Cyril G. Hopkins.

The Story of the Soil; from the Basis of Absolute Science and Real Life, online

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here last spring told me he showed one Northern man a farm for $12 an
acre and he was afraid to buy. Then he took him into another county and
showed him a poorer farm for $45 and he bought that at once.

"The road there runs out through the fields. Our land runs back to the
other public road and beyond that is the farm I told you of where the
saw mill is running. I've got some pretty good cowpeas you'll pass by. I
haven't got them off the racks yet."

Percy found the cowpea hay piled in large shocks over tripods made of
short stout poles which served to keep the hay off the ground to some
extent, and this permitted the cowpeas to be cured in larger piles and
with less danger of loss from molding.

"I find that the soil on your farm and on the other farm is very
generally acid," said Percy a few hours later when Mr. Thornton asked
what he thought of the condititons of farming. "Have you used any lime
for improving the soil?"

"Yes, I tried it about ten years ago, and it helped some, but not enough
to make it pay. I put ten barrels on about three acres. I thought it
helped the corn and wheat a little, and it showed right to the line
where I put cowpeas on the land, but I don't think it paid, and it's
mighty disagreeable stuff to handle."

"Do you remember how much it cost?" Percy asked.

"Yes, Sir. The regular price was a dollar a barrel, but by taking ten
barrels I got the ton for eight dollars; but I'd rather have eight
dollars' worth of bone meal."

"I think the lime would be a great help to clover," said Percy.

"Yes, that might be. They tell me that they used to grow lots of clover
here; but it played out completely, and nobody sows clover now, except
occasionally on an old feed lot which is rich enough to grow anything.
It takes mighty good land to grow clover; but cowpeas are better for us.
They do pretty well for this old land, only the seed costs too much, and
they make a sight of work, and they're mighty hard to get cured. You see
they aren't ready for hay till the hot weather is mostly past. If we
could handle them in June and July, as we do timothy we'd have no
trouble; but we don't get cowpeas planted till June, and September is a
poor time for haying."

"It seems to me that clover is a much more satisfactory crop," said
Percy. "One can sow clover with oats in the spring, or on wheat land in
the late winter, and there is no more trouble with it until it is ready
for haying about fifteen months later, unless the land is weedy or the
clover makes such a growth the first fall that we must clip it to
prevent either the weeds or the clover from seeding. This means that
when you are planting your ground for cowpeas the next year after wheat
or oats, we are just ready to begin harvesting our clover hay; and
besides the regular hay crop we usually have some growth the fall before
which is left on the land as a fertilizer, and then we get a second crop
of clover which we save either for hay or seed. Even after the seed crop
is harvested there is usually some later fall growth, and some let the
clover stand till it grows some more the next spring and then plow it
under for corn."

"I can see that clover would be much better than cowpeas if we could
grow it; but, as I said, it's played out here. Our land simply won't
grow it any more. Not having to plow for clover would save a great deal
of the work we must do for our cowpeas."

"Some of our farmers follow a three-year rotation and plow the ground
only once in three years," said Percy. "They plow the ground for corn,
disk it the next spring when oats and clover are seeded, and then leave
the land in clover the next year. In that way they regularly harvest
four crops, including the two clover crops, from only one plowing; and
in exceptional seasons I have known an extra crop of clover hay to be
harvested in the late fall on the land where the oats were grown.

"In regard to the lime question," Percy continued, "I wonder if you know
of the work the Pennsylvania Experiment Station has been doing with the
use of ground limestone in comparison with burned lime."

"No, I never heard of ground limestone being used. I supposed it had to
be burned. I should think it would be very expensive to grind

"No, it costs much less to grind it than to burn it," Percy replied.
"Mills are used for grinding rock in cement manufacture, and the rock
phosphate and bone meal must all be ground before using them either for
direct application or for the manufacture of acidulated fertilizers; and
limestone is not so hard to grind as some other rocks. Furthermore it
does not need to be so very finely ground. If fine enough so that it
will pass through a sieve with ten meshes to the inch it does very well.
That you see would be a hundred meshes to the square inch; and, of
course, a great deal of it will be much finer than that. In fact the
ground limestone used in the Pennsylvania experiments was only fine
enough so that about ninety per cent. of it would pass a sieve with ten
meshes to the inch, and yet the limestone gave decidedly better results
than the burned lime, and it is not nearly so disagreeable to handle.
Besides this, the ground limestone is much less expensive. It can be
obtained at most points in Illinois for about a dollar and fifty cents a

"A dollar and fifty cents a ton!" exclaimed Mr. Thornton. "Well, that is
cheap, but how about the freight and the barrels and bags? Freight is a
big item with us."

"The dollar and fifty cents includes the freight," was the reply.

"Includes the cost and the freight both?"

"Yes, and the Illinois farmers have it shipped in bulk, so there is no
expense for barrels or bags. Of course the supplies of both coal and
limestone are very abundant, and with a well-equipped plant the actual
cost of grinding does not exceed twenty-five cents a ton. The original
cost of the material ground and on board cars at the works varies from
about sixty cents to one dollar a ton, and this leaves a very fair
margin of profit.

"The men who furnish the ground limestone realize that very large
quantities of it are needed if the soils of Illinois are to be kept
fertile, and they also realize that the ultimate prosperity of the
country depends upon agricultural prosperity. Their far-sightedness and
patriotism combine to lead them to try to sell carloads of limestone
instead of tons of burned lime. As a matter of fact five or ten dollars
profit on a car of limestone, the use of which in large quantities is
thus made possible in systems of positive soil improvement, is very much
better for all concerned than a profit of half that much on a single ton
of burned lime which is used as a soil stimulant in systems of soil

"It is certainly true," said Mr. Thornton, "that all other great
industries depend upon agriculture, directly or indirectly. I have
thought of it many times. It seems to me that fishing is about the only
exception of importance."

Mr. Thornton requested that Percy remain for lunch in order that they
might return to the field to let him see the soil acidity tests made.



"I AM interested to know where you learned these things about acid
soils and lime and limestone," said Mr. Thornton.

"Mostly in the agricultural college," replied Percy, "but much of
the information really comes from the investigations that are
conducted by the experiment stations. For example, the best
information the world affords concerning the comparative value of
burned lime and ground limestone is furnished by the Pennsylvania
Agricultural Experiment Station. Those experiments have been carried
on continuously since 1882, and the results of twenty years' careful
investigations have recently been published. A four-year rotation of
crops was practiced, including corn, oats, wheat, and hay, the hay
being clover and timothy mixed. With every crop the limestone has
given better results than the burned lime. In fact the burned lime
seems to have produced injurious results of late years, and the
analysis of the soil shows that there has been large loss of humus
and nitrogen where the burned lime has been used, the actual loss
being equivalent to the destruction of more than two tons of farm
manure per acre per annum."

"Well, we surely need this information," said Mr. Thornton. "I have
always supposed that the teachers in the agricultural college knew
little or nothing of practical farming."

"I did not go to college to learn practical farming, if we mean by
that the common practice of agriculture," replied Percy. "I already
knew what we call practical farming; that is, how to do the ordinary
farm work, including such operations as plowing, planting,
cultivating, and harvesting; but it seems to me, Mr. Thornton, that
this sort of practical farming has resulted in practical ruin for
most of these Eastern lands. The fact is there is a side to
agriculture that I knew almost nothing about as a so-called
practical farmer, and I am coming to believe that what we commonly
call practical farming is often the most impractical
farming, - certainly this is true if it ultimately results in
depleted and abandoned lands. The truly practical farmer is the man
who knows not only how to do, but also what to do and why he does
it. The Simplon railroad tunnel connecting Switzerland with Italy is
twelve miles long, - the longest in the world. It was dug from the
two ends, but under the mountain, six miles from either end, the two
holes came together exactly, within a limit of error of less than
six inches, and made one continuous tunnel twelve miles long. Now,
this was not all accomplished by the practical men who knew how to
handle a spade in digging a ditch. The work was controlled by
science, and it was known in advance what the results would be. I do
not mean that it was known how hard the digging would be, nor how
much trouble would be caused by caving or by water; but it was known
that if the practical work was done, the final outcome would be

"I think it is even more important that we understand enough of the
sciences which underlie the practice of agriculture so we may know
in advance that when the practical farm work is done the soil will
be richer and better rather than poorer and less productive because
of our impractical farming.

"As I said, I did not go to the agricultural college to learn the
practice or art of farming; I went to learn the science of
agriculture; but, as a matter of fact, I found the college professor
knew about as much of practical agriculture as I did and a great
deal of science that I did not know. I found that the Dean of the
college, who is also Director of the Experiment Station, had been
born and raised on the farm, had done all kinds of farm work, the
same as other farm boys, had gone through an agricultural college,
and after his graduation had returned to the farm and remained there
for ten years doing his own work with his own hands. He has had as
much actual farm experience as you have had, Mr. Thornton, and ten
years more than I have had. He was finally called from the farm to
become an assistant in the college from which he was graduated, and
in a few years he was advanced to head professor in agriculture.
About ten years ago he was made dean and director of the
agricultural college and experiment station in my own state; and I
have been told that he will not recommend any one for a responsible
position in an agricultural college unless he has had both farm
experience and scientific training. He and most of his associates
are owners of farms and would return to them again if they did not
feel that they are of more service to agriculture as teachers and

"I am very glad to know about this," said Mr. Thornton. "Certainly
your opinion, based upon such knowledge as you have of your own
college, is worth more than all the common talk I have ever heard
from those who never saw an agricultural college. I wish you would
tell me something more in regard to what crops are made of and about
the methods of making land better even while we are taking crops
from it every year."



"THE subject is somewhat complicated," Percy replied, "yet it
involves no more difficult problems than have been solved in many
other lines. The chief trouble is that we have done too little
thinking about our own real problems. Even in the country schools we
have learned something of banking and various other lines of
business, something of the history and politics of this and other
countries, something of the great achievements in war, in discovery
and exploration, in art, literature, and invention; but we have not
learned what our soils contain nor what our crops require. Not one
farmer in a hundred knows what chemical elements are absolutely
required for the production of our agricultural plants, and one may
work hard on the farm from four o'clock in the morning till nine
o'clock at night for forty years and still not learn what corn is
made of.

"All agricultural plants are composed of ten chemical elements, and
the growth of any crop is absolutely dependent upon the supply of
these plant food elements. If the supply of any one of these plant
food elements is limited, the crop yield will also be limited. The
grain and grass crops, such as corn, oats, wheat, and timothy, also
the root crops and potatoes, secure two elements from the air, one
from water, and seven from the soil.

"The supply of some elements is constantly renewed by natural
processes, and iron, one of the ten, is contained in all normal
soils in absolutely inexhaustible amount; while other elements
become deficient and the supply must be renewed by man, or crop
yields decrease and farming becomes unprofitable.

"Matter is absolutely indestructible. It may change its form, but
not a pound of material substance can be destroyed. Matter moves in
cycles, and the key to the problem of successful permanent
agriculture is the circulation of plant food. While some elements
have a natural cycle which is amply sufficient to meet all
requirements for these elements as plant food, other elements have
no such cycle, and it is the chief business of the farmer to make
these elements circulate.

"Take carbon, for example. This element is well represented by hard
coal. Soft coal and charcoal are chiefly carbon. The diamond is pure
crystallized carbon, and charcoal made from pure sugar is pure,
uncrystallized carbon. This can easily be made by heating a lump of
sugar on a red hot stove until only a black coal remains. Now these
different solid materials represent carbon in the elemental form or
free state. But carbon may unite with other elements to form
chemical compounds, and these may be solids, liquids, gases.

"Thus carbon and sulfur are both solid elements, one black and the
other yellow, as generally found. If these two elements are mixed
together under ordinary conditions no change occurs. The result is
simply a mixture of carbon and sulfur. But, if this mixture is
heated in a retort which excludes the air, the carbon and sulfur
unite into a chemical compound called carbon disulfid. This compound
is neither black, yellow, nor solid; but it is a colorless, limpid
liquid; and yet it contains absolutely nothing except carbon and

"That seems strange," remarked Mr. Thornton. "Yes, but similar
changes are going on about us all the time," replied Percy. "We put
ten pounds of solid black coal in the stove and an hour later we
find nothing there, except a few ounces of ashes which represent the
impurities in the coal."

"Well, the coal is burned up and destroyed, is it not?"

"The carbon is burned and changed, but not destroyed. In this case,
the heat has caused the carbon to unite with the element oxygen
which exists in the air in the form of a gas, and a chemical
compound is formed which we call carbon dioxid. This compound is a
colorless gas. This element oxygen enters the vent of the stove and
the compound carbon dioxid passes off through the chimney. If there
is any smoke, it is due to small particles of unburned carbon or
other colored substances.

"As a rule more or less sulfur is contained in coal, wood, and other
organic matter, and this also is burned to sulfur dioxid and carried
into the air, from which it is brought back to the soil in rain in
ample amounts to supply all of the sulfur required by plants.

"Everywhere over the earth the atmosphere contains some carbon
dioxid and this compound furnishes all agricultural plants their
necessary supply of both carbon and oxygen. In other words, these
are the two elements that plants secure from the air. The gas,
carbon dioxid, passes into the plant through the breathing pores on
the under side of the leaves. These are microscopic openings but
very numerous. A square inch of a corn leaf may have a hundred
thousand breathing pores."

"Now, as we go on, I am especially anxious to get at this question
of supply and demand," said Mr. Thornton. "I think I understand
about iron and sulfur, and also that these two elements, carbon and
oxygen, are both contained in the air in the compound called carbon
dioxid, and that this must supply our crops with those two elements
of plant food. I'd like to know about the supply. How much is there
in the air and how much do the crops require?"

"As you know," said Percy, "the atmospheric pressure is about
fifteen pounds to the square inch."

"Yes, I've heard that, I know."

"Well, that means, of course, that there are fifteen pounds of air
resting on every square inch of the earth's surface; in other words,
that a column of air one inch square and as high as the air goes,
perhaps fifty miles or more, weighs fifteen pounds."

"Yes, that is very clear."

"There is only one pound of carbon in ten thousand pounds of
ordinary country air. Now, there are one hundred and sixty square
rods in an acre, and since there are twelve inches in a foot and
sixteen and one-half feet in a rod, it is easy to compute that there
are nearly a hundred million pounds of air on an acre, and that the
carbon in this amounts to only five tons. A three-ton crop of corn
or hay contains one and one-fourth tons of the element carbon; so
that the total amount of the carbon in the air over an acre of land
is sufficient for only four such crops; while a single crop of corn
yielding a hundred bushels to the acre, such as we often raise in
Illinois on old feed-lots or other pieces of well treated land would
require half of the total supply of carbon contained in the air over
an acre. However, the largest crop of corn ever grown, of which
there is an established authentic record, was not raised in
Illinois, but in the state of South Carolina, in the county of
Marlborough, in the year 1898, by Z. J. Drake; and, according to the
authentic report of the official committee that measured the land
and saw the crop harvested and weighed, and awarded Drake a prize of
five hundred dollars given by the Orange Judd Publishing
Company, - according to this very creditable evidence, that acre of
land yielded 239 bushels of thoroughly aid-dried corn; and such a
crop, Mr. Thornton, would require as much carbon as the total amount
contained in the air over an acre of land."

"Well, that is astonishing! Then there must be some other source of
supply besides the air."

"There is no other direct source from which plants secure carbon;
but of course the air is in constant motion. Only one-fourth of the
earth's surface is land, and perhaps only one-fourth of this land is
cropped, and the average crop is about one-fourth of three tons; so
that the total present supply of carbon in the air would be
sufficient for about two hundred and fifty years. But as a matter of
fact the supply is permanently maintained by the carbon cycle. Thus
the carbon of coal that is burned in the stove returns to the air in
carbon dioxid; and all combustion of coal and wood, grass and weeds,
and all other vegetable matter returns carbon to the atmosphere. All
decay of organic matter, as in the fermentation of manure in the
pile and the rotting of vegetable matter in the soil, is a form of
slow combustion and carbon dioxid is the chief produce of such
decay. Sometimes an appreciable amount of heat is developed, as in
the steaming pile of stable refuse lying in the barnyard, while the
heat evolved in the soil is too quickly disseminated to be apparent.

"In addition to all this, every animal exhales carbon dioxid. The
body heat and the animal force or energy are supplied by the
combustion of organic food within the body, and here, too, carbon
dioxid is the chief product of combustion.

"Thus, as a general average, the amount of carbon removed from the
atmosphere by growing plants is no greater than the amount returned
to the air by these various forms of combustion or decay. In like
manner the supply of combined oxygen is maintained, both carbon and
oxygen being furnished to the plant m the carbon dioxid.

"As a matter of fact, the air consists very largely of oxygen and
nitrogen, both in the free state, but in this form these elements
cannot be utilized in the growth of agricultural plants. The only
apparent exception to this is in case of legume crops, such as
clover, alfalfa, peas, beans, and vetch, which have power to utilize
the free nitrogen by means of their symbiotic relationship with
certain nitrogen-fixing bacteria which live, or may live, in
tubercles on their roots.

"Carbon and oxygen constitute about ninety per cent. of the dry
matter of ordinary farm crops, and with the addition of hydrogen
very important plant constituents are produced; such as starch,
sugar, fiber, or cellulose, which constitute the carbohydrate group.
As the name indicates, this group contains carbon, hydrogen, and
oxygen, the last two being present in the same proportion as in

"Water is composed of the two elements, hydrogen and oxygen, both of
which are gases in the free state. Water is taken into the plant
through the roots and decomposed in the leaves in contact with the
carbon dioxid under the influence of sunlight and the life
principle. The oxygen from the water and part of that from the
carbon dioxid is given off into the air through the breathing pores,
while the carbon, hydrogen, and part of the oxygen, unite to form
the carbohydrates. These three elements constitute about ninety-five
per cent. of our farm crops, and yet every one of the other seven
plant food elements is just as essential to the growth and full
development of the plant as are these three."

"Then so long as we have air above and moisture below, our crops
will not lack for carbon, oxygen, and hydrogen. Is that the summing
up of the matter?"

"Yes, Sir," Percy replied.

"And those three elements make up ninety-five per cent. of our farm
crops. Is that correct?"

"Yes, Sir, as an average."

"Well, now it seems to me, if nature thus provides ninety-five per
cent. of all we need, we ought to find some way of furnishing the
other five per cent. It makes me think of the young wife who told
her husband she could live on bread and water, with his love, and he
told her that if she would furnish the bread he'd skirmish around
and get the water. But, say, did that South Carolina man use any
fertilizer for that immense crop of corn?"

"Some fertilizer, yes. He applied manure and fertilizer from
February till June. In all he applied 1000 bushels (about 30 tons)
of farm manure, 600 bushels of whole cotton seed, 900 pounds of
cotton seed meal, 900 pounds of kainit, 1100 pounds of guano, 200
pounds of bone meal, 200 pounds of acid phosphate, and 400 pounds of
sodium nitrate."

"I would also like to know the facts about this nitrogen business,"
said Mr. Thornton. "I've understood that one could get some of it
from the air, and I would much rather get it that way than to buy it
from the fertilizer agent at twenty cents a pound. Cowpeas don't
seem to help much, and we don't have the cotton seed, and we never
have sufficient manure to cover much land."

"It is a remarkable fact," said Percy, "that of the ten essential
elements of plant food, nitrogen is the most abundant, measured by
crop requirements, and at the same time the most expensive. The air
above an acre of land contains enough carbon for a hundred bushels
of corn per acre for two years, and enough nitrogen for five hundred
thousand years; and yet the nitrogen in commercial fertilizers costs
from fifteen to twenty cents a pound. At commercial prices for

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Online LibraryCyril G. HopkinsThe Story of the Soil; from the Basis of Absolute Science and Real Life, → online text (page 5 of 23)