southern cultivator. 
251 
THE CIIEIVIISTKY OF TILLAGE. 
There are so many qualifying, and modifying circum- 
stances connected with the Chemistry of Tillage that the 
subject needs to be discussed with caution not to mis- 
inform nor mislead the practical culttvator. It is safe, how- 
ever, to state, as a general rule, that no chemical action 
will take place in the soil, nor elsewhere, between 
two or more solid bodies. One at least must be dis- 
solved, in order to give its particles perfect freedom ot mo- 
tion, that they come fully into contact with the atoms in 
the body with which a chemical union is to be consum- 
mated. 
The first, and not the least efrcct of tillage is to increase 
the solubility of earthy minerals and vegetable mould, 
which are an indispensable part of the food of plants. In 
the attainment of the disintegration a»d solution of solids, 
the atmosphere greatly assists the implements of tillage; 
its gaseous atoms have that perfect freedom of motion 
which enable oxygen and carbonic acid to permeate all 
the earth stirred with the plow, and attack all substances 
subject to the chsmical influence of either. A bag of 
thoroughly pressed cotton burns on the surface only, but 
so soon as the ropes are severed, and the cotton expands 
so as to let in air throught the mass, the most obvious 
and remarkable chemical action (combustion) ensues. A 
sudden change in the physical condition of the cotton has 
a wonderful effect on the combination of oxygen in the at- 
mosphere with the carbon in its fibres. Less in degree 
and vehcmance but similar in character, is the chemical 
union of this powerful elements with both minerals and 
organic bodies in soils when pulverised into fine particles. 
Oxygen can be made to burn iron with greater intensity 
than fine charcoal, or gun-powder. Plantinum sponge 
also illustrates the power of mere mechanical comminu- 
tion of a metal to condense vital air, and intensify its chemi- 
cal properties. Tillage being purely mechanicid in the first 
instance, it is valuable, with but few exceptions, in the 
ratio in which it pidverizes and thoroughly comminutes 
the solids operated upon. Insoluble mould, and insoluble 
silicates and phosphates, aided in a large degree by the 
carbonic acid eliminated from mould, are rendered avail- 
able food for growing crops, which, without tillage, no 
plant grown by the cultivator could appropriate. In case 
vegetable mould is deficient in quantity, as it is apt to be on 
all old, or long cultivated fields, there often arises a doubt 
as to how deep one had best plow to command the best 
returns for his land and for labor 7 
It is to throw light on such difficult problem in tillage 
as this that chemistry, and chemical philosophy are use- 
ful to farmers, and planters. While a special prescrip- 
tion adapted to each field, v/ith its peculiar circumstances, 
is out of the question, from any analysis of its soil, ex- 
cept in extreme cases, yet sound principles in cultivation 
can have no other basis than a scientific knowledge of the 
elements of fertility, of their affinities, solubility, and 
other properties and functions, which adapt them to the 
wants of organic beings 
Taking wheat as the best expression of fruitfulness, 
and studying its earthy part drawn from the soil, we find 
about 80 per cent, of it, (the ash of the seed) to be phos- 
phoric acid and potash, but in what^ state of chemical 
combinations we will not now enquire. Tiie same sys- 
tem of tillage that will best supply the acid and alkali 
named to the valuable seeds of the wheat plant, will serve 
a similar purpose for tlie seed of the cotton plant, corn plant, 
and for all other crops. Now, chemistry tells us in what 1 
forms and places both potash and pho.sphoric acid exist 
in soils whether in an available, or in an unavailable, con- 
dition. Phosphoric acid locked up in masses like gran- 
ite, in hard and large crystals of apatite^ or in combination 
combination with iron or alumina, is unavailable because 
insoluble in water. Potash forms an insoluble salt with 
silicic acid, (flint) and in this condition it abounds in most 
primitive rocks ; but water charged with carbonic acid 
decomposes this salt, and then dissolves both the carbon- 
ate of potash and the new silicate which has a large 
amount of alkaline base. If all the salts of potash were 
as soluble in rain water as most of them are, this alkali 
would soon be so far washed out of the soil that very few 
plants of any kind would grow therein. Silica, or as it 
is commonly called by chemists, silicic acid, appears to 
be nature’s favorite for keeping potash, soda, and mag- 
nesia stored up in the subsoil to avoid the utter and hope- 
less destruction of forests and grasses by the hand of man 
or by other means. It is quite impracticable to remove 
all the phosphates and alkalies from an acre of ground ; 
although it may be so impoverished as to cost three times 
more to renovate it than to buy another acre as good as 
that was in the beginning. 
As the writer conceives, the oniy progress made in the 
present century in the art of tillage is limited to deeper 
plowing, and thereby drawing more on the subsoiliot the 
raw material of agricultural plants. Where fields are 
plowed no deeper than they were fifty years ago, we do 
aot see that they yield better crops now than they did 
then, whether old or new. Where more manure is ap- 
plied, that of course indicates a gain; but confining our- 
selves to tillage alone, the improvement has been mainly 
if not exclusively, in stirring more earth, rather than in 
hiving a wise adjustment of mould to minerals, and the 
more perfect commixture of both in the mass. Carbonic 
acid, as shown by chemical experience, being so valuable 
to dissolve both silicates and phosphates in the soil, and 
being, moreover, furnished so largely by vegetable mould, 
the wise cultivator will adapt both his tillage and his 
crops to the increase rather than decrease of mould in all 
his upland. Whoever neglects this is a bad planter ; or 
he is killing the goose that lays his golden eggs. 
Good mould is more valuable than poor stable manure: 
and it has the additional advantage of being formed over 
an indefinite surface where it is needed, whereas manure 
has to be handled and spread by the labor of man and 
beast. 
There may be some difference in cultivating renovating 
plants to enrich a soil, and staple crops for market; but 
the difference is slight. In either case, a large growth is 
desired, though one can better wait for the chemical re- 
sults of thorough tillage in fallow crops than in grain or 
cotton culture. Few men can know the true value of 
their subsoil before they test it by years of deep and 
thorough agriculture. Two years ago, some of our land 
that appeared too poor to cultivate at all without manure, 
did better last year, and promises a fair profit this season. 
It needs more organic matter before its latent mineral re- 
sources can be fairly tested. Possibly we may be better 
able a few years hence than at present, to say what plant.% 
are best to grow and plow in to be incorporated with a 
lifeless surface soil, or subsoil, for in many instances both 
are the same in character and composition. As bare cul- 
tivation adds no element to the soil, to improve a farm by 
tillage alone — drawing fertiiizersfrom the atmosphere and 
the deep subsoil— is a somewhat slow proce.ss. Much de- 
pends on the strength of the subsoil for agricultural pur- 
poses. It may contain more lime than it readily yields 
either to rainwater or acids : but which deep tillage will 
bring out after a few years. We have noticed with inter- 
est the increase snail-shells in a field which lias bee» 
only four years under the plow. Lime is not wholly ab- 
