495 
 Dpy 1 
 
 , -■ MANUAL OF 
 
 • AGRICULTURE 
 
 FOR THE COMMON SCHOOLS 
 OF ILLINOIS 
 
 PREPARED BY 
 
 D. O. BARTO, B.S. 
 
 INSTRUCTOR IN AGRICULTURE, COLLEGE OK AGRICULTURE, 
 UNIVERSITY OF ILLINOIS 
 
 D. APPLETON AND COMPANY 
 
 NEW YORK CHICAGO 
 
 1908 
 
MANUAL OF AGRICULTURE 
 
MANUAL OF 
 
 AGRICULTURE 
 
 FOR THE COMMON SCHOOLS 
 OF ILLINOIS 
 
 PREPARED BY 
 
 D. O. BARTO, B.S. 
 
 INSTRUCTOR IN AGRICULTURE, COLLEGE OF AGRICULTURE, 
 UNIVERSITY OF ILLINOIS 
 
 D. APPLETON AND COMPANY 
 
 NEW YORK CHICAGO 
 
 1908 
 
h 
 
 :^ 
 
 A 
 
 LIBKARY of 00N««ES3 
 Two GoDies rtetwvd.' 
 
 JUN 10 1908 
 
 L\S» A XXC. Nu. 
 
 COPY B. 
 
 Copyright, 1908, by 
 D. APPLETON AND COMPANY 
 
CONTENTS 
 
 PAGE 
 
 Introduction ^ 
 
 PART I.— STUDIES WITH THE SOIL 
 
 What Agriculture Means 5 
 
 What Are the Essentials in Growing Crops? ... 5 
 
 How Is THE Soil Necessary to Growing Plants? ... 5 
 
 The Soil Is the Natural Home of the Plant ... 6 
 
 What Is a Soil? ^ 
 
 Exercise I. — ^What Constitutes a Soil? 6 
 
 Exercise II.— Of What Are Soils Composed? .... 8 
 
 Exercise III.— How Soil Particles Look When Magnified , 9 
 
 Exercise IV.— Helps in Classifying Soils 10 
 
 Exercise V.— A Study of the Weight of .Soils . . . .10 
 Exercise VI.— How a Part of the Water Is Held by the Soil . 11 
 Exercise VII. — To Determine the Differences in the Water- 
 Holding Powers of Different Soils 12 
 
 Exercise VIIL— Will Compact Soils Hold More Water than 
 
 Loose Soils? 13 
 
 Exercise IX. — How Does Organic Matter in a Soil Affect Its 
 
 Water-Holding Powers? 13 
 
 Exercise X.— The Capillary Action of Different Soils . . 14 
 
 Water 1^ 
 
 The Demands That Crops Make upon the Water Supply in the 
 
 Soil 1^ 
 
 Saving the Soil Water l' 
 
 Exercise XL— How to Check Evaporation of Water from 
 
 Soils • • 17 
 
 The Effect of Color on the Temperature of Soils . .18 
 
 Exercise XI I. —Dark Soils Are Warmer than Light Soils . 19 
 
 Exercise XIIL— A Wet Soil Is Colder than a Dry Soil . . 19 
 
 V 
 
vi CONTENTS 
 
 PART II.— STUDIES IN GROWING CROPS 
 
 PAGE 
 
 The Plant 21 
 
 Essentials in Crop Production 21 
 
 The Seed 22 
 
 Exercise XIV. — Essentials for Seed Germination ... 22 
 
 The Testing of Seed 24 
 
 Exercise XV.— How to Test Seed 24 
 
 Importance of Fine Tilth 25 
 
 Exercise XVI. — Why a Good Seed-Bed is Necessary . . 25 
 Exercise XVII.— Heavy Soils Should Not Be Cultivated 
 
 When Wet 26 
 
 Exercise XVIIL— The Color of the Soil Influences Plant 
 
 Growth 26 
 
 Seed Planting 27 
 
 Exercise XIX.— How Deep Should Seeds Be Planted? . . 28 
 
 What is the Effect of Light on Germination? 28 
 Exercise XX. — The Young Plant Depends on the Food Stored 
 
 in the Seed 29 
 
 Exercise XXI. — The Young Bean Plant Brings Its Supply of 
 
 Food above Ground with Its Stem 29 
 
 Exercise XXII.— Light Is an Essential of Plant Growth 29 
 Exercise XXIII. — To Show How Rapidly Plants Transpire 
 
 Water 30 
 
 Exercise XXIV. — How Weeds May Rob the Soil of Moisture 31 
 
 Exercise XXV.— What Proportion of a Green Plant Is Water? 31 
 
 Roots 32 
 
 Exercise XXVI.— How Roots Search for Water ... 33 
 Exercise XXVII. — How Do Roots Know Where to Look for 
 
 Food? ' 33 
 
 Exercise XXVIII. — How Plants Use the Reserve Food 
 
 Stored in Their Roots 34 
 
 Root Tubercles 35 
 
 Exercise XXIX. — How Leguminous Crops Increase Soil 
 
 Nitrogen 37 
 
 Exercise XXX.— Inoculating the Soil with Bacteria . . 39 
 
 Inoculating the Soil for Alfalfa 41 
 
 Plot Experiments 41 
 
 Purpose of the Experiments in Soil Fertility ... 42 
 
CONTENTS 
 
 How THE Necessary Fertilizers Can Be Obtained 
 
 Exercise XXXI. — A Test in Plant Food Requirements 
 
 How Plant Food is Applied 
 
 Kinds of Crops for Plot Experiments 
 
 Suggestions for Planting 
 
 Local Conditions Vary 
 
 The Practical Lesson . 
 Care of Plot Experiments in Vacation 
 
 Studies in Corn 
 
 Exercise XXXH. — Identification of Leading Varieties of Corn 
 Exercise XXXIII. — Questions of General Information about 
 
 Corn 
 
 Exercise XXXIV. — Shrinkage of Corn 46 
 
 Exercise XXXV. — Number of Hills of Com and the Yields 
 
 per Acre 47 
 
 Exercise XXXVI. — Corn Studies in the Field .... 47 
 Exercise XXXVII. — Relation between the Tassel and the 
 
 Silk 47 
 
 Pollination 48 
 
 Cross-Pollination Preferred 48 
 
 Exercise XXXVIII, — Pollination Necessary to Production . 49 
 References 51 
 
 Vll 
 
 PAGE 
 42 
 
 43 
 43 
 42 
 44 
 44 
 44 
 44 
 
 45 
 45 
 
 46 
 
MANUAL OF AGRICULTURE FOR 
 
 THE COMMON SCHOOLS 
 
 OF ILLINOIS 
 
 INTRODUCTION 
 
 Because the experiences that come to the country child 
 are drawn so largely from Nature's laboratory and deal with 
 the wonderful mysteries of life, with beginnings, and with 
 things that are young and growing and constantly changing, 
 and for that reason peculiarly fascinating for boys and girls, 
 the study of agriculture is especially adapted to school work. 
 That is, it is especially adapted to make intelligent and 
 efficient men and women of the pupils by training them to 
 think. 
 
 The writer has tried to outline in this little guide sets 
 of studies and exercises in agriculture on topics of general 
 importance and interest to farmers in all sections of Illinois 
 and to make treatment of each topic sufficiently complete to 
 give a fairly comprehensive idea of the main facts and of 
 their relations to other problems in agriculture. Especially 
 has the writer tried to make all statements in the presenta- 
 tion of each topic accord strictly with the teachings of the 
 highest authorities in agricultural science. 
 
 Teachers frequently underestimate the pupil's ability to 
 comprehend and to think. It is necessary in teaching agri- 
 culture, even in its simplest lessons, to use terms and prin- 
 ciples that belong to other sciences, such as botany, physics, 
 chemistry, physiology, and zoology. May there not be a great 
 advantage for the child to make his first acquaintance with 
 these sciences in a field where he is somewhat at home? 
 
 1 
 
2 INTRODUCTION 
 
 The subjects presented in this outline have been selected 
 because of their generally recognized importance in the field 
 of agriculture, and because they deal with matters of common 
 interest in all parts of the state. As the work grows, and the 
 preparation of teachers in the subject becomes more extended, 
 the field will naturally widen, and schools will properly in- 
 clude in their courses those topics that are related to the 
 particular agricultural interests of their section of the 
 country. 
 
 There is probably more work outlined here than any 
 school can accomplish in a one-year course. The schools of 
 a county, or of a smaller area, with the cooperation of their 
 County Superintendent, might agree at the beginning of the 
 year on the part of the work they would attempt to cover 
 and the order in which they would take up the exercises; 
 then, by holding joint meetings occasionally and reporting 
 and discussing the results of their experiments, the work 
 would gain much in interest and value for all. 
 
 It is not intended that the order in which the exercises 
 are given in this outline shall be closely followed in practice. 
 The present arrangement makes it possible to present each 
 division of the subject by itself and in more natural and 
 logical sequence than would be possible were the exercises 
 arranged in groups suited to each month in the school year. 
 Everyone will readily understand that certain exercises, like 
 several of those relating to corn, must come at the beginning 
 of the school year in the fall. Others having to do with the 
 preparation of plots and the planting of crops must be re- 
 served for the work of April and May. Some of the work 
 necessarily belongs to the summer months and must be 
 planned either as home work or as vacation school work. 
 But a large part of the exercises is laboratory work and can 
 be done during any part of the year, particularly if some 
 place be provided where things will not freeze at night. 
 
 All the work outlined here is real agriculture, as serious 
 
INTRODUCTION 3 
 
 as that taught in the colleges ; but in the hands of competent 
 teachers, it is no more difficult for the pupils to comprehend 
 and perform than the other school work for the seventh and 
 eighth grades. The course is not intended for pupils of the 
 lower grades. They are too young and inexperienced to profit 
 by it. 
 
 A list of agricultural books, bulletins, and other publi- 
 cations is given ; and teachers are urged to read and use them 
 as freely as time allows. Bulletins and circulars can be ob- 
 tained simply by writing for them. Of course every teacher 
 of the subject will own some good books on agriculture, and 
 every school where it is taught should start a reference library 
 of agricultural works. 
 
PART I 
 
 STUDIES WITH THE SOIL 
 
 What Agriculture Means. — Ask a country boy or girl 
 what agriculture is, and the answer doubtless will be : " Ag- 
 riculture is the business of growing crops, of raising and 
 feeding farm stock, of producing milk, perhaps of making 
 l)utter and cheese from the milk." While agriculture in- 
 cludes many more things than these and is really a very 
 complex business, the answer names what may be considered 
 the fundamental things of agriculture; and the lessons and 
 exercises in this little outline deal with this side of the busi- 
 ness of agriculture. 
 
 What Are the Essentials in Growing Crops? — Again ask 
 the boys and girls in the country what are the necessary 
 things in the business of growing crops, and the answers will 
 certainly be: "Land (soil) and seed." Implements and 
 teams to be used in preparing the soil for planting the seed 
 and in tilling the crops while they are growing and in har- 
 vesting them when they are mature will probably be included 
 in most answers, but they will not be named, or thought of, 
 first. Everj'body knows, however, that crops cannot be grown 
 without the use of soil and seed. That being the case, it is 
 plain that the study of agriculture may well begin with a 
 study of these two essentials, soil and seed. 
 
 How Is the Soil Necessary to Growing Plants? — We can- 
 not think of fishes living anywhere except in the water. It is 
 true that a plant may be made to grow in the water, where it 
 has no contact with the soil, if some means be provided to hold 
 it fast and support its stem ; but this is because the water con- 
 tains certain substances that it has dissolved out of the soil, 
 
 5 
 
6 MANUAL OF AGRICULTURE 
 
 and which the plant can thus get. So really in this case the 
 soil is as much a necessity to the plant as water is to fishes. 
 
 But what does the soil do for the plant? (A crop is 
 only a group of the same kind bf plants grown together, and 
 we may study a single plant to learn the needs of the crop.) 
 Has the soil more than one relation to the plant? Does it 
 serve several needs? Let us begin our study of agriculture 
 with the attempt to answer these points. 
 
 The Soil Is the Natural Home of the Plant. — By " natural 
 home ^^ is meant that situation where the individual, either 
 animal or plant, finds those conditions and surroundings 
 which it likes, which best satisfy its needs and help it develop 
 to its fullest capacity. 
 
 The plant finds this situation in the soil. The roots spread 
 through the soil, forcing their way between the particles, 
 wrapping their delicate root-hairs about the separate grains 
 of soil, thus securing the necessary anchorage and support 
 for the whole plant, and absorbing from the soil certain food 
 substances that the soil water has dissolved. 
 
 Besides anchoring it and providing a reservoir for water 
 and a portion of the plant's food, the soil acts as a moderator 
 of temperature. It absorbs the rays of heat from the sun 
 and gradually gives up this warmth at night. There are 
 other services, though these are the principal ones, which the 
 soil performs for the plant.^ 
 
 What Is a Soil ? — I suppose you are saying : " The soil is 
 dirt, ground, earth — everybody knows that." Well, let us 
 try an experiment. Perhaps that will teach us something 
 about soils that we have never thought of. We will call it : 
 
 Exercise I 
 
 What Constitutes a Soil? — Get 3 flower pots or boxes that 
 will hold about a quart and label them I, II, III. Fill I nearly 
 
 The Principles pf Agriculture, pp. 25, 26. 
 
STUDIES WITH THE SOIL 7 
 
 full of pure sand such as can be obtained along the shores of 
 Lake Michigan. In II put earth that came from a depth of 
 two or more feet below the surface. (You can get this where 
 a cellar or a cistern is being dug.) Use the earth from the 
 surface of a field or a garden to fill III. In each pot plant a 
 grain of corn, a bean, and an oat grain. Treat the pots alike 
 in respect to warmth, light, and watering. 
 
 Use only pure rainwater or distilled water to water them, 
 as this contains no plant food which has been leached out of 
 the ground. At first the plants will probably thrive equally 
 well in each pot ; for every little plant at first lives on the food 
 its mother has packed about it in the seed. But in about a 
 week this will be consumed, and each plant must find its food 
 for itself from the material surrounding it. Do you notice a 
 difference in the growth of the plants in the three pots? If 
 you are using only pure sand in I, and in II material that came 
 from some depth below the surface, and are watering them 
 with pure rainwater, the plants in I and II will soon begin to 
 die. They are starving. We said that a soil is the natural 
 home of the plant because it supplies its needs. The materials 
 in I and II are failing to do that. A difference between the 
 materials in I and II and what was placed in III is that the 
 earth in III is a mixture of finely ground rocks, which we 
 call mineral or inorganic matter, and small bits of decaying 
 plant and animal tissues. These latter are termed organic 
 matter. 
 
 But in pots I and II there is no organic matter, — only the 
 mineral substances that have come from the disintegration of 
 rocks. Now certain parts of the food that a plant must have 
 in order to make its full growth and mature its seeds come 
 from the organic matter in the soil, called the humus, and 
 other parts are derived from the mineral or inorganic sub- 
 stances. A true soil, then, must always he a mixture of these 
 two materials.^ 
 
 » Soils, pp. 7, 26, 27. 
 The Principles of Agriculture, pp. 28-36. 
 The Soil, pp. 1-26. 
 Practical Agriculture, pp. 33-36. 
 
MANUAL OF AGRICULTURE 
 
 Exercise II 
 
 Of What Are Soils Composed? — Spread a teaspoonful of 
 soil from each sample on sheets of white paper and carefully 
 examine the particles of each. Notice that by far the greater 
 portion of most of the samples is fine pieces of rock (sand), 
 and that in all of them are many — more in some than in others 
 — particles of rotting plant and animal matter and bits of roots 
 and stems and leaves that are not yet much decayed. 
 
 Carefully Aveigh out an ounce of each kind of soil, put it 
 into an iron spoon and heat red-hot for several minutes over a 
 gas jet or on live coals. After cooling weigh the contents of 
 the spoon again. There will be a loss in weight. A part of 
 the soil has burned up. This part is called the organic matter 
 of the soil and is vegetable and animal substance. As it decays 
 it grows dark in color and forms what is called humus. The 
 part of the soil in each sample that did not burn was made of 
 rock, inorganic matter, or mineral. The soils should be per- 
 fectly dry before they are weighed into the spoon. Do all the 
 samples of soils lose the same amount by weight in the burn- 
 ing? Which loses the greater weight, the dark garden soil or 
 a sample of light colored soil? At least one of the samples 
 should be taken from 20 to 40 inches below the surface. This 
 layer is called subsoil. Samples can be procured from the side 
 of a bank where a cellar or a ditch is being dug. Notice the 
 difference in color between the two layers of soil, the surface 
 and the subsoil. How do you account for the difference in 
 color? Does the ounce of subsoil lose as much by burning as 
 the ounce of surface soil? Why not? One of the most im- 
 portant substances which plants get from the soil, and must 
 have in large quantities to make their best growth, is nitrogen. 
 The largest part of this necessary food the plants get from 
 the humus, the material that makes soils black and that fire 
 will consume. This is why we have learned to think of the 
 black soils as the most fertile.^ 
 
 This second experiment is to show, then, that soils are 
 
 ' Soils, pp. 71-74. 
 Physical Properties of Soils, pp. 1-51. 
 
STUDIES WITH THE SOIL 9 
 
 always mixtures of inorganic with organic matter; and that 
 the greatest part, from 85% to 99%, of nearly all soils is min- 
 eral — composed of pieces of rock which we call stones or gravel 
 or sand or silt or clay according to the size of the pieces or 
 grains. 
 
 There is a kind of soil occurring in several places in Il- 
 linois called peat. This is found in beds where a dense growth 
 of plants has sprung up and fallen down year after year for 
 ages, as on the margins of lakes and along banks of streams. 
 As the mass of roots and stems and leaves decayed, some sand 
 was mingled with it by the action of the water; but the great 
 bulk of this soil is organic matter. 
 
 Exercise III 
 
 How Soil Particles Look When Magnified. — Sprinkle a few 
 grains of dry soil on a glass slide or a sheet of white paper 
 and examine with a microscope or magnifying glass. Make 
 drawings of several of the particles. Is their color white, gray, 
 brown, red, or black? In shape are they round or irregular, 
 smooth or angular? Are the particles single grains or several 
 grains fastened together like crumbs ? ^ 
 
 The ordinary classification of soils, as gravel, sand, silt, 
 clay, and loam is based mainly on the size of the particles 
 composing them : ^ 
 
 Gravel — a soil composed largely of pieces of rock whose 
 diameters lie between 3 inches and -^ of an inch. 
 
 Sand — a soil whose particles range from -gV of ,an inch to 
 6-^0 of an inch in diameter. 
 
 Silt — a much finer soil in which the particles have diam- 
 eters lying between -g^o of an inch and -btoo-o- of an inch. 
 
 Clay — a soil in which the diameters of the particles range 
 from -670-oir of an inch to only -tsotwoo of an inch. 
 
 Loam — a name given to a soil which is a mixture of two or 
 more classes of soils. Most surface soils are loams, and are 
 
 » Practical Agriculture, p. 40. 
 2 The First Book of Farming, pp. 26-30. 
 Soils, pp. 51-53. 
 
10 MANUAL OF AGRICULTURE 
 
 subclassified as sandy loams, clay loams, brown silt loams, etc., 
 according to the class of soil that predominates in the mixture. 
 
 Exercise IV 
 
 Helps in Classifying Soils. — Place a spoonful of each sam- 
 ple of soil on a board and moisten it with water. With the 
 fing-ers mold each sample into a ball. Notice that the sand 
 and sandy loams are crumbly, but that the clay and finest silts 
 are plastic and sticky. 
 
 In a pint glass fruit jar place two or three large spoonfuls 
 of soil and fill the jar half full of water. Shake thoroughly, 
 then let the soil particles settle to the bottom of the jar. The 
 heaviest particles sink most quickly, first the gravel, then 
 the coarse sand, fine sand, silt, and clay in the order named. 
 The finest silts and clays will remain for days suspended in the 
 water. The relative thickness of the layers of the different 
 sized grains in the bottom of the jar will help to classify the 
 soils by showing the proportion of each in the mixture. 
 
 From the tests and examinations of the soils in Exercises 
 
 11 and III, try to classify each sample as gravel, sand, silt, clay, 
 or peat, or as a gravelly loam, sandy loam, silt loam, clay loam, 
 or peaty loam.^ 
 
 Exercise V 
 
 A Study of the Weight of Soils. — Take any small box and 
 accurately measure its cubical content. Be sure that the sam- 
 ples of soil used are thoroughly dry. Fill the box and calculate 
 successively the weights of a cu. ft. of sand, clay, loam, and 
 peat. An acre-foot of soil = 43,560 cu. ft. What is the weight 
 of an acre-foot of each of the types of soil that you have ex- 
 amined ? * 
 
 Farmers speak of clay as a " heavy soil," and of sandy soils 
 as "light." You will see that this cannot be because of their 
 relative weights. The expressions in this case refer to the 
 
 » Soils, pp. 53-60. 
 2 Soils, p. 26. 
 Physical Properties of Soil, pp. 41-49. 
 
STUDIES WITH THE SOIL H 
 
 comparative ease with which they can be cultivated. Clay soils 
 when moist are sticky and clinging, hard to till, while sandy 
 soils crumble readily and are much easier to work. 
 
 Exercise VI 
 
 Hoiu a Part of the Water Is Held hy the Soil—U a marble 
 or a pebble be dropped into a dish of water it comes out wet. 
 That is, a very thin film of water adheres to the solid body and 
 completely surrounds it. In Exercise III the microscope 
 showed us that the soil is made up of little particles of matter 
 more or less round in form. Since they are of this shape they 
 cannot be packed perfectly tight and close; there will be little 
 spaces, or pores, all through the mass composed of these spher- 
 ical grains. This is a very important fact in its bearing upon 
 farming, and we shall have more to say about it in other les- 
 sons. The water that falls upon the ground as rain and snow 
 flows down through these pores, and a part of it clings to the 
 surface of each little particle of soil. This water is called film 
 water ' and is of immense interest to the farmer because it is 
 from this source that growing plants get their whole supply of 
 water and all of the plant food which is taken from the soil. 
 N"ow this fact should be clearly and firmly fixed in our minds: 
 The feeding ground of a crop is measured hy the sum of the 
 surfaces of the soil particles that make up that portion of the 
 soil occupied hy the roots of the crop.^ 
 
 It is in this respect that soils vary most. Suppose you 
 have a box whose three dimensions are 12 inches each. How 
 many croquet balls whose diameter is 6 inches can be packed 
 in this box? You answer 8. Find the sum of the surfaces of 
 these 8 spheres. You remember that the formula for the sur- 
 face of a sphere is the square of the diameter multiplied by the 
 factor TT (approximately 31). So we have: Q X Q y^ tt X8=- 
 288 TT, as the total surface area of the 8 balls. 
 
 Suppose that the balls have a diameter of only 3 inches. If 
 these ar e arranged in the same box in regular layers there will 
 
 » The First Book of Farming, pp. 50-52. 
 a Soils, pp. 29-31. 
 
12 MANUAL OF AGRICULTURE 
 
 be 4 layers of 16 balls each or 64 balls in the box. Computing 
 the total surface of these 64 spheres as follows : 3 X 3 x ir x 
 64 = 576 TT, we see that the sum of the surfaces of all the 
 spheres in the box has been doubled while the volume remains 
 the same. Each time that the diameters of the spheres filling 
 a given space are divided by 2, the total surface is multiplied 
 by 2. 
 
 Although the particles in any type of soil are not perfect 
 spheres nor all of the same size, this principle holds true 
 always, that as you reduce the size of the soil grains you in- 
 crease in the same ratio the total interior surface of the soil/ 
 
 King in his book. The Soil, estimates that the total surface 
 of the soil grains in one cubic foot of sandy soil is about one 
 acre, while in a clay soil it is nearly four acres.^ Since, in a 
 moist but well drained soil all the water is held in the form of 
 a film adhering to the surfaces of the grains, and this water 
 holds in its solution the various substances that the roots of 
 the plants need for food, thorough cultivation which pulverizes 
 and fines the soil increases its water-holding, and therefore its 
 feeding, powers.^ 
 
 Exercise VII 
 
 To Determine the Differences in the Water-holding Powers 
 of Different Soils. — Get 5 small tin cans, make several fine 
 holes in the bottom of each, and fit circular pieces of cheese- 
 cloth in the bottoms of these cans to prevent any fine soil 
 from sifting through. Then find the exact weight of each can 
 and weigh out carefully just the same number of ounces of 
 material for each, putting gravel into I, coarse sand into II, 
 fine sand into III, clay into IV, and loam into V. Weigh 
 again to be sure that you have the correct weights. Now set 
 the cans in a shallow dish and fill them with water until the 
 soils are saturated, — that is until all of the pores of the soils 
 are filled. Next stand the cans where all of the free water — 
 all of the water that is not retained as a film about the grains 
 
 > Physical Properties of Soil, pp. 1-8. 
 
 2 The Soil, pp. 72, 73. 
 
 3 Soils, pp. 80, 81. 
 
STUDIES WITH THE SOIL 13 
 
 of soil — can drain away by force of gravity. When drainage 
 ceases, weigh each can again. The excess in weight over that 
 of the can filled with dry soil indicates the amount of water 
 absorbed by the soil. 
 
 Which soil absorbed the most water? Which soil has the 
 least power to hold water? Do these results agree with pre- 
 vious statements about the amount of interior surface of soils 
 as related to the fineness of the soil particles ? ^ 
 
 Exercise VIII 
 
 Will Compact Soils Hold More Water than Loose Soils? — 
 Conduct this experiment exactly like the previous one, but 
 pack the soils firmly in the cans before adding the water. If 
 a farmer wants his soils to store up an abundant supply of 
 moisture for his growing crops is it better to leave the surface 
 of the soil loose or to roll it down as solid as possible ? "' ^ 
 
 Exercise IX 
 
 How Does Organic Matter in a Soil Affect Its Water-hold- 
 ing Powers? — In this experiment get some dry, w^ell-rotted 
 manure and rub it between the hands until it is fine. Now 
 mix with the gravel, sand and clay of the sorts used in Exer- 
 cise VII, about one-tenth the bulk of this fine manure. Weigh 
 the same amounts into the cans and add water. How does the 
 amount of water retained by these soils compare with the re- 
 sults in Exercise VII? 
 
 Crops on sandy soils frequently suffer severely for want of 
 water . in times of drought. Would working more organic 
 matter into the soil improve their power to resist droughts?'' * 
 
 In speaking of the w^ater in the soil three terms are used 
 to describe the three forms in which it exists there : ^ 
 
 » The First Book of Farming, pp. 40-42. 
 Principles of Agriculture, pp. 47-63. 
 Soils, pp. 80-83. 
 
 2 The First Book of Farming, pp. 46-52. 
 
 3 Physical Properties of Soil, p. 134. 
 
 * The Principles of Agriculture, p. 52. 
 
14 MANUAL OF AGRICULTURE 
 
 The free water — gravitation water, as it is usually called — 
 is that portion of the water falling upon the surface of the 
 ground, that the soil particles are not able to take up and hold 
 by the power of adhesion as a film, but which flows downward, 
 by the force of gravity, through the open spaces between the 
 soil particles, and is carried off in underground drains, or 
 reaches the level where water stands in the soil. 
 
 The film water, which has already been described, is called 
 also capillary moisture from the Latin word, capilla, meaning 
 hair. Where the soil grains are very fine the spaces between 
 them are correspondingly small; and as they connect with each 
 other they form little hair-like passages, or tubes, through 
 which this film water is able to rise, because, where these tubes 
 are small enough, the attraction of their walls for the liquid 
 is able to overcome the force of gravity that would force the 
 liquid to flow down. In this way, as the water in the surface 
 soil is taken up by the growing plants, or evaporated by the 
 sun and winds, a new supply is being constantly pumped up 
 from below to take its place, if the soil is kept in the right 
 condition for these little tubes to do their work. This is one 
 of the greatest problems that the farmer has to deal with. 
 Unless an abundant supply of water is caught and held by the 
 soil, and the system of little pumps kept in working order so 
 that by capillary action they can raise this water where the 
 roots can reach it, it is no more possible to grow large crops 
 than it would be to grow good live stock on a farm where there 
 is not a sufficient supply of drinking water. 
 
 The third form of soil water is called thermal moisture or 
 hygroscopic moisture and refers to a small amount of water 
 that adheres so closely to the soil grains that it can be sepa- 
 rated from them only by the use of considerable heat.^ 
 
 Exercise X 
 
 The Capillary Action of Different Soils. — For this experi- 
 ment get 6 student lamp chimneys. Find a small wooden box 
 the width of whose top is about the length of the chimneys. 
 
 » The Soil, p. 252. 
 
STUDIES WITH THE SOIL 15 
 
 Turn the box on its side with the open end toward you. Bore 
 6 holes in a row through the upper side so that the chimneys 
 will pass through as far as the shoulder. (If you can not easily 
 bore the holes, knock one of the boards off the side of the box 
 and stretch two wires tightly across the right distance apart 
 for the chimneys to pass between and be suspended by the 
 shoulders.) 
 
 Tie pieces of cheese cloth firmly over the smaller ends of 
 the chimneys and fill them up to the shoulders each with a 
 different kind of soil. Pour the soils in loosely and do not try 
 to pack them. Now fix it so that the lower ends of the chim- 
 neys shall stand in about one inch of water. Notice how the 
 water rises through the pores of the soils. In which soils is the 
 capillary movement most active? Fill one chimney with 
 lumpy soil. Can the water rise through such a soil? This 
 shows one reason why it is important to prepare the ground 
 carefully before planting the seeds. About 3 inches from the 
 top of the soil in one chimney put in a teaspoonful of fine dry 
 chaff and then fill up with soil. Can the water rise through 
 this chaff? 
 
 Sometimes farmers plow under a heavy crop of clover or 
 rye, or a very thick coat of unrotted, stra\vy manure, and if 
 the season is dry the crop suffers for lack of water because the 
 capillary movement of the water from below is stopped by the 
 loose layer of vegetable matter before it can reach the roots of 
 the plants. 
 
 This same experiment can be performed by using large 
 plates or pie tins, piling the soils in the center of these in the 
 form of cones. Pour the water slowly upon the dishes at the 
 base of the pile and observe how it rises through the different 
 soils.^ 
 
 Water. — No problems in agriculture are of greater im- 
 portance to the farmer than those that deal with water. 
 How to provide for the storage in his soil of an ample sup- 
 
 1 The First Book of Farming, pp. 49, 50. 
 The Principles of Agriculture, pp. 55-59. 
 Soils, pp. 87-96. 
 
16 MANUAL OF AGRICULTURE 
 
 ply for the needs of his crops; how to get rid of an excess 
 of water in his soil ; how to cultivate the soil so that the water 
 stored in the subsoil can rise by capillary movement when 
 it is needed to supply the demands of the plant roots near 
 the surface ; how to prevent the great loss of water by evapo- 
 ration from the surface of the soil; and how to prevent the 
 water in hilly regions from washing and gullying out the 
 soil on the hillsides and carrying off into the streams the 
 most fertile portions of the land — these are all questions that 
 make the study of the control of water on the farm of the 
 greatest interest and value. 
 
 The amount of water that falls from the clouds as rain 
 and snow is measured by inches. The average annual rainfall 
 in Illinois is 37.39 inches.^ This means that if none soaked 
 into the ground or ran off^ and none evaporated into the air 
 for a year, and that if the ground were perfectly level, there 
 would be all over the state of Illinois on every acre of land 
 a pond more than 3| feet deep as the result of the rainfall 
 and snowfall for one year. 
 
 We sometimes speak of an acre-inch of water. That 
 means the amount of water that would cover an acre with 
 water one inch deep. There are 43,560 sq. ft. in an acre. 
 An acre-foot of water would be 43,560 cubic feet on an acre. 
 A cubic foot of water weighs very nearly 62| lbs. Compute 
 the number of tons of water that fall annually on an average 
 on each acre in Illinois. 
 
 The Demands That Crops Make Upon the Water Supply- 
 in the Soil. — The amount of water that is found in the plant 
 at any one time is a very small part of what the plant uses 
 in growing. Far the largest part of the water that the roots 
 of plants drink up from the soil serves simply as a carrier 
 of plant food and flows up through the roots and stems, leav- 
 
 1 University of Illinois Agricultural College Experiment Station 
 Bulletin No. 86, pp. 61, 62. 
 
STUDIES WITH THE SOIL 17 
 
 ing its loads in the cells of the leaves, and passing out into 
 the air. 
 
 The amount that is thus used by our farm crops sounds 
 enormous. For instance, to grow one pound of dry vege- 
 table substance it has been proved by experiments that the 
 plant uses from 300 to 600 pounds of water. The following 
 statements are made by prominent scientists who have con- 
 ducted tests to learn how much water different crops use 
 while making their growth (the figures are given for the 
 average-sized crops per acre) : clover uses 400 tons of water 
 per acre; potatoes, 400 tons; wheat, 350 tons; oats, 375 tons; 
 corn, 300 tons.^ 
 
 Saving the Soil Water. — Since these various crops use such 
 enormous amounts of water during the time they are making 
 their growth, and since, if this supply is not provided for them 
 as they need it, the crop yields are seriously shortened, the 
 farmer should be taught to regard the supply of moisture 
 stored in his soil as a part of his capital and so valuable that 
 he must try to prevent its being wasted.^ 
 
 Exercise XI 
 
 How to Check Evaporation of Water From Soils. — Fill four, 
 tin pails of about 5-lb. size with loam to within two inches of 
 the top. Moisten the soil well, measuring out the same amount 
 of water for each pail. Whenever more water is added during- 
 the experiment, treat all alike. Put the same amount of soil 
 by weight into each of the four pails and press the surface 
 down smoothly, about as it would be left by a field-roller. Set 
 
 > Practical Agriculture, pp. 12-15. 
 
 Soils, pp. 76-79; 237-239; 264. 
 
 The First Book of Farming, p. 40. 
 
 The Soil, pp. 155, 156. 
 2 The First Book of Farming, pp. 53-57. 
 
 The Soil, pp. 184-190. 
 
 Soils, pp. 90-92. 
 
 Farmers' Bulletin, No. 266. 
 
18 MANUAL OF AGRICULTURE 
 
 the pails, numbered I, II, III, IV, where the sun will shine on 
 them and the air circulate over them. The surface of the soil 
 in No. I should be left smooth. Each morning with a lead 
 pencil stir the surface of the soil in No. II thoroughly to the 
 depth of one inch. Treat the soil in No. Ill the same as in 
 No. II except to stir it to a depth of two inches. Sprinkle over 
 the surface of No. IV an inch layer of dry sawdust or wheat 
 bran. Set down in four columns under I, II, III, IV the 
 weights of each pail and contents at the beginning of the ex- 
 periment and then the successive weights taken each morning. 
 Continue the experiment for ten days or two weeks. What 
 was the total loss of weight from each pail? That is, how 
 mueh water has evaporated from each? Does stirring the sur- 
 face of the soil check the loss of water? Does cultivation to 
 a depth of one inch prove as effective as to a depth of two 
 inches? This loose layer of soil obtained by surface cultiva- 
 tion is called a dust mulch and is the simplest and most satis- 
 factory means by which the farmer can check the great loss 
 of water from the soil by evaporation. How did the mulch of 
 sawdust or bran compare in effectiveness with the dust mulch? 
 In gardens and orchards of young trees a mulch of strawy 
 manure, leaves, or the clippings of the lawn can be used to 
 help prevent the loss of moisture. The loose mulches check 
 the rise of moisture to the surface from below by capillary 
 movement because the particles do not lie in close contact 
 with each other and the water cannot pass from one soil grain 
 to the next. 
 
 Another way in which there is a great loss of water from 
 the soil is through the weeds that are often allowed to cover 
 the ground. Each weed is a pump drawing the precious water 
 out of the soil and passing it up through the stem and leaves 
 into the air. This is unquestionably the worst of the many 
 injuries that weeds cause the crops.^ 
 
 The Effect of Color on the Temperature of Soils. — An 
 abundance of humus in the soil gives it a dark color. Usu- 
 
 » The First Book of Farming, p. 54. 
 Soils, pp. 158, 159. 
 
STUDIES WITH THE SOIL 19 
 
 ally for this reason the surface soil is darker than the sub- 
 soil. Peaty soils and the leaf mold in the forest are nearly 
 black.i 
 
 Exercise XII 
 
 Dark Soils Are Warmer than Light Soils. — Fill two or 
 three boxes or basins with soils of different colors, having one 
 as dark and one as light as you can find. Set them where the 
 sun can shine on them for some time. Then take the tem- 
 perature of each soil with a thermometer, placing the bulb 
 about two inches below the surface. 
 
 If you cannot easily find soils that differ considerably in color, 
 cover the surface of one of the soils with a thin layer of crayon 
 dust or lime, and the surface of another soil can be made black 
 by sprinkling some soot over it. How much difference do you 
 find between the temperature of a dark soil and that of a 
 light one when the sun has been shining upon them for five 
 or six hours ? ^ 
 
 Exercise XIII 
 
 A Wet Soil Is Colder than a Dry Soil. — A wet soil is kept 
 cooler than a dry one. The heat that is used in evaporating 
 the water with which the ground is saturated is taken from 
 the soil, thus lowering its temperature. 
 
 Fill three boxes respectively with wet sand, loam, and clay; 
 and three other boxes with the same soils in a dry condition. 
 Set them in the open air where evaporation will be rapid. 
 Placing the bulb of the thermometer two inches below the sur- 
 face, test the differences in temperature between the wet and 
 dry soils. This is one reason why wet land does not produce 
 as good crops as a well-drained soil.^ 
 
 » The Soil, p. 230. 
 Physical Properties of Soil, pp. 161, 162. 
 How Crops Feed, pp. 190-193. 
 
 2 Physical Properties of Soil, pp. 174-177. 
 Soils, p. 33. 
 
 3 The First Book of Farming, pp. 60, 61. 
 The Soil, pp. 225-228. 
 
PART II 
 
 STUDIES IN GROWING CROPS 
 
 The Plant. — To most people farming is, first of all, the 
 business of growing crops. The skilful and successful farmer 
 is the one who can grow large crops at a good profit and with- 
 out lessening the power of the land to continue to produce 
 equally good or better crops each succeeding year. 
 
 The study of agriculture has for one of its objects to 
 teach how to accomplish these results.^ 
 
 Essentials in Crop Production. — There are certain things 
 that are absolutely necessary to grow crops ; namely, the seed, 
 the soil, moisture, heat, light, and plant food. Let us con- 
 sider each of these in turn : The life history of a plant forms 
 a complete cycle. Starting at the place in its existence which 
 we call the seed and passing through its different stages of 
 development, it comes in time to the point where it in turn 
 produces seeds like the one from which it started; and then, 
 having completed the work for which it was created, it dies ^ 
 and its parts are gradually broken up and decomposed and all 
 of the materials which were used in its growth are finally given 
 back to the air, the water, and the soil in the same forms 
 and amounts as those in which they were taken. Nothing 
 has been lost and nothing gained; there has occurred simply 
 a marvelous series of changes caused by the mysterious forces 
 of Nature which work always according to the same laws. 
 
 Some plants complete the whole cycle of their life his- 
 tory in one season and then die. Such plants are called an- 
 
 1 The Principles of Agriculture, pp. 1, 2; 106-144. 
 
 2 In the case of perennial plants the process of producing seeds may 
 be repeated many times before the death of the plant occurs. 
 
 21 
 
22 MANUAL OF AGRICULTURE 
 
 nuals. Those that need two seasons to accomplish their life 
 work, and die the second year, are termed 'biennials. The 
 third class is named perennials and comprises those plants 
 that do not die after producing a single crop of seeds, but 
 live on many years, some many centuries. 
 
 The plant during its life has two kinds of work to do 
 that are spoken of as nutrition and reproduction. That is, 
 the plant must first take care of itself — feed and grow; 
 then it must produce other plants like itself. These off- 
 spring when first produced by the parent plant we call the 
 seed.^ 
 
 The Seed. — You must think of a seed as a haby plant 
 tucked up in its lunch basket with its food closely packed all 
 about it and a covering — sometimes two or three coverings 
 — tightly stretched over baby and lunch for protection from 
 wet and other injuries. 
 
 Here the little fellow lies just as his mother fixed him last 
 summer, waiting to be set free. This process by which the 
 plantlet emerges from the seed and establishes itself in the 
 soil and the air is called germination.^ 
 
 Exercise XIV 
 
 Essentials for Seed Germination. — Select five flower pots or 
 boxes holding about a quart of soil. Number them in a series 
 (1), (2), (3), (4), (5), and fill nearly full with good garden 
 soil that is thoroughly dry. In each pot plant two kernels of 
 corn and two beans. (Any seeds may be used, but corn and 
 beans are large and more easily studied.) Before planting the 
 seeds in pot (1) put them in a cup and pour boiling water on 
 them. Leave them in the hot water but a few seconds and 
 
 1 Farmers' Bulletin, No. 257. 
 
 2 The First Book of Farming, pp. 70-80. 
 Farmers' Bulletin, No. HI. 
 Practical Agriculture, pp. 1-5. 
 Farmers' Bulletin, No. 229. 
 
STUDIES IN GROWING CROPS 23 
 
 then plant them about two inches deep in the soil of pot (1). 
 In the same way plant the same number and kinds of seeds in 
 each of the other pots. Next moisten the soil in all of the 
 pots except in (2), but leave that perfectly dry. Set No. (3) 
 where the temperature is below 40° F. If the experiment is 
 tried in the winter this pot may be kept in a cold room, but in 
 the summer it will be necessary to set it in the ice-box at home. 
 In the case of No. (4) put a cork in the bottom of the flower 
 pot so that the water cannot drain out. Then pour on water 
 until the soil in this pot is fully saturated and can hold no 
 more. 
 
 In No. (5) the conditions are the same as those that we try 
 to secure for the seeds that we plant in the garden and field; 
 namely, the seeds that are planted have received no injury and 
 so the little plants within the seeds possess strong vitality (the 
 seeds in No. (1) were injured by extreme heat) ; the soil has 
 sufficient moisture to soften the seed coat and cause it to swell 
 and burst open so that the root and stem can escape and to 
 dissolve the foods which the plant needs (the soil in No. (2) 
 was left dry) ; the soil is warm from the sun's heat which it 
 has absorbed, and this warmth is necessary to set in motion the 
 activities of the little plant (in No. (3) the seed is kept where 
 the temperature is too low for the germinating process to 
 start) ; the soil is porous and full of interstices through which 
 air can pass and reach the roots, for air is just as essential to 
 their existence as it is to an animal's (in No. 4, since the soil 
 was saturated with water, there was no space for the air to 
 reach the little plant and it must smother). 
 
 This experiment should be continued for ten days and then 
 the seeds dug up from each pot and their condition examined. 
 This is an exercise that every pupil should conduct for himself, 
 for his interest will be greater in the results of his own work 
 and he will be more apt to think for himself.'^ 
 
 1 Practical Agriculture, pp. 1-5. 
 The First Book of Farming, pp. 70-79. 
 The Principles of Agriculture, pp. 124, 133, 134. 
 How Crops Grow, pp. 349-357. 
 Farmers' Bulletin, No. 253. 
 
24 MANUAL OF AGRICULTURE 
 
 The Testing of Seed. — The seed is one of the essentials of 
 crop production. Vitality is one of the conditions necessary 
 for the germination of the seed. A great many things may 
 happen to seed to affect its vitality, either to destroy it en- 
 tirely or so to weaken it as to render it of no value in increas- 
 ing the crop yield but only a detriment to the other plants 
 among which it stands. The quality of the seed that is sown 
 holds the same relation to the possible profits from the crop 
 that the character of the cows on a dairy farm maintains to 
 the profits of the dairy. 
 
 Every farmer should thoroughly test all of his seed for 
 field and garden use before planting. Comparatively few 
 farmers test any of the seed they sow. The reason is that 
 they have not been trained to this practice.^ 
 
 Exercise XV 
 
 How To Test Seed. — Get two large plates, fill one of them 
 even-full of sand in which the seeds are to be planted, and, 
 after moistening the sand moderately, cover with the second 
 plate and set where the temperature is from 70° to 80°. Do 
 not make the sand too wet, as that will exclude the air. If this 
 work is to be done in cold weather in buildings where heat is 
 not kept up during the night, get a tight box of desired size, 
 fit on a lid with leather hinges, and line all the sides of the 
 box with several thicknesses of newspapers. To supply heat 
 place an earthen-ware" jug, holding one or two gallons, filled 
 with hot water and tightly corked in the bottom of the box. 
 
 To test seed corn, number each ear to be tested with a piece 
 of paper pinned to the butt. Make grooves in the sand on the 
 plate and number these with bits of paper to correspond to the 
 numbers of the ears. Select kernels from different points both 
 lengthwise and around the ear; for one portion is sometimes 
 injured while the other part is sound. Leave the kernels in 
 the moist sand for five to eight days before examining them. 
 The test should show not only whether the germ is alive, but 
 
 1 The First Book of Farming, pp. 75-77. 
 
STUDIES IN GROWING CROPS 25 
 
 whether it is vigorous. Sometimes a seed of weak vitality will 
 send out a root but lacks strength to develop the stem of the 
 young plant. It is not safe to use such ears for seed. Have 
 the pupils make their own tests independently for the same 
 ears and compare results. 
 
 Also test in the same way other seeds— clover, grasses, 
 wheat, oats, and garden seeds— planting 25, 50, or 100 seeds of 
 each kind and recording the percentages of germination. Exer- 
 cises in testing seeds may be conducted with profit throughout 
 the whole year in order to fix the habit and impress the im- 
 portance of doing this work on the farm.' 
 
 Importance of Fine Tilth.— The conditions of moisture, 
 temperature, air, and light which the baby plant meets in 
 its immediate environment when it first emerges from the 
 seed determine its chances of success. If it gets a " set-back '' 
 at the start it rarely recovers vigor. ^ 
 
 Exercise XVI 
 
 Why a Good 8eed-hed is Necessary.— Fill one of two b3xes 
 or flower pots with fine, mellow loam and the other with coarse 
 soil m which the lumps are as large as peas or larger. Plant 
 two or three grains of corn and of wheat or oats or radish seed 
 in each. Give to each pot the same amount of water and ob- 
 serve whether the seeds in each pot germinate at the same time 
 and grow with the same vigor. 
 
 In the coarse soil the spaces between the soil particles are 
 so open that the film-water cannot pass freely upward by ca- 
 pillary movement and the tiny rootlets are liable to die or 
 seriously suffer for lack of moisture. 
 
 The soil in which seeds are sown should be fine and pressed 
 down so that it is in close contact with the seeds. 
 
 'University of Illinois Agricultural Experiment Station Bulletin. 
 No. 96. 
 
 Farmers' Bulletin, No. 253. 
 2 The Soil, pp. 277-279. 
 Soils, pp. 98-100. 
 
26 MANUAL OF AGRICULTURE 
 
 Exercise XVII 
 
 Heavy Soils Should Not Be Cultivated When Wet. — Soils 
 whose particles are very fine, such as clay and silt, are sticky 
 and difficult to handle when wet, and lose their granular tex- 
 ture if cultivated at this time. These soils are called heavy in 
 contrast with the light sandy soils in which the grains never 
 stick tightly together even when wet. 
 
 Fill two pots with dry, fine clay soil and one with sandy 
 soil. Add water enough to make one of the pots of clay and 
 the pot of sand quite wet, and then thoroughly stir the wet 
 earth with a stick until it becomes pasty. Plant seeds in each 
 of the three pots, moistening the second pot of clay after plant- 
 ing the seeds, but not stirring the earth while it is wet. Set 
 the pots where the sun can shine on them. Notice that a hard 
 crust forms over the clay soil which was handled when wet and 
 may exclude the air so completely that the seeds under it can- 
 not germinate, and it will be very difficult, or impossible, for 
 the young stems to force their way up through it. This will 
 not be the case with the wet sand nor with the clay that was 
 handled while dry.^ 
 
 Exercise XVIII 
 
 The Color of the Soil Influences Plant Growth. — This ex- 
 periment should be conducted about October 1st, or May 1st, 
 when the nights are cool and the soil is not thoroughly warmed 
 through. 
 
 Get a box 4 to 6 feet long and 2 feet wide ; set it on benches 
 where the sun can shine on it all day and fill it to a depth of 
 10 to 12 inches with good surface soil. Draw a line length- 
 wise through the center of the box; also draw cross lines divid- 
 ing each half of the box into plots of one square foot. If the 
 box is 6 feet long, there will be 6 plots above the dividing line 
 and 6 plots below it. Number these plots from 1 to 6 on each 
 side of the line. In each of the two plots numbered (1), plant 
 
 » The First Book of Farming, p. 45. 
 Soils, pp. 57, 58. 
 Farmers' Bulletin, No. 77. 
 
STUDIES IN GROWING CROPS 27 
 
 10 grains of corn; in plots (2), 10 beans; in plots (3), 10 ker- 
 nels of wheat; in plots (4), 10 grains of oats; in plots (5), 10 
 peas; in plots (6), 10 radish seeds. 
 
 If the color of the soil is naturally dark, cover the 6 squares 
 on one side of the line with a thin coat of white sand, or of 
 lime; but if the soil is a light color, darken one side of the 
 box with a thin covering of soot. See that the soil is properly- 
 moist. 
 
 At the same time each day record the number of plants of 
 the same sort that show above the surface. For example : 
 
 Oct. 5, Oct. 6, 
 
 C dark— 3 ^ C dark— 5 ^ ( dark— 6 
 
 Com S T 1 , ^ Beans ■{-,.,. ^ (Jorn 
 
 ght— ( light— 2 ( light— 2 
 
 This exercise will demonstrate two facts ; namely, dark soils 
 absorb more heat from the sun than light 'soils; seeds ger- 
 minate in less time, and plants grow more rapidly, in a warm 
 soil than in a cool one.^ 
 
 The color of the soil is, to a considerable degree, within the 
 control of the farmer, since increasing the organic matter in 
 the soil (as by use of farm manure) makes the color darker.^ 
 
 Seed Planting. — This is a subject about which it is easy 
 to get exact information for one's self through experiments 
 with the seeds and the soil. Why do seeds need to be buried 
 in the soil in order to germinate and grow? Has the action 
 of light on the roots of the young plant any effect, and if 
 it has, is it helpful or harmful? How deep ought seeds to 
 be planted? Do some seeds endure deeper planting than 
 others? Does the depth of planting affect the later growth 
 of the plant ? ^ 
 
 1 The Principles of Agriculture, pp. 119, 120. 
 The First Book of Farming, pp. 73, 74, 81-83. 
 Soils, pp. 35, 36. 
 How Crops Feed, pp. 190, 191. 
 - « How Crops Grow, pp. 355-357. 
 
 The Principles of Agriculture, pp. 135, 136. 
 
28 MANUAL OF AGRICULTURE 
 
 Exercise XIX 
 
 How Deep Should Seeds Be Planted? What Is the Effect 
 of Light on Germination? — Make a box that shall have one 
 side enclosed by a pane of window glass. The box should allow 
 from 10 to 12 inches depth of soil, a width of 6 inches and a 
 length of 12 to 20 inches. Prepare some fine, mellow garden 
 soil and place 2 inches of it in the bottom of the box. At the 
 right-hand end of the box lay one kernel of corn on the soil 
 close against the glass and another kernel near the back of the 
 box away from the light. At the left-hand end plant in the 
 same way 2 beans. Then cover with 1 inch of soil and plant 
 2 more seeds of each kind in the same way as before, only 
 placing them a little nearer the middle of the box so that they 
 shall not be directly over those planted below. Continue with 
 successive layers of soil 1 inch in thickness until near the top 
 of the glass, then cover the last planting of seeds with but J 
 inch of soil. Place 2 other seeds of each kind on the surface 
 with no covering at all of soil. 
 
 Set the box in a sunny window and supply the necessary 
 water to keep the soil moist. Make records of the time when 
 each plant appeared above the surface, and compare from week 
 to week the height and vigor of the different plants. What 
 depth of planting gave the best results in growth with corn? 
 Was the Fame depth the best for beans, also? Does it seem 
 more difficult and require more energy for the bean plant to 
 get its stem up through the soil than is the case with the com 
 plant? Why is this? 
 
 Does there seem to be any difference in the rate of growth 
 between the plants from seeds exposed to the light and from 
 seeds placed in the back of the box? If there are differences, 
 can you give any theory to explain them ? What has happened 
 to the seeds lying on top of the soil? 
 
 If this experiment is attempted in school, let each member 
 of the class have his own box and perform the work inde- 
 pendently ; and when the records are all finished compare them 
 and see what they teach.' 
 
 » How Crops Grow, pp. 353-357. 
 
STUDIES IN GROWING CROPS 29 
 
 Exercise XX 
 
 The Young Plant Depends on the Food Stored in the Seed. 
 — In moist sand between two plates germinate 10 kernels of 
 corn. When the roots are about 2 inches long carefully re- 
 move with scissors the kernels from 5 of the plants and then 
 transplant the whole 10 plants into a box of moist soil or sand. 
 Notice the difference between the rates of growth of the 5 
 plants having the grains attached to their roots and the 5 other 
 plants from which the grains have been removed. Can you see 
 why plants grown from large, plump seeds should be more vig- 
 orous than those from small and shrunken seeds ?^ 
 
 Exercise XXI 
 
 The Young Bean Plant Brings Its Supply of Food ahove 
 Ground with Its Stem. — In a pot of moist sand plant 4 beans. 
 Notice how the stems get up through the soil, bending to form 
 a loop and pulling, instead of pushing, their seed-leaves up 
 into the air. Now carefully with the scissors, so as not to in- 
 jure the other parts of the plant, remove the seed-leaves from 
 2 of the 4 plants. For the next two or three weeks compare 
 the growth of these 2 plants with the others. The results are 
 like those of the corn plant.^ 
 
 Exercise XXII 
 
 Light Is an Essential of Plant Growth.— Prepare 4 boxes 
 or pots of garden soil and plant a half dozen grains of corn 
 and beans in each. After the shoots appear above the surface, 
 place one pot where it will be in direct sunlight, and a second 
 in the center of a light room, but where the sun cannot reach 
 it ; set a third pot in the dimmest corner of the room, and put 
 the fourth pot in a dark closet. Try to have the conditions of 
 temperature and moisture the same for all of the pots. At the 
 
 1 The First Book of Farming, pp. 77-80. 
 
 2 How Crops Grow, pp. 350, 351. 
 
80 MANUAL 6^ AGRICULTURE 
 
 end of 10 days place them together on a table, compare them 
 and record their differences. Then exchange the places of No. 
 (1) and No. (4), and of No. (2) and No. (3). At the end 
 of a week compare again and notice results. Now set them 
 all together in the sunshine for a few days and notice if they 
 assume the same appearance.^ 
 
 Exercise XXIII 
 
 To Show How Rapidly Plants Transpire Water. — Get a 
 wide-mouthed pint bottle, a thick cork that fits the bottle, and 
 a vigorous, straight-stemmed plant 10 or 12 inches high. A 
 thrifty tomato plant or a rag^veed does very well for this ex- 
 periment. Remove the plant from the soil carefully so that 
 the roots shall be injured as slightly as possible and gently 
 wash off all soil particles. Place the roots and lower part of 
 the stem in the bottle and fill with water up to the neck of 
 the bottle. Cut the cork into two equal pieces and in each 
 half hollow out with a knife grooves so that when the cork is 
 inserted in the neck of the bottle the two pieces will fit snugly 
 about the stem of the plant. Now spread a few shavings of 
 paraffine on the cork, warm the blade of a knife and with it 
 melt and spread the wax over the top of the cork and around 
 the stem of the plant so that no water can escape when the 
 bottle is inverted. It is now certain that all water that gets 
 out of this bottle must pasg up through the roots, stem, and 
 leaves of the plant. Set the bottle and plant in a window 
 where the sun can shine on it all day long and notice how fast 
 the water is taken out. If a single root reaches to the bottom 
 of the bottle, every drop of water will disappear. 
 
 If several pupils are trying this experiment, notice that the 
 plants having the greatest leaf surface take up the water most 
 rapidly. As the water becomes exhausted, watch the changes 
 taking place in the plant.^ 
 
 ' The First Book of Farming, pp. 108-115. 
 2 The Principles of Agriculture, pp. 114, 120, 125. 
 How Crops Feed, pp. 202 and 208. 
 
STUDIES m GROWING CROPS SI 
 
 Exercise XXIV 
 
 Weeds May Roh the Soil of Moisture.— Get 2 small tin 
 pails, such as were used in Exercise IX, and fill each with good 
 garden soil. Into one of them carefully transplant a young, 
 lusty-growing plant (something like ragweed answers the pur- 
 pose well, but the size of ^ the plant selected, especially the de- 
 velopment of its roots, should be suited to the capacity of the 
 pail used). 
 
 Now make the weights of the 2 pails and their contents ex- 
 actly the same by removing, if necessary, a little soil from one 
 of them. Place both pails in a warm, sunny spot and give the 
 soils in each exactly the same treatment ; that is, keep the sur- 
 face of the soil in each pail cultivated in the same way, and 
 whenever water is added to the growing plant in the one pail, 
 pour exactly the same amount upon the soil in the other pail. 
 At the end of one or two weeks take the weights again. The 
 difference in weights will show how much more water has been 
 lost into the air from the soil in one pail than from that in 
 the other because of the plant growing in it. 
 
 This is a practical question for farmers to consider in the 
 preparation of their corn ground in the spring. If the plow- 
 ing of the field is left until just before planting and the clover 
 or grass is allowed to grow, so much moisture may be taken out 
 of the soil that the corn crop will suffer for lack of water.^ 
 
 Exercise XXV 
 
 What Proportion of a Green Plant Is Water? — With a 
 sickle cut off close to the roots a few bunches of clover or of 
 oats, a green potato top, a tomato plant, or handfuls of any 
 green weeds. Tie up each bunch carefully by itself and take 
 the weights accurately of all of them. Then hang them up 
 where they will become thoroughly air-dried and once more 
 take their weights. The differences between the first and sec- 
 ond weights show how much water, in the form of sap or juice, 
 
 » The First Book of Farming, p. 54. 
 Soils, pp. 158, 159. 
 
32 MANUAL OF AGRICULTURE 
 
 was in each bunch of green plants. In each case divide the 
 weight of water that has been evaporated from the bundle by 
 the weight of the dried plants and express the quotient in per- 
 centages of the air-dried material. 
 
 Roots. — One of the three main divisions of a plant is the 
 root. Roots perform three principal offices for the plant; 
 namely, (1) they anchor it securely in the soil where it is 
 to grow; (2) they gather and absorb the water and plant 
 foods from the soil; (3) in many cases they serve as the 
 storehouses where the plant lays up its reserve stock of foods 
 for future use.^ 
 
 The usual home of the roots is in the soil ; but sometimes, 
 as in the case of the brace-roots of a corn plant, or the or- 
 gans b}^ which the ivy clings to a wall, roots grow in the air. 
 On the other hand, not all the parts of a plant that grow 
 underground are roots. Some plants have underground 
 stems, so commonty seen in certain grasses; and the tubers 
 of our ordinary potato plant are not parts of the root of the 
 plant, but of the stem, the eyes being merely huds on these 
 stems. 
 
 There are two different kinds of root systems among 
 plants known as the tap-root system and the crown-root or 
 fihrous-root system. The carrot represents an extreme type 
 of the first sort, and a strawberry, plantain, and all the 
 grasses and cereals belong to the fibrous-rooted class of 
 plants. 
 
 In collecting plants for class study, remove them from 
 the soil with as much of the root system attached as pos- 
 sible, and by supporting the plant with its roots suspended 
 in a glass vessel of water, the roots will show their natural 
 position in the soil, and very correct mental pictures of how 
 
 1 The First Book of Farming, pp. 9-22. 
 The Principles of Agriculture, pp. 113, 124, 130, 131. 
 How Crops Grow, pp. 256-282. 
 
STUDIES IN GROWING CROPS 33 
 
 they spread through the ground may be obtained and draw- 
 ings made. 
 
 Sow seeds of different kinds of plants in boxes of light, 
 sandy soil, so that the plants can be taken up easily without 
 breaking the roots, and examine and sketch the different root 
 formations at various stages in the plant's growth.^ 
 
 Exercise XXVI 
 
 How Boots Search for Water. — Fill 2 flower pots with sand 
 and plant in each 2 kernels of corn and 2 beans. Set one of 
 the pots in a shallow dish in which about an inch of water is 
 allowed to stand. At first moisten the surface of the sand 
 enough, so that the seeds will germinate, and then give the 
 plants no more water from above, but let them seek it in the 
 bottom of the pot. On top of the sand in the second pot lay 
 a handful of fine moss, or two or three thicknesses of cloth, 
 and keep this constantly moist, but never put on water enough 
 to moisten the soil more than 2 inches deep. After the plants 
 have grown in these pots 3 or 4 weeks, carefully invert and 
 jar the pots so that the contents will slip out, then wash the 
 sand away from the roots and compare their positions and de- 
 velopment in the two pots. 
 
 Does this show you why it is a mistake during a hot, dry 
 spell to give frequent light sprinklings of water to the lawn 
 and garden rather than occasional heavy drenchings in which 
 the water will saturate the soil to a depth of several inches? 
 
 Will not the first method induce the roots to grow close to 
 the surface where a single hot day may seriously injure them ? ' 
 
 Exercise XXVII 
 
 How Do Roots Know Where to LooTc for Food? — During 
 the period of germination, while the plants are living on the 
 
 1 The First Book of Farming, p. 65. 
 
 The Principles of Agriculture, pp. 113, 114. 
 How Crops Grow, pp. 39, 40. 
 
 2 How Crops Grow, pp. 276, 277. 
 
34 MANUAL OF AGRICULTURE 
 
 food stored in the seeds, the roots develop equally well in a 
 sterile sand or a fertile loam; but after the food supply in the 
 seeds is exhausted, the roots in the poor soil grow long and 
 slim and have a " hungry look," while those in the rich soil 
 grow short and thick. 
 
 In this experiment you may use several cubical boxes of 1 foot 
 dimensions. Fill part of the boxes with sand that has little 
 or no plant food in it, and the others with as poor clay soil 
 as you can find, where plants grow poorly. In one box, place 
 a handful of rich well-rotted manure in the bottom and close 
 to one side; in another box, spread a layer of such manure 
 over the whole bottom of the box ; in a third, place the manure 
 in a compact mass in the center of the box directly under the 
 plants; in the fourth, mix the manure evenly through the 
 whole soil; and in the last one, do not use any fertilizer. In 
 the center of each box plant 2 or 3 seeds of corn and beans 
 and set the boxes in a light warm place. Water them properly, 
 and at the end of 3 or 4 weeks knock off the sides of the boxes, 
 carefully wash away the soil from the roots, and notice what 
 has been the character of their growth in each case. 
 
 Such exercises furnish excellent material for work in draw- 
 ing, and training in keeping note books. 
 
 The results of this exercise should teach the importance of 
 mixing the fertilizers in the soil as evenly as possible, as well 
 as the value of supplying plant food to the crops.^ 
 
 Exercise XXVIII 
 
 How Plants Use the Reserve Food Stored in Their Roots. — 
 Notice how in the early stages of growth the roots rapidly in- 
 crease in size and are juicy and brittle. The starch food (car- 
 bohydrate) made each day in the leaves of the plant from the 
 raw (inorganic) materials taken from the air and the soil, is 
 being packed away in the root for future needs. As the season 
 advances, look for a radish plant that has begun to send out 
 from the top of its stem a flov/er-stalk. Now another kind of 
 work is being done by the plant. The process called reproduc- 
 
 » How Crops Grow, p. 263. 
 
STUDIES IN GROWING CROPS 35 
 
 Hon is in operation. This new work makes a heavy demand 
 upon the energy and food of the plant, and the amount which 
 the leaves can make each day is not sufficient to meet this de- 
 mand. But the provident little radish plant has a plump 
 bank account and begins to draw upon it. Pull up the plant 
 and cut across the root. It is spongy and stringy. Much of 
 the starch that made it so brittle at first has been removed in 
 building the flower and seeds, and the strings are the cellulose 
 fibers that served as the framework and partitions of the store- 
 house in which the food was packed. 
 
 Plant the roots of beets, carrots, and turnips in the spring 
 and notice that this same thing happens to them as they form 
 the seed. In the case of wheat, oats, corn, and the other cereal 
 grains, this extra food needed to help make the flowers and 
 seeds is stored for the most part in the stems or stalks, and 
 as the processes of seed-building go on, these stems lose their 
 juices and become more hollow and brittle and yellow and 
 finally give up their lives altogether, or transfer them, to the 
 baby plants that now lie tucked away so snugly in the dry, 
 hard seeds. 
 
 Root Tubercles. — Of all the remarkable things that sci- 
 ence has done for agriculture, perhaps none has attracted so 
 much notice or promises to play so important a part in 
 the business of farming as the discovery that by growing cer- 
 tain kinds of crops, called legumes, nitrogen can be obtained 
 from the atmosphere and fixed in the soil in a form that is 
 available as plant food. So important is the knowledge which 
 this discovery has given to the farmers that its general accept- 
 ance and use will mark the beginning of a new agriculture. 
 
 Nitrogen is one of the ten elements absolutely essential 
 to the growth of every plant. Of all the substances except 
 water taken from the soil by the plant through its roots 
 nitrogen is used in much the greatest amounts. To grow 100 
 bushels of corn, 148 pounds of nitrogen are removed from 
 the soil; a 40-bushel crop of wheat takes away 65 pounds of 
 nitrogen; a 75-bushel crop of oats, 69 pounds of nitrogen; 
 
36 MANUAL OF AGRTCULTURE 
 
 3 tons of clover hay, 120 pounds of nitrogen; 8 tons of al- 
 falfa, 400 pounds of nitrogen; 300 bushels of potatoes, 63 
 pounds of nitrogen. 
 
 The supply of nitrogen in most soils is not so great but 
 that a few years of heavy cropping under the systems of farm- 
 ing that have been in common practice will so reduce the 
 stock of this essential plant food that large yields from the 
 land are impossible. Wide areas of our country reached this 
 condition years ago. 
 
 Many farmers have tried to keep up the supply of nitro- 
 gen in the soil necessary to meet the needs of large crops 
 by the use of commercial fertilizers containing this element, 
 but their cost in the market is so great that it is doubtful 
 whether there is any profit in using them on ordinary farm 
 crops. In the forms in which nitrogen is generally sold for 
 fertilizing purposes, it costs the farmer about 15 cents a 
 pound. At this price the farmer who raises 100 bushels 
 of corn and sells it, both grain and stalks, is shipping off 
 from his farm in this one crop $22.20 worth of fertility m 
 the form of nitrogen alone, to say nothing of the other 
 plant foods, phosphorus and potassium, which must be ac- 
 counted for. That is, if he returns to the land, by purchasing 
 commercial nitrates, as much nitrogen as he has taken out 
 of it in this single crop, it will cost him this amount; and 
 if he does not return it in some way, the land is rapidly 
 losing its power to produce good crops. 
 
 In the atmosphere everywhere about us and circulating 
 through the open spaces in the soil is a measureless supply 
 of this valuable plant food in the form of a gas; for about 
 four-fifths of the air by weight is nitrogen. However, the plant 
 unaided cannot use this material and will starve for want of 
 it while surrounded by it. But it has been discovered that a 
 certain class of plants, called legumes (plants that produce 
 their seeds in pods, like the beans, peas, clovers, etc.), have a 
 means, which other classes of plants have not, of getting ni- 
 
STUDIES IN GROWING CROPS 37 
 
 trogen from the air. Every pound of nitrogen thus secured 
 is, of course, clear gain ; for it does not cost the farmer a cent, 
 nor is he taking it from his neighbor. Every boy and girl 
 before leaving school ought to know about this provision of 
 Nature, which makes it possible for the farmer to use and 
 still have, if he understands how to accept the gifts that are 
 offered him. 
 
 The legumes most commonly grown as farm crops in Illi- 
 nois are the clovers, alfalfa, soybeans, cowpeas, Canada field 
 peas, and vetch.^ 
 
 Exercise XXIX 
 
 How Leguminous Crops Increase Soil Nitrogen. — Find 
 some place where clover, cowpeas, or soybeans grow vigorously 
 and with a spade lift a few plants out of the soil. Examine 
 the roots to find attached along their sides little tubercles, or 
 nodules. These will vary in size from that of a pin-head, on the 
 clovers, to a large pea, on the soybeans and cowpeas. These little 
 masses of matter are homes where colonies of microscopic organ- 
 isms, so small that it is said 10,000 of them placed side by side 
 would not measure more than an inch, have located themselves. 
 The plant on whose roots they grow is called the host. The 
 bacteria that make their homes on the roots of the red clover, 
 for instance, are not like those that live on the cowpeas, and 
 these in turn differ from the bacteria that are found on the 
 soybean. As far as is known there are only two legumes that 
 serve as hosts for the same kind of organisms, and they are 
 alfalfa and sweet clover. 
 
 The relation established between each kind of bacteria and 
 the sort of plants congenial to it is one of mutual benefit. 
 Such a relationship is called symbiosis. In this case the bac- 
 teria draw their nourishment from the juices of the roots of 
 
 » The First Book of Farming, pp. 68, 144-146. 
 Soils, pp. 329,330; 333, 334. 
 The Soil, pp. 124, 125. 
 
 University of Illinois Agricultural Experiment Station Bulletin, 
 No. 94. 
 
38 MANUAL OF AGRICULTURE 
 
 tlie plant, and in return they give to the plant a food rich in 
 nitrogen, which they have made out of the free nitrogen in 
 the air. So if these leguminous crops, which have built into 
 their tissues the nitrogen taken from the atmosphere, are 
 plowed under as green manure, or are fed to stock on the place, 
 and the manure thus made is returned to the field, a consider- 
 able addition can be made to the stock of nitrogen in the soil. 
 
 These bacteria live in the soils where plants congenial to 
 them grow. They will not thrive and multiply in a soil that 
 is not in a good physical condition — that is wet, cold, not well 
 ventilated, or acid. Therefore if we want these remarkable 
 creatures to work for us we must find what their tastes are and 
 then provide the conditions that suit them. If you examine 
 some legumes and fail to find any nodules on their roots it is 
 probably because the soil conditions are not favorable to them 
 and ought to be improved, or because their particular host 
 plant has not been growing in that soil for several years, at 
 least. In such case it is necessary to introduce these bacteria 
 by placing a few of them in the soil. 
 
 Make a collection of as many kinds of leguminous plants as 
 you can find with these tubercles growing on their roots. Good 
 specimens of some of these plants should be preserved in glass 
 fruit jars in a solution of formalin. 
 
 In Bulletin No. 94, issued by the Agricultural Experiment 
 Station of the University of Illinois, Dr. Cyril G. Hopkins 
 says : " In general the clover bacteria are well distributed over 
 the northern and central part of Illinois, but we now have some 
 very strong evidence that they are not well distributed in some 
 soils of wide area in Southern Illinois. There is also some evi- 
 dence that they were not originally present even in the soils 
 where they are now found in great abundance; and, further- 
 more, it seems very probable that these bacteria may cease to 
 live in a soil where they have once been present, provided clover 
 is not grown on the land for several years. 
 
 "When clover is cut for seed, it is frequently left to lie, 
 upon the ground until the straw becomes half rotten and very 
 dirty; and, consequently, when it is threshed, it practically 
 always happens that there is at least some small amount of dust 
 
STUDIES IN GROWING CROPS 39 
 
 and dirt taken with the seed. This dirt is ahnost sure to carry 
 with it some bacteria from the soil. If these few bacteria are 
 scattered with the clover seed when it is sowed they will inocu- 
 late at least a few plants, and if they are allowed to multiply 
 on these plants, and especially if the same field is repeatedly 
 seeded with clover, the soil will ultimately become thoroughly 
 infected with the clover bacteria. Of course they may be car- 
 ried from one part of the farm to another, or even from one 
 farm to another, by various agencies, as dust or wind storms, 
 surface drainage or flood waters, manure from clover hay, im- 
 plements used in cultivating the soil," etc., etc. 
 
 Exercise XXX 
 
 Inoculating the Soil with Bacteria. — Experiments to dem- 
 onstrate how bacteria may be introduced into soils, and what 
 the power of these organisms is to secure nitrogen for the 
 legumes which serve as hosts, may be tried by growing the 
 plants in pots or on small plots outside. 
 
 Get 3 flower pots or boxes that will hold about 4 quarts 
 and fill them with soil. If this soil is heated 2 or 3 hours in 
 a hot oven before putting it into the pots, it will ensure that 
 no living bacteria are jDresent in the soil except those that we 
 put there. 
 
 Number the pots I, II, III, and plant in each a half dozen 
 seeds of red clover or soybeans. Dissolve a tablespoonful of 
 saltpeter (potassium nitrate) in a gallon of water and twice a 
 week moisten the soil of pot I with this. In pots II and III 
 add no plant food to the water used after planting. However, 
 before the seeds for pot III are planted, get about a pound of 
 soil from a field where the legume with which you are experi- 
 menting is growing and where plenty of tubercles can be 
 found on their roots. Put this soil into a fruit jar containing 
 a quart of pure water, shake it well for a few minutes, and then 
 let it settle. When the seeds are placed in pot III pour a 
 little of this clear liquid over each seed. 
 
 Now the differences in the conditions of these 3 pots are 
 these: 'No. I has no nitrogen-gathering bacteria, but an abun- 
 
40 MANUAL OF AGRICULTURE 
 
 dance of nitrogen for plant growth; No. II has neither 
 the bacteria nor the nitrogen; No. Ill has no fertilizer supply- 
 ing nitrogen, as No. I has, but the soil has been inoculated 
 with the organisms that can get it for the plants from the 
 air. 
 
 At first the growth in No. I will probably be much stronger 
 than in II and III because in I the nitrogen is ready for the 
 plants to use from the start; but after four or five weeks No. 
 Ill will possibly outstrip I, and will far surpass II. 
 
 The soil that is used should be one that is quite deficient in 
 nitrogen, or no marked results will be obtained ; for if the soil 
 is well supplied with nitrogen, few, if any, tubercles are formed 
 even though there are bacteria in the soil. To get satisfactory 
 results, this experiment should be continued for several weeks, 
 and care must be taken to keep the plants from freezing. In 
 any school where real interest in agriculture has been aroused 
 some plan can be devised for getting around the difficulties. 
 Suppose one pupil in the class is so much interested in trying 
 this experiment that he offers to take the pots to his home, 
 after they have been prepared and planted, and keep them in 
 the window of a warm room until the plants are large enough 
 to show results; then they can be taken back to the school and 
 examined by the class. Remove the roots from the soil and ex- 
 amine them for tubercles. 
 
 If the school is in a town there will doubtless be some green- 
 house where it will be possible to get permission to leave them 
 for a few weeks ; and it would not be a difficult matter to build 
 in the fall on the south side of the schoolhouse or some near 
 building a small hot-bed which can be covered with an old win- 
 dow, and on cold nights still further protected with a blanket 
 or piece of carpet, and such a place may be made to answer 
 admirably for growing and keeping plants that are needed for 
 these exercises.^ 
 
 » Soils, pp. 333-337. 
 Farmers' Bulletin, No. 240. 
 
 University of Illinois Agricultural Experiment Station Circular, 
 No. 70. 
 
STUDIES IN GROWING CROPS 41 
 
 Inoculating the Soil for Alfalfa. — The tests that have 
 been made with alfalfa in different parts of the state war- 
 rant the belief that this will become one of our most valu- 
 able crops when more is known about how to grow it. Let 
 each school that teaches agriculture prepare two or three 
 small plots for experiments in alfalfa. The plots need not 
 be more than one square rod in area and all the work in 
 the preparation of the * seed-bed, inoculating the soil and 
 sowing the seed can be done by pupils. For information 
 about inoculating the soil for growing alfalfa consult Bul- 
 letin 94, previously referred to, where Dr. Hopkins describes 
 the procedure in a series of pot experiments, and shows the 
 results very effectively by photographs taken at different stages 
 of growth. In all of the pictures the alfalfa plants growing 
 in the pot of sand not inoculated wnth bacteria are feeble 
 and stunted, making scarcely any growth after the first two 
 or three weeks, while the plants in the other pots are grow- 
 ing luxuriantly and at the end of eight weeks appear to be 
 more than ten times as large. Dr. Hopkins's conclusions 
 should be carefully noted, containing, as they do, many prac- 
 tical suggestions for the farmer.^ 
 
 Plot Experiments. — Pot experiments can be used during 
 those months when outside work is impossible, and where it 
 is desired to keep certain conditions under absolute control. 
 The advantages in the plot tests are that the work is more like 
 real farming and is carried on mainly under the same condi- 
 tions. Moreover, if permanent plots can be established on or 
 near the school ground, many of the experiments may be con- 
 tinued through a period of years, and the results obtained will 
 grow in value as the time which they cover lengthens. 
 
 The circular prepared by Dr. Hopkins and printed by 
 
 1 Soils, pp. 340, 341. 
 University of IlUnois Agricultural Experiment Station Circulars, 
 Nos. 110 and 70; Bulletin, No. 76. 
 
 Farmers' Bulletin, Nos. 215 and 240. 
 
42 MANUAL OF AGRICULTURE 
 
 the University of Illinois, in 1904 (from which we quote in 
 the following pages), gives directions for laying out plots and 
 for securing and applying fertilizers for experimental work 
 in soil fertility/ 
 
 Purpose of the Experiments in Soil Fertility. — The three 
 food elements which must be kept in available supplies for 
 the plant, are nitrogen, phosphorus, and potassium. 
 
 ^^ To find what elements of plant food are most deficient 
 in the soil we should experiment and see what effect is pro- 
 duced on the growth of plants by adding different plant food 
 elements to the soil/' - 
 
 How the Necessary Fertilizers Can Be Obtained. — " For 
 nitrogen, dried blood should be applied. This contains from 
 12 to 14 percent of nitrogen in a form which is not likely 
 to injure the plant even if used in some excess. A 100- 
 pound bag of ground dried blood can be obtained from Swift 
 & Company, Union Stock Yards, Chicago, for about $2.50. 
 
 " For phosphorus, steamed bone meal should be applied. 
 The best steamed bone meal contains from 12 to 14 percent 
 of the element phosphorus in a very good form for plants. 
 A 100-pound bag of extra fine ground steamed bone meal 
 (^Big Six' brand) can be obtained from Morris & Company, 
 Union Stock Yards, Chicago, for about $1.25. 
 
 '^ For potassium, use potassium chlorid. This is a salt 
 which usually contains from 40 to 42 percent of the element 
 potassium. A 100-pound bag of potassium chloride can be 
 obtained from Armour Fertilizer Works, Union Stock Yards, 
 Chicago, for about $2.50. 
 
 " Armour Fertilizer Works, Union Stock Yards, Chicago, 
 
 1 LTniversity of Illinois Agricultural Experiment Station Bulletin, 
 No. 94. 
 
 2 University of Illinois Agricultural Experiment Station Bulletins, 
 Nos. 99, n5, and 123. 
 
 University of Illinois Agricultural Experiment Station Circulars, 
 Nos. 72, 96, 100, and 108. 
 
STUDIES IN GROWING CROPS 43 
 
 have agreed to furnish a one-pound package of potassium 
 chloride, a two-pound package of fine ground steamed bone 
 meal, and a four-pound package of ground dried blood for a 
 total charge of seventy-five cents, the purchaser to pay express 
 charges. 
 
 " These quantities are ample for pot culture experiments/' 
 
 Exercise XXXI 
 
 A Test in Plant Food Requirements. — " For plot experi- 
 ments, a series of ten plots should be laid out with division 
 strips (sunken paths) between them at least two feet wide. 
 (Care must be taken not to mix the soil from adjoining plots 
 by cultivating, especially if the experiments are to be con- 
 tinued for several years.) Each plot should be at least ^ rod 
 wide and 2 rods long, which would make one square rod or 
 160th part of an acre." 
 
 Where, for any reason, plots cannot be used the same ex- 
 periments may be carried on in earthen-ware pots. 
 
 " A very complete experiment can be made with 10 pots, 
 or with 10 plots, arranged as follows with the applications of 
 plant food indicated: 
 
 How Plant Food Is Applied. — 
 
 1 None (Check). 6 Nitrogen, phosphorus. 
 
 2 Nitrogen. 7 Nitrogen, potassium. 
 
 3 Phosphorus. 8 Phosphorus, potassium. 
 
 4 Potassium. 9 Nitrogen, phosphorus, potassium. 
 
 5 None (Check). 10 None (Check). 
 
 " Ten 4-gallon pots are very satisfactory for pot culture 
 tests, and i ounce (16 grams) of dried blood, i ounce (8 grams) 
 of bone meal, and | ounce (4 grams) of potassium chloride per 
 pot, are good amounts to use for 4-g'allon pots. The plant 
 food should be thoroughly mixed v/ith the surface soil to a 
 depth of about seven inches. 
 
 " Oats, barley, and spring wheat are good crops to grow in 
 pot cultures. Garden crops may also be grown. 
 
44 MANUAL OF AGRICULTURE 
 
 " For one square rod, 16 pounds of dried blood, 8 pounds of 
 bone meal, and 4 pounds of potassium , chloride are satisfactory 
 applications, even for intensive agriculture. The plant food 
 should be thoroughly mixed with the surface soil to a depth 
 of about seven inches, preferably a few days before the crops 
 are planted." 
 
 Kinds of Crops for Plot Experiments. — " Several different 
 field and garden crops should be planted in rows across all of 
 the ten plots. Oats, barley, wheat, clover, alfalfa, etc., can be 
 planted in rows 8 inches apart, dropping the seeds about one 
 inch apart in the row; radishes, lettuce, carrots, beets, peas, 
 etc., in rows 16 inches apart; sweet corn, potatoes, cowpeas, 
 soybeans, etc., in rows 32 inches apart; field corn in rows 40 
 inches apart, and cucumbers and melons 64 inches apart." 
 
 Suggestions for Planting. — " A marker with five runners 
 16 inches apart is easily made of boards, and it will serve to 
 mark good straight rows across all of the plots for all crops. 
 
 " By this system of planting every crop will be represented 
 on every plot and the effect of all of the different kinds of soil 
 treatment can be noted on each crop." 
 
 Local Conditions Vary. — " In planning these soil fertility 
 experiments, it is well to bear in mind th?t very sandy soil is 
 likely to be most deficient in nitrogen. In ordinary Illinois 
 soil, especially that which has been under cultivation for many 
 years with clover in rotations, the element phosphorus is most 
 deficient. In peaty soils, potassium is most deficient." 
 
 The Practical Lesson. — " In drawing conclusions from re- 
 sults which may be obtained in these experiments, it should 
 be understood that while we may apply purchased nitrogen in 
 order to obtain information quickly as to the needs of the soil, 
 the nitrogen should be obtained in all general farming by the 
 slower process of growing leguminous crops which, when pro- 
 vided with the proper bacteria, can get nitrogen from the air." 
 
 Care of Plot Experiments in Vacation. — It certainly will 
 not be worth while to attempt plot experiments if they are 
 to receive no care all summer. Suppose, however, that, be- 
 fore the school closes in June, the teacher and class plan the 
 
STUDIES IN GROWING CROPS 45 
 
 work for the summer and arrange that the members of the 
 class shall meet on the experiment fields every Saturday 
 afternoon and give whatever attention is necessary to the 
 crops, harvesting and caring for them at the proper time 
 and making records of all results. If the children are inter- 
 ested the parents will be also, and will help and encourage 
 them in the work. The work must be so planned and carried 
 out that all will feel that it is real agriculture and serious 
 school work, and the pupils should receive credit for it as 
 for any other school work that they do successfully during 
 the school year. 
 
 These plot experiments are especially adapted for home 
 work. What proof of a teacher^s value to his community 
 it would be if, -through the interest he had awakened in his 
 class in agriculture, several of the pupils should undertake 
 to conduct plot culture experiments in soil fertility and crop 
 production on their fathers' farms at home, and at the begin- 
 ning of the next school year should compare their results 
 and conclusions with one another. 
 
 Studies in Corn. — Corn is America's greatest agricultural 
 crop. Illinois is the leading corn growing state in the Union. 
 More acreage is allotted to this crop, more money realized 
 from it, more scientific study and interest are devoted to the 
 production and improvement of corn than to any other prod- 
 uct of the farm. It is a crop that is pa^:'ticularly well adapted 
 to school study, both as a growing plant and as matured 
 grain.^ 
 
 Exercise XXXII 
 
 Identification of Leading Varieties of Corn. — Get good 10- 
 ear samples of 5 of the leading varieties of corn grown in your 
 section of the state. Describe each variety as to (1) color of 
 grain; (2; color of cob; (3) smoothness of surface; (4) length 
 
 ^ University of Illinois Agricultural College Extension: Studies of 
 Corn and Its Uses. 
 
 Farmers' Bulletin, Nos. 199 and 229. 
 
46 MANUAL OF AGRICULTURE 
 
 of ear (average of the 10 ears) ; (5) shape (tapering or cylin- 
 drical). 
 
 Exercise XXXIII 
 
 Questions of General Information ahout Corn. — Get a 
 half-bushel of ears of good corn. Do not select the best ears, 
 but take them as they come from the crib. 
 
 What is the length of the longest ear? 
 
 What is the length of the shortest ear? 
 
 What is the average length of all the ears? 
 
 What is the weight of the heaviest ear? 
 
 What is the weight of the lightest ear? 
 
 What is the average weight of all the ears? 
 
 What is the greatest number of rows on any ear in the lot ? 
 What is the least number of rows? What is the average num- 
 ber of kernels on the largest 5 ears? Measuring one-third of 
 the distance from the butt, what is the average circumference 
 of the best 10 ears? 
 
 Select 5 of the best ears, 5 of the smallest ears, and 5 of the 
 average ears. Take the weight of each ear. Shell and weigh 
 the grain of each ear. Divide the weight of grain on each ear 
 by the weight of the ear and express the quotients in percent- 
 ages. Do the best ears give the highest percentage of grain? 
 
 Exercise XXXIV 
 
 ShrinTcage of Corn. — At time of husking weigh out 75 
 pounds of corn and put it into an open crate whose weight you 
 know. Hang this crate of corn in a dry place where nothing 
 can disturb it, and on the same day each week during the 
 school year take its weight. How much weight has it lost at 
 the end of the school year by shrinkage? During which month 
 did it lose the most? If at husking time a farmer put 5,000 
 bushels of corn, counting 75 pounds per bushel, into his cribs, 
 and it has shrunk 12% in weight during the winter, how many 
 bushels, counting 70 pounds to the bushel, are there in the cribs 
 June 1st?' 
 
 » University of lUinois Agricultural Experiment Station Bulletin, 
 No. 113. 
 
STUDIES IN GROWING CROPS 47 
 
 Exercise XXXV 
 
 Number of Hills of Corn and the Yields per Acre. — There 
 are 43,560 square feet in an acre. If corn is planted in rows 
 3'-4'''' apart each way, how many hills will there be on an acre? 
 If each hill has 3 stalks, how many stalks will there be on an 
 acre? If each stalk bears one ear of corn and the average 
 weight of all the ears is 9 ounces, what will be the yield in 75- 
 Ib. bushels of corn per acre? What would be the yield if the 
 average weight of ears was 15 ounces? What was the average 
 weight of the ears in Exercise XXXIII? 
 
 Exercise XXXVI 
 
 Corn Studies in the Field. — In a field of corn measure the 
 width of the rows each way and compute the possible number 
 of hills per acre. In different parts of the field select squares 
 that should give 100 hills and count the actual number of hills 
 growing in each square. From the average of these counts 
 what is the number of missing hills per acre? Determine the 
 average number of ears per hill. What percentage of the stalks 
 are barren? Husk and weigh several 10-hill lots of corn in 
 different parts of the field. What is the average yield of corn 
 (in pounds and ounces) per hill? What is the average yield 
 per stalk? At this rate what would have been the yield of 
 corn per acre if there had been a full stand of corn with 3 pro- 
 ducing stalks per hill? 
 
 Exercise XXXVII 
 
 Relation between the Tassel and the Silk. — As soon as the 
 silks begin to appear on the corn plants where the ears are 
 borne get a half-dozen little paper bags and tie them over the 
 ends of as many young ears of corn so that they will com- 
 pletely cover the silks. Do not remove these sacks for several 
 weeks, not until the yellow powder (pollen) produced in the 
 tassels, ceases to fall. Examine a young ear on another stalk 
 when it is just " silking out.'' Observe that each silk is at- 
 
48 MANUAL OF AGRICULTURE 
 
 tached to the place where a kernel is to be formed on the cob, 
 a separate silk for every kernel. Also observe that great quan- 
 tities of a light, yellow powder are being shed from little ves- 
 sels in the tassels and that this pow^der is scattered by the 
 wdnd over every part of the com plants, on the ground, and 
 even across wide fields. 
 
 Pollination. — The organs that produce the pollen in the 
 tassels of corn are called stamens, and the silks which grow 
 lower down on the stalk are parts of organs called pistils. 
 Most of the plants with which 3'ou are familiar have the 
 stamens and pistils growing together in the same flower, 
 the pistil or pistils in the center of several stamens. Un- 
 less the pollen from the stamens of some plant falls upon 
 the pistil of a flower of a plant of the same family, there 
 can be no seed produced in that blossom. The seed is 
 formed in the lower end of the pistil in a little sac called 
 the ovary. In some kinds of plants, as in the case of 
 corn, there are two sets of blossoms, one bearing the sta- 
 mens and called staminate flowers, and the other containing 
 the pistils and so called pistillate flowers. Of course seeds 
 can be formed only in the pistillate flowers. In corn the 
 tassels are staminate flowers and the silks are pistillate 
 flowers. When the grains of pollen from the stamens of a 
 plant fall upon the pistils of that same plant, the occurrence 
 is called close-pollination, but when the pollen from the 
 stamens of some other plant of the same variety is shed 
 upon the pistil, the plant is said to be cross-pollinated.'^ 
 
 Cross-pollination Preferred. — Now it has been discovered 
 that seeds produced by the process of cross-pollination show 
 much more vigor of germination and growth when planted 
 than do those grown by close-pollination. This is the reason 
 why corn breeders practice detasseling every alternate row 
 
 » The First Book of Farming, pp. 130-135. 
 
STUDIES IN GROWING CROPS 49 
 
 of corn on their breeding plots and use for seed only the 
 ears grown on the detasseled plants where close-pollination 
 has been impossible.^ 
 
 Exercise XXXVIII 
 
 Pollination Necessary to Production. — After a few weeks 
 remove the paper sacks used in Exercise XXXVII and observe 
 that no kernels have been formed on the cobs where the silks 
 were covered. Pollination was made impossible there. You 
 can see why so much pollen is produced, since so large a pro- 
 portion of it is wasted when carried by the wind. 
 
 It is also seen how different varieties of com " mix " when 
 grown in the same vicinity. 
 
 1 University of Illinois Agricultural Experiment Station Bulletin, 
 No. 100. 
 
 University of Illinois Agricultural Experiment Station Circular, 
 No. 56. 
 
REFERENCES 
 
 The books and bulletins named in the following lists will 
 be found very helpful to both teachers and pupils interested 
 in the exercises in agriculture given in this Manual. 
 
 There is no attempt to include in this list all of the good 
 texts and reference books on agriculture. Those that are 
 mentioned here are books with which the writer is familiar, 
 and they treat the topics taken up in the Manual in a clear 
 and interesting manner. 
 
 James: Practical Agriculture. D. Appleton & Co., Chicago. 
 
 Bailey: Principles of Agriculture. The Macmillan Co., 
 Chicago. 
 
 Fletcher: Soils. Doubleday, Page & Co., New York. 
 
 Goodrich: First Book of Farming. Doubleday, Page & Co., 
 New York. 
 
 Johnson: How Crops Grow. Orange Judd Co., Chicago. 
 
 Johnson: How Crops Feed. Orange Judd Co., Chicago. 
 
 King: The Soil. The Macmillan Co., Chicago. 
 
 Snyder: Soils and Fertilizers. The Chemical Publishing 
 Co., Easton, Pa. 
 
 Warington: Physical Properties of the Soil. Oxford Edi- 
 tion. McClurg & Co., Chicago. 
 
 BULLETINS 
 
 To obtain any of the following bulletins write to the 
 Secretary of Agriculture, Washington, D. C. The bulletins 
 are sent free on application. 
 
 Farmers' Bulletin No. 77: The Liming of Soils. 
 
 " " No. Ill: Farmers' Interest in Good Seed. 
 
 " " No. 194: Alfalfa Seed. 
 
 51 
 
52 MANUAL OF AGRICULTURE 
 
 Farmers' Bulletin No. 199: Corn Growing". 
 
 " No. 215: Alfalfa Growing. 
 " " No. 229: The Production of Good Seed 
 
 Corn. 
 " " No. 240: Inoculation of Legumes. 
 
 " " No. 245: Eenovation of Worn-out Soils. 
 
 " " No. 253: The Germination of Seed Com. 
 
 " " No. 257: Soil Fertility. 
 
 " " No. 266: Management of Soils to Conserve 
 
 Moisture. 
 
 The following bulletins and circulars of the University 
 of Illinois Agricultural Experiment Station will be sent free 
 on application to the Dean of the College of Agriculture, 
 Urbana, 111. 
 
 76 : Alfalfa on Illinois Soil. 
 
 Nitrogen, Bacteria and Legumes. 
 The Testing of Corn for Seed. 
 Directions for the Breeding of Corn, etc. 
 Shrinkage of Ear Com in Cribs. 
 " " 99: Soil Treatment for Lower Illinois Glacia- 
 
 tion. 
 " " 115: Soil Improvement for the Worn Hill Lands 
 
 of Illinois. 
 " " 123 : The Fertility in Illinois Soils. 
 
 Circular No. 56 : Corn Experiments — Detasseling Corn. 
 " 70: Infected Alfalfa Soil. 
 " " 72: Present Status of Soil Investigation. 
 
 " " 82 : The Physical Improvement of Soils. 
 
 " " 96 : Soil Improvement for Illinois Corn Belt. 
 
 " " 100: The "Gist" of Four Years Soil Investiga- 
 
 tion in the Illinois Corn Belt. 
 " " 108: Illinois Soils in Kelation to Systems of 
 
 Permanent Agriculture. 
 " " 110: Ground Limestone for Acid Soils. 
 
 Agricultural College Extension: Studies of Corn and Its Uses. 
 
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