been completed to the height at which it is desired to
commence the door, two blocks are laid upon the wall across
the doorway. These should be placed out far enough so that
the door may be set down inside without touching the
cross blocks. The shoulder or ledge thus formed should be
1% inches wide. Through this crosstie, and extending into
the hollow spaces in the blocks on either side of the door-
way, should extend the reinforcing steel, unless cement
blocks are used, in which case this is not practicable, and the
reinforcing steel may simply be hooked into vertical steel.
Upon this bottom crosstie must be placed the outer half of
the continuous door form. Then the vertical reinforcement
may be hooked to the lower crosstie and secured in a vertical
position by tieing it to the form. Then the horizontal rein-
forcement of the wall may be hooked to or placed inside of
the vertical reinforcement. When the wall is completed to
the top of this form, the inner portion of the form may be
bolted to the outer. The form, crosstie, and the wall into
which the steel projects should be then filled with moderately
wet concrete made up of reasonably fine gravel. The second
form may be secured to the first by means of 2x6's. The use
of the second form is similar to the first. It will thus be seen
SILOS: CONSTRUCTION AND SERVICE
Fig. 24. Reinforcing
that the door frame
consists of inter-
locking steel, thor-
oughly set in ce-
ment, which locks
it, protects it from
rust, and secures it
in an air-tight man-
ner to the hollow
blocks of the wall
by running into
them a short dis-
the Door Forms.
^ A detailed drawing
4> of these forms, two
of which are re-
quired, is shown in
Fig. 26. The up-
per left-hand view
shows the eleva-
tion; the upper
shows the form as
seen from the side,
while the lower
plan view presents
the form as seen
One method of
procedure in the
construction of a
THE IOWA SILO
Fig. 25. Concrete roof construction.
set of these forms is as follows, each part being designated by
letters and dimensions shown in the drawing. All surfaces
coming in contact with cement should be dressed. First, two
members, A, may be cut and pieces, lettered C, may be
made from a 2x6. The edge nailed to B should be beveled so
that the piece will be flared in order that it may be easily re-
SILOS: CONSTRUCTION AND SERVICE
69 r "n
to Silo Wo 11 wth
'x6" Dolf, IP,
_f Mor-tor- Uoint"
Flare to facilitate
removal of -forms
FORMS FOR CONTINUOUS
CONCRETE DOOR FRAME
Fig. 26. Door forms
moved from the concrete. The outer edge of this member
should be beveled about % m h in order to have it fit the
circular wall against which it must be clamped.
Two pieces, D, are required, and are cut from a 1-inch
board. The corner of the piece where A and E join should be
less than right angles, in order that each of the boards, E, may
THE IOWA SILO
slant y% inch toward each other. This is also for conven-
ience in removing the form from the concrete. The mem-
ber E should be nailed back to D, as seen in Fig. 26. In
Fig. 27. Perspective view of Iowa Silo.
: CONSTRUCTION AND SERVICE
order that the crosstie blocks may be set into each side of the
form, it is necessary to saw a notch in E.
The length of these forms and the location of the notch
cannot be determined accurately until the wall is built up to
the top of the first form. Then the top of the form should
be sawed so that it will be flush with the top of the crosstie
when the top of the
crosstie is level with the
wall mortar joint. The
notch will then be of a
depth equal to the width
of the block and wide
enough to permit the
crosstie block to rest
loosely between the out-
er and the inner form.
The necessity of this
will be readily seen in
Fig. 27. The inside
corners formed by B, C,
and E should be filled
with a three-cornered
strip, which causes the
concrete door frame to
be chamfered, leaving
In the 2x6's, lettered
F, Fig. 26, holes should be bored and J^-inch bolts used.
Holes should also be bored in the end of members A and
notches made as indicated. Holes should also be bored in A
for a long bolt to extend through the inner portions of the form.
The inner portion of the form is built as follows : Mem-
bers, lettered G, are cut, and to them are nailed 10-inch
Wooden door for continuous door-
THE IOWA SILO 83
boards, H, which are placed 22 inches apart. The boards, H,
should be beveled on the edge J4 mc h m two inches, to con-
form to the curvature of the inner side of the silo wall. The
edges need not be beveled thinner than % inch. The bev-
eled strips, 7, are nailed to the end flush with the inner edge
of H. Only a bevel of ^g inch is necessary here, as the lum-
ber of the door extends horizontally, therefore there is little
or no shrinking or swelling of the lumber in this direction.
Holes must be bored in G to receive the bolts which hold the
two parts of the form together. The cost of these forms need
not exceed $12.
SAFE STRENGTH OF MATERIALS
The Factor of Safety. In the use of any material it is of
course important to know how much force or pressure it will
resist. In testing materials the actual weight necessary to
strain, bend, break, or crush them is accurately determined.
It is evident that the largest load which a given material will
carry cannot safely be placed upon it. The fractional part
of the greatest strength which it is considered advisable to
use, determines what is generally spoken of as the " factor
of safety." For instance, a steel rod one inch square, which
of course has a cross-sectional area of one square inch, would
probably support, without breaking, any load up to 60,000
pounds, providing the load was suspended directly by it.
But in case of silo building there should not be a force of more
than 15,000 pounds placed upon it. This is called the safe
strength of this material for this purpose, and is approxi-
mately J4 of the ultimate or greatest strength. It is gener-
ally spoken of as the use of a factor of safety of 4. If human
life were more continuously depending upon this material,
as is the case in residences, office buildings, or theatres, the
factor of safety used would probably be 5 or 6. Thus the
safe strength of this material would then be 10,000 to 12,000
pounds per square inch. In masonry materials for silos the
factor taken is not less than 8.
Just what portion of its ultimate strength can be safely
utilized, depends considerably upon the material and the seri-
ousness of results in case a failure should occur. As already
SAFE STRENGTH OF MATERIALS
Fig. 29. Elevation of water tank.
86 SILOS: CONSTRUCTION AND SERVICE
mentioned, where only property value is concerned, greater
loads naturally are imposed than where human life is at stake.
Causes of Failure. As to their strength, materials may
fail in any one of three different ways, or by combinations of
two or all three of them.
First, pressure may be brought to bear which will crush the
material; for instance, a block of wood may be put between
the jaws of a vice and enough pressure brought to bear upon
it to crush the fibers together. This is spoken of as failing
in " compression." An example of this is a wall that is poorly
built, of made too thin, and subjected to a greater weight
than it will bear. In failing in this manner it simply means
that the fibers or fine particles of the material have been
Second, the force known as " tension" may cause failure.
This is a force which tends to pull materials in two. The
force tending to separate the ends of a straight piece of mate-
rial may be sufficient actually to separate the fibers or parti-
cles of the material. The intensity of this force is also given
in pounds per square inch of cross section of the material.
Third, a force known as shear may cause failure. As the
name infers, portions of the material which fail in this respect
are simply forced past each other sidewise. An example of
failure in this respect is the unequal settling of a foundation.
This simply means that the foundation is more thoroughly
supported in one place than in another, and the rigidity of the
material is not sufficient to support the pressure without
breaking. Another illustration of this method of failure is
in case of blocks pushed out of the wall, the shear occurring
between the mortar and the block, causing the mortar to
slide upon the block. The intensity of this force is generally
spoken of as so many pounds per square inch, and indicates
SAFE STRENGTH OF MATERIALS
Jo Ja</ 7/7 mor-
'Fig. 30. Detail of water tank.
SILOS: CONSTRUCTION AND SERVICE
base. ofl5//o -
ib/aced '//? m&icf/ case
Fig. 31. Further detail of water tank.
the result obtained by dividing the square inches of fractured
area of the material into the pounds of force required to frac-
ture the material.
SAFE STRENGTH OF MATERIALS
In bending, there is a combination of all three of these
forces. As an illustration of this take a green twig, cut it off
square and bend it near the cut end. It results in the crush-
ing of the fibers on the inner part of the curve, the failure by
tension of the fibers on the outer part of the curve, and often
that the portion of the stick between the bend and the end is
split, indicating that the endwise compression on the inner
side of the curve and the tension on the outer part of the curve
have been so great, pulling in opposite directions, that the
material of the twig shears through the heart.
In this connection it is interesting to notice the impor-
tance of the depth of a beam. For instance, an increase in
the depth of a beam increases its stiffness more rapidly than
the amount of material is increased. In fact, the ability to
support a load increases as the square of the proportional in-
crease in the depth of the material. That is, a 2x8 will sup-
port 4 times as much as a 2x4, but contains only twice as
Safe Strength of Materials. The following table will
show the safe strength of several materials:
Table III. Safe strength of materials.
Lbs. per sq. in.
Lbs. per sq. in.
Lbs. per sq. in.
Pine, G. yellow
California redwood ....
Hollow clay blocks
A No. 3 bright Bessemer steel wire will safely stand 1000 pounds in
90 SILOS: CONSTRUCTION AND SERVICE
In the use of any material the possibility of destruction in
time, by natural agencies, such as decay or corrosion, should
be considered. The probable length of life of all parts should
be taken into consideration, and that which will probably
give out first should be planned with the largest factor of
safety. Thus in building a structure of any kind it should be
built so that each part will last as nearly as possible the same
length of time as every other, and when it does submit to the
agencies of time it should, like the "One-Horse Shay," all fail
in a day.
Splicing and Welding. The method of splicing materials
should receive careful attention in order to make them as
strong as other parts. Pieces of steel in concrete or mortar
should hook into each other if the steel is smooth. The hooks
should, of course, be thoroughly imbedded in the masonry.
If twisted, corrugated, or other special reinforcing material is
used, the ends should extend past each other a distance equal
to at least 18 diameters of the material. Welding should be
avoided where possible, as in general it is difficult to make sure
that a forge weld is perfect.
However, in cases of anchor rods, eye bolts, or similar
parts, the hooks or eyes should, if possible, be welded, because
the strength would then depend not only upon the stiffness of
the material in the hook or eye, but also upon the strength of
the weld. Hooked portions of any material should be
welded unless the steel is held firmly by being imbedded in
SPECIFICATIONS FOR STEEL
Ordinary steel rods or wires do very well for silo building,
and can be depended upon to withstand a pull of about 12,000
pounds per square inch. Where steel is bought especially for
this purpose it is best to buy reasonably high-carbon steel or
SAFE STRENGTH OF MATERIALS 91
hard wire. It is usually safe simply to specify bright Bes-
semer or hard open-hearth steel wire. This will ordinarily be
safe at 16,000 pounds per square inch. In other words, the
No. 3 wire, which is a convenient size for silo work, will
safely withstand a pull of about 1000 to 1200 pounds. For
reinforcing rods to be used at the door frame, or for other
general reinforcing work, corrugated or twisted bars will be
found best; or, if smooth rods are used, they should be
hooked at the ends so that they will not slip.
The proper proportion for mixing material composing
concrete will depend upon the kind of material used and the
strength required by the service to which the concrete will be
put. Concrete of the strength given in Table III is made by
mixing 1 part cement with 2J/ parts of sand and 5 parts of
crushed stone, or by mixing 1 part cement with 5 parts of
bank gravel which, if sifted out, would give 1 part sand to 2
The theory is that the particles of cement should thor-
oughly coat all of the particles of sand and stone, and at the
same time fill in all spaces between the particles of sand and
gravel which are not already occupied by smaller particles.
It will be readily seen that if only sand and cement were
mixed, it would be necessary, in order to get the same strength
as before, to mix 1 part of cement with 2% parts of sand, thus
giving only YT, the quantity of concrete otherwise obtained.
This indicates the importance of knowing the grade of gravel
or other aggregate.
Testing the Concrete. It is easy to determine, in a prac-
tical way, the amount of cement to make a dense concrete
from any quality of aggregate that is available. A represen-
92 SILOS: CONSTRUCTION AND SERVICE
tative sample of the moist aggregate should be measured and
the quantity of water determined which is required to fill to
the surface of the aggregate. The proportion that this
quantity of water, plus 10 per cent, is to the quantity of
aggregate, is the proportion of cement to the aggregate which
is required to make a dense concrete.
Tamping. From this discussion it is easy to see why
concrete should be tamped, or, more properly speaking,
vibrated, as any motion of the mass will cause the finer parti-
cles to settle more closely into the spaces between the larger
particles. In all silo work a very dense concrete should be
used. In order to remove forms promptly it is also very
desirable to have a mixture rich enough to set quickly. This
is especially true of the concrete used in the roof,
The presence of clay or dirt prevents the union of the
cement and the particles of sand and gravel. Small quanti-
ties of dirt are usually present in bank gravel, but should not
be more than 10 per cent. It is a simple matter to determine
the quantity of dirt in gravel by simply washing a measured
portion of the material. The wash water should be set aside
to settle, and the quantity of dirt settling out should be meas-
ured. The proportion of this to the quantity of gravel is
Storing Cement. It seems almost needless to say that
cement should be very carefully stored in a dry place. Any
cement having hard lumps distributed through it should not
be used. Aside from what has been given, little or no testing
seems advisable on the average job.
If there is any question as to the quality of the cement, a
trial sample may be mixed in the proper proportions with the
gravel and allowed to stand a few days before the main
SAFE STRENGTH OF MATERIALS 93
quantity is to be used. If it sets up quickly it is, in all proba-
bility, a safe cement to use.
Working Quality. In the mixing of mortar it is very
important to get a mortar that will be conveniently plastic
under the trowel. A good mortar is usually spoken of as
tough. A sand and cement mortar is not tough, but very
short. In order to improve the working qualities of such a
mortar it is necessary to use some lime with the cement.
Proportions. The proportion of 1 part of cement to 2 or
2}/2 parts of sand and % P ai> t or 1 part of lime putty (slaked
lime) , will result in a very good mortar. A good mortar saves
time and sets up rapidly enough to permit the building of a
considerable height of wall each day.
Vitrified Brick. Brick clay is made up of two classes of
materials, one which melts at a temperature within the kiln,
and the other a nonfusible substance which does not melt but
holds the brick in shape. The flux or fusible material, in
melting, fills the pores between the other particles of clay and
melts out over the surface, giving it a glassy appearance, that
is, what is known as vitrified brick. If either the shale clay
or surface clay tile have these materials properly propor-
tioned, the result of thorough burning will be very dense or
The modern kiln is so arranged that the fire passes up the
side of the wall and down among the brick or other material
to be burned, so that the highest temperature occurs in the
top of the kiln, and the most thorough burning occurs there.
So even though the clay is right, only that portion located
in the top portion of the kiln is right for silo construction.
94 SILOS: CONSTRUCTION AND SERVICE
Blocks for Silos. In silo construction we have two
reasons for specifying hard-burned brick; one is that it must
not absorb a great amount of moisture from the silage;
another is that if soft or porous brick are exposed to the
weather they are not durable, as moisture freezing in the pores
of the brick expands and causes the block to disintegrate.
This has been noticed by every one in the case of soft drain
tile which have been allowed to lie in a slough over winter.
In order to make sure that brick or clay blocks are right
for silos it is necessary to buy only such brick or blocks as will
absorb an average of 5 per cent or less of their weight of
moisture. No block should be used that absorbs over 8 per
cent. If this quality is secured the result will be a good
durable silo, if it is put together with other good material by
a good workman.
In addition to this, it should be specified that all blocks
fit the circle within Y% of an inch. When ordering blocks it
should be borne in mind that uniform color of blocks is quite
desirable and greatly increases the appearance of the
Absorption Test. A convenient method of determining
the amount of water these products will absorb is either to
take the blocks hot from the kiln or place them in an oven
where they will have a temperature higher than boiling water
continually for two days. Then they should be weighed and
placed in water for a couple of hours or until they cease to
increase in weight. The increase in weight divided by the
dry weight gives the percentage of the absorption.
This same test will indicate whether or not there are lime
nodules in the clay. Sometimes pebbles of limestone occur in
the clay, which, when the clay is burned, become quicklime,
and this exerts a swelling force when it comes in contact with
water. This force is such as to chip off or split the material.
SAFE STRENGTH OF MATERIALS 95
If the concrete absorbs more than 10 per cent of its weight of
water it should be plastered or coated with asphalt in order
that it will not draw too much moisture from the silage.
BUYING AND CONTRACTING OF SILOS
When to Plan. The man who gets what he wants is the
man who looks the farthest ahead. Ordinarily a man can as
well decide in January as in August or September whether
or not he can profitably use a silo, and he should do so. It is
important, in buying or arranging for the building of any
kind of silo, that plenty of time be allowed for its delivery
and other fulfilment of the contract. This is a matter of
importance to everyone concerned, in securing a better
grade of material and workmanship. It gives the farmer
time in which to return any inferior material in case such is
delivered. Even though a certain grade of material is speci-
fied, it is difficult to secure a second shipment in exchange for
inferior material when it is not delivered until late in the
In buying wood, the kind and grade of wood should be
specified. The choice of the grades of lumber will usually
depend upon the amount of money which can be invested.
It is also important, with most kinds of wood, to specify that
little or no sapwood shall be found in the lumber; that is, it
should be very largely heartwood. It should always be
agreed in writing that any lumber not coming up to the
specifications shall be replaced, with no cost to the pur-
chaser, and that delivery shall be made early enough in the
season to give opportunity for this replacement.
BUYING AND CONTRACTING 97
THIS AGREEMENT made and entered into this
day of 191 . . , by and between
, County of , State of
, hereinafter called the
"owner," and of
Town of , State of ,
called the "contractor."
WITNESSETH: That in consideration of the sum of
dollars to be paid the contractor by the
owner as soon as work hereinafter contracted for has been
completed, said contractor hereby agrees to erect and con-
struct, or cause to be erected and constructed for the above
named owner on his premises, to-wit, on ,
in County, State of ,
a silo of the type known as Said silo
to be in size and constructed as
follows, to-wit :
The foundation shall extend below frost feet and
shall be at least 16 inches wide at the bottom. The top of said
foundation shall be at least one foot above the surface of the
ground, foundation to be made of concrete, mixed by taking
five parts sand and gravel and one part cement, said founda-
tion to be sixteen inches wide at the bottom and high,
and to be wide at the top. On top of
said foundation a wall shall be con-
structed of to be used from the footing
98 5/7,05: CONSTRUCTION AND SERVICE
to the top of silo. The silo wall is to be securely and prop-
erly reinforced with steel. On one side of said silo a door 22
inches wide in the clear is to be constructed, commencing
near the bottom of said silo and extending to within about
five feet of the top of the silo. On each side of said door
opening from the bottom of the first opening and extending
to the top of the last opening, door-jambs are to be built of
concrete, made by mixing four parts sand and gravel and one
part cement. In said door space are to be placed horizon-
tally reinforced concrete crossties about every four feet. The
silo is to be covered with concrete roof conical in shape, prop-
erly reinforced, and an opening of convenient size is to be left
therein for the filling of the silo.
Absorption test, 94.
Acidity in silage, 11.
Air spaces in wall, 20.
Bacteria in silage, 11.
Blocks, construction, 94.
Block silo, 35, 65.
Brick silos, 37, 93.
Buying and contracting
Capacity of round silos, 43.
Cattle, amount of silage to
Cement block silos, 35.
Cement, storing, 92; tamping, 92;
testing, 91; wash, 65.
Clay blocks, 93.
Clay products silos, 35, 65.
Concrete mixtures. 91.
Concrete silos, 32, 34; mono-
Continuous doors, 8, 25, 28, 76, 82'
Contract for silos, 96.
Corn for silage, time to cut, 11.
Cost of silos, 41.
Cresote for wood silos, 24.
Cro=stie of block silos, 68, 77.
Doors, details of, 48; hinge, 30;
improvement, 8; independent,
27; Indiana, 29; wooden, 82.
Door forms, construction, 78, 80.
Door frames, construction, 74;
Drainage of silos, 47.
Early development, 7.
Ensilage, poisoning from, 13;
preservation of, 11.
Factor of safety, 84.
Failure, causes of, 86.
Feeding silage, amount, 44.
Fermentation of silage, 11.
Fire exposure, 17.
Forage or mold poisoning, 13.
causes, 13; prevention, 16;
Frame silos, 24.
Frozen silage, 18.
Guide for wall, 71.
Curler silo, 25.
Guying the silo, 28.
Heat, how lost in silo, 18.
Hinge door, 30.
Hoisting, methods, 64, 74, 75.
Independent door, 27.
Indiana door, 29.
Influence of material on silage, 21.
Interlocking block silos, 38.
Iowa silos, 65; building, 71;
perspective view, 81; scaffold-
Location for silo, 39.
Masonry silos, advantages, 31;
development, 10; kinds, 32.
Material for silos, influence of,
21; safe strength of, 84.
Mold, cause of in silage, 12.
Mold poisoning, 13.
Monolithic concrete silos, 60.
Painting wood silos, 23.
Planning the silos, 39, 96.
Pit, 7, 46.
Plastered silos, 34.
Plastering concrete silos, 64.
Poisoning from silage, 13.
Preservation of silage, 11; air
spaces in walls, 20; frozen
silage, 18; influence of materials,
21 ; nature of process, 11 ; moldy
silage, 13; settling, 17.
Reinforcement, 60, 63; of door
Reinforcement table, 78.
Roof construction, 79.
Roof plans, 49, 79.
Round silo, development, 8.
Safe strength of materials, 84.
Scaffolding, for block silo, 67;
stave silos, 52.
Settling of silage, 17.
Sheep, amount of silage for, 44.
Silage preservation, 11.
Shear stress, 86.
Size of silo, 43.
Square silo, 8.
Stave silo, 21, 27; erection, 52.
Steel, 63, 90.
Stone silos, 32, 33.
Tamping concrete, 92.
Testing concrete, 91.
Unandilla door, 28.
Vitrified brick, 93.
Wall, air spaces in, 20; construct-
ing, for Iowa silos, 65 ; materials
of, 17, 21; quality of silage at,
Water tank on silo, 85, 87, 88.
Wisconsin silo, 8, 24.
Wood for silos, 23, 96.
Wood hoop silo, 25.
Wood silos, 23.
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Webb Publishing Co., St. Paul, Minn.
Agricultural Engineering David-
son, Iowa State College of Agriculture. A com-
plete and practical handy manual text book of
all engineering problems of the farm, including
land surveying, drainage, irrigation roads, farm
machinery and farm motors, farm buildings,
and sanitation. It will be the most effective
aid in farm management; 544 pages; over 300
illustrations; a handsome book. Cloth $1.50;
postage 16c extra.
Popular Fruit Growing
Green, Minn. College of Agri. A very popular
treatise on horticultural methods and practices.
Gives principles of successful orchard manage-
ment and small fruit culture, fruits adapted to
each state, how to ward off insects and diseases,
harvesting and marketing methods. A standard
text in many schools. 300 pages; profusely il-
lustrated. Cloth, $1.00; postage 12c extra.
Swuii B Gmra
Horticulture, Minn. College of Agri. A handy
manual on the growing of all kinds of vegetables
for home use and for the market. It is used as a
practical school text book and is indispensable to
farmers and gardeners everywhere. 122 il-
lustrations; 252 pages. Twelfth edition. Cloth
$1.00. Paper cover, 60 cts. Postpaid.
Agriculture for Young Folks
By A. D. Wilson, Supt. of Farmers' Institutes
and Agricultural Extension, University of Minn.,
and E. A. Wilson. This is the most practical
elementary agricultural text book for rural and
graded schools ever published. It presents the
elementary principles of agriculture through les-
sons based on practical farm problems. 340
pages; well illustrated; cloth bound. Price $1.00.
By mail 10 cents extra.
Webb Publishing Co., St. Paul, Minn.
Pmilfrv Manual A standard guide
roimry manual for Baccea8fu]
try keeping, by F. L. Sewell and Ida E. Til-
son, both well known authorities on domestic
fowls and their keeping. Selection and
breeding for egg production, rations and
methods of feeding and general care of fowls
are emphasized. Well illustrated; 148 pages.
Cloth, 50 cents. Paper covers, 25 cents.
The Country Kitchen
recipes, all contributed by farmers' wives and
daughters, readers of The Farmer. This is a
choice collection of over 900 of the best recipes
which have been received. It has been printed
in many editions, and is today the most popular
book of its class published. It is sure to prove
a most helpful servant in your kitchen. Cloth
bound, 50 cents. Paper covers, 25 cts. Postpaid.
Weeds and How to Eradicate
TflPfTl B V P r f- Thomas Shaw, author of nu-
ll C 111 merous agricultural works. In this book
simple but practical means of distinguishing
different weeds are taught, the manner of growth
of each explained, and the best methods for their
eradication and control advised. 208 pages; il-
lustrated. Cloth bound, 50 cts. Paper cover, 25
Quack Grass Eradication
practical farmer who has worked out a system of
soil treatment which results in a permanent de-
struction of quack grass. It is not necessary to
lose a crop by this method, nor are expensive
tools needed. The principles involved are plainly
stated and the process itself in not complex.
This book should be in the hands of every farm-
er on whose farm quack grass is spreading.
Cloth bound, $1.00. Postpaid.
Webb Publishing Co., St. Paul, Minn.
Evergreens and How to Grow
ThPITl ^* y ^* ^' Harrison. The practical
1 11 CHl va i ue O f evergreens for windbreaks
and shelterbel cs and for ornamental purposes
makes this book of value to every farmer of
the United States. Evergreens are not hard
to grow, but unless certain details are looked
after, failure is likely. Mr. Harrison tells very
plainly, from his extensive experience, the
correct treatment to follow. Varieties illus-
trated. 100 pages. Paper cover, 25c. Postpaid.
and Civil Government.
mi j strated a nd made
plain. Everyone, at some time or other, is likely
to require some knowledge of rules of order. But
few are willing to take the time or trouble to
master all the fine points. This book puts the
rules in so simple and brief a manner that all the
knowledge that one needs to know for the con-
duct of the average meeting is easily grasped.
The fundamentals of Civil Government are also
made exceedingly plain. Handy size; 110 pages; illustrated.
Cloth bound, 60c. Postpaid.
The Gold Mine in the Front
By C. S. Harrison. This is an ex-
tremely interesting book describing
the improvement of the home grounds. Mr.
Harrison is a well-known floriculturist, who
tells m a very interesting style of the varieties
of flowers and vines to grow, how to grow
them, and their proper arrangement for the
best effect. A delightful book for flower lov-
ers. 280 pages; illustrated. Cloth bound,
gives the latest authentic information about va-
cant government land and how it may be home-
steaded. It locates all vacant land by counties
in each state, gives a digest of the homestead
laws, and many necessary and valuable facts
needful in making a location. Latest edition.
Sent postpaid to any addrers for 25c.
Vacant Government Lands
Webb Publishing Co., St. Paul, Minn.
UNIVERSITY OF CAUFORNIA LIBRARY