CORNELL READING-COURSE READING-LESSON
FOR FARMERS. No. 2.
Issued by the College of Agriculture, Cornell DECEMBER, 1902.
University, Ilhaca. N. Y., in the months of By JOHN W SPENCER.
November, December, January, February and
March. 2D EDITION.
Entered at the Post Ofice, at Ithaca. N. Y., as RaVISED By JOHN CRAIG.
second-class matter, under act of uly, z894.
TILLAGE AND UNDER-DRAINAGE: REASONS WHY.
i. The soil is tilled to improve its texture and to assist the plant
in obtaining thefood which it needs.-In Lesson i, Caption io, it is
stated that "plant-food is available when it is in such condition
that the plant can use it." The trouble with many of the so-called
"worn-out" lands of the State, is that although sufficient plant-
food exists in the soil it is in a form that the plants cannot make
use of it. The problem confronting the farmer of to-day is to
so treat the soil that its fertility may not only be made available
to the crops which he grows, but that the total store of plant-
food shall not be diminished. This calls for a rotation which
shall contribute to the immediate needs of the plant and lay by
a store for future draft. See Caption 6, Lesson I.
2. Tillage improves the physical condition of the soil: by
fining the soil and extending the feeding grounds for roots; by
increasing the depth of the soil, or loosening it so that plants
obtain a deeper root-hold; by causing the soil to dry out and
warm up in spring; by making the conditions of moisture and
temperature more uniform throughout the growing season."
(Principles of Agriculture, Bailey, p. 65.)
By tillage the farmer donserves the moisture of the soil; by
tillage chemical action is promoted and plant-food is set free.
3. The plant needs water. It is the vehicle by means of
which food is carried from the soil to the leaves of the plant. In
dry weather plants wilt. We say they are suffering from lack
of -water. Water is needed to keep the cells expanded so that
the plant may have sufficient rigidity to enable it to maintain
its natural position. But this is only part of the natural use
and function of water. The plant-food of the soil is dissolved
before it is used. Water acts the part of carrier in transporting
this food from the soil to the topmost branch of the tree. Just
how this is done is discussed in Lesson 4. For the present we
shall remember that water is an absolute necessity in promoting
plant growth. It is statedin Cornell Bulletin 120, page 419, that
in a dry season a bushel of potatoes requires about three tons of
water for its production. For a crop of 200
bushels of potatoes per acre then 600 tons of
water will be required. It has been esti-
mated that there are very few soils in New
York State that do not possess a storage
capacity of 300 tons of water per acre in
the first eight inches of the soil. It is there-
i-A kernel of Corn. Soil fore the business of the farmer to see that
particles surrounded by
lm moisture In goode the natural water of the soil is utilized to
condition, the fullest extent.
4. The most usefulform of waterfor plants is film moisture.-
Water is capable of assuming many forms, such as steam, vapor,
ice, or free-moving liquid. The condition most valuable in the
soil is none of these, but is in the form of film moisture. This
film moisture can be shown by dipping a marble into water and
observing the film of water surrounding it on all sides. When
each soil-grain is covered with film moisture
as the marble is, the ideal conditions of soil
moisture exist. This form of water is
largely independent of gravitation and
travels readily in all directions, as can be
seen by dipping a cube of sugar into a spoon-
ful of coffee. It is capable of transport-
ing plant-food to the roots of plants from
2-A kernel of Corn.
remote corners, where the roots do not Inltrspaces filed with
moisture. Too wet.
It will be observed that film moisture is held only on the sur-
face of soil-grains. The more the soil is pulverized, the more
soil-grains there will be, and therefore the greater amount of sur-
face to hold film moisture.
The difference in the capacity of lumpy and fine soils to hold
film moisture is surprising to one whohas not given the question
study. George W. Cavanaugh, assistant chemist at the Cornell
Experiment Station, has very graphically shown this by the fol-
lowing experiment: He put some small marbles in a tumbler, as
shown by Fig. 3, and the total amount of film moisture
that the marbles would carry is represented in the tube
placed beside the tumbler. The soil in the other tumbler
(Fig. 4) is of the same weight as the marbles in Fig. 3, and it
represents the marbles reduced to the fineness of common
sand. Its capacity for holding film moisture is represented.
by the water in the standing tube (Fig. 4). Theweightof
material is the same in each tumbler, and the reason why
one holds three times more film moisture than the other
is due to the increase, of surface that comes by dividing
a coarse lump into fine particles.
The marbles represent careless tillage and the -
finer particles thorough.tillage.
The coarse soil, as represented by the marbles, will lose
its film moisture by evaporation much more readily than
the soil represented by Fig. 4, particularly if the surface
of the latter is covered by fine particles representing
5. Tillage makes plant-food available.-Good tillage
enables the plant to secure more food from all fertilizers
which may be applied than bad tillage. There is also a
benefit in making avail-
able some of the plant-
food thatnaturehas put I
in the soil. Broadly
stated, the native plant-
food in a layer of soil 16
inches deep, covering
one acre, amounts to as,
much as can be bought
in $2,000 worth of com-
3. Waterheldby a coarse mercial fertilizers. 4. Water held byfine soil.
soil. The finer soil has an-
other advantage in affording a greater area for root pasturage.
It is not uncommon for farmers to think of plant-food in
the soil as in the condition of salt or sugar which is capable of
being immediately dissolved by water and at once appropriated by
the plant, or like potash in ashes that can be soaked out. Plant-
food exists in this form only to a limited extent. A man might
famish if locked up in a granary filled with wheat; yet, a
chemist would say that there was enough food near him to feed
a hundred men. This illustrates how nature has stored much of
the plant-food in the soil. It has to go through many changes
before it can be appropriated by the plant.
6. The soil is a laboratory.-The soil is a factory in which the
work of preparation is carried on. Some of the agents employed
in this factory are film moisture, air and heat; and if these are not
furnished in the proper extent and manner, the factory runs in
a sluggish way, if it does not stop altogether. Good tillage does
much to hasten the activities of this factory by allowing free
ingress to the soil of film moisture, air and heat. Air is neces-
sary for a supply of oxygen, and heat to facilitate fermentation
and other vital processes.
The importance of air and heat in the soil brings us to the
question of drainage. Air cannot freely enter a soil which is
filled with standing water, and growth of micro-organisms is
7. Wet soils are cold.-Standing water is a great absorbent of
heat. If no provision is made to drain.it away, it must be evapo-
rated away. Thereby heat is lost. The soil is cold. A great
many barrels of water can be standing on an acre of ground and
not attract much attention.
To appreciate the amount of heat necessary to evaporate water
one has only to chop, split and burn beneath a caldron kettle
enough wood to evaporate-a barrel of water. Every barrel that
is evaporated from the soil by the sun absorbs as much heat as
was utilized in the wood used under the kettle. The soil and
plants are perhaps chilled for want of that heat. This is the
reason that a wet soil is said to be cold. When plants appear
on wet soils they are noticeably yellow. The germinating seed
needs air, and the roots of the growing plant must have it.
Standing water excludes air. Under drainage removes this
8. Drained soils resist drought.--Some farmers have the notion
that well drained soil will not withstand a drought as well as
an undrained soil. The contrary is true. Everyone who has
tilled the soil is familiar with places that are wettest in a wet
time and driest in a dry time. When these places dry at all, they
dry like a brick. The soil has been puddled," the particles
have run together. A wet soil can never be tilled so as to pre-
sent the greatest amount of surface for film moisture and give it
a mellow texture to receive a gentle filtration of air; and stand-
ing water robs it of much heat required by the soil and plants.
5. Compacting effect of surface pressure. The farmer's
9. Drainage makes a soil reservoir.-There is a place in every
soil at which the free water stands. This place is called the
water-table. It may be three inches dowr, or a hundred feet.
It is the bottom of the soil reservoir, the bottom of our dish-pan.
This dish-pan, or the upper and tillable soil, is the reservoir. It
is the part in which the water is held as films on the soil particles.
These films travel from particle to particle, the general tendency
being upward because the moisture is passing off near the top of
the soil by means of evaporation and appropriation by plants.
Moisture is constantly supplied from the water-table below.
We speak of this movement as capillary attraction.
Under-drainage lowers the water-table. It lowers the bottom
of the dish-pan; and thereby there is a deeper reservoir above it
for the holding of film moisture and the distribution of roots.
But, the reader says, if the water-table supplies moisture to
the upper soil, then it must be useful and necessary. Certainly;
but it must not be too high, for roots of farm plants do not thrive
in standing water. If the upper soil is well tilled, capillary
attraction will bring the moisture up.
ixo. Do not let the moisture get away.-We want this film mois-
ture in the upper soil in order that roots may use it. The plants
do not use it, to any extent, after it has passed off into the
atmosphere. Therefore, stop this water before it reaches the
How ? Put a layer of loose dry earth between the moist soil
and the atmosphere. This layer will stop the upward capillary
flow (see.Caption 3). This layer is the earth-mulch. It con-
serves, or saves, moisture.
11. Dry and hard soils may be benefited by under-drainage.-
The water-table is lowered. Air is admitted. The soil does not
puddle. It becomes fine. Under-drainage makes wet soils dry
by removing the free water ; it tends to make dry soils moist by
deepening the reservoir and fining the particles of soil.
12. early all soils are benefited by under-drainage.-It is
important that the farmer should be able to work his land early in
spring; under-drainage enables him to do this by drawing off the
standing water. Great injury to crops and soil is caused by water
flowing over the surface; under-drainage lessens the damage, by
carrying the water away through under-ground channels. The
rainfall of the year is in itself a fertilizing agent. It contains
ammonia equal to six or eight pounds of nitrogen per acre. By
means of under-drains this rainfall passes downward and leaves
the ammonia in the soil. In short, a good system of under-
drainage lessens soil erosion and waste, cheapens tillage and
increases the fertility of the land.
13. What tillage tools are for.-Some tools, as plows, are
to mellow up the soil and to deepen the moisture reservoir.
Others, as cultivators, are to tear up and to pulverize the soil to
greater or less depths. Cultivators lift and turn the soil. The
spring-tooth harrow is really a cultivator. Other tools, as har-
rows, prepare the surface of the soil. They make the seed-bed
and put on the earth-mulch. The true harrows stir the soil, but
do not lift or invert it.
14. Weeds do not like well tilled lands.-The first and greatest
value of tillage is to put the soil in such a condition that plants
can grow, and then to keep it so. Incidentally, it prevents from
growing those plants which we do not want,-the weeds. Usu-
ally, the process is reversed: weeds make us till; and we get the
other benefits without knowing it. The best tillage prevents
*weeds rather than kills them.
14. Summer-fallowing is a means of cleaning land and of cor-
recting mistakes.-It may be necessary to fallow the land in order
to clear it of stones, stumps and brush. But after the land is
once thoroughly subdued, summer-fallowing is very rarely neces-
sary if the land has been well handled. If the land has been
plowed when too wet and thereby has become lumpy; if it has
been allowed to become foul with weeds, or if it has lost heart by
too continuous cropping with one kind of crop, summer-fallow-
ing is a good means of bringing it back into condition. The
better the farming the less the necessity, of, summer-fallowing.
In the old days, the poor tillage tools rendered fallowing more
necessary than it is to-day.
Fallowing is tillage; and tillage liberates plant-food. Some of
this plant-food may leach away and be lost, although the small
rainfall of the summer months,-during which time fallowing is
practiced,-makes this loss slight.
I5. The kind of tillage should vary with the soil, the time of
year, the kind of crop.-Too many farmers seem to think that til-
lage is tillage, no matter how it is performed. The same tool is
used for clay or sand or muck, and for fitting the land for wheat
or corn or apple trees. A harrow that is best for one field may
be worst for the adjoining field. A man would not think of
using a buggy for carrying grain to market, but he will use one
tool for many kinds of work. The work is not only poorly done,
but it is not economical. It costs too much. Persons who will
economize to the smallest degree in expenditures of money, may
be very wasteful in expenditures of labor and muscle.
Persons are always asking if deep plowing is best. The ques-
tion cannot be answered on general principles. Deep plowing
may be best for one field and one crop, and shallow plowing best
for another field and another crop. The same remarks will
apply to fall-plowing and spring-plowing. One must first learn
principles, or the why ; then the practice, or the how, will come
NOTE. The reader should have other sources of information than this
Lesson. He may read our Bulletins r ig, Texture of the Soil ;" 120, The
Moisture in the Soil;" 72, The Cultivation of Orchards ;" and the three
bulletins on potato culture (Nos. 130, 140, 156). His library should also
have King's Soil" and Roberts' "Fertility of the Land."
2-Rolling dry soil compacts the surface, bring the particles closer together
and makes the moisture more available to plants. The illustration
shows the kind of roller some gardeners use.
NOTE. The extension Department of the College of Agriculture issues
certificates to those members of the Reading-Course who answer in a satis-
factory manner all the quizzes. A charter will also be issued to regularly
organized Cornell Reading-Clubs in good standing.