BOYS DEPARTMENT. 
leave it for two or three years in pasture. By this 
means, the field, instead of lying idle, yields a prof- 
itable return ; all the benefit ordinarily derived from 
fallowing is obtained; a firm sod is made, which, 
when turned over with the plow, forms a fine bed 
of humus, and the fertility of the soil is restored 
to a remarkable degree. 
This method has almost entirely superseded the 
old one of naked fallowing, and is decidedly prefer- 
able, in most cases, though circumstances may occur 
where the other can be more judiciously practised. 
Thus, stiff, argillaceous, (clayey,) soils, are often 
very materially benefitted by repeated plowings 
while lying fallow, as by this means the hard lumps 
become divided, air and moisture are freely admit- 
ted, and the land thus becomes well prepared for 
sustaining a vigorous growth of vegetation. 
While all are willing to admit the advantages of 
a fallow, all are not agreed as to the manner in 
which these advantages are brought about. The 
explanation usually given by the unlearned is, that 
land, after producing several crops in succession, 
requires rest, and, like a wearied animal, is recruit- 
ed by repose. But this explanation conveys an 
erroneous impression, and shows how easily the 
minds of many are satisfied by substituting a com- 
parison, or a name for a reason. The term rest 
is certainly very improperly employed when applied 
to land in the same sense in which it is used with 
reference to animals. I will endeavor to explain 
to you, in accordance with the views of some of 
our best modern chemists, the process which Nature 
adopts to reinvigorate an exhausted soil. 
I told you in a former number, that soils were 
originally formed by the degradation and decompo- 
sition, (crumbling and wasting away,) of rocky 
masses, and that the solid structures were origin- 
ally composed of the same inorganic constituents 
as are found in the soil. Now the agency which 
reduces rocks to the form of powder, does not 
cease its operations when this change is effected, 
but continues acting upon the mineral particles un- 
til those portions essential to vegetable life are 
brought to such a state as to be soluble in water, 
when the roots of plants can readily imbibe and 
appropriate them, as needed. 
The progress of this decomposition is slow, and 
when a field is required to furnish food for a crop 
every year, for a succession of years, it cannot be 
furnished as fast as it is needed ; the supply is in- 
adequate to the demand ; and time is required to 
allow a new accumulation, or fresh supply. Al- 
though the necessary ingredients, or food, may be 
in the soil, yet it is not in such a form as to be 
available, and Nature refuses to change her laws, 
or to act more vigorously than she is wont, merely 
to gratify the inordinate cravings of her creature, 
man. 
And now another question arises — Can a field 
always be kept in a state of fertility by careful 
fallowing % I reply, it cannot. The soil does not 
contain an exhaustless supply of those ingredients 
which our crops require, and though land can be 
induced, by fallowing alone, to produce abundant 
harvests for a limited period, yet the time must ar- 
rive, when, unless manure be supplied, barrenness 
will ensue. There are, as I have previously in- 
formed you, sixteen elements belonging to plants, 
twelve of which must be furnished by the soil, 
and if any one of these which is required, be ab- 
sent, the plant cannot mature though all other cir- 
cumstances be favorable. Now, as by far the 
greater portion of all soils consists of matter 
which cannot contribute to the growth of plants, 
and as nearly every soil is lacking in a full supply 
of every ingredient which our crops require, it is 
unreasonable to expect perpetual fertility without 
returning, occasionally, to our fields a portion of 
those constituents which have been taken from 
them. 
Before closing this article, I will add a few more 
remarks on the subject of fallow crops, or green 
manuring. As the crop plowed into the soil can 
only return to it the same inorganic ingredients 
which were drawn from it, we naturally" inquire, 
what benefit can be derived from this source. The 
question is well worthy of consideration ; for it 
would seem that if land can be thus enriched, it 
must disprove the theory that the fertility of the 
soil can only be preserved by returning to it, occa- 
sionally, new supplies of the matter which has 
been withdrawn. But the advantages of this sys- 
tem are only temporary, and may be thus accounted 
for : — 
1. The bed of humus thus formed, improves the 
texture of the soil; allowing air and moisture to 
gain admittance, and these agents hasten that final 
decomposition of mineral particles which fits them 
for entering the circulation of plants. 
2. The green, or fallow crop, draws nutritive 
principles from the air, especially carbon, and, (in- 
directly,) nitrogen, and these, becoming incorpora- 
ted with the soil, are ready to aid in promoting the 
growth of the succeeding crop. (For farther par- 
ticulars on this point, I would refer you to what I 
said on the subject of humus in my tenth number.) 
3. The roots of the green crop, having penetra- 
ted to a considerable depth in the soil, lower than 
the plow has ever reached, have drawn from below 
such nutritive ingredients as had become deficient 
near the surface. 
These constituents, after contributing to the for- 
mation of the stalks, leaves, &c, of the fallow crop, 
are again disengaged and left near the surface when 
this crop is buried in the soil, and are now within 
the immediate reach of the roots of the succeeding 
crop. Clover and buckwheat are well adapted for 
fallow crops on account of their roots extending to 
a. much greater depth than those of most other cul- 
tivated plants. 
The effect, thus produced, may be compared to 
that of very deep or trench plowing, as in both 
cases these ingredients, which lie below the reach 
of most plants, are brought near the surface. The 
roots also render the hard and compact soil beneath, 
into which they penetrate, more loose and porous, 
and thus, as in deep plowing, the texture is im- 
proved to a considerable depth. When, after sow- 
ing a fallow crop, the land is left for several years 
undisturbed, we must attribute much of the benefit 
afterwards observed to the decomposition of min- 
eral portions, as above mentioned. 
J. Mc Kinstrt. 
Greenport, N. ¥., April 1st, 1849. 
