1846. 
THE CULTIVATOR. 
301 
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nourishment by pores only seen by powerful micro¬ 
scopes; the nourishment is drawn from vapors and 
floating gases in the air, and liquids in the earth 
charged with many substances in minute proportions; 
and the whole process is entirely beyond the reach of 
the closest scrutiny of the eye. 
It is not surprising therefore that there should be a 
dilFerence of opinion among high authorities. The 
constituents of vegetable mould have led to much dis¬ 
pute, and no less than twenty different substances have 
been discovered or named by various chemists. Dr. 
Dana, in attempting to prove the inutility of applying 
lime and potash as manures, shows that nearly all soils 
contain lime and potash enough for the growth of all the 
crops which may be produced on the land for thousands 
of years. Yet other chemists dwell on the importance 
of these substances applied as manures, and direct ex¬ 
periment shows their utility.* Liebig says that “ wheat 
does not flourish in a sandy soil, and that a calcareous 
soil is also unsuitable for its growth unless mixed with 
a considerable quantity of clay ”—“ because these soils 
do not contain alkalies, in sufficient quantity.” But 
Johnston shows not only that excellent wheat crops are 
reaped from those soils, but that turneps, universally 
admitted to be finely adapted to sandy land, contain in a 
single crop of ordinary productiveness, nearly ten times 
as much potash and soda, as a crop of fifty bushels of 
wheat with the straw included. The contradictions of 
chemists on the single article of gypsum alone would 
perhaps fill a volume. According to Kollner, its ac¬ 
tion depends on the powder possessed by lime to form, 
with the oxygen and carbon of the atmosphere, com¬ 
pounds which are favorable to vegetation; according to 
Mayer and Brown, it merely improves the physical 
properties of the soil; while according to Riel, it is an 
essential constituent of the plant. Hedwig called it the 
saliva or gastric juice of the plant; Humboldt and 
Thaer considered it a stimulant; Chaptal ascribed its 
action to a supposed power of supplying water f and 
carbonic acid to plants; and Davy regarded it as an es¬ 
sential constituent of plants.J According to Liebig, it 
fixes the ammonia of the atmosphere; according to 
Sprengel, it supplies sulphur for the formation of the 
legumin of leguminous plants; and according to Dana 
it merely assists the decomposition of other substances 
in the soil. 
The question has been much oftener asked than an¬ 
swered, c< Who shall decide when doctors disagree?” 
If great men who have spent their whole lives in ex¬ 
amining such questions, are so much at variance, to 
what power is the farmer to look, to dissolve the thick 
mist and remove his doubts, in relation to such matters? 
The answer cannot be avoided, To repeated, varying , 
and actual experiments in practical cultivation. Such 
experiments have long since established the value of 
gypsum, lime, and other manures; while eminent che¬ 
mists are still disputing not only on their theory of ac¬ 
tion, but whether they are really of any value what¬ 
ever. 
The distinction must be drawn between The Appli¬ 
cation of Science to Agriculture , and The Science of 
Agriculture. The former has been already ex¬ 
plained; the latter consists of the facts which practice 
has established, and the truths it has developed, reduced 
to a system, and in some degree arranged under fixed 
principles. The Science of Agriculture explains the 
theory and operations of draining plowing, subsoiling, 
and manuring, of rotation of crops, of cultivating the 
soil, of adapting culture to crops, and many other prac¬ 
* It has been asserted by Liebig and others, that the benefit of 
Sane is owing to the potash it contains. Lime has been applied 
with great success to sods in Western New-York, which con¬ 
tained many broken fragments oflimesione. The lime was from 
localities, where, by the analysis of Dr. Beck, no potash existed. 
'< Tlie opinion that gypsum owed its efficacy to the absorption of 
moisture, has been common in this country. H. Davy exposed a 
portion of gypsum to the air three foggy nights, and found it ab¬ 
sorbed only a 720th part. Calculation will show that two bushels 
spread over an acre, would absorb at the same rate, a stratum of 
moisture only one-tmlliouih of an inch in thickness, or five thousand 
limes thinner than paper. 
+ Hlubeck. 
tices which distinguished the best modern specimens of 
farming. It is a systematic arrangement of knowledge, 
which the experience of centuries has accumulated. 
Many of its principles, it is true, are those of other 
sciences; but they were usually discovered in the course 
of cultivation, before those sciences had a distinct ex¬ 
istence. A professor of one of our colleges has cited 
the practices of draining, subsoil plowing, trenching, 
and clovering and plastering, as specimens of the ap¬ 
plication of science to agriculture. But these have all 
resulted entirely from experience; they are indeed spe¬ 
cimens of scientific farming, but they originated from 
the science of agriculture, as just explained, and not 
from science to agriculture in its common acceptation. 
The best modern practices of agriculture, are in 
nearly all cases much in advance of the theory. It is 
for this reason that the cause of agricultural improve ¬ 
ment would be much better served by holding up for 
imitation the experience and management of the best 
farmers of the day, rather than a too frequent reference 
to chemical authority. How many ofour citizens might 
have avoided shipwreck of their property, and made 
handsome profits, if they had followed the best estab¬ 
lished courses of cultivation. But, have any failed for 
want of knowing the sciences? Some of our farmers 
make money rapidly,—that is, they farm well. Others 
make a scanty living; and others are reduced to insol¬ 
vency. What is the reason of the success of the former 
—what the cause of the failure of the latter? Is it a 
knowledge of chemistry in one case, and a deficiency in 
the other? No one will ever think of ascribing the re¬ 
sults to such causes. 
It is not denied, that important aid may yet be de¬ 
rived from agricultural chemistry. But its advance 
must be slow and attended with caution. Years of care¬ 
ful and accurate analyses of soils, and of the trial of 
manures, separate and mixed, in connection with ex¬ 
periments on growing crops performed with the utmost 
judgment and precision, can only settle uncertain points. 
Reasons will thus be rendered clearer by science, and 
practices explained, enforced and established. But 
these experiments must be performed chiefly by the en¬ 
terprising few, and not by the common farmer. The 
study is indeed deeply interesting and fascinating; and 
every one who has a knowledge of the natural sciences, 
will not unfrequently find useful applications in the 
every-day business of life. But to hold them up as a 
means by which the young farmer is to conduct his 
business most profitably, while he yet remains wholly 
or partially ignorant of the most improved modern sys¬ 
tems of practice and management, cannot be followed 
by the best results. The most important knowledge 
must be first attained, and afterwards that which is less 
essential in practice. If possible, neither should be 
neglected. We should not denounce any study because 
it is encompassed with some difficulties. Chemistry is 
affording many valuable suggestions for trial and prac¬ 
tice; and as Professor Johnston very justly remarks, 
es It is foolish to refuse to avail ourselves of the morn¬ 
ing light because it is not equal to the mid-day sun.” 
IS DEEP PLOWING- ALWAYS BEST. 
L. Tucker, Esq.-— It appears to me, an error exists 
in the minds of some agriculturists, on the subject of 
deep plowing, especially in cultivating light soils, ex¬ 
cept where heavily manured. 
The prevailing opinion has been, and probably still 
to a great extent obtains, that, to be a good farmer or 
planter, it is necessary to plow deep, without reference 
to the depth of the soil. We find crops designed for 
premiums, usually plowed deep, and of course manured 
strongly; doubtless this is the best method for that 
purpose. I have invariably found deep plowing on 
deep and rich soils to answ T er well. On alluvial soils, 
(for example, on some parts of the Mississippi bottoms,) 
by plowing deep, a richer mould is often turned up. 
A few years since I had a piece of pasture swap;l 
turned over for a winter crop, plowed about three 
