£86 
AMERICAN AGRICULTURIST. 
[June, 
“Foot and Mouth” Disease. 
“ Foot and Mouth” disease has long been 
a terrible calamity throughout the United 
Kingdom, but if it becomes the means of 
stopping the importation of animals, it will be 
changed into a blessing. The loss of cattle is 
often very large, and the sufferings of the ani¬ 
mals are terrible during transportation, even 
from the Continent to Great Britain, and much 
more so on the longer voyages from America. 
All this might be avoided by shipping meat 
instead of cattle. That the former practice is 
not only the most humane, but also the most 
profitable, is now fully proved,for refrigerator 
railroad cars and ship compartments are so 
well constructed, that fresh meat can be kept 
in them a long time, and transported thou¬ 
sands of miles without being injured. In 
fact, it is improved, because it is given time 
to ripen, and English consumers almost in¬ 
variably confess that American beef thus 
brought to them is superior to that killed at 
home and sold immediately in their markets. 
It is astonishing that Parliament does not 
pass a law prohibiting the importation of 
cattle. It is said that the reason for not 
doing so is, that it would raise the price of 
beef in the Kingdom, and the people at 
large would suffer. But surely their loss 
would be nothing in comparison with that 
sustained by the breeders of cattle. During 
the past twenty years their losses from “ foot 
and mouth ” disease have been millions of 
pounds sterling; and they would be able to 
furnish meat cheaper than foreign breeders 
do if the foul disease were stamped out. 
This could be soon accomplished if the im¬ 
portation of cattle was forbidden. 
The Essentials in Fertilizers. 
Practice and experiment in the growth of 
crops have shown that nitrogen, phosphates, 
potash, and lime, in assimilable form, are the 
substances which most strikingly benefit 
land ; and chemical analysis has determined 
in a measure the varying proportions in which 
different crops draw upon these and upon 
other constituents of the soil. 
Acting on this knowledge, chemists have 
given specifications for the preparation of 
manures for all the different crops, these 
schemes being professedly based on the com¬ 
position of the crops themselves. But ma¬ 
nuring on this principle would often cost more 
than the consequent increase of the crop 
would repay ; for it makes no allowance for 
natural fertility, and it makes no distinction 
between the composition of the crops grown 
and the composition of the produce sold off 
the farm. We know that soils are of very 
unequal fertility, that some have an unlimit¬ 
ed food-supply compared with others, and 
that it is only the materials sold off the farm 
that the maintenance of fertility requires to 
be restored. More than this, crops differ 
greatly in their capability of self-supply. 
Take, as an example of the latter character¬ 
istic, the relations of wheat and clover to 
nitrogen. Chemical analysis shows that 
clover contains more nitrogen than wheat; 
and yet the wheat finds its nitrogen with 
difficulty, while the clover seems to have a 
power of self-supply in this particular. Thus, 
in defiance of the chemical composition of 
the two crops, the farmer’s practice, when 
he manures wheat liberally with nitrogen and 
gives little or none to clover, is justified. 
Economic manuring must supplement the 
plant’s weakness, while it makes good the 
deficiencies of the soil. 
A general manure contains all the constit¬ 
uents of the crop, or at least all those in 
which soils are most deficient; but it by no 
means follows that every substance which 
may act beneficially as a manure ought to be 
applied. If a soil is deficient in one particular 
element, and contains all the other requisites 
of fertility, that one substance may act as 
beneficially when applied as though it were 
a manure containing all the constituents of 
the crop. The crop in this case is thrown 
upon the natural resources of the soil for all 
its other elements. After a heavy dressing 
of one substance, that substance may not be 
required for several years, but some other 
substance may be needed; and this all the 
more because the larger crops now grown 
will exhaust such other substances more rap¬ 
idly than the smaller crops did previously. 
By persisting in the exclusive use of a special 
manure, an ultimate exhaustion of the soil is 
inevitable. Judiciously used, special manures 
are the agents which bring into useful activi¬ 
ty the dormant resources of the soil; they 
restore the proper balance between its differ¬ 
ent constituents, and supply the excessive 
demand for some particular elements. Still, 
the application useful on one soil may be 
quite useless on another, and the application 
may be useful on a soil in one season and 
useless in another. 
A general manure may be used year after 
year in a perfectly routine manner, but where 
a special manure is employed, the importance 
of watching its effects and altering it as cir¬ 
cumstances indicate, cannot be over-estimat¬ 
ed. This forces upon us the necessity for 
studying the succession of manures as well 
that of crops. In many cases in which am¬ 
monia when first used proved beneficial, it 
now begins to lose its effect, and the reason 
no doubt is, that by its means the amount of 
phosphates existing in these soils have been 
reduced, while the ammonia has accumulat¬ 
ed, so that change of manuring is needed. 
How to Build a Dam- 
Several letters sent us are answered here¬ 
with : A common form of crib shown in fig. 
Fig. 1. —A CRIB FOR A DAM. 
1 is built of logs, about eight feet square for 
ordinary streams. The bottom should have 
cross-pieces pinned on the lowest logs. The 
stones that fill the crib rest on these cross¬ 
pieces, and hold everything secure. The 
crib can be partly built on shore, then 
launched, and finished in its place in the 
dam. All the logs should be firmly pinned 
together. The velocity of the stream will de¬ 
termine the distance between the cribs. The 
intervening spaces are occupied with logs, 
firmly fastened in their places. Stone is 
filled in between the logs, and the bottom is 
made water-tight with brush and clay. 
A dam without cribs, built of timbers 
spliced together, and reaching quite across 
the stream is shown in fig. 2. The frame is 
hound together with tiers of cross timbers 
about ten feet apart. The sides of this 
Fig. 2.—LOG FRAME FOR A DAM. 
framework of spliced logs are slanting and 
nearly meet at the top. The interior is filled 
with stone and clay, and planked over 
tightly, both front and rear. For a small 
stream with an ordinary current, this is per¬ 
haps the cheapest and most durable dam 
made. The engravings fully illustrate the 
construction of the two forms. 
The Sweet Potato. 
Not many years ago the supply of sweet 
potatoes for Northern consumption came 
so generally from Southern localities, that 
they were frequently called “Carolina Pota¬ 
toes.” For a long time it was supposed that 
New Jersey was the northern limit of their 
successful cultivation, but of late years they 
have been grown in many other Northern 
States. There are two essentials in raising 
sweet-potatoes at the North; a very light, 
sandy soil, and a good supply of well- 
decomposed manure. The manure should 
be deposited on the surface of the ground, 
in rows or strips about three and a half 
feet apart from center to center. Then 
with a plow turn furrows over this manure 
from each side, to form ridges, as high as 
the soil can be thrown with the plow. The 
ridges are finished by the use of the hoe, 
and the plants set on the tops of the ridges 
every 15 or 20 inches. The plants generally 
have several leaves, with roots at the bottom. 
In setting, use a common plasterer’s trowel, 
thrusting it into the soil, and moving it back 
and forth until an opening is made deep 
enough to admit the plant down to the last 
good leaf. In a very dry time, make the 
holes, fill them with water, and when that 
has soaked away, set the plant. Should a 
late frost kill that part of the plant which 
shows above ground, a new growth will start 
from below. The plants are slow in starting, 
but afterwards grow very rapidly. The 
ridges must be kept clear of weeds until the 
vines cover them, and for this no implement 
is more useful than a sharp rake. In the 
Northern States, June is quite early enough 
for setting the plants, and we have had a 
good crop from a planting made early in 
July. When the vines begin to run, they will 
show a disposition to form roots at the joints. 
This must be checked by moving the vines 
