The Middlebury register. [volume] (Middlebury, Vt.) 1850-1882, 1872-04-16
From the Vermont Farmer
Exhaustion of Soils.

Exhaustion of Soils.
Abstract OF a Paper read before the Yer
mont Board Of Agriculture, at Bur-
lington, Jan, "a 1872, By Samuel W.
johnson, Professor Of Chemistry in the
Sheffield Scientific School, New Haren,
Conn.
In our older states we hear continual
ly of exhausted soils, fields worn out and
reproductive from over cropping. 1t is
important to know what is really meant
by this exhaustion" Its nature has
been misunderstood by writers on agricul-
ture, and there are many alarmists who
do not hesitate to say that this departed
fertility is gone forever. Fields are call
ed "worn out" when they no longer pay
to cultivate under the old system, or no.
system, of tillagc, and one would suppose
that the world is coming to an end by the
way In which this thing is spoken and
written about.
1t is necessary that we understand
precisely what the condition Of such soils
is. Exhaustion consists in the removal
by the crops of those elements requisite
for their perfect growth which are in an
available condition to be taken up by
their roots. 1t is not an absolute ex-
haustion there is hardly in the world a
soil that was ever fertile that can be truly
exhausted, or deprived of the mineral
Clements of plants, The entire bulk of
the soil is made up Of these substances in
great part and so long as the soil exists
at all, those elements are there. But
though these, they may not be in such
form that plants can take them up. Most
New England soils contain potash suffici-
ent for an unlimited succession of crops.
But it exists in the form of feldspar,
mineral that contains IA per cent. oil
potash, it is true, yet in an lnsoluble form
the water of the soil cannot dissolve it il
sufficient quantity to supply the needs oil
plants. To be available, all these sub
stances must not only exist there in
soluble form.
When any soil becomes exhausted offs
necessary element of plant food in a
soluble state, it becomes the business OF
the farmer to restore that which continual
cropping has taken away. A crop has
been produced year after year, and carri-
ed off Of the farm, which was continually
removing particular ingredient, as pot
ash or phosphate of lime. This must be
replaced, and when that is done the ex-
haustion is cured. For this purpose ashes
and bones are applied, But oftener it is
only necessary to make available the
matter already in the soil. The farmer
must understand the processes by which
this is cheaply and effectively DONE Farms
so situated that commercial, fertilizers
are inaccessible can only be restored in
this way,-by following, blowing under
green crops, or returning portion of the
crops in some way as manure. 1t is not
required to put back all the land yields
in order to continue its fertility; that is
impracticable and unnecessary Thore
are alterations steadily going on in the
soil, weathering, pulverization, solution
that tend continually to supply plant
food. The rapidity with which this nat
urally takes place constitutes the differ
ence between soils as regards natura
fertility. These processes 60 on slowly
in unfertile soils, and if We can aid OF
hasten them by art we can increase theil
fertility. AS rule, farmers must main
ly depend upon these changes for the fer
tility of their land. The fertiizng effect
Of good tillage, without manure, which
are we'll known, depend upon these pro.
cesses, which are fastened by exposure
to the air, the rain, frost and snow. w
pulverize the soil, and in this way ADM
the action of these forces upon its parti
Giles, breaking them down and fitting then
for the use Of crops. Among the thing
that then occur, besides the partial solu
ton Of mineral matter, is the Formation
OF compounds Of nitrogen in the loos
soil by the process known as nitrifcator
or the formation of nitre, (saltpeter,
which is compound Of nitrogen, an
thus an important element of fertility
In some dry, hot climates,as in India an
South America, the process Of nitrifca
tion, the nature of which is not yet we
understood by chemists, goes on so rapid
ly, and nitre accumulates so fast in tn
soil, that it can be extracted by leachin
the earth, just as we extract potash froI
wood ashes. This is the source, indeed
Of most of the saltpeter of commerce. |
our soils this does not take place to s
great an extent, but it is one of the way
in which fertility is maintained or resto
ed by thorough tillage. On some soil
particularly those rich in vegetable ma
ter, like the fertile bottom lands of II
West, or the valley of the Nile in Egyp
nitri6cation is sufficiently rapid to supp
all the nitrogen that the heaviest
require. But it is not so in New En-
land, and we have to resort to nitroge
Gus fertilizers, sucn as Peruvian guam
But one strong point in judicious hu
bandry is to place the soil, by tillage,
condition for nitri6cation, putting it i
to chemical communication with the al
There are other conditions besides smp
tillage that favor this, such as the inco
poration with the soil of vegetable matte
litter, barn manure, green crops, niue
&c. These favor both notification al
weathering. In agriculture as in Chri
tian grace it may be said, that "to hi
that hath given" for farmer who a
plies such manures freely, gets the ben
fit, not only Of the elements of fertili
that those manures contain in themselv,
but they absorb more from the air, a.
also develop more in the soil by the 81
vent action they exert upon its constit
ents. Thus he who makes his land yie