Agriculture through the laboratory and school garden

Front matter

OTGH THE LAI D SCHOOL G

AGKSON &DAUGHE

Class _jl^il Book - J/^ Copyright}!^

Introduction

From the growth and drift of public sentiment it is evident that education in Agriculture will soon be offered in all good elementary schools of our country. This, from the nature of the case, seems unavoidable, because such instruction is essential both for utility and for culture. It is an essential utility, because it is the only means of furnishing adequate conceptions of the one fundamental occupation of mankind upon which all other occupations depend.

For the masses it is an essential basis of true culture and refinement, as illustrated in its earliest fruitage, which is the adornment of homes through improved lawns, shade-trees, walks, driveways, gardens, flowers, etc., thereby opening the avenues to consciousness and revealing in the most pleasing way the beauty world all around us.

This volume is unique. It is not the product of its authors' imaginations. No one designed it to exploit a theory or a person. It is an outline of work done — done by ordinary people under ordinary conditions.

The Agricultural Laboratory and the School Garden of the Kirksville Normal School have yi INTRODUCTION.

grown from very small beginnings. They are now the objects of keen interest in many parts of the United States. Their purpose at all times has been to prepare teachers to give practical and definite agricultural instruction in public schools of all kinds.

John R. Kirk.

Preface

The preparation of this book was undertaken, primarily, that the classes in Agriculture of the State Normal School of Kirksville, Missouri, miofht have in one book the directions for all laboratory experiments and exercises, and such information as would enable them to understand the results of these experiments.

We believe that the book will meet the needs of most schools where Agriculture is taught or should be taught.

It has been deemed necessary to embody in the text such facts and principles of Geology and Botany as are absolutely essential to the understanding of agricultural principles and processes.

The work is intended to cover one year's time, but any part of it may be omitted if the necessary materials cannot be obtained. The time to be spent upon each phase of the work must be determined by the class, the materials accessible, and the teacher.

It is neither pedagogical nor scientific to tell a student what he can find out for himself. It takes away both the incentive and the necessity for experimental work to foretell the result.

Viii PREFACE.

Our aim has been to present actual experimental work in every phase of the subject possible, and to state the directions for such work so that the student can perform it independently of the teacher, and to state them in such a way that the results will not be suggested by these directions. One must perform the experiment to ascertain the result.

Any energetic teacher can, by carefully going over the work in advance, working out the experiments himself and reading the references, be able to do creditable class work if he is willing to " dig," but it is useless for any one else to undertake to be an agriculturist or to teach agriculture.

Every available source has been drawn upon for the material used in this book, but the plan of presenting it is original, as well as most of the experiments and exercises, and many practical ideas gained from experience in teaching.

We wish to express our grateful appreciation to all those who have so kindly helped us by reviewing the manuscript or by loaning us illustrations.

The following persons from the United States Department of Agriculture at Washington have been very helpful: The manuscript was examined by B. T. Galloway, Chief of the Division of Plant Industry; W. J. Spillman, Agrostologist ; A. F. Woods, Pathologist and Physiologist ;

PREFACE. ix

and M. B. Waite, Assistant Pathologist. The chapters on " Propagation," " Improvement," and " Pruning " were read by L. C. Corbett, Horticulturist, and the one on *' Enemies of Plants " by the Entomologist, Mr. Wilcox. " Ornamentation of School and Home Grounds" was read by Mr. Crosby. The chapter on " Enemies of Plants " was also read by H. Garman, State Entomologist of Kentucky. The first half of the book was examined also by Professor Mumford, Acting Director of Missouri Experiment Station, and by W. T. Carrington, State Superintendent of Schools. The second half was examined by J. C. Whitten, Horticulturist, Missouri Experiment Station. The first chapter was criticised by C. F. Marbut, Assistant Professor of Geology, University of Missouri.

The second half of the manuscript was examined by Dr. L. S. Daugherty, of the State Normal School, Kirksville, Missouri. The entire manuscript was submitted to H. J. Waters, Superintendent of Agriculture, World's Fair, St. Louis, Missouri. The chapter on Milk and Its Care was written by C. H. Eckels, of the Missouri State University.

We are indebted to the following persons and Experiment Stations for illustrations : Experiment Stations of Minnesota, West Virginia, Rhode Island, New Hampshire, Kansas, Missouri, Ithaca, New York, New Jersey, Texas,

X PREFACE.

and that of Hampton Institute (Va.) ; to the United States Department of Agriculture ; the United States Geological Survey ; Ladies Home Jotirnal ; OrdiUgit Judd Co.; Waugh's "Landscape Gardening" ; D. C. Heath & Co. ; Leggett & Brother; The Deming Co., and others mentioned with the figures.

The Authors.

KiRKSVILLE, Mo., 1903.

To the earlier edition has been added a chapter on " Farm Animals" by E. A. Trowbridge, of the Missouri Experiment Station. Several figures have been inserted and additional text has been written on the School Garden. A number of changes and additions have been made in other chapters. The whole book has been gone over critically and parts which have proved impracticable or doubtful have been omitted.

The Authors,

July ist, 1908.

Contents

CHAPTER. PAGE.

I. Nature and Formation of Soils .... 3 II. Classification and Physical Properties

OF Soils •. • • 43

Chapter I. Nature And Formation Of Soils

Soil is derived, primarily, from rock * in the broadest sense of the term. The cycle of tearing down in one place and building up in another has been constantly going on for ages, and is still going on to-day. It is to this cycle of changes, discussed in the following pages, that we owe the presence of the loose surface material of the earth (some places a few hundred feet in depth, and in some places entirely wanting) which makes it possible for plants and animals to live, and which loose material forms the basis of all soil.

y^.— SOURCES OF ENERGY.

The matter which constitutes the earth and atmosphere, though it cannot be destroyed, is constantly changing its form, under the action of existing forces. The soiu^ces of all these forces, or of our supply of energy, are the earth and the sun.

I. The Earth's Energy.

The earth's energy is from within, and some of its manifestations are the upheavals and disruptions of the crust, and, greatest of all, the

* " Any substance constituting a portion of the earth's crust ... is called a rock." — Leconte's Conupeitd of Geology, p. 17S.

force of gravity, without which nothing could remain upon the surface of the earth, owing to the centrifugal force caused by the rotation of the earth.

Other forms of energy are the molecular!^ forces of cohesion^ and adhesion,;^ and the atomic force of chemical affinity, all of which exist within the substances themselves, and act at insensible distances.

II. The Sun's Energy.

The great source from which we derive, either directly or indirectly, most of our energy is the sun. " The circulation of winds and waters, the changes of temperature, and the activities of living beings all depend upon the sun's energy," * without which there could be upon the surface of the earth no motion and no life.

The sun's energy comes to us, it is believed, by means of waves in the ether of space. Some of these waves produce the various colors, or are what we might call light waves ; others are not perceptible to the human eye, but are heat waves ; still others are especially productive of chemical changes, as is manifested in photography.

When the sunshine falls upon the soil a portion of it is absorbed, and the molecular motion

+ Terms thus marked (double dagger) throughout the book are found in the Glossary. * Scott's Geology, p. 29.

within the soil is increased, producing a certain amount of heat. This heat, when transmitted to the air, causes it to expand and thus become lighter, when the cooler and heavier air rushes in from the sides, forces it upward, and wind results ; if transmitted to the water, the increase of the molecular motion of the water overcomes the force of cohesion, and evaporation ensues.

As the vapor rises it gradually becomes cooled and condensed, and clouds composed of minute particles of water* are formed; these minute particles of water, after further cooling and condensing, are united by cohesion into drops, and are drawn back to the earth by the force of gravity, in the form of rain, snow, or hail. These few examples may serve to show how the sun's energy is transformed into a multitude of activities.

^.—FACTORS OF SOIL FORMATION.

I. The Atmosphere.

I. It Regulates the Tempei'atMre. — On winter nights the lower layer of air — especially if laden with dust and moisture — acts as a blanket in checking radiation of heat from the earth's surface. But, in the intense heat of summer, this lower layer of air would, through radiation

* " Clouds formed at temperature above 32° consist of minute spherical drops of water 1-4000 to i-iooo of an inch in diameter; those formed below 32° consist of minute ice spicules which increase in size and become snow." — YiSi.vK's,' Meteorology,-^^. 159, 160.

of heat from the earth, become unbearable for all living beings were it not for its currents, caused by the expansion of the heated air which renders it lighter and causes it to rise, while the cooler air above, being heavier, descends by the force of gravity."^'

2. Movements of the Atmosphere. — It is to these movements — due, primarily, to the counteraction of the sun's energy by the force of gravity — that we owe the formation of clouds and the condensation of their moisture ; the distribution of gases to act upon the rock surface, or to be consumed by living beings; the circulation of air in the soil, so essential to plant life; the transportation of plant food and of seeds ; and the maintenance of the relative composition of the whole atmosphere. It is through these movements that the air travels to the sea and back again, bringing moisture for the thirsty life.

The winds play an important part in the formation of soil : {a) in the disintegration of rocks, by pelting them with sand or rain, thus mechanically wearing them away by friction ; (^) by keeping them bare, so that they are exposed to other atmospheric forces ; (^) by stir-

* " Professor Langley, after a long and careful experiment at the base and summit of Mount Whitney, California, concludes that had our earth no atmosphere its surface temperature under the equator at noon would be 328° F." — The Soil, King, p. 13.

ring up the ocean into waves and billows, which beat upon the rocks, carrying with them sand and pebbles, which grind each other into powder.

On the sandy beach of the ocean and of the great lakes, and in the great sandy plains, or wherever the sand is loose and unprotected by vegetation, the wind becomes a potent factor (Figs. 1-2). Along the shore of Lake Michigan sand-dunes are destroying forests^ and often when the forests have been cut off, fertile farms are covered by these great accumulations of wind-blown sand. In conjunction with sand, the wind builds or destroys islands. The loess in China is a deposit of wind-blown soil.

In the desert of Sahara and in our great western plains great blinding storms of dust and sand occur. The sand, too heavy to be lifted more than a few feet high, is rolled along and drifted in wave-like mounds, which change their shape and position with the changes in the direction of the wind — just as the snow-drifts are formed in waves— and the particles are sucked up into the whirling air, and redeposited in a new place by the force of gravity as the motion subsides. One of our "blizzards" is a good illustration of a sand-storm, only the substance transported by the wind is snow instead of dust and sand.

3. Che7nical Action. — Another phase of atmospheric work is that of chemical action. Dry air

FIG. I. — WIND-BLOWN SAND-DRIFTS.

FIG. 2. — PLANTING BEACH GRASS TO HOLD THE SAND AT CAPE COD, MASS.

has little chemical effect, but moist air is very active. The oxygen, which is now known to combine with nearly every other element, seeks to unite with the minerals of the exposed rocks.* Iron, which in some form is contained by most rocks, unites readily with oxygen in the presence of moisture, forming rust, which stains, softens, and ultimately causes the disintegration of the rock.

Carbon dioxide (COj), though present in a comparatively small quantity, is a powerful agent both in moist air and in rain-water. It acts upon the rocks, especially upon limestone, causing them to crumble away or to be entirely dissolved.

Experiment i. — Before beginning to perform any experiment in this book, read over the entire directions for it, get necessary apparatus ready, and know what you are going to do a fid 7i>hy you are going to do it. Record your observations at the tifne they are made, not after leaving the laboratory.

Throughout this book, wherever the word " ?tote " is used, it means to observe and record your observations or expla?iatio?is.

{a) Break pieces of limestone, marble, or clam-shells into tiny bits, and place a small quantity in a wide-mouthed bottle.

{b) Pour in small successive portions of dilute hydrochloric acid (HCI). Note what takes place as the acid comes in contact with the stones or shells. Both the hydrochloric acid and the calcium carbonate of the stones or shells are decomposed, and calcium chloride

* Gilbert and Brigham, Physical Geography, p. 78.

AGRICULTURE.

(CaCl,), water (H^O),and the gas carbon dioxide (COJ are formed.

(c) Now pass some of this gas, or carbon dioxide, from the bottle into the solution of clear lime-water (Fig. 3).

(d) To prepare lime-water, dissolve common lime in pure water, let stand until clear, and carefully pour off the liquid, or pass it through a filter-paper. J What takes place when the carbon dioxide passes into the lime water? Allow the gas to continue to pass, and note the result.

(e) Boil the liquid, and again note result.

(/) Write up this experiment, stating the materials used, observations made, and what the experiment teaches, together with any further remarks or conclusions you may make concerning each step.

When the carbon dioxide was first passed into the lime-water, a precipitate of calcium carbonate (CaCOj), or limestone, was formed.

It continued to pass until there was no more calcium hydroxide, or lime-water, Ca(OH)2, to combine with it, when the carbon dioxide united with the water (H^O) to form carbonic acid (H2CO3).

This acid at once acted upon the precipitate of calcium carbonate, forming a soluble bicarbonate of calcium, HjCa (COj)^, which is dissolved, and the liquid becomes clear. The boiling drives out part of

FIG. 3. — APPARATUS FOR EXPERIMENT I.

NATURE AND FORMATION OF SOILS. H

the carbon dioxide, and the calcium carbonate is again precipitated.

Other substances of the air which bear important relations to agriculture are nitrogfen and its compounds, ammonia, nitrous and nitric acids, and ozone.

4. Alternations of Heat and Cold. — In dry, hot countries, rocks become excessively heated during the day and rapidly cooled at night. As the outer layer cools it contracts upon the hot and expanded interior, which tends to produce snapping and crumbling of the brittle minerals.

Thus we see the work of the atmosphere is constant ; it is universal ; it is not, however, uniform.''^ Both the rapidity and the extent of disintegration are dependent upon the differences of climate in various latitudes and altitudes, the differences in the rock substances themselves, the differences of seasons and of the amount of precipitation, and upon the presence or lack of protection from vegetation or soil.

* The composition of the air varies greatly in different localities, or under different conditions in the same localities; but, under ordinary conditions, its constituents in a given volume are, approximately: oxygen, 20.6 per cent.; nitrogen, 77.18 per cent. ; water vapor, 1.4 per cent.; carbon dioxide, .04 per cent. ; argon, .78 per cent. The water vapor and carbon dioxide are the most variable. And there is present a variable quantity of ammonia, nitrous and nitric acids — a very small fraction of i per cent, altogether.

II. Water.

Among the factors of soil formation none is greater than that of water in its various phases — as, rain, rill, river, lake, and sea ; frost, ice, avalanche, and glacier.

I. Chemical Action. — In many of its forms water exerts a violent and stupendous force, but there is a silent and subtle force whose results are often overlooked. It is the great solvent power of water. It absorbs both oxygen and carbon dioxide from the air, and these give it great chemical power in dissolving, or decomposing, rock substances."^* The simplest effects are the uniting of oxygen and of water with the minerals composing the rocks. But as the rain sinks into the ground it is provided with new weapons through the absorption of the humic acids and, possibly, of alkaline substances. For this reason, many rocks disintegrate more rapidly under ground than they do when exposed to the atmosphere.

Calcium carbonate, or limestone, is the substance dissolved or decomposed in the greatest quantity ; but magnesium carbonate (MgCOj), organic matter, silica (SiO^), and many other substances are held in solution by clear river water. (See " Field Exercise No. i," Part 2.)

* " Perfectly pure water has very little effect, but perfectly pure water does not exist in nature." — Scott's Geology.

The amount of these dissolved materials — though far less than that produced by mechanical action — is astonishing. That carried into the Gulf of Mexico by the Mississippi River annually reaches over 112,000,000 tons — -not all derived from the river-bed, but taken up by the water from the time it falls in rain till it reaches the sea, whether it flows through the river and its branches, or whether it comes from springs or other underground sources.

2. Mechanical Action. — The mechanical action of water is threefold, (i) It disintegrates. (2) It transports. (3) It assorts.

The mechanical action of rain is due to the friction produced by the drops in striking the rocks, and by the abrasion of solid particles as they are carried to lower levels. It forms into little rills and gullies, washing out and carrying with it as it goes all the loose material which it can hold in suspension (Fig. 8). The amount thus obtained depends partly upon the solubility of the rock over which it flows (though even a granite would be slightly dissolved by ordinary rain-water), and partly upon the violence of the precipitation, and the volume and velocity of the stream.

The velocity is affected by several influences, but the greatest of them is the constant, neverfailing action of gravity. Hence, the steeper the descent the greater the velocity. The power is supplied by the volume and velocity of the stream, but the work of abrasion is performed, for the most part, by the sand, pebbles, and rock fragments as they are rolled along. They cut down into the river-bed, wearing it deeper; they polish each other into rounded or flattened shapes, or grind each other into powder in their mad rush to the sea.

The transpo7^ting power of running water varies as the sixth power of its velocity, so that if its velocity be doubled it can carry sixty-four times as much solid matter as before. Thus it is that a slight increase in the velocity will greatly increase the load of a stream if the materials are obtainable, while the slightest decrease in the velocity will cause a part of the load to be deposited. These river deposits are commonly in sheets or bars, but when the river suddenly enters a plain at the foot of a steep slope an alluvial fan is formed by the deposition of the sediment.

According to the calculations of the United States government made many years ago, the Mississippi River transports to the gulf every year enough solid substance to make a column one mile square and 268 feet high — 200,000,000 tons.

The student can find no better example of the carrying power of water than that of the roadside rills and gullies after a heavy rain.

Experiment 2. — (a) Weigh a glass fruit jar, and collect in it the clouded or muddy water — from a gullj' or stream, after a rain — and allow it to stand until clear.

{/?) Weigh again; then carefully pour off the water, and weigh the sediment remaining in the jar.

(c) Calculate the per cent, of sediment. ~

(i) Rivers. — When rivers overflow their banks the water loses its velocity, and a layer of sediment is deposited on either side of the stream. In the great rivers these flood-plains are broad fertile tracts of land very valuable for agriculture. Those of the Mississippi are many miles in width, but have to be protected by levees from the overflowing of the river.

Where the river empties into the quiet waters of a lake or sea the velocity is checked and the stream deposits its load. As the stream slackens the heavier particles are dropped first, and so on, until in the quiet waters only the finest silt is carried. Hence it is that, on lake or seashore, we find the coarser materials thrown down first, and farther out the finer sands (Fig. 4). There is usually a pause after such deposition is made until a fresh supply of sediment is obtained. This allows the surface to assume a somewhat different arrangement. This surface forms the plane of contact for the next layer, and is called the "stratification plane."

Experiment 3. — The assorting power of water may be illustrated by (a) placing a mixture of rock material of

IG

AGRICULTURE.

various sizes — pebbles, sand, clay, and vegetable mouldin a candy-jar, and nearly filling the jar with water.

(d) Now thoroughly stir the mixture, and allow it to stand until the water clarifies.

(c) Observe the arrangement of the sediment. Where are the largest pebbles found ? Where the finest clay ?

Of course the change here will be gradual, and

FIG. 4 — DEPOSITION OF MATERIAL UPON SLACKING OF STREAM

the layers will not be so distinct, as there was no time for the formation of the stratification^ plane between the depositions of different kinds of sediment.

(2) Underground Streams. — Part of the water after a rain sinks into the ground. The natural breaks in the rock serve as channels which it may enlarge if the rock be soluble.

These underground streams perform various kinds of work, such as weakening rocks, dissolving minerals, carving channels, rising in springs or in artesian wells, bringfing" mineral matter to the surface, and forming caves and making peculiar deposits in them.

(3) Landslides are caused by the undermining of masses of rock and soil by water, which produces a slippery surface of bed-rock, and makes it easy for gravity to move an enormous quantity of soil or rock down the declivity.

(4) Lakes differ from oceans in being (usually) above the sea-level; in size; and in the freshness of their waters, provided they have an outlet. Their chief movements are zuaves produced by ivi'ids. These waves often erode the shore. They carry with them and distribute over the bottom of the lake the sediment brought by the rivers, thus making stratified rock.

(5) The ocean, with its waves, tides, and currents, which constantly beat upon the shore, plays an important role in this great drama. As we have seen, the material transported by the rivers may form deltas and bars, or be wide.y distributed, according to the strength of the tides and the power of the currents along the shore.

More than one-half of the rocks have been laid down in the sea and then raised above it.

These deposits were not made out in the open sea, but near the shore in shallow w?.ter. Their thickness is accounted for by the theory that the ocean bottom was sinking g-radually, and fresh deposits were made above the preceding ones.

In the open sea are found the deposits of very fine particles carried out by the rivers — on the continental slopes from the one hundred fathom line to the oceanic abysses — and they are known under the indefinite term of "mud." There are also volcanic deposits and great accumulations of organic remains. Every animal in the sea which has a shell or hard skeleton helps to make these deposits, but by far the greater part of them is made up of the shells of minute organisms''^ which live near the surface. The diatom ooze is composed of the siliceous remains of microscopic plants.

(6) Frost. — Frozen water has done a great share of the work in this process of mantling the earth with loose material. Some rocks are more porous than others, though those apparently solid will, upon examination, be found to be crossed by joints which divide them into blocks. These are filled with minute crevices and pores, through which the water percolates even to the very center. Water, upon passing

* Jordan and Kellogg's Animal Life, p. 18. Scott's Geology, pp. 176-180.

into a solid state, expands about one-eleventh of its original bulk. This expansion exerts an irresistible force, as is seen in the bursting of iron pipes, the cracking of the rocks into blocks, or shattering them into fragments, thus increasing their exposed surfaces many-fold, and exposing them to the action of other forces.

Exercise i. — Let the student calculate the area of the exposed surface of a cubic foot of rock (a) befor^ and (d) after it has been broken up into cubic inches** (c) Compare a and l>. :

Another effect of the freezing of rock is to cause the fragments to " rise slightly at right angles to the inclined surface, and each thawing produces the reverse movement " * under the influence of gravity. Consequently, they slowly "creep" down the declivity (Fig. 5). '4

(7) Ice. — The ice of a stream expands with great force, pushing against the bank. It holds in its mighty grasp all loose stones, boulders, and trees along the banks, and when it breaks up transports them to great distances.

If the student has an opportunity, let him watch the breaking up the ice in a river, or even in a smaller stream, and see with what wonderful force the great blocks of ice with their burdens are crushing each other to pieces in the fury of a spring torrent. Iron bridges are often swept away by the enormous pressure.

* Scott's Geology, p. 82.

AGRICULTURE.

(8) Snowslides. — On the mountain sides great masses of snow which have accumulated throusfh the winter become loosened bv water, as in the case of the landslide, and are drawn down the slope with great momentum, carrying

FIG. 5. — SHALES "creeping" UNDER THE ACTION OF FROST. (U. S. G. S.)

boulders, vegetation, everything within their path, and literally scraping the solid rock bare. (9) Glaciers. — It is now well established that in both North America and Europe glaciers, or great sheets of moving ice, existed in com-

FIG. 6. FORMATION OF GLACIERS. (u. S. G. S.)

paratively recent geological times; indeed, they are found to-day, though in mtcch /ess size and iiiivibe7' tJian formerly.

The causes of the climatic changes which led to the formation and again to the disappearance of the glaciers are unknown. At the time of the great expansion these ice sheets covered nearly all of North America down to 40^ north latitude.

Wherever, in high latititudes or altitudes, more snow falls in winter than melts in summer, glaciers are formed (Fig. 6). These glaciers carry with them (i) upon their surfaces, (2) frozen in their interior, and (3) pushed along in front or beneath them, great quantities of rock of all decrees of coarseness, from the gigantic boulders weighing tons to the finest clay. Rocks over which they pass are striated and polished (Fig. 7), and both these and the materials carried may be ground into clay by the enormous pressure of the slowly moving mass. The drift, or this deposit, is distributed over vast tracts, and is stratified or unstratified. The stratified drift is deposited by the water of glacial streams, while the unstratified is simply dropped by the melting ice.

At the present time there are great tracts of glacial ice : {a) the Alpine, occupying narrow mountain valleys, as those of the Alps ; (<5) the Piedmont glacier, like the Malaspina, of Alaska

PIG. 7.— ACTION OK GLACIER DRIFTS. (U. S. G. S.)

— lakes of ice formed by the union of many valley glaciers — which occupies an area of thirty by seventy miles, and which is covered along its southern border with morainic soil and great forests ; and (c) continental glaciers, covering vast tracts, comprising hundreds of thousands of miles, like those in Greenland and the antarctic land.