^-— ^^^'^'^''^ ADVERTISEMENT. I GIFT OF Prof. E.J.\Uckson v^ V>a;N LI13RARY-AGKICUT-TUWE DErT m^ ters, [AVE 3litmbits, Minx. — O LOTTIsviLLir, itT.=-Dut Ell comffiuiiications snouia be addressed to DUANE H. NASH, SOLE MANUFACTURER. MILLINGTON, MORRIS COUNTY, N. J. ^%^c: ^-''c^--^/ Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/cultureoffarmcroOOstewrich THE CULTURE OF Farm Crops. ^ iEanual OF THE SCIENCE OF AGRICULTURE, AND A HAND-BOOK OF PRACTICE FOR AMERICAN FARMERS. By HENEY STEWART, Author of ' Tho Shepherd's Manual," " Irrig'ation for the Farm, Orchard and Gard Civil Mining' and Agricultural Engineer. Member of the Western Society of Engineers. PUBLISHED BY DUANE H. NAS MiLLiNGTON, Morris County, New 1887. Ssgs S7 7^ ? lAJ/^-i^S-^*-^!^^ MAHI I illiil"'' '^1 — •" •^'*^*' Entered,- according to Act of Congress, in the year 1887, by DUANE H. NASH, In the Office of the Librarian of Congress at Washington. i-.. <^TSBLE OF CONTENTS.^ PART FIRST PAGE. CHAPTER I. The Culture of Farm Crops 7—11 CHAPTER II. Kinds and Condition of matter 12—15 CHAPTER III. Carbon. Its Properties and Relations to Vegetable Life 16—20 CHAPTER IV. Oxygen. Its Properties and Relations to Life 21—27 CHAPTER V. Hydrogen and Nitrogen. Their Compounds and Relations to \egetable Growth 2*— 32 CHAPTER VI. Combinations of Organic Substances 3S— 39 CHAPTER VII. The Atmosphere 40 — 44 CHAPTER VIII. Water. Its Relations to Vegetable Life 45 — 51 CHAPTER IX. Heat and Cold, Their Influence upon Matter and Vegetation 52 — 59 CHAPTER X. Carbonic Acid. Its Properties and Functions in Plant Growth 60—64 CHAPTER XL Nitric Acid. Its Composition and Uses in the Growth of Crops 65 — 69 CHAPTER XII. Ammonia. Its Composition, Properties and Relations to Vege- table Growth 70—77 r)2i]<}U2 4 . CONTENTS. CHAPTER XIII. Sources of the Carbon of Plants * 78—83: CHIPTER XIV. Sources of the Nitrogen of Plants 84—92. PART SECOND. CHAPTER XV. Inorganic Elements of Plant Growth ♦ 93—98 CHAPTER XVI. The Ash of Plants and its Composition 99—106. CHAPTER XVII. Compounds of the Inorganic Elements of Plants 107—118 CHAPTER XVIII. The Soil. Its Composition 119—122. CHAPTER XIX. The Rocks. Their Composition and Relations to the Soil 123— 12a CHAPTER XX. Physical Properties of the Soil 130— 14a PART THIRD. CHAPTER XXI. Exhaustion of the Soil 144—154 CHAPTER XXII. Mechanical Improvement of Soils 155—166 CHAPTER XXIII. How to Drain Land 167—172 CHAPTER XXIV. Irrigation of Farm Crops 173—177 CHAPTER XXV. Plowing. Its Purposes and Results 178 -18a CHAPTER XXVI. Harrowing. Its Effects upon the Soil and Relation to the Growth of Crops 184— 18T CHAPTER XXVII. Cultivating. Its EflFects upon the Soil and the Growth of Crops 188—191 CHAPTER XXVIII. Manures. Their Mechanical Effects upon the Soil 192—195 CONTENTS. 5 PART FOURTH^ CHAPTER XXIX. Improvement of the Soil by Chemical Means. Animal Manures 196—202 CHAPTER XXX. Vegetable Manures 20:3—208 CHAPTER XXXI. Composts 209—212 CHAPTER XXXII. Mineral Manures 213—223 CHAPTER XXXIII. Manufactured Manures 224—233 PART FIFTH. CHAPTER XXXIV. The Structure and Growth of Plants 234—240 CHAPTER XXXV. The Functions of the Roots 241—245 CHAPTER XXXVI. The Functionsof the Stems .• 24&— 248 CHAPTER XXXVII. Ihe Functionsof the Leaves : 249—252 CHAPTER XXXVIII. The Functions of the Flower 253—257 CHAPTER XXXIX. The Fruit ; its Formation and its Characteristics 258 — 263 CHAPTER XL. Improvement of Plants by Breeding and Crossing 264—270 PART SIXTH. CHAPTER XLI. The Culture of Farm Crops 271—273 CHAPTER XLII. Implements of Tillage 274 — 277 CHAPTER XLIII. The Rotation of Crops 278—281 6 CONTENTS. CHAPTER XLIV. Grass 282—285 CHAPTER XLV. Fodder and Soiling Crops 286—292 CHAPTER XLVI. Grain Crops 293—303 CHAPTER XLVII. Root Crops 304—307 CHAPTER XLVIII. Textile Crops 308—311 CHAPTER XLIX. Culture of Tobacco 312—316 CHAPTER L. Special Crops 317—327 Appendix 328—329 Index 3b0— 334 The Culture of Farm Crops. PART FIRST. CHAPTER I. THE ART OF AGRICULTURE.— IMPORTANCE OF A KNOWLEDGE OF ITS PRINCIPLES. No farmer can be successful in the pursuit of his indus- try without a knowledge of the principles upon which the practice of it is founded. Every work of the farm has more or less of mystery attached to it. No other art, among all the industries of the human race is so intricate or has so many varying conditions and circumstances environing and affecting it. The soil, the season, the character of the plants grown, the time and manner of their cultivation; the air, water and mineral matters which furnish them with food; and many other things related to these; are all involved in an inextricable maze and mystery to the farmer who knows nothing of them or their relations to and reactions upon each other. But these mysteries are unfolded in the most beautiful and interesting manner, and the laws which re- late to the growth of plants are seen to form a system which gradually developes — as the farmer progresses in this study — into form and method from w^hich rules may be laid down for his guidance; or from which he may form his own rules and practice as any emergency may arise. When principles are known and understood, one may form his own practice. Otherwise he is the slave and the victim to the innumerable accidents which befall him in the various operations of the farm, which are controlled in 8 THE CULTURE OF FARM CROPS. a great measure by the qualities and characters of differ- ent soils; by temperature, moisture, the action of the var- ious manures and fertilizers — not only upon the soil and the crops, but upon each other — the habits of the plants, and the vicissitudes of the season. But when the farmer has a sufficient knowledge of these and of the laws which con- trol their action, he is able to guide himself through the labyrinth, just as the sailor steers his ship safely among the rocks and shoals which environ his desired port, by the aid of the chart which lies before him, and his knowledge of the currents which sweep about them. For a farmer to succeed, and grow large crops, without this knowledge of his art, is as impossible as for the sailor to reach his port in darkness, without a compass or a chart, and wholly ignor- ant of his bearings, and the obstacles in his w^ay. That so few farmers wholly fail in their business is a proof not to the contrary of this, but to the rich rewards which the pro- lific soil offers to man's labor and industry, and of which a moderate share only is sufl[icient for all his needs; but the whole of which brings competence and wealth to the most skillful and studious farmers. It is about forty years since agricultural knowledge took a scientific turn, and students began to search for the caus- es of the results which they reached by the slow process of a life long practical service in the field. Then a young man had to learn slowly, day by day, and year by year, often waiting many years to verify, through repeated con- tradictions, any facts which he learned by the closest ob- servation. All the gathered lore of the most successful farmers was then comprised in a very few books, and some popular beliefs, current only verbally, and handed from one to another amid dispute and contradiction The old writers upon agricultural topics merely repeat what they learned from the results of their practice; they wrote of manures from what they had seen of the results of their use; but they had no conception of the fact that manures supplied the cropt with certain elements which were ab- sorbed into their substance and became a part of them. SIMPLICITY OF AGRICULTURAL SCIENCE. H ^ot a farmer of that day, nor a chemist, knew that bones furnished phosphoric acid to plants; or that gpano provided in its ammonia the materials from which their gluten and other nitrogenous substances were derived. Indeed the renowned father of agricultural science: Liebig — when he propounded his mineral theory, which was that the ashes of plants contained everything which they drew from the «oil, and that if the mineral substances contained in the " ashes, were supplied in sufficient quantity to the crops, there would be scarcely a limit to the product, excepting the space in which they were contained — knew nothing about the invaluable nitrogen which we now know to be wholly indispensable to plant growth. But light has grad- ually dawned upon us, and by slow and sometimes faltering progress, there has been built up a system of agricultural science which explains the laws of plant growth and affords the most important information to the cultivator of the soil. Science is based upon fact. Philosophy is based upon speculation. Science is the outgrowth of philosophy, be- cause before we can reach a true knowledge of any fact we must approach the study of it by a well devised theory, changed as may be necessary, and tested patiently and slowly until the knowledge sought is found. This know- ledge, when verified by practice, sufficiently proved and classified, becomes science. Science then is nothing for the farmer to fear, or cast doubt and suspicion upon. Theory as has been said, has no part or lot in it; it is a summary of known facts, and is therefore of the most valuable use to the farmer as it gives him a sound basis upon which to build up such conclusions in regard to his practice as will enable him to meet the various difficulties which are al- ways arising in his work. Nor need the farmer be afraid of science because of any difficulty in comprehending it. Truth is very simple, and is so plain that he who runs may read. And there is noth- ing in agricultural science, and nothing will be oflfered in the pages to follow, that would give any difficulty to any 10 THE CULTURE OF FARM CROPS. farmer's boy, or girl to understand and comprehend, to it& full extent. Nothing need be said of the importance of the farmers- vocation further than as it relates to his own interest. While he feeds and clothes the world, he is most interested in feeding and clothing himself, and in advancing his own condition as far as possible. Society exists now upon a much higher base than it did a score of years ago. Edu- cation and intelligence have made necessary a much higher civilization, and a more luxurious and less laborious living. All this calls for increased income. Scientific skill in any art necessarily increases the value of the labor expended and enhances the profits of it. This is true of agriculture as of all other arts. Hence the farmer is compelled by the general advance of other industries to advance his own. He can only do this by increasing the products of his labor by means of more skillful work, and the help of every ap- pliance. Better culture, better manuring, better mechani- cal aids in the form of improved implements and machinery, and an economical division of labor, are all indispensable to him. The culture of farm crops, then becomes a most important subject for study and critical examination and whatever in the study can be turned to practical use should be adopted into practice. The age is advancing in every way; but agriculture lingers behind, perhaps because of its- vastness and the unavoidable inertia and slow movement of vast interests. But it must advance with the world. Mechanical ingenuity has given it a wonderful impetus and from the far better hoes of the present time, to the gigantic twelve-wheeled locomotives and the great ocean steam ships- which are at his service, the farmer is helped in a thousand ways. Then he must improve his own work consistently and stand in the front as becomes the feeder of the world and the importance of his vocation. In every other country than ours, the vast importance of agriculture is recognized by the general governments, and the investigation of the principles upon which the rational practice of the art is founded, is made a prominent care of THE IMPORTANCE OF AGRICULTURE. 11 the state and commands the principal attention of the lead- ing men. Here the citizen is less closely iavolved in the affairs of government, and looks after his own class inter- ests himself An American citizen glories in his indepen- dence, but in this case he suffers considerably as compared with farmers in other countries. There is then all the more need of private and personal enterprise among farmers. American farmers are better educated, read more and are better able to advance their own interests by skillful industry and untiring energy than any others. Hence, technical literature of the highest class abounds, and agri- culture is well represented in it. And these pages are of- fered as a modest contribution of a farmer and student to> this literature, and to his brother farmers and students. THE CULTURE OF FARM CROPS. CHAPTER II. kinds' and conditions of matter.— the ELE- mentary constituents of plants. All matter in existence, presents itself to our view in two forms only. The solid rock, the water of the ocean, the atmosphere, the plants which clothe the earth's surface and the animals which move over it; are all formed of two kinds of matter which are called organic and inorganic. Of all these everything which is and has been devoid of life, is classed under the head of inorganic substances; while liv- ing bodies whether plants or animals or the remains of these, are classed as organic matter. There are cases in which the two classes seem to approach very closely if not to mingle; but this is only apparently and not in fact, for the distinction between them is broad and marked and must appear on a close examination. This distinction is life. Anything which has lived, w^hich has performed any of the various functions of life however simple and low in char- acter these may have been, is organic matter; and all else is inorganic. Thus while the rocks and the soil are classed among inorganic substances, yet the coal which we find imbedded deep in the bowels of the earth, or the soft porous sand or fine clay which is known as infusorial earth, or the limestone which is made up of an infinite number of the skeletons and shells of microscopic animals, are organic substances; because the coal has been formed from various mosses and ferns, with the larger plants and great trees, which have lived and died and fallen and have in time been buried under the soil brought by vast floods, and have formed the beds of coal now lying under thousands of feet in thickness of rocks. And the minute insects which have lived and died in the primeval oceans have all been en- dowed with life ; although they appear to the casual obser- ORGANIC MATTER. 13^ ver as mere stony or earthy matter. All organic matter,, shows on examination, a certain structure or, form which is. visible to the eye or can be made so. This structure is either cellula-r or fibrous, as may be seen in the pores of wood or the fibers of various plants, and of muscular tissue; and it serves to distinguish between these two classes of matter. But there are many substances of organic origin which do not exhibit any observable trace of organized structure; as sugar, starch, gum, and yet these are formed in plants in great abundance. They do not possess any cel- lular or fibrous tissue and have never possessed any organs; nevertheless as they are the productions of living organized bodies, they are included in the general term of organized matter. So the ash of plants which consists of mineral matter only; and the decomposed dust of plants and ani- mals are recognized as organic matter, and as such, have a specially favorable effect in the soil upon the growth of plants. So all the ultimate products of organic matter; the charcoal made from wood, the vinegar, spirit, and tar, also derived from wood by distillation; and the vinegar and alcohol which are produced by the fermentation of sugar;, are all included in the general term as organized matter. The cells and fibers of organic matter are in fact the or- gans or instruments of life by which the vital functions are performed and growth effected. Thus the pores of wood or the cells of a potato are centers of life, and as will be hereafter explained, are able to effect a distinct re- productive action; absorb nutriment, grow and produce organs like themselves, and so increase the substance of the plants of which they form a part. If we take any one of these forms of matter of either class, excepting comparatively a few, and subject it to cer- tain chemical processes we shall find that it is resolved or separated into more than one, or several substances, as the case may be. Thus a piece of limestone subjected to heat — which is a chemical process — undergoes a very consid- erable change by the separation of its component parts ; 14 THE CULTURE OF FARM CROPS. carbonic acid and lime ; and these by further process, but much more difficult, can be separated into carbon and oxygen and the metal calcium and oxygen. If an attempt is made to separate or resolve these further, it is fruitless and we find these substances remain unchangeable under every known chemical process ; and they remain, carbon and oxygen and calcium. These ultimate unchangeable substances, are called elementary bodies ; and those which are formed by the union of two or more of them are called compound bodies. There are now in existence sixty-five known and recognized elementary substances ; but the com- pound bodies which exist and are formed by combinations of the elementary bodies, are infinite in their variety. The rocky and earthy crust of the globe, the ocean which bathes it, the atmosphere which envelopes it, the plants which grow upon it, and the animals which cover the face of it ; are all made up of diversified forms of matter which are absolutely innumerable. A man can no more count them than he can number the sand upon the sea shore. It is one of those wonders of nature, which appeal so strong- ly and in a manner so full of interest to the farmer as he goes about his daily labors, with observant eye and thought- ful mind, that these infinitely varied forms of matter, which are — so to speak — the raw materials from which he is enabled to elaborate by his skillful use of nature's forces, all the vegetable and animal products of his farm ; are *inade up of a few only of the sixty-five elementary sub- stances, by a most intricate system of combinations. This is sufficiently surprising, yet it is far more amazing that nearly the entire mass of these vegetable and animal products consists of, and may be resolved into one or more of only four of these simple substances. When any vegetable or animal substance is destroyed — as is commonly said — but more correctly decomposed, or resolved into its elements by intense heat and combustion, it either entirely disappears, or leaves behind it a very small quantity of ash. Oils, fats, gum, sugar, starch, cotton fiber, wool, horn, hair, when burned, either disappear en- THE ELEMENTARY BODIES. 16 entirely or leave an insignificant remnant behind; while wood or flesh leaves but little more of earthy matter or ash unconsumed. All that has disappeared of these sub- stances consist generally of three of the elementary bodies, and rarely of four; while of all agricultural products the greater part, inclusive of the combustible and inconbusti- ble portions together, is made up of no more than twelve. The four bodies referred to are carbon, oxygen, hydrogen, and nitrogen. The tAvelve consist of these four, and cal- cium, chlorine, magnesium, phosphorous, potassium, sili- con, sodium and sulphur. An acquaintance then with the most important four ele- ments mentioned is indispensable to the farmer; for it is quite impossible for him to comprehend the laws which govern the operations of nature in the growth of plants, or the reasons why he adopts certain processes in his farm work to aid and facilitate these natural operations, without a previous knowledge of the nature of these elements and their reactions upon each other. And at the same time it is of the greatest interest to him that he should have some knowledge at least of the nature of the other eight elemen- tary substances which enter more or less into the ash or incombustible mineral portion of the plants which he cul- tivates. A brief consideration of the properties of these four el- ements which make up the organic constituents of plants and of the eight which go to make up their inorganic sub- stance, will lead the way for a study of the means whereby, and the manner in which, they enter into the circulation of plants and form their substance. THE CULTURE OF FARM CROPS. CHAPTER III. CARBON.— ITS PROPERTIES AND RELATIONS TO VEG- ETABLE LIFE. Carbon, a word derived from the latin carho, coal, is the name given to a mineral substance which occurs in an in- organic condition in the diamond, in graphite or plumbaga (commonly called black lead) in bitumen, petroleum, am- ber and a number of mineral resins, and in an organic condi- tion as charcoal, mineral coal, lampblack, soot, etc. Its three best marked forms are the diamond which is pure carbon ; graphite; which is found sometimes nearly pure, but mostly mixed with more or less iron ; and charcoal which contains- a small proportion of mineral matters which form the ash of the wood of which the charcoal is made. An interesting- form of vegetable carbon is the fiber of the cotton plant which is almost pure. Carbon forms a large proportion of the substance of vegetable matter when it is freed from water ; amounting to from forty to fifty per cent, by weight of all the parts of plants grown as farm ci'ops. It therefore performs an im- portant part in the growth of plants and becomes an in- teresting subject of study for' the farmer. The diamond is the hardest substance known, and re- sists a high degree of heat, but is combustible at a very high temperature. When made red hot, and placed in a vessel of pure oxygen, it burns wdth a brilliant steady glow, combining with the oxygen, and forming carbonic acid. It has been artificially, but accidently produced, in iron furnaces in which charcoal has been used as fuel ; but in every other way it has resisted all the efforts of the chem- ists to produce it. Sir Isaac Newton predicted that the diamond would prove to be of organic origin and this has some show of probability from the fact that on burning CARBON. 17 the crystals a residue of ash has remained in the form of a cellukir net work. Graphite is a well known and useful mineral which al- though seemingly very soft, its particles are so hard as to wear out with great rapidity the steel saws with which it is cut. It is produced artificially in charcoal iron furnaces and in the manufacture of coal gas. Charcoal is the form in which carbon appears of the most interest lo the farmer, because it is derived from veg- etable matter, chiefly from wood, although it is made from peat, by charring it in heaps covered with earth and thus protected from the oxygen of the atmosphere which would change it into carbonic acid. It is brittle, black, taste- less, and inodorous; and perfectly insoluble. Its perfect insolubility disproves the common impression that it can be used as a fertilizer or as plant food in any manner ; but its peculiar behavior with other substances does give it an indirect agency in this way. It resists the action of thei air as well as of moisture, hence it is almost indestructi- ble. The charred remains of timber, and of wheat and rye grains which have been found in the ruins of Herculaneum where they have remained unchanged for eighteen hun- dred years proves its unchangeable character. This prop- erty of charcoal has been made use of in preparing posts to be set in the ground by charring them, by which they are made exceedingly durable. When pure and dry, charcoal burns without any flame; the light blue flame sometimes seen when it is burned, is caused by the com- bustion cf water of w^hich it absorbs, in the form of vapor from the atmosphere, from ten to twenty per cent, in a sin- gle week's exposure. Having the porous structure of the wood or peat from which it may be prepared, charcoal possesses a remarka- ble power of absorbing gases and of condensing them in its pores; hence it becomes at times of much value in the soil, and it is to this fact that its notable effect upon vegetation is due. This effect is the dark green color of the herbage 18 THE CULTURE OF FARM CROPS. and the luxuriance of the vegetation in its vicinity; caused doubtless by its absorption of ammonia. It will absorb ninety times its bulk of this gas, thirty-five times its bulk of carbonic acid, and nine times its bulk of oxygen. Char- coal made from the hard and dense woods exerts this absorbing power jn the greatest degree; having as much as one hundred square feet of surface in its ex- ceedingly fine pores, in every cubic inch. This power to condense gases gives it a very great importance in agri- culture in various ways. It absorbs noxious gases and of- fensive odors, and when crushed so as to expose its greatest absorbing surface wall filter water and purify it from foul matter, and restore tainted meat to its former sweetness. It will absorb the deadly carbonic acid which accumulates in wells and pits, and thus remove the danger of loss of life in entering such places. It will purify and remove the dark color from cider, syrups, wines and vinegars, and is thus used to a large extent. Charcoal is thus a powerful disinfectant as well as a de- odorizer; for by condensing in its pores noxious vapors and gases, it removes poisonous substances from the air and avoids the danger of fatal diseases. It however does not act as an antiseptic and prevent decomposition, but hastens it, by absorbing oxygen, which is the most active agent of decomposition; and which rapidly destroys or- ganic matter; but while thus accelerating the decay of substances which are brought into contact with it, it pre- vents all offensive results by continually seizing upon these products and causing their immediate oxidation. This process goes on continually and thus a small quantity of powdered charcoal may have a surprisingly disproportion- ate effect. It is turned into valuable use in this way by surgeons for poultices to corrode and decompose sloughing and gangrenous flesh, in malignant sores and in serious wounds. It changes ammonia into nitric acid and thus serves a most useful purpose as an ingredient of manure heaps and composts; preventing the loss of valuable am- monia and changing it into the stable forms of nitric acid HUMUS OR VEGETABLE MOLD. 19 and nitrates. It also changes the disgustingly offensive sulphuretted hydrogen of decaying manure and other or- ganic matter, into sulphuric acid, and thus removes a sometimes intolerable nuisance of barn yards and hog pens to uninitiated passers on the road. Humus is another form of carbon, although an impure one, which deserves notice. It is the decomposed remains of vegetable matter which has undergone the slow process of decay — a kind of combustion and oxidation — in the open air. It exists in swamps in the form of peat and black porous soil ; in woods as a dark spongy mass on the sur- face, covering the lower soil, and wherever a mass of veg- etation has. slowly decayed. The leaf mold so much prized by gardners is chiefly humus. When the woody matter of plants, large and small alike, is exposed to moisture and air, it undergoes a slow decom- position, in whicli oxygen is absorbed. It is in fact pre- cisely similiar in its operation and effects to a slow com- bustion or charring, although accompanied by so small a quantity of heat as to be almost imperceptible. With the absorption of oxygen and its combination with a portion of the carbon, carbonic acid is formed. Some of the oxy- gen also combines with hydrogen and forms water ; but as the hydrogen is taken first, a large portion of carbon re- mains and the mass gradually assumes a dark brown or black color and becomes what is termed : "vegetable mold.'* To this crumbled porous substance the term humus is ap- plied. It contains various acids, as geic, ulmic and humic acids. This class of substances is of great importance in agriculture, as by their decomposition they yield up car- bonic acid to plants, and have the power of absorbing and retaining ammonia to be yielded up for the same purpose. Carbonaceous matter gradually accumulates in soils that are always covered with vegetation, as in forests, pastures and prairies. This is a conclusive proof that the carbon of it is derived from the atmosphere, and that growth is more rapid than decay. When land is brought under cul- tivation this carbonaceous matter is consumed by the crops 20 THE CULTURE OF FARM CROPS. and unless it is restored by a course of good culture, by- plowing under green crops, or by furnishing manure to the soil, or by cultivating such crops as clover and grass Avhich leave a large amount of vegetable matter behind them in their roots, the land is gradually exhausted and becomes, unable to produce profitable crops. A crop of clover has been found to leave in the soil more than three tons weight of roots, while the roots left by wheat do not amount to one-fifth of this quantity. Hence we have the explanation of the deep rich soils of newly cleared forest land, of drained swamps, and of the western prairies, as well as of the valuable effects of clover upon the land. THE PROPERTIES OF OXYGEN. CHAPTER IV. OXYGEN.— ITS PROPERTIES AND RELATIONS TO LIFE. Oxygen is the most remarkable and important of all the elementary substances. It is a gas. This term gas was iirst used in the seventeenth century and is a reminder not only of the origin of a great part of our present chemical knowledge, but of the superstitions of the early periods of chemical investigation ; and of the recent emancipation of chemistry from those superstitions. The early chemists, known as alchemists, who believed in such notions, as the existence of an "elixir" or fluid, which would make man immortal ; and of a substance which could transmute all the base metals to gold, and which they termed the "phil- osophers stone," were surprised and alarmed by the sudden explosions of their retorts, often accompanied by the violent death of the experimenters, or of the sulphurous exhalation and fumes which produced suffocation. They were led to believe in their ignorance that these disasters were due to the agency of spirits which refused to be imprisoned and brought under the power of their tormentors, and burst the vessels and slew the operators in revenge. The alchemists therefore began their work with prayers and marked their vessels with the holy cross from which we have had brought down to us the word "crucible;" a vessel in which substan- ces are subjected to great heat for the purpose of procuring their decomposition. Hence we have the origin of the terms spirits ; as spirits of wine, spirits of nitre, etc., and al- so the term gas ; which was derived from the German gahst , a ghost or spirit. Oxygen is a recent discovery, having been first discovered in 1774 by Dr. Priestly. Its discovery was claimed by the French chemist Lavoisier; but the honor is generally ac- corded to Priestly. Its discovery, like all others of that and 22 THE CULTURE OF FARM CROPS. previous periods, was the result of an accidental submission of the red oxide of mercury to the rays of the sun concen- trated by a lens or burning glass. It is an interesting coin- cidence that the sun, the central focus of the chemical action of the universe, should be the agent by which the most po- tent of chemical agencies should have been brought to the knowledge of mankind. This discovery may well be classed as the most important in the history of human knowledge, rivaling the great dis- covery of gravitation by Newton in the preceding century, and throwing floods of light upon the investigations of the mysteries of what we call nature. Of the discovery of this potent substance. Prof. Liebig has observed that "it has produced a revolution in the manners and customs of man- kind. With it are linked, as results, our knowledge of the composition of the atmosphere, of water, of the solid crust of the earth, and of the influence of these upon the existence and life of plants and animals. Every human industry has been aflected by it ; all trades and manufactures and by no means least agriculture, have been aided and advanced im- measurably by our knowledge of it." The study of its properties may be made a profitable and most interesting pursuit in the farmers household, in the leisure hours which may be devoted to the acquisition of all useful knowledge connected with his vocation, and no better subject could be selected for the most pleasing and instructive experiments. It is easily procured and managed by means of simple and cheap apparatus. Oxygen is a transparent, colorless, tasteless, inodorous gas, one-tenth heavier than the atmosphere of which it forms 23 per cent, of its weight. It has never been condensed into a liquid. It exerts a weak magnetic force which is supposed to cause, or to be concerned in, the daily fluctuations of the magnetic needle ; and this property varies with its tempera- ture. It is slightly soluble in water, 4 J parts of it being ab- sorbed by 100 parts of water. It is neutral, possessing neither acid nor alkaline qualities, and although mild and bland, it exerts the most amazing COMBINATIONS OF OXYGEN. 23 power in its combinations. It combines with every other substance and produces the most diverse and opposite com- pounds. With some substances it forms gases, with others liquids or solids ; with some it forms acids of the most cor- rosive quality ; with others it forms alkalies equally corro- sive; while a union of two of these — an acid and an alkali — often forms neutral compounds perfectly bland and in- noxious. An instance may be given. With sulphur, oxygen forms sulphuric acid, the intensely burning and destructive "oil of vitriol" as it is commonly called. With calcium — a metal — it forms caustic lime, an intensely acrid and de- structive alkali, which corrodes and destroys all vegetable and animal substance. These two combined form sulphate of lime, the well known gypsum, an inoffensive and useful compound well known as "plaster" to every farmer. The oxygen of the air is equally diffused through it in the form of a mixture, and not combined. If this oxygen were to become combined with the other element of the air, all life, of whatever kind it might be, would be destroyed in an instant ; for the product of the combination would ])c that most corrosive substance nitric acid ; but as it is only mixed it exerts only a beneficent action in supporting life. All combustion is the result of the action of oxygen, it has a powerful affinity for carbon and the other elements of which fuel is composed and unites with them so violently as to produce the heat and light of our fires and lamps. Com- bustible substances burn with greatly increased heat and brilliance in pure oxygen, and the reason why a furnace that is supplied with a blast is so intensely hot, is because a large.volumn of oxygen is forced into it with the increased supply of air. Iron and steel burn with wonderful bril- liancy in ajar of oxygen, if tipped with sulphur, and ignited to start the combustion. This combustion is called oxida- tion and it goes on slowly in the absence of heat ; but is al- ways accompanied by some slight rise of temperature. A piece of iron which slowly oxidizes, or rusts away, to a brown powder — which is oxide of iron — is subjected to pre- cisely the same amount of heat in the aggregate, as if burn- 24 THE CULTURE OF FARM CROPS. ed in ajar of oxygen or consumed in an intensely heated furnace. The heat and time, in both instances, multiplied together, would produce precisely the same sum. Vegetable matter decomposes or is consumed by the action of oxygen in a similar way. The oxygen breaks up the organic sub- stance into simpler compounds; separating the other ele- ments previously mentioned (see chap. II) and uniting with them ; forming carbonic acid with the carbon, water with the hydrogen, nitric acid with the nitrogen, potash with the potassium, soda with the sodium, lime w^ith the calcium, magnesia with the magnesium, phosphoric acid with the phosphorus, silica with the silicon, and sulj^huric acid with the sulphur. All of these constituents of plants are thus seen to be composed in part of this common element, which pervades all nature. Oxygen is the universal supporter of respiration; and plants perform this function in much the same manner as animals. That is, they imbibe air through the pores in their leaves and separate oxygen from it and utilize this in their vital functions. Animals draw it into their lungs where it comes in contact with the blood, then and there loaded with impure matter brought through the veins from the extremities of the system, and oxidizing it changes these impurities, frees the blood from them, and sends the vital fluid back through the arteries, bright, clear and fitted to reinforce and build up the muscular tissue. And this oxi- dizing effect of this "vital air" as it has been called, is ac- companied by a certain elevation of temperature for it is accompanied by a chemical process closely akin to com- bustion. The air over every square inch of the earth's surface weighs 15 pounds. Three pounds of this is oxygen. A man consumes by respiration about 2 j^ounds of oxygen daily. One pound of coal in burning consumes 2f pounds of oxygen, so that the heat produced in a man's system by the process of respiration is equal to that produced by the combustion of one pound of coal. Oxygen not only contributes the vital element to the at- DOMINANT POWER OF THE SUNBEAM. 25 mosphere but it also comprises 8 ninths of the water we drink ; water consisting of 8 pounds of oxygen and 1 pound of hydrogen combined. It also forms the larger portion of all the rocks which form the solid crust of the earth. Of these the three chief minerals are lime, silica and alumina, and of these about one-half of the mass consists of oxygen. Thus about one-half of all the mass of the earth and every- thing upon its surface is made up of this simple element, which no man has ever seen or will probably see ; and when this great fact is considered along with the vast force of this all pervading gas, it seems to call to the mind of man a type of eternal existence and resistless power. It is an omnipresent, all powerful spirit, benevolent and destructive at the same time; which holds all nature in its embrace; evolves life and action, and yet revels in consuming fire and is able to reduce all things to death and ashes. But the vast force of this grand element is controlled and reduced to order and system by the beams of the sun. These are the grand antagonists of oxygen. The solar rays with their genial vivifying warmth bring the dormant forces of vegetable life into action. They start the vital germ into active life. The spire appears and soon brings forth the green leaves. These leaves absorb carbonic acid from the air, rescue the carbon from the grasp of the all devouring oxygen and store it into their cellular tissue. The roots sup- ported by the leaves, extract nutriment from the matter which has been reduced from organized substance by the destroying influence of oxygen and form it again into living organism. What oxygen has decomposed the plants recon- struct ; and if this element is the main spring of destruction and decomposition, the solar ray which staits vegetable life into action and gives it vitality, is the still m.ore powerful controlling and counteracting agent and brings life and beauty from death and desolation. An ancient fable tells that Prometheus stole a spark of celestial fire and with it warmed into life an earthly body which he had formed. This is no fable; it is but a poetical fancy which contains in pleasing picturesque form a great truth. Perhaps the 26 THE CULTURE OF FARM CROPS. ancient poet realized through some inspiration this fact as yet then unknown, and put it into a form of life and per- sonality. The spark is the sunbeam ; which indeed starts dead matter into life and fills the earth with vitality ; caus- ing the luxuriant vegetation which in turn supports directly and indirectly every form of animal life. The sunbeam is then the master spirit of the universe ; controlling the great agent of destruction and building up again the structures which oxygen reduces to dust. OZONE. This subject is too important to leave without a reference to a form of oxygen which plays a most important part in nature and is believed to have some effect upon vegetation. This is called ozone. When an electrical spark is passed through dry air a peculiar odor is perceived. The cause of this was not understood until recently when Prof. Schonbien proved that it w^as a form of oxygen greatly increased in intensity. It is believed by some chemists that ozone (as it was termed by its discoverer because of its peculiar odor) is formed by the combination of two atoms of oxygen with each other; or in other Avords, an oxide of oxygen. This substance is therefore of great intensity, equal in force to that of oxygen multiplied by itself. It has an extraordinary energy and produces changes which oxygen is unable to do. It corrodes silver, bleaches colors untouched by oxygen, destroys the odor of tainted flesh instantly, by decomposing^ the gases which escape from it, and causes the decay of woody fiber with excessive rapidity. It is believed to be the cause of the mysterious souring of milk in dairies Avhich so often occurs after thunder storms, when the peculiar odor of ozone pervades the air. The vivid greenness of the herbage of the meadows after thunder showers is also supposed to be due to the effects of the ozone produced and washed into the soil by the rain. This substance is readily detected by means of slips of test paper made by soaking them in a mixture of iodide of potassium dissolved in water, and starch. The ozone frees OZONE. 2T the iodine from its combination with the potassium and the iodine then instantly acts upon the starch in its usual man- ner and turns the paper blue. At present very little is known of this substance, its manner of production or its econ- omy in nature, yet its connection with oxygen gives it an importance which calls for its recognition in this treatise. THE CULTURE OF FARM CROPS. CHAPTER V. HYDROGEN AND NITROGEN AND THEIR COMPOUNDS. THEIR RELATION TO VEGETABLE GROWTH. Hydrogen, like oxygen, is a colorless, tasteless gas with- out any odor ; slightly soluble in water and exceedingly inflammable. It is never found free, but always in combin- ation, forming one-ninth by weight of water, and a consid- erable proportion of all organized matter. When combined with nitrogen in the proportion of three parts to one of the latter it form.s ammonia, and this compound is always formed during the decomposition of organic matter. Its part in the formation of water by the union of one part with eight parts of oxygen gives to it, its greatest importance in the economy of nature ; and its name hydro-gen or "gener- ator of water" is derived from this, its chief property. But it is no more entitled to this name than oxygen is, but received it because it was discovered and became known a few years before oxygen. The English chemist, Cavendish, first discovered it as an element in 1766. The only impor- tant solid mineral into whose composition it enters is coal. This gas is the lightest of all known substances being 14i times lighter than air, and hence is employed to inflate balloons. It will not support life, but is not noxious ; an animal immersed in it dies simply for want of oxygen. When mixed with oxygen and ignited, the gases explode violently and water is formed. It burns when pure with a light blue flame, giving out intense heat, but very little light and also forms water. When mixed with carbon, it forms the common marsh gas, and the fatal fire-damp of coal mines. This gas is produced by the decomposition of vegetable matter and accompanies the fermentation of man- lue in heaps in the barn yard. When mixed with air it is NITROGEN. 29" explosive, and it then produces the peculiar blue flames which occur by spontaneous ecmbustion as the gas es- capes in bubbles from wet marshes. It is also the gas which is found in deep crevices in the rocks far beneath the surface in localities where petroleum exists, and which is sought for by boring, and used for illuminating purposes and for fuel for engine furnaces. Another compound of carbon with hydrogen i^ the com- mon gas distilled from coal and used for illuminating pur- poses. Its more brilliant light is due to the fact that it contains twice as much carbon as the previously mentioned gas. It also forms a part of all oils, fats, resins and wax ; be- ing combined in these with carbon and oxygen in varying proportions. It is a constituent of petroleum and all its products, including the beautiful aniline dyes which are made from it. It also enters into the composition of woody fiber, and the starch, gum, sugar and alcohols, which are products of it ; both naturally and artificially. It is thus a most important element, and offers to the studious farmer a subject for study of great interest. A number of very pleasing experiments may be made with it, such as its production by the decomposition of water ; the formation of water by its combustion and union with oxygen ; its combustion and oxidation by means of a porous substance, as spongy platinum and the formation of its compounds. NITROGEN. This gas was discovered in 1772 by a chemist named Rutherford. It is diffused extensively in nature forming four-fifths of the atmosphere ; entering largely into the com- position of vegetable and animal substance, and being a most indispensable part of the food of plants and animals. About one-sixth of all animal tissue consists of this gas. It forms a part of many of our powerful medicines, as qui- nine and morphine, and of the most dangerous poisons as^ strychnine and prussic acid. It is not found in any of the '30 THE CULTURE OF FARM CROPS. Tocks excepting those of an organic origin, as coal, which contains 2 or 3 per cent, of it. Its name signifies the generator of nitre, because it exists largely in this substance in the form of nitric acid and may be produced from it. It may be produced from air by a very •simple and beautiful experiment. A small piece of phos- phorus is placed in a little saucer and floated on water in a dish or trough; the phosporus is set on fire and -covered with a bell glass. The combustion of the phos- phorous produces phosphoric acid by its combination with the oxygen of the air, which is all taken up in this way ; this acid is absorbed very quickly by the water and the nitrogen is left. It is then found to be a transparent gas, without color, taste or smell ; which is unable to support combustion or life. A lighted match introduced into the gas is immediately extinguished and a mouse put under the bell glass dies in a short time for want of oxygen. It is not poisonous, but simply has no active properties, being when uncombined wholly inert, and for this reason was formerly -called azote, or "life destroyer." Its purpose in nature, in its free state, seems to be to act as a dilutent of the exceed- ingly active oxygen, and to thus adapt it to the condi- tions of life. Water absorbs about li per cent, of its bulk of this gas, ^nd it is not unlikely that plants may procure some of their nitrogen from this source. Nitrogen is most interesting when we come to consider its combinations. It combines with oxygen to form five remarkable compounds. The first of these is nitrous oxide, called from its peculiar effects when breathed, laughing gas. This is a colorless transparent gas, of a sweetish taste and soluble in water to the extent of three-fourths of the bulk of the latter. It supports combustion actively, relighting a glowing ember when this is plunged into it and causing an intense combustion of ignited substances almost equal to the effect of oxygen. At a pressure of 750 pounds to the isquare inch it condenses into a clear liquid which boils on- ly at the great heat of 1126 degrees, which is considerably riiOPERTIES OF NITROGEN. 31 above the melting point of lead, and freezes at 150 degrees below zero. The second is nitric oxide, which, although it ■contains a larger quantity of oxygen than the preceeding, jet is averse to combustion and extinguishes flame. Nitrous acid is a gas, orange red in color, and is soluble in water to a large extent ; by the absorption of oxygen it becomes ni- tric acid. This acid is of surpassing interest to the farmer because it is a form in which nitrogen enters into the substance of plants and w^ithout which, in sufl[icient quanti- ty, farm crops cannot be produced profitably. Nitric acid is a colorless liquid with an intensely sour taste, and when combined with potash, forms the well Ivuown substance, saltpeter or nitre. It exists thus com- bined in large deposits in South America, and is found in small quantities in large caves in the United States. In combination with soda, as nitrate of soda, or Chili saltpeter, it is found in very extensive beds in Peru, Chili and Boli- via and other places along the Pacific coast of South America. This substance is very largely used as a ferti- lizer, for which purpose it is exceedingly valuable. Nitric acid is composed of nitrogen and oxygen combined and is an exceedingly active substance. On account of the large quantity of oxygen in this acid it possesses very active properties and is one of the most eflTective oxidizing agents known. It stains animal substances yellow and is thus used as a yellow dye. It corrodes metals very quickly and is used by engravers for "biting" in the etchings upon cop- per plates ; it ignites oil of turpentine and powdered char- coal, and causes such rapid oxidation of phosphorous as to produce explosion. Another most important compound of nitrogen is that with hydrogen, which is known as ammonia. This is a gas of a most pungent odor and acrid caustic taste, and has strongly alkaline properties. It is rapidly absorbed by water, which takes up more than 700 times its bulk of it, and then forms the water of ammonia or aqua ammonie of the druggist. It is produced by the distillation of horn, and as it was first made from deers horns, it was called 32 THE CULTURE OF FARM CROPS. "spirits of hartshorn." It is largely contained in decom- posing urine and causes the pungent odor of stables in which horses are kept. Being volatile, it escapes into the- air with great ease, and unless combined with some acid into a permanent form it is disengaged readily from decom- posing manure by fermentation and heat, and is lost to the farmer. It has been supposed heretofore, that this gas was the source from Avhich plants derived their nitrogen, but re- cent investigations go to prove that ammonia is oxidized in the soil and changed into nitric acid before it can become available for the nutriment and support of plants. Ammonia combines freely with acids. With sulphuric acid it forms a stable compound, sulphate of ammonia; hence it is useful to employ solutions of sulphate of iron,, (copperas) or sulphate of lime, (gypsum or plaster) to fix any escaping ammonia which may be in danger of loss from stables and manure yards. The employment of plaster in this way and for this purpose is quite common among care- ful and economical farmers, who scatter it liberally about the stables and yards, and so deodorize and purify them ; make them more agreeable and healthful, and save all this exceedingly valuable fertilizing agent. The ammonia hav- ing an exceedingly strong affinity for sulphuric acid takes this from the sulphate of iron cr lime and combines with it» leaving the iron in the form of an oxide, or the lime in the form of a carbonate. ATOMIC WEIGHTS. CHAPTER VI. THE COMBINATIONS OF ORGANIC SUBSTANCES. It is one of the grand laws of nature, that however often matter may change its form, it is never lost. Matter is in- destructible. It is changed and rechanged into infinitely numerous and varied forms, but it never loses a particle and there is no waste. Another universal law is that "of noth- ing, nothing only comes," and that mankind with all their work and labor can expect nothing more from the soil or from any natural element than it contains. Labor only, changes the forpi of matter; it never creates anything. Another grand law of nature is that all matter of whatever kind, exists in the form of very minute particles, which are so small as to be invisible; that these are unchangeable; and that as the various elementarj^ substances combine with each other, they invariably do so in j^recisely the same pro- portions. Thus 8 atoms or particles, (or pounds ; the quan- tity makes no difference) of oxygen, and 1 part by weight of hydrogen, combine to make water ; that potash consists ever and always of 89 parts of potassium and 8 of oxygen ; and common salt of 35 i:)arts of chlorine to 23 of sodium ; and so on through the whole list of the 65 known elemen- tary substances. Certain numbers, known by long contin- ued experiment, and called combining numbers, or atomic weights, represent the proportions, by weight, in which the elements unite to form all their compounds. A compound is not a mixture. If we take salt ftnd sand and mix them together, no matter how intimately, the salt remains the same and so does the sand, and they can be separated by adding water which will dissolve the salt and leave the sand as it was before. The salt and water are also mixed and can be separated by boiling away the water and leaving the salt dry. The water may be converted into steam or vapor; 34 THE CULTURE OF FARM CROPS. but the only difference between the water and the steam or vapor is that the particles of the water are separated widely apart by the heat and they become invisible ; but they exist still and can be brought together again and condensed into a fluid and reappear as water by the action of cold or the loss of the heat. These are mixtures. A chemical combination is entirely different. If w^e take some sulphur and burn it, it combines with oxygen from the atmosphere, and the solid sulphur becomes a powerfully corrosive gas which when mixed with water is known as sulphuric acid. This acid is a combination — not a mixture — of the two elements, and it cannot be separated into these without a complicated chem- ical process. If a piece of copper is put in a quantity of this acid, the copper disappears and the liquid becomes a solution of sulphate of copper. If the water is evaporated the copper sulphate remains in the form of clear blue crys- tals which are commonly called blue vitriol. This is a combination of the elements oxygen, sulphur and copper, but is not a mixture. All organic vegetable and animal substance consists of the four elements which have been previously described. The peculiar characters or properties of organic matter by which they are distinguished from inorganic matter and on w'hich their connection with the culture of farm crops depends, are chiefly the following. They are all easily decomposed, or apparently destroyed by heat. Starch, sugar, cotton fiber, straw or wood, w hen subjected to heat or flame, turn black and take fire and are consumed. This is true of all vegetable substances. But clay, sand or stone cannot be thus decomposed. They putrefy and decompose in warm moist air, and after a time almost wholly disappear. This is not the case with inorganic substance which is not subject to putrefactive de- composition. They consist almost wholly of two or more of the few organic elements previously described. They cannot be formed by art. Many of the inorganic compounds may be, and have been, produced in the chem- COMPOSITION OF VEGETABLE MATTER. 35 ist^s labratory ; but no chemist has yet produced starch or T/oody fiber, or sugar, or milk, or flesh, by jcombining the elements of these substances. This is an important distinc- tion and is likely to exist permanently ; although one can- not safely say what chemistry may not be able to perform in the direction of producing these articles of food, and of textile fiber, for which the world is now indebted to the art of agriculture, and so make the farmers labors useless. At present it is easy for the chemist to take apart, to analyze , but to put together and construct, has so far eluded all his skill, excepting in a very few instances. The four organic elements enter into the constitution ot plants in variable proportions. The following table shows the precise quantity of each element contained in 1000 parts by weight of the vegetable substances mentioned. Carbon. Hydrogen. Oxygen. Nitrogen. Ash. Hay from young clover Oats Clover seed Ripe Hay '. 471 Peas W^hcat 455 Hay Potatoes...... The above named products were dried at a heat of 230 degrees, sufficient to expel all the moisture from them. The <|uantity of water thus extracted was as follows : 1000 parts of potatoes.. lost 722 parts of water. " " wheat " 16G •' " early cut hay " 15S *' " late hay " 140 *' " oats " 151 " " cloverseed " 112 " " peas " 80 A large quantity cf water is contained in the crops grown upon farms even Avhcn they are dried for use. When en- tirely free from water, the carbon is nearly one-half the weight ; the oxygen is more than one-third ; the hydrogen about 5 per cent, and the nitrogen varies from IJ to 7 per cent.; the variation being greater than that of any other of these elements. These proportions represent very nearly 487 CO 369 38 40 507 64 367 22 40 494 58 350 70 28 471 56 349 24 100 465 61 401 42 31 455 57 431 34 23 458 50 387 15 90 441 58 439 12 50 36 THE CULTURE OF FARM CROPS. the relative weights in which the organic elements enter in- to combination in all the vegetable products which are grown for the support of animal life. All vegetable products contain some inorganic matter which remains behind in the form of ashes w hen the plants are consumed by fire, or as dust when they aro entirely de- composed and reduced by decay. In both cases, when these operations are entirely completed, the results are exactly the same. This inorganic remnant varies considerably; oats leaving but 4 per cent.; while ripe hay leaves 10 per cent.; but each variety of plant contains a certain propor- tion cf inorganic matter which is pretty nearly constant and is peculiar to itself. These facts are exceedingly im- portant in the practice of agriculture, and are simply no- ticed here, coming hereafter under special consideration when the nature of soils and the food for plants are under discussion. After having studied the character of the organic elements it will appear very clearly that they will not enter into the substance of plants in their natural state, or as they exist free and uncombined with other elements. Carbon is a solid substance and is not soluble in water; and as plants cannot take up anything that is solid into their circulation and tis- sue, but only matter that is dissolved in w^ater, or which is mixed with it in a gaseous form, or is in a free gaseous state, it is clear that plants cannot derive their carbon di- rectly from the element itself, as it exists in nature. Hydro- gen does not occur in the soil or in the atmosphere in a free state in any appreciable quantity, and in its simple condi- tion cannot form any part of the food of plants. Oxygen and nitrogen exist in the atmosphere in well known propor- ticns, in a gaseous state, and the former is absorbed or in- haled under certain conditions by the leaves of plants, while it ii quite possible that nitrogen may also be absorbed in the eanie manEer. But while it is known thr.t oxygen is taken up by the leaves, there is no knowledge that nitrogen is ; but every reason to believe that it is not. These two gases are slightly soluble in water and may occasionably be DIFFERENCE BETWEEN COMPOUNDS AND MIXTURES. 3/ tibsorbed with water by the roots of crops ; but by far the hirgest quantity of these elements enter into plants in the form of simple or complex combinations, or chemical com- pounds of a distinct character, and these being absorbed by the plants, are separated ' or decomposed ; the plants then selecting w^hat they require for their subsistence, and re- jecting the rest. It is then necessary for the farmer to study not only the nature of these compounds, but the laws by which their combinations are regulated and the manner in ■which they are effected. The difference between a mixture and a compound has been already explained, and it should always be borne in mind in considering this part of our subject. Combination is not a mechanical but a chemical action, and results ifl a permanent change in some or all of the substances employed ; decomposition is also a chemical action, and results also in permanent change of a combined substance or compound. When sulphur, a solid substance, is burned in the air, it is converted into a gas ; which is a compound of the sulphur with oxygen from the air. When limestone is burned in a kiln it is changed into lime, which is quite different from the original stone. This is a case of chemical decomposition for the limestone is a compound of lime and carbonic acid, and the acid is driven off by the heat, and the lime is left remaining. The limestone is quite neutral and inert ; it has no action upon w^ater, nor any taste ; but the lime is strongly alkaline and will effervesce strongly if put in vinegar or any other acid ; if put into water, it w^ill combine w^ith it and produce great heat, and it will destroy any organic matter brought into contact with it. If hydrogen gas is burned in the air and a piece of cold glass is held over the flame, the vapor produced by the un- ion of the two gases, is condensed into drops of water on the glass. It is thus seen by these examples which could be extended almost infinitely ; how important changes in matter are produced by chemical combinations and decompositions ; gases are combined and form liquids or even solids ; liquids imd solids are changed to gases; mild substances become 38 THE CULTURE OF FARM CROPS. corrosive and destructive ; and corroding substances com- bined become mild and innoxious. The laws which regulate chemical action are precise and inviolable, and the elements unite with each other only in constant and definite proportions. We can mix any twa gases together, as oxygen and hydrogen; or oxygen and nitrogen, in any proportion we please ; but we cannot com- bine them except in strictly definite quantities. We can burn a pound of hydrogen in any number of pounds of oxy- gen, but the hydrogen will unite with only 8 pounds of oxy- gen and make 9 pounds of water ; and this proportion never varies. We can discharge an electric spark in a jar con- taining a mixture of oxygen and nitrogen, and 8 parts by weight of the oxygen will unite with 14 parts of the nitrogen and form an oxide of nitrogen. If there is any surplus of nitrogen it will be left, and any surplus of oxygen will re- main; only so much of either will combine with the other,, and no more and no less under w^hatever circumstances may exist. Moreover, the very same proportion in which any two bodies will combine with each other is precisely the same in which they will combine w^ith any other. Thus 1 pound of hydrogen combines with 8 pounds of oxygen, and 8 pounds of oxygen combines with 14 pounds of nitrogen; therefore 1 pound of hydrogen combines with 14 pounds of nitrogen. These numbers are known as the combining or equivalent numbers ; but there are multiple proportions required in some cases to produce definite compounds ; for instance, to produce ammonia, it is necessary to take 3 proportions of hydrogen to 1 of nitrogen. The emblems of combinations or the mode of representing them is by using the initial let- ter of the element followed in case of multiple proportions or equivalents by a small figure. Thus N H3. represents one proportion of nitrogen or 14 (pounds) and 3 propor- tions (pounds) of hydrogen, making 17 pounds of ammonia. This beautiful law; beautiful in its precision and its simplicity exemplifies the general law of the universe ; which is, order, invariable and unchangeable. This regulates not only the motions of the planets, the earth, moon and stars^ CHEMICAL LAWS INVARIABLE. 39 around the sun ; but it also rules the formation of an atom of salt from its component parts ; or the structure of the mi- nute cells of a plant. Everything in nature is subservient to this unchanging law, that certain causes produce certain effects ; which are constant and invariable under all circum- stances. The farmer then as he cultivates his soil and watches the growth of his crops, knows that when he does his part ; which is to prepare the soil properly, and to fur- nish whatever is required to fertilize it and feed the growing plants ; nature provides the unfailing rules by which eifect is given to his work. There is no chance or uncertainty about it ; but the same surety that the results will appear in due time as that the sun will set in the west when the day is done, and will rise in due time to the fraction of a second in the morning. While the combinations of the four or- ganic elements with each other are almost endless, there are but few which contribute directly to the growth cf plants. Of these, carbonic acid, nitric acid, ammonia and water, are of the greatest importance; others being of less interest. The atmosphere, however, which is a mixture of the two most important elements, and which is the grand purveyor of vegetable life, contributing from 90 to 95 per cent, of their bulk to living plants, requires careful study and notice. THE CULTURE OF FARM CROPS. CHAPTEK VII. OF THE ATMOSPHERE. The earth is surrounded by a gaseous body known as the atmosphere or the air, which is supposed to extend to a height of forty-five miles above its surface. The actual height however is indefinite and immeasurable, because be- ing a gas, the air is capable of infinite expansion, according to the pressure upon it, and while we know that the pressure at the earth's surface of the vast mass of the air above it is equal to 15 pounds to the square inch, yet as the height above the surface increases, the pressure decreases ; and as the pressure decreases, the air expands, therefore the exten- sion of the atmosphere upwards cannot be marked by any distinct boundary, but gradually fades to a limit which can- not be precisely defined. The limit however of 45 miles is suflSciently precise for all practical purposes. The physical propeities of the atmosphere however, are of the greatest importance, as a great many results interesting to the far- mer as aflfecting the growth of his crops depend upon them. Air, as has been already stated, consists of 79 parts by bulk of nitrogen, and 21 parts by bulk of oxygen; or by weight 77 parts of nitrogen and 23 of oxygen. These two gases are mixed or difiiised together according to a law by which gases mixed together become evenly or uniformly (li Abused or mingled with each other, without reference to their weight. One may be much heavier than the others, yet it will diffuse itself perfectly through evers^ part of them. If it were not for this law the air would not be fit to sup- port life. In one place there would be masses of pure oxy- gen which would be equally destructive of life as the masses of pure nitrogen which has no vital qualities at all. This law of diffusion has another interesting application as regards the behavior of the air, and moisture in the soil. PROPERTIES OF THE AIR. 41 and the even distribution of plant food ; but this will be noticed more fully hereafter. The air contains, also evenly diffused through it, a very small proportion of carbonic acid. This averages about one part by bulk to every 2500 of air ; and varies slightly according to circumstances. This carbonic acid is of the highest importance to the growth of plants, inasmuch, as it is from this source chiefly, that, as is believed, plants derive -, this necessary nutriment, from which is formed, the cellular tissue, the starch, sugar, gum and fats, which they contain, and which makes up so large a portion of their dry sub- stance. The air also contains a varying quantity of watery vapor diffused through it, amounting to 1 per cent, of its weight on an average of season and locality. This proportion is largest in summer, increasing with the temperature, and least in the winter ; thus supplying the crops in their growl- ing season out of the abundance gathered up for their sup- port ; as well as to moderate the heat. This moisture is condensed as the temperature is reduced, and forms clouds, which, floating in the air, shade and protect the earth from the too ardent rays of the sun, and at night they reflect the heat which is radiated from the earth's surface, the loss of which in cloudless countries cau:3es intense cold in the night, following equally intense heat at midday, when nothing in- tervenes to intercept the burning rays of the sun. The air also contains varying quantities of matter con- tributed by decaying organic substances and from the dry soil; as ammonia evolved from putrefying plants; decaying leaves, and decomposing dead animals, and the excrements of living ones, and dust from this dried debris of animal life. A ray of light or a sunbeam passing through a crev- ice into a darkened room, shows this contribution to the atmosphere — which is not without its use and importance to vegetable life — in a myriad of particles which glisten as they float in the light. Air, like all other matter, has weight. This was first discovered about 200 years ago. A cubic foot of air weighs 42 THE CULTURE OF FARM CROPS. 538 grains, or more than an ounce, and the air con- tained in a room 40 feet square and 18 feet high will weigh a ton. The weight of the air, the ease with which a gas is moved, and the fact that the pressure of the weight is ex- erted in all directions, tend to force it into every vacancy, and to diffuse itself everywhere. Every pore and interstice of the soil is filled with it. There it yields up its oxygen to dead matter and quickly converts it into plant food; it carries with it its carbonic acid upon which the roots seize and convey it into the tissues of the plants, where it is elab- orated into new cells and the starch which fills them. Like all other gases it expands with heat and contracts with cold. Every change of temperature therefore expels a portion of the air from the soil or impels a portion to enter it. Thi& causes a constant current and change by Avhich the air is renewed and that vitiated by the loss of its useful properties is replaced by a fresh supply. Every shower of rain expels it from the soil, and as the water sinks to lower depth, the atmospheric pressure forces air again into the vacant spaces. All this has a most beneficial effect upon vegetation, the re- sults of which are to be considered hereafter. This vast body of air, like the watery ocean, has its tides^ its great currents, and its storms, which keep it in j^erpetual motion. AVhen the farmer hies to his field in the summer morning, the gentle zephyr fans his cheek. In the season of storms the boisterous gale beats him from his path and forces him to take shelter. All these motions serve to mix the air; to purify the centers of corruption; and bring ta them renewed springs of health and vigor. If one could float upon the surface of the atmosphere, great waves would be seen coursing over the vast aerial ocean. These extend for thousands of miles ; have many miles of elevation and their courses extend across oceans and continents. These enormous waves and the following depressions, necessarilly changs the pressure of the air on the -surface of the earth, and are marked by a change of the barometer. The result is an increased pressure under the wave with a rise in the barometer; and a decreased pressure under the depression CAUSES OF RAIN. 43- or trough of the wave with a fall in the barometer. This indicates the approach of wind. The high pressure under the wave forces the air to the center of the depression and the winds blow from all quarters to restore the pressure. Thus with every wave which ruffles the surface of the vast ocean above us, currents are set in motion around us, and the air is never still. The watery vapor suspended in the air is affected by this oscillation of pressure to some extent ; but far more by the changes of temperature. When the air is heated, evaporation from the ocean and the land is active, and the atmosphere is charged with moisture. A wave rising in the north with a depression in the south, brings a cold wind. This strikes the warm moisture — laden air, and the vapor is condensed in clouds. The condensation increases with the fall of tem- perature ; the clouds become heavy and black, and soon the pattering rain drops fall upon the thirsty soil, refresh the crops and gladden the husbandman. Or the friction of the cool current passing over a warmer one, engenders elec- trical disturbance, w^hen the lightnings flash and suddenly condense the gathered vapor, and the thunder showers pour down amid the deafening crashes and reverberations. All these facts of surpassing interest and which explain so simply the causes of these phenomena, are based upon a series of natural laws, which are as beautiful as they are wonderful, and they have been unfolded by science within a few years past. Our fathers knew nothing of them, and vainly imagined causes for them. But we knowing them, find ever new delights in their contemplation. We see that the vegetable worlel is derived in greater part from the air, and consists of condensed gases that have been reduced from the atmosphere by the agency of the sun's heat. Animals which derive all the materials of their structure from plants, destroy these w^hile living by respiration, and when dead by decomposition, and return them in gaseous form to the air again, whence they were taken. Thus the offices of plants and animals neutralize each other ; the one takes the materials for its substance from the air and builds. 44 THE CULTURE OF FARM CROPS. up its varied and beautiful organisms ; the other consumes these and undoes the work so performed, and pours back into the air, the materials for a new generation of plants. And so the cycle is completed ; but it never ends, because with each completed round a new round begins. THE PROPERTIES OF WATER. CHAPTER VIII. WATER.— ITS RELATION TO VEGETABLE GROWTH. AVater is a compound of oxygen and hydrogen in the proportion of 8 parts by weight of the former to 1 part of the latter: and by volume or bulk of 1 part of oxygen to 2 of hydrogen. It is more universally diffused throughout nature than any other chemical com[)ound, and performs the most important functions in regard to animal and veg- etable life Its remarkable properties are most wonderfully adapted to the existing condition of things and offer to the farmer and student of natural science the most interesting subjects for study and experiment. It exists in the 3 forms; a solid, as ice ; a liquid in its com- mon form; and a gas; as steam or watery vapor. At 32 degrees of temperature it becomes ice and remains solid ; at any higher temperature it melts and becomes liquid and at 212 degrees it changes to a gas, which continues to ex- pand under the influence of increasing heat. Steam is 1700 times lighter and more bulky than water and is a little more than half as heavy (sixty-two one hundredths) as air. It therefore rises quickly and becomes diffused through the air. Liquid water is 815 times heavier than air and a cubic foot of it weighs 62 J pounds. Water in the form of ice and snow has an important ac- tion upon the soil and consequently affects considerably the interests of the farmer. In the act of freezing — which is a process of ciystallization — water expands in bulk about one-eleventh. This expan- sive force is irresistible, because water is incompressible and cannot be reduced in bulk by any amount of pressure which can be applied to it. A very small quantity of water tliat may be absorbed by rocks, in expanding as it freezes, bursts asunder the particles of the stone and these flake off and form soil. In the soil a similar action goes on. The water 46 THE CULTURE OF FARM CROPS. •contained among the particles of the soil expands and loos- ens these particles and separates them from each other. When the soil is thawed by returning warmth, a thin crust is loosened from each clod and fragment and falls apart into exceedingly fine particles, and as the warmth penetrates the mass this gradually crumbles down and forms a larger bulk of fine porous earth. Moreover the particles of soil themselves are ruptured ; stones are gradually disintegrated, and new soil is made; and these particles are thus subjected to the solvent action of the 'water of the soil by which fresh plant food is liberated and the soil is enriched. This effect is the more remarkable when we learn that one single cubic inch of clay when reduced to fine particles by the action of frost presents in the aggregate superficial areas of the frag- ments, a surface of at least 100 square inches. The bene- ficial effect of this result of freezing upon the soil is of incalculable value to the farmer, both as regards the me- chanical condition of the soil and its fertility. On clay soils both of these effects are produced to the greatest extent. In the form of snow too Avater exerts a considerable effect which is beneficial to the farmer. The snow is exceedingly porous, being made up of a mass of crystals formed like 6 rayed stars, which lie very loosely upon each other. The interstices contain air and act as a non-conductor of heat, and as a protection against the severity of the cold, and also against sudden changes of temperature. In very, cold countries, the snow covering the soil early in the winter, prevents the freezing of it altogether, and tender plants such as potatoes, often remain green under the snow the whole winter, without injury in the warm soil. Such a climate obviously favors very much the successful growth of winter grain. Snow has also the power of absorbing ammonia, oxygen, and nitrogen from the air. Ammonia held in the snow is gradually taken in by the soil and is not lost as when it is brought down by rain, which not only carries it off in floods, but also washes a more considerable quantity of it from the soil into brooks and rivers. The air which is held in the open spaces in the snow holds only 17 per cent. SOLVENT POV/ER OF WATER. 47 of oxygen, against 21 per cent, in the ordinary atmosphere; the difference being absorbed by the snow, is carried into the soil with the water as the snow melts and thus conveys to the roots an additional supply of this vitalizing element. In its fluid condition, water is the vehicle by which all nutriment of whatever kind, is carried into the circulation of plants. It is itself a most important nutritive element — food in fact — for all plants and animals, forming about three-fourths of their substance and weight. It thus softens all tissue and gives it elasticity and strength. It is a uni- versal solvent; and thus brings to the roots of plants ^7hat- «ver nutriment is needed in such a form that it can be taken into their tissues. It dissolves about one-thirty-sixth part of its volume of air; and this air contains 10 per cent, more oxygen than other air. It also contains from two to twelve times as much carbonic acid as the ordinary air. One hundred volumes of water absorb directly 3.55 of oxygen ; 1.53 of hydrogen; 1,47 of nitrogen; l06 of carbonic, acid, or 7800 of ammonia. In this property we see how plants may derive the large supply of carbonic acid which they need for the structure of their carbonaceous tissue ; and a large proportion of their nitrogen which may thus be pro- cured from the dissolved ammonia. Water is never pure. As an example of its solvent power over solid mineral substances the following analysis of the water of the Dead Sea is given. Specific gravity of the water 1.172 Chloride of sodium (salt) 0702.73 grains. Chloride of potassium 682.63 Chloride of ammonium 3.35 Chloride of lime 1376.75 Chloride of magnesia 4457.23 Chloride of aluminium 31.37 Chloride of iron 1.50 Chloride of manganese 3.35 Bromide of soda 156.53 Iodide of soda trace Sulphate of potassium trace Sulphate of Magnesia trace Sulphate of lime 38.07 Phosphate of soda trace ■Carbonate of lime 48 THE CULTURE OF FARM CROPS. Silver Copper Lead Arsenic Silica Bitumen Organic matter 34.59 Total in one gallon 13489.17 grains. Per cent. 19.73 The water of springs, wells and rivers is thus never pure^ but holds in solution more or less of solid substances. Hence we find that land watered by irrigation from rivers produces much larger crops than that watered by rain ; also that land that has been or is periodically overflowed by floods, becomes exceedingly fertile. Even rain water is not pure except in the wettest seasons, when the atmosphere has been washed clean from its impure matter which is brought down by the showers. In this way a large quantity of solid fertilizing matter, as well as of fertilizing gases, is brought within reach of the roots of the plants by the rain which is absorbed by the soil. The water also dissolves matter from the soil and presents it to the roots in such a condition that it can be absorbed and utilized as nutriment. These facts prove how indispensable it is that the soil should be brought by thorough culture, and the use of the most perfect implements, into such a condition of porosity and mellowness that the water may be absorbed and held in it and not flow off^ from the surface and carry away into the streams, not only all its own burden of rich fertilizing matter but also rob the i^oil of a large j)ortion of its own possession. The solvent power of water is increased by heat, in regard to nearly all tiubFtr.nces excepting lime and ammonia which are dissolved r.nd absorbed by cold water more readily than by warm. This property will be further explained in a future chapter on heat. Water has a strong aflinity for various substances, indeed it exists in a greater or less proportion in almost all solid bodies and in every crystallized substance ; forming in these cases what is known as "the water of crystallization." When limestone is burned, water and carbonic acid are DECOMPOSITION OF WATER. 49 driven off by the heat and lime remains. (This lime is the oxide of the metal calcium.) When lime is brought into contact with moisture, about one-third of its weight of water is absorbed and the lime, swells, breaks apart and falls into a very fine powder which is perfectly dry. This water is combined with the lime and cannot be expelled at less than a red heat. Gypsum contains in the same manner 21 per cent, of water; alum contains 24 parts of water to two of solid matter ; Epsom salts contain 50.2 per cent, of water ; and so on through a long list of crystallized minerals. It has also a strong affinity for clay and all the more so, as the clay is finely pulverized and disintegrated ; carbonized veg- etable matter also takes up a large quantity of water ; hence the great advantage of securing as large a quantity of de- cayed organic matter, as may be possible in the soil. This is quite distinct from the mechanical grasp upon water exerted by porous substances, which merely hold it in its interstices by capillary attraction, as is the case with a sponge, and give it out again with great facility and with- out any chemical action. The elements of water are held together loosely and are combined with great ease. When hydrogen is burned in the air it combines with oxygen (as has been previously described) and forms water. If a piece of zinc is placed in a vessel of water — a glass bow 1 or a wide mouthed bottle, for instance — and a little sulphuric acid (a few^ drops) is added, the water is in part decomposed and the hydrogen is set free. As this experiment is a pleasing one and very simple, the chemical operation is here explained. The sul- phuric acid acts upon the zinc and combines with it ; but as this acid has only three equivalents of oxygen (S. O3) and zinc requires one more equivalent to make the combin- ation as sulphate of zinc (Z. S.O4) this excess of oxygen is taken from the water, leaving the hydrogen free, when it escapes in bubbles apparently from the surface of the zinc. If the bottle is corked and a glass or rubber tube is put through the cork, the hydrogen gas may be collected. But as it is explosive when mixed with air, great care must be 50 THE CULTURE OF FARM CROPS. exercised in igniting the gas, and the first ^yhich is set free should be permitted to escape until the air has been all car- ried off. Water undergoes continual decomposition and recombi- nation in the interior of plants and animals. As a fluid it finds its way into every cell and pore and passes out by transpiration after it has given up to the tissues the matter wliich is extracted from it. And so slight is the hold which its elements have upon each other, and so strong is their affinity for other elements, that they are ready to separate upon very slight impulses ; the oxygen forming compounds with one and the^ hydrogen Avith others, as the production of the various substances of which the plants form them- selves, require-and demand. And when the nature of chem- ical combinations begins to be understood, there is no more wonderful fact in the study of vegetable physiology than the great variety of changes which are continually going on through the agency of the elements of water and others which it conveys into the tissues of plants and animals. In the state of vapor too, water exerts a very potent in- fluence upon the life and growth of farm crops. Vapor escapes from water into the air, or is absorbed by the air, not only at boiling heat, but at all temperatures. Even at a zero temperature the air takes up water, as is known by the housewife whose linen freezes dry in the cold, crisp, wintry, air. A piece of ice exposed to the air in the coldest weather gradually evaporates and disappears. It is how- ever in the summer that the evaporation of water is most active; and it is then that the efiects of the condensation of the at- mospheric moisture is most perceptible and useful. Dew is the product of this condensation. The air charged with the vapor which has been gathered during the heat of the day, is cooled at night by contact with the soil, from which the heat is rapidly lost by radiation. The cooling of the air causes the moisture to condense, forming sometimes visible vapor, seen in the evening and night fogs which prevail in some localities ; but always a burden of moisture which is too heavy to be suspended in the air. This moisture then FORMATION OF DEW. 51 falls and settles in fine globules upon the vegetation, the soil, and upon all other objects which have been sufiiciently cooled. This process goes on mostly at night, but constantly at other times when the temperature falls, and especially in the soil, in which with the constant circulation of air (prev- iously described) there is always the accompanying mois- ture ; which is condensed and deposited in the interstices and so supplies the demands of the plants. The more com- pletely the soil is made fine and pulverized the larger is the deposit of atmospheric moisture. This behavior of water under the beautiful and compre- hensive laws to which it is subject, affords an instance of the provident as well as bountiful operations of nature. Every one of these operations tend towards the good of mankind. It is the cultivator of the soil who reaps the benefits of these Tiniversal and beneficent laws. Yet the rewards are not given to all alike. AVe are told that the rains descend, the dews are distilled and the sun shines upon the just and the unjust ; upon the industrious as well as the idle and neglect- fa\. An impartial and kind Providence offers these bene- fits with an open and generous hand ; overflowing with good to mankind. But Providence does nothing more. The farmer who avails himself of these invaluable gifts and does his part by studying the nature of them and their adaptation for his purposes ; and thus adapts them with skill and in- dustry to the preparation cf the soil and the culture of his crops, gains the highest rewards. The prizes are his ; but the blanks in the distribution are for those who neglect these grand provisions and refuse to avail themselves of them. It is "the hand of the diligent which maketh rich:" the neglectful careless tiller of the soil has no promise of wealth from the free gifts of nature ; these are for the farmer who uses every possible means to secure these gifts by the prac- tice of an intelligent and effective culture of crops. THE CULTURE OF FARM CROPS. CHAPTER IX. HEAT AND COLD.— THEIR INFLUENCE UPON MATTER AND VEGETATION. Heat and cold are merely relative terms. Cold is a low- degree or absence of heat, just as darkness is the absence of light, and has not in any sense, or in fact, any specific ex- istence, as separate from heat. It is only quite recently that the nature of heat has been understood. It was for- merly supposed to be an element, a subtle fluid to which the name Caloric was given ; and whose entrance into a body produced warmth and whose loss produced cold. As some bodies, such as marble, felt cold and others, as wool, felt warm, it was believed that various substances contained less or more of this fluid stored up in its interstices according to their varying capacities. It was given, in fact, all the properties of a gas with some others which were believed to belong to it specifically. This ancient notion was exploded when it was discovered that heat was simply the effect of motion of the particles of a body, and that the intensity of the motion determines the temperature. It is not the purpose here to discuss the various theories which are held in regard to the nature of heat ; these may be studied in special works on the subject such as that of Prof. Tyndall. It is most important for us to consider how it affects those elementary and compound bodies which have a close relation to the growth of plants, and its effects upon - germination and plant growth. It will be sufficient here perhaps to repeat the words of Dr. Locke uttered a hun- dred years ago in which the true idea of heat was enuncia- ted. He said, "heat is a very brisk agitation of the insen- sible parts of any object which produces in us that sensation from which we call the object, hot; so that what in our sensations is heat, in the object is nothing but motion." A LATENT HEAT. 03 familiar instance may be given. If a person slide down from an elevated place by means of a rope held in the hands and he descends rapidly he feels a burning sensation in his hands and the skin is blistered precisely the same as if he held a hot iron rod in his hands. This heat is the re- sult of an intense vibration of the fibers of the muscles and skin of the hands ; and is equal in degree exactly to the vi- bration of the particles in an iron rod whose heat would cause precisely the same sensation and result in the hands. To study the relations of heat with intelligence it must not be regarded as a thing, but as a condition of matter and an effect of the change of a condition. The chief source of heat is the sun. All combustion is a source of heat, and as we have seen, combustion is a chemi- cal effect. Mechanical force is also a source of heat; and friction, pressure, or any other result of force is accompanied by heat. Heat once produced is never lost or destroyed : it may disappear but it always exists. The heat of the sun communicated to the earth is absorbed in various ways, that is we use this expression ; but in truth we should say the force is communicated to every object brought under its influence. It is absorbed by the waters of the ocean and their particles move and separate more widely apart form- ing vapor. The amount of force (which we call heat) thus commun- icated has been accurately calculated. If we take an ounce of ice at 32 degrees and one of water at 174 degrees and put them together, the ice will be melted and there will be two ounces of water; but the temperature will be only 32 degrees. Where has the excess of 142 degrees of heat which has been apparently lost by the hot water, disappeared? It has not been lost but has become stored up in the water and has become the latent or hidden heat of the liquid. This latent heat can be found again when the water is froz- en, for in the formation of ice precisely 142 degrees of heat are given out by the water in the gradual change of the liquid to a solid. In the same way when water is changed to steam a very 5-i THE CULTURE OF FARM CROPS. large quantity of heat is rendered latent in the vapor. Water at 32 degrees absorbs 180 degrees of heat and reaches a temperature of 212 degrees which is the boiling point. But it does boil only slowly and steam is produced very gradually. It is found that if the consumption of one pound of coal will raise a quantity of water from 32 degrees to 212 degrees; 5? lbs. more will be required to change it all to steam of the same temperature. 5 2 times 180 or 990 units of heat will then have been expended, but have not been lost ; they are stored in the steam and are the latent heat of the vapor of water. And when the vapor of w^ater is condensed into liquid this heat is given out again. And here is another most wonderful instance of the infinite wisdom and beneficent adaptation of the laws of nature to the stability of the universe and the comfort and happiness- of mankind. The expansion of water as it changes into ice has been already mentioned. This is one more effect of heat, that is a reduction of it, upon this liquid, and has an intimate connection with this part of our subject. When water reaches its maximum density which is 39 degrees, un- der the influence of the abstraction of heat, it then begins to increase in bulk until ice crystals form when the total expansion amounts to one-eleventh of the bulk. Conse- quently the ice floats on the surface and after a time it be- comes thick enough to protect the underlying water from the effects of cold. Were it otherwise, ice would sink to the. bottom and as the surface water cooled it would also sink and the whole water would soon be changed into ice. The ocean would then become a vast bed of solid ice, which by the very force of this law would remain permanently and re- sist all the heat of the sun to change it. Then the earth would be uninhabitable. No green blade would appear on the surface ; no animal would find subsistence ; there would be no clouds, no rain ; everything would be cold and drear and lifeless ; a dead world. Again, were it not for the gradual absorption of heat by the melting ice and the evaporating water, the earth would THE FORCE OF HEAT. .65 be destroyed by the sudden catastrophe of an overwhelming flood at the approach of every spring. The, accumulated ice and snow of the winter would be changed to vast bod^ ies of water as soon as they reached the temperature of 32 degrees; and when the boiling heat should be reached, the water w^ould change into steam with the force of an ex- plosion and rend everything near it to atoms. Instead of being useful to man it would be a most destructive agent, which men would avoid as they would avoid nitro-glycerine. The contemplation of these thoughts gives a new force and interest to the fact that "the earth was given to man" and truly the gift was perfectly well adapted to his uses, and for his enjoyment. It has been shown that the force equivalent to the heat required to produce 9 lbs. of steam at 212 degrees by the union of 8 lbs. of oxygen and 1 lb. of- hydrogen is equal to that represented by the fall of a ton weight down a preci- pice 22,320 feet high : to change this vapor into liquid a force is exerted equal to that of the fall of a ton down 2,900 feet; and to change the water into ice the force is equal to the descent of a ton down 433 feet. And yet these enormous forces are going on in the soil and in the tissues of delicate plants> continually, silently, but omnipotently; without any out- ward indication. Prof. Tyndall has remarked of this lat- ent force hidden in a drop of water, "I have seen the Avild stone avalanches of the Alps; which thunder and smoke down the declivities with a force almost sufficient to stun the observer. I have also seen snowflakes, descending so softly as not toi injure the fragile spangles of which they were composed; yet to produce from aqueous vapor, a quan- tity of that tender material that a child might carry, de- mands an exertion of energy competent to gather up the shattered blocks of the largest avalanche I have ever seen and to pitch them to twice the height from which they fell."" Combustion is a source of heat; and the decay of organic substance is a slow combustion. This fact is exemplified in the decomposition of vegetable matter. When the farmei* 56 THE CULTURE OF FARM CROPS. makes a heap of manure, or a hot bed, the mass soon begins to heat and in time is changed from its previous condition into a black powdery substance having no resemblance to vegetable tissue. The heat produced by the chemical ac- tion which has resulted in this change has been precisely equal to that which would have been required to drive off the moisture; set free the gases; and reduce the matter to its mineral, carbonaceous, and nitrogenous elements w^hich remain in the mass. In like manner heat is produced by every chemical change. The union of water with sul- phuric acid is accompanied by violent heat; so is the solu- tion of a piece of copper in nitric acid. And as the decom- position of a vegetable cell in a manure heap is accompanied by heat so is its decomposition in the soil; and its formation in the plant. The effects of heat — and cold — upon the soil are great and varied. It is the sun's heat, penetrating the soil which causes the germination of the seed. At low temperatures seeds will remain in the soil for many years unchanged. The heat of the sun does not penetrate very deeply and at a very moderate depth the heat of the soil is constant, dur- ing summer and winter. This is caused by the effect of evaporation, as well as by the nonconducting property of the air spaces between the particles of the soil. Seeds of weeds and plants which remain at some depth in the soil are thus kept dormant for many years, starting into growth whenever they are brought under the influence of the warmth of the sun's rays. The heat of the sun also causes the evaporation of water from the soil and dries it and makes it fit for the labors of the farmer. But this result has also another effect which is unfavorable. It cools the soil and reduces the temperature, and when the soil contains an excess of water and the evap- oration is copious, this cooling is exceedingly hurtful to the crops. There are soils which are called cold clays; and swampy lands are always cold and unproductive of the bet- ter class of crops, favoring the growth of mosses and ferns and other useless plants. This is due to the constant evap- THE EFFECTS OF VARIATIONS OF TEMPERATURE. 57 oration from the surface. To change the water into vapor, has been shown to require a large expenditure of heat; and precisely the same heat is drawn from the soil when vapor rises from it as is imparted by the fuel of a fire which pro- duces the same amount of evaporation. This heat drawn from the soil necessarily reduces its temperature. An ex- periment which exemplifies this result may be made as follows : A few drops of ether are placed upon the skin ; and the breath is blown upon it. The current of air evap- orates the volatile ether quickly, and causes a large absorp- tion of heat. The abstraction of the heat from the skin to supply this requirement of the evaporation causes a sensa- tion of cold upon the skin. This is precisely the effect up- on the soil, when the warm air blowing over wet clay or swampy land causes copious evaporation and is all the greater as the evaporation is excessive. This effect operates to relieve persons from the results of excessive heat. AVhen the temperature rises to 90 degrees and over, the animal system becomes oppressed. The blood Avhose normal heat is 98 degrees, rises in temperature and produces serious disturbance of the nervous system, which if not relieved quickly ends in what is known as sunstroke, and speedy death. But the evaporation of the water of the system in the form of perspiration relieves the oppression; carries off the heat ; cools the blood and the skin; and prevents the fatal results of the unrelieved heat. When an incau- tious person suddenly plunges into cold water, or drinks oold water to excess, the pores of the skin are closed in the one case and a chill is produced in the other; either of which checks the perspiration; and prevents the escape of the internal heat; when fatal results are often produced. So the wearing of wet clothes abstracts heat from the body and thus produces pernicious effects; while the use of wet sheets in which fever patients are wrapped; rapidly cools the parched skin ; induces natural perspiration; and saves the sufferer. The abstraction of heat by evaporation is so great under some circumstances that water can be frozen by it. This 58 THE CULTURE OF FARM CROPS. may be shown by a simple experiment. A shallow vessel containing sulphuric acid is placed in another containing water and both are placed under the receiver of an air pump. When the air is exhausted the vapor of the water is so rapidly absorbed by the acid that the water is frozen. By using liquid sulphurous acid which evaporates with in- tense force, and pouring it into a red hot vessel, and then adding w^ater, the water is suddenly frozen into ice under the intense cold produced by the rapid evaporation of the acid. The low^est degree of cold ever produced; 220 degrees below zero ; was by means of the vaporization of liquid Y)yo- toxide of nitrogen mixed with bisulphide of carbon in a va- cuum. These examples however are not of practical interest to the farmer further than to exemplify the vast and varied changes produced in matter by heat and cold. The same kind of result may be produced by the sudden liquefaction of solids. Thus a mixture of salt and ice causes the rapid melting of the ice and a sufficient reduction of temperature to freeze w^ater. In this case both the solids are liquefied and the effect is intensified. The cold thus produced is 40 below^ zero. Four ounces of sal ammoniac and the same quantity of saltpetre, finely powdered and dis- solved in 8 ounces of water, will cause a reduction of 40' degrees of temperature; and powdered Glauber's salts, drenched wdth hydrochloric acid, will sink the temperature from 50 degrees to zero. These mixtures are in common use as the so called freezing mixtures. The newly intro- duced ice machines by which ice is produced at a cost or one dollar per ton, are operated by the vaporization of am- monia in the gaseous form from its solution in water. A very useful practical application of the liberation of heat by freezing is that often used to evade the freezing of the contents of cellars in very cold w^eather, by placing a pail full of water in the cellar. The w^ater freezes more eas- ily than any other liquid or solid containing liquid ; as fresh vegetables and fruits; and in the act of freezing gives out the latent heat of the water which actuallv warms the eel- EFFECTS OF EVAPORATION ON CLIMATE. 5^ lar. For the same reason the coolness of the early winter is subdued and greatly modified by the heat given out by large bodies of water in the act of freezing; and in this way lakes and rivers, as well as the ocean, have a very import-^ ant influence upon the climate of adjacent localities. Late frosts are avoided and the intense cold is delayed until later in the winter. This fact has given rise to the common adage, "As the days begin to lengthen, the cold begins to- strengthen," by which is meant that the cold does not be- come severe until the beginning of the new year, when the waters and the ground have become frozen and all their latent heat has been given out. The heats of the summer are also much reduced in in- tensity by the excessive evaporation from bodies of water and from cultivated soil. It has been found that the climate of the great western plains has been favorably modified by the in- troduction of irrigation and the breaking up of the vast areas of dry prairie which have been brought under tillage. Evaporation of the water thus used, or gathered in the por- ous soil by the rains, which are absorbed instead of flowing as heretofore, from the dry hard surface in vast sheets and floods to the nearest stream, both cools and moistens the air; supplies the vapor for clouds which shade the soil and temper the sun's rays, and which in turn descend again to the soil whence they came in genial cooling showers. This ia a remarkable instance of how man's industry modifies- climate by changing the natural conditions prevailing and so fits the earth for his occupation and use. THE CULTURE OF FARM CROPS. CHAPTER X. CARBONIC ACID.— ITS PROPERTIES AND FUNCTIONS IN PLANT GROWTH. Carbonic acid is one of the three materials which together form the starting point of vegetable growth ; the others be- ing water and nitric acid. This acid is formed of carbon and oxygen in the proportion of one part of the former to two of the latter chemically combined. It is a colorless gas, having an acid taste and smell; is soluble in water; weighs one-half more than air and can be poured from one vessel to another, as a liquid may be; 100 parts of water dissolve 106 parts of this gas, and it is from this source that the roots ■of plants derive the needed supplies of it. It is produced by the combustion of carbon in the atmos- phere; when it unites with oxygen in the proportions men- tioned. An easy way to produce it is to burn charcoal on an open hearth. In a close room this combustion takes the oxygen from the atmosphere and fills the whole space with carbonic acid. This necessarily is a dangerous proceeding and at times causes fatal results, by the keeping of char- decaying animal and vegetable matter, induces this matter to attract oxygen from the air with greater rapidity and abundance. That is, in simple words, ammonia assists in and hastens the decomposition of organic substances, and the result of this is that compounds are formed which react upon the ammonia, combine with it and form ammoniacal salts- When these are in their turn decomposed by lime or other substances in the soil, they become more available plant food, being more advanced towards a fit condition for this purpose and for assimilation into the circulation and cellular tissue of vegetables. Seventh. — The most important property of ammonia, and that consequently of the greatest interest to farmers, is the ease with which it undergoes decomposition, in the air, the soil, and the interior of plants. In the atmosphere it is intimately mixed with a large quantity of oxygen and it also comes into close contact with this gas in the soil. By certain influences already referred to it undergoes a slow and constant decomposition, or oxi- dation, its hydrogen being converted into water, and its ni- trogen, wholly or in part, is changed into nitric acid. This change certainly goes on within the soil and most probably within the substance, or in the sap, of plants. That some- thing of this kind goes on within the plants, as well as in the soil, seems to be clearly indicated by the extraordinary eflfect of a small quantity of ammonia or of its comjDounds; in a remarkably short period of time; upon the condition of vegetation. This is very conspicuously seen, in the sim- ple experiment of growing plants in pots where the condi- tion of the soil can be controlled and the effects of plant food noted. A few drops of ammonia added to the w^ater used for the plants, will be seen to change the color of the leaves in a very short time; producing a deep vivid verdure, where before a pale yellowish color prevailed. Investiga- tions are in progress to decide this question but a speedy solution is not likely to be reached. The conditions under which plants exist and the reactions of the compounds of which they are made up upon each other are so varied, that 76 THE CULTURE OF FARM CROPS. a judicious student hesitates to form conclusions, and pa- tiently repeats and verifies his experiments; and at the last when he is himself convinced of the truth of any result, he is slow to declare it to the world, but watches it and tries it in other ways until doubt has no longer any existence. Hence the slow progress of knowledge in the true science of agriculture and the caution with which farmers who are following up the experiments of professional students, should watch the results, and form practical conclusions therefrom. But the peculiar action of ammonia upon plant growth, and the analogy which exists between its action and that of other compounds, lead us to believe that ammonia enters in- to the circulation of plants, and that the hydrogen of which it contains so large a proportion, there separates from the nitrogen, and combines with other organic elements which enter by the roots or leaves and thus aids in producing the various solid substances of which plants are constructed and made up. The nitrogen is then fixed in the flowers, helping to produce the bright coloring matter and the agreeable odors; and to form the gluten and albumen of the seeds, and other parts. These and other important considerations will be more fully considered in another chapter. It may be exceedingly interesting to note here, the results of some careful tests made by a German agricultural chem- ist and experimenter, in regard to the effects of ammoniacal manures upon the yield of grain and the proportion of the nitrogenous substances contained in it under varying cir- cumstances. A number of experimental plots were treated as follows, and were sown with wheat. Then from 100 parts of the produce of these plots the various amounts shown of gluten and starch, and the increased product, were estimated. Gluten. Starch. Produce. Without manure 9.2 66.7 3 With rotted vegetable matter only.. 9.6 65.94 5 Cow dung 12.0 62.3 7 Horse dung 13.7 61.64 10 Sheep dung 33.9 42.8 12 Night soil 33.14 41,44 14 Dried blood 34.24 41.3 14 Dried urine 35.1 39.3 12 EFFECT OF AMMONIA UPON WHEAT. 77 These facts seem to show that as the ammonia in the man- ures increase, the yield of the crop grown is larger, and the more nitrogen is contained in the produce. Similar results have occurred in the ordinary operations of the farm and the facts have led farmers to use artificial manures rich in ammonia for the express purpose of procuring more valua- ble grain and a larger yield of it. Millers knowing these facts have taken special pains to acquaint ^rmers with them, with the purpose to procure a better quality of grain for making more valuable flour. THE CULTURE OF FARM CROPS. CHAPTER XIII. 'THE SOURCES OF THE CARBON OF PLANTS.— HOW IT ENTERS INTO THEIR CIRCULATION AND SUBSTANCE. It is obvious to the cultivator of the soil that the various plants of which his crops consist, are supported by the earth and the air, both. It is necessary to the intelligent culture of farm crops then to learn how much plants owe to each of these; and for which of their elements they are indebted to the soil and for which to the air. As carbon contributes the larger part of their substance to plants this element de- mands the first consideration. Carbon is a solid substance and is therefore incapable of entering directly into the structure of plants. It must then present itself to the roots of plants in the soil, in solution in water; and to the leaves in a gaseous form; for it is a law of plant grow^th that no solid substance can enter into the roots; and no liquid or solid substance can enter the leaves or any other portion of the plant which is above the ground. Therefore the sources of all vegetable carbon must be the soil in which the roots of plants exist, and through which they penetrate; and the air in which the stems and leaves of plants are constantly bathed. There is always a large quantity of vegetable matter in a decaying state in the soil, and which is made up of the remains of previous vegetation ; and the farmer is continually adding to this by the manure which he applies to the land for the purpose of feeding his crops. And it has been shown that about one-half of this matter consists of carbon. The question then arises; is this carbon of the soil, the source from which plants derive their supply; and do they feed upon it by and through their roots; or do they derive it from the air, in which we have learned that a vast amount of carbonic acid exists in the form of an evenly diffused mixture. It is not usual for far- WHENCE DO PLANTS DERIVE THEIR CARBON. 79 mers to consider this question with much interest, if at all; giving more attention to the other elements of plant growth and leaving the carbon to take care of itself. 'But it is a question which should be carefully considered, because of its importance and because other questions which draw atten- tion from it, may become more prominent than they deserve. We know that there was a time when no vegetable mat- ter existed in the soil and when vegetation first covered the earth's surface. Then the first plants must have grown and matured without the aid of any vegetable or animal matter in the soil and could have derived their carbon from no other source than the atmosphere, directly; or indirectly, by its presence in the water in the soil. It is also known that soils which have been perfectly arid and have produced no vegetation, or very little previously, yield abundant crops when brought under culture by irrigation, and that plants are often grow n in water and in some cases grow lux- uriantly without having any connection with the soil. Further it is a common practice for farmers, when their lands are unable to produce maximum crops, to seed them to grass or clover and to leave them for years to recuperate and become enriched by the gradual accumulation of veg- etable matter in the soil; and when these lands are again plowed a rich black soil filled with carbon is found, where but little organic matter existed previously. This also ap- plies to lands under forest growth, and to the rich prairies of the west, where the dark vegetable mold- lies many feet in thickness and contains an inexhaustible supply of carbon; as well as to the peat swamps in which enormous quantities of carbon have been accumulated. We may also take into consideration the vast beds of coal which have been made up of accumulations of vegetable matter, the luxuriance of which, proved by its remains, still to be recognized in the coal, almost surpass imagination; and may then ask, whence did all this vegetable growth procure its carbon, which has gradually accumulated in the soil to this vast extent; and which we can perceive still accumulates under our own personal observation ? 80 THE CULTURE OF FARM CROPS. Any reasonable person will be impelled to reply, the atmoS' phere must have been the first source of it; that all these- plants must have existed upon such carbon as they could gather from the air, and that as they perished, they left a supply in the soil which was not fit to nourish succeeding generations, and hence accumulated during the vast periods of time which have elapsed since vegetable growth first began. This reasoning is plausible and seems free from objection, and would seem to justify us in concluding that plants de- rive their carbon directly from the atmosphere. In some cases this must be certainly true, for there is no other ex- planation to be given of the circumstances. But as regards the culture of farm crops it would not be safe to conclude that the vegetable matter of the soil has no relation to the growth of plants, and that the carbon existing in the soil does not contribute to the carbonaceous substance of vege- tables. For facts prove otherwise. Just now the public interest is in a lively condition of agitation in regard to the question, whence do plants gather their nitrogen, and the equally important question in regard to carbon is neglected. Farmers are actively engaged in procuring nitrogen in va- rious forms at very considerable expense, believing this to be the chiefly indispensable agent in fertilizing their crops. But a few farmers of intelligence, and used to closely ob- serve what is going' on in their fields, have not lost sight of the importance of a large supply of combined carbon, and are adding to their fields as large a quantity of carbona- ceous matter as they can procure, with such nitrogen as may seem to be adequate, and are thus avoiding the ex- treme to which the popular belief seems to have turned. In considering this question in the light of present expe- rience, it may be considered that at first only a very poor and weak growth of inferior plants covered the soil; or that by reason of the exceedingly active chemical changes which were then occurring, the soil was highly charged with carbon in such forms as were available for plant food. In the one case vegetable growth would proceed slowly to fill CARBON DRAWN FROM THE AIR. 81 the soil with decomposing matter and prepare it for a bet- ter product; and plants procuring a portion of their carbon from the air and gradually finding an increased supply in the soil from the decomposed organic matter, there would, in time, be a surplus, and this surplus would constantly in- crease, and gradually accumulate and fill the soil. In the other case the vegetation would be developed on an enor- mous scale, just as we have reason to suppose it was at the period when the carbonaceous matter which supplied the materials for the vast coal beds was deposited. Climate necessarily would have much to do with this, as it has now; for in tropical regions the vegetation is exceedingly luxu- riant, forming dense jungles through which it is impossible to pass without laboriously cutting a way with axes, over an enormous deposit under foot of the tangled and decompos- ing remains of previous luxuriant growth. We are forced to believe from the evidence that plants may derive a large portion of their carbon from atmospheric sources, and that they derive a considerable portion of it from the soil. That they are fitted by nature to draw sus- tenance from either source or from both; and that the pro- portion of their food which is derived from either source depends upon a variety of circumstances; such as the nature of the plant; the period of its growth; on the soil; on the abundance of provision furnished by the soil; upon cli- mate; season; and other circumstances; so that the most reasonable conclusion would be, that plants, like animals, have a power of adapting themselves, to a certain extent, to the conditions in which they are placed, and of finding aliment, and supporting life, and of making growth, by the help of such nutriment as they may most easily reach. Just as sheep, which are herbivorous animals, under cer- tain conditions are known to live upon fish, and to thrive as well to all appearances upon this unusual diet, as upon the pastures. But supposing that plants derive the whole of their car- bon from the air, or are able to do so; then knowing that no other compound of this element is found in the atmosphere 82 THE CULTURE OF FARM CROPS. to any appreciable extent, than carbonic acid, and that diis compound is everywhere diffused throughout the atmos- phere and is always found in solution in water, the con- clusion cannot be avoided, that it is from carbonic acid that the carbon of plants is derived, primarily. This con- clusion is supported and confirmed by the knowledge that plants absorb carbonic acid through their leaves in the sun- shine, and that they will die in an atmosphere from Avhich carbonic acid is wholly excluded. Again supposing that plants derive their carbon wholly from the soil or are able to do so, then, knowing that the most abundant product of the decay of vegetable matter is carbonic acid ; and that in a well manured soil filled with decaying vegetable matter, this gas must be quite abun- dant; and that water dissolves it freely, we must be satisfied that it is from this carbonic acid, absorbed with the water of the soil by the -roots that the carbon of plants is derived. In either case it is the carbonic acid w^hich supplies the car- bon, and it is most probable that this enters the plant both by the roots, and leaves. Thus whether from the earth or the air, this gas furnishes an unfailing supply of food for plants from which their carbon is derived. But when w^ater passes through the soil it takes up what- ever soluble substance it may meet — potash; soda; lime; magnesia; silica; &c.; and conveys them into the plants by the medium of their roots. Do the roots exercise a super- vision over the absorbed waters and reject every soluble form of carbon but that of carbonic acid ? This is a ques- tion of interest too to the farmer and applies directly to the practice of manuring the land. This subject is out of place as yet, but the question is pertinent to the present enquiry. It is know-n that plants do not exercise such a watch and have no discretionary power over the water which they ab- sorb; for various coloring matters as madder and the juice of poke root berries have been absorbed into the circulation of plants and have imparted their color to the flowers, and other parts. These coloring matters then undergo a chem- ical change in the plants and even afford nutriment. Sugar CARBONIC ACID A FOOD FOR PLANTS. 83 gum and gelatine have been thus fed to plants, with the ef- fect of making them grow vigorously. A great variety of organic substances containing carbon may therefore be ab- sorbed into the plants and afford nourishment. Practical farmers act on this principle and it forms the basis of many of his operations and daily labors as he accumulates a stock of organic substances in the form of manures as food for his crops. THE CULTURE OF FAEM CROPS. CHAPTER XIV. SOURCES OF THE NITROGEN OF PLANTS.— ITS COM- POUNDS AND THEIR EFFECTS UPON THE GROWTH OF PLANTS. While the quantity of nitrogen contained in plants is small as compared with that of other elements, yet its office in the structure of plants, and especially of their seeds, is- so important that careful and patient study of the character and changes of this element is well worthy of the time em- ployed. It is not always the most abundant elements in nature that are the most worthy of regard. The chief pur- pose of many farm crops is the seed, and although this part of their substance may be quite insignificant in quantity, yet it is often the most precious and highly valued ; and it is in the seed that the nitrogen of plants is most abundantly stored. Again while the nitrogen in the more bulky crops- may be but 1 to 2 per cent., this element is the most impor- tant for the profitable feeding of farm stock: as it contrib- utes largely to the formation of the muscular tissue and supplies the waste of it by muscular exertion. Moreover, any substance is to be valued according to the dififtculty of obtaining it. A diamond is so highly valued as it is, because a whole year's labor of several men may be spent in the vain search for one, and its enormous price in commerce merely represents the labor spent in its success- fill discovery. Nitrogen is the most costly substance the farmer is obliged to procure for the purpose of feeding his crops, and although it is the most abundant constituent of the atmosphere, yet it is so inert and passive and submits to combination with other elements so unwillingly, that na- ture supplies only a small portion of what the soil requires of it, to produce a profitable crop. It is a most serious fact in regard to this point, that the greater part of the farmers THE IMPORTANCE OF NITROGEN. 85 labor and his largest expenditures for fertilizing matter, are made necessary for the purpose of supplying his field with an adequate amount of nitrogen for the growth of good crops. Does he spend labor and care in the preparation of the soil ? it is that nitrogen compounds may be developed in it. Does he feed his cattle with rich food purchased at great cost? it is that the manure may be enriched with as large a quantity as possible of this valued element. Does he laboriously gather organic matter and lime, and compost these with his manure, and sedulously watch over the de- cay of these materials? it is that the nitrogen developed may not be lost, but preserved for use to supply the never satisfied needs of his crops. And thus his thoughts by day, and his reflections by night ; his labors ; studies ; and ex- penditures ; all center upon this one most important, but otherwise inconsiderable element of vegetable matter. With regard to an element so diflScult to be procured, it is a serious fact that its consumption in the soil is compara- tively large. A crop of hay takes 60 lbs. of it from one acre of the soil; a crop of clover removes 180 lbs. ; wheat carries off 45 lbs. Hereafter this subject will be pursued to its completion, here it is the purpose to consider the sources from which plants can procure their supply rather than the amount of it which they need. When we come face to face with this question we are met with the fact, that the only source from which any- large quantity of nitrogen can be obtained is the atmosphere. Nitrogen does not exist in the rocks excepting in those of an organic origin as coal ; the atmosphere is the great store- house of it. Organic matter contains a considerable quan- tity of it, and its decay in the soil furnishes the crops with a large part of their demands ; but the first plants which covered the soil must have procured their supply, as they procured their carbon ; viz, from the atmosphere, primarily. But in coming to this conclusion it by no means follows that the nitrogen of the atmosphere is directly absorbed by plants and made subservient to their growth ; or that it is absorbed in an uncombined state through any other me- 86 THE CULTURE OP FARM CROPS. dium. Though the leaves of plants are continually sur- rounded by nitrogen, and the roots may be bathed in water containing it in solution, yet there is no evidence to show that any plant is so constituted as to avail itself of this supply. Indeed there is a. good deal of evidence to prove that the leaves do not absorb nitrogen and that if any uncombined nitrogen at all is contributed by the at- mosphere and used by plants, it is through the roots that it must enter into their circulation. But that even this oc- curs is a matter of opinion only, with no evidence to sup- port it. It is an essential part of good farming to break up the land and reduce it by thorough tillage, by means of the most effective implements, to a loose and mellow condition, so that the air can have access to the decaying organic mat- ter in the soil ; as well as to the living roots which permeate the earth in all directions to considerable depths below the surface. When the air is thus admitted to the roots, it is not impossible that some of the nitrogen, as well as some of the oxygen, may be absorbed and made use of by the plant di- rectly ; but in the changes in the organic matter which oc- cur, it is known that nitrogen is disengaged in a form in which it can be appropriated by plants ; and it is probable that some atmospheric nitrogen may also be seized upon and converted into plant food at the same time. To what extent this may happen however we have as yet no certain re- sults from which any definite knowledge has been reached. If any nitrogen enters the roots of plants in solution in wa- ter, the quantity is very small and uncertain. When water is exposed to the air it gradually absorbs- both oxygen and nitrogen ; as has been previously men- tioned. The whole quantity of these mixed gases thus tak- en up amounts to about 4 per cent, of the volume of the water and in rain water about two-thirds of this quantity consists of nitrogen. A hundred cubic inches of rain water will therefore carry into the soil 2| inches of this gas. But this water in passing through the soil dissolves also other substances; carbonic acid and various solid matters and in THE NITROGEN DERIVED FROM THE AIR. 87 doing so gives off a portion of the other gases which it had previously taken up and absorbed from the air. But if the water should actually carry to the roots and ^ke with it into the circulation of the plants 2 per cent, of its bulk of nitrogen, the whole amount of this nitrogen would be quite inadequate to supply the requirements of a crop. For the whole rain fall in this country, during the season when a crop of hay, wheat, or oats is grown, amounts to about 8 inches ; and of this at least one-hali' is evaporated very soon after it has fallen. If we suppose the quantity left in the soil during this period amounts to 6 inches there would be 864 cubic inches of water fall upon a square foot, contain- ing of nitrogen about 17 cubic inches, or about 5 grains in weight. This would give something over 30 lbs. to the acre of nitrogen carried into the soil. But it would be un- reasonable to suppose that more than one-third of this quan- tity would be carried into the roots and be transpired by the leaves of any growing crop. There would then be about 10 pounds of nitrogen carried into the circulation of the plants, which is only one-sixth part of that which is contained in a crop of hay, and one-eighteenth part of that removed from the soil in a crop of clover. This is a rough estimation, but it affords convincing proof that plants cannot depend upon the atmosphere for their supply of this element ; but that they draw their chief sup- ply of it from its combinations with oxygen and hydrogen. If it is asked how the first plants grown upon the soil, the origin of vegetable growth upon the earth, gained the nitrogen they required to build up their tissues, it may be replied, that in this case, the earliest plants grown were not of that highly organized character which demanded a large proportion of nitrogen. In the coal beds, which were form- ed of vast deposits of vegetable matter accumulated during lengthened periods of time, are found plants t)f a far lower character than those grown as farm crops. Mosses, ferns, and semi-aquatic plants made up the larger bulk of them, and as these died and decayed, the little nitrogen they pos- sessed gradually accumulated in the soil in the mass of de- 88 THE CULTURE OF FARM CROPS. cayed matter which remained. This process continually- repeated, laid a foundation for a higher character of vege- table growth ; until in time the soil became well supplied with organic matter; and fitted for the occupation of man, who afterwards appeared upon the scene, and entered into possession of a soil abounding in accumulated fertility. We know of our own knowledge that the soil we cultivate, however rich it may be at the first, is very quickly ex- hausted of nitrogen, and that a renewed supply is indispen- sable to the growth of crops. This exhaustion is so rapid that there connot be any material addition to the supply, from the atmosphere. The most important combination of nitrogen is that with hydrogen, known as ammonia; and that this gas enters into the circulation of plants is rendered probable by a variety of circumstances. It is known that ammonia exists in the sap of many plants ; as in the beet, birch, and maple, in which it is asso- ciated with cane sugar ; in the leaves of tobacco, in elder flowers, in various fungi and in other plants. A species of chenopodium actually exhales ammonia from its leaves ; it also appears in the odorous exhalations of many other plants and flowers. Ammonia can be procured from nearly all vegetable sub- stances by distillation; and many vegetable extracts are found to contain it. When wood is distilled in retorts for the manufacture of acid, ammonia is produced. These and other facts of similar bearing are in no wise proofs that ammonia is the form in which nitrogen enters into the substance of plants ; either through the roots or the leaves ; because there are ways in which it could be pro- duced in the plant by the same converting power which produces sugar and starch in the interior of the plant from carbonic acid and water ; and while ammonia is easily pro- duced from coal and wood, yet we know that it does not actually exist in these substances in their natural condition. In the case of tobacco, the production of ammonia by means of a high temperature may be illustrated by a simple ex- EFFECT OF AMMONIA UPON VEGETATION. 89 periment. The sap and dried leaves of this plant contain nitrate of potash (saltpeter) and a small quantity of am- monia. When the dried leaves are burned kmmonia is given ojff in sensible quantities with the smoke, and can be detected by bringing a piece of reddened litmus paper into contact with the smoke when the color will be changed to a blue; or by using a feather dipped into vinegar or any weak acid, the white cloud of carbonate of ammonia will appear. (Litmus paper is used for testing the presence of acids and alkalies. It is absorbent paper steeped in a red or blue vegetable coloring matter, as the juice of red cabbage, of the red beet, or of the berries of the poke root. Litmus is a red color obtained from some species of lichens, and is changed to blue by ammonia. An alkaline liquid or vapor will change the red to blue, and an acid will change the blue to red again. This test can be used by farmers in a variety of ways; in detecting the escape of ammonia from manure, or acidity in milk). In this case however the ammonia may be in part pro- duced by the combustion, which decomposes the water con- tained in the tobacco — to the extent of 14 per cent, in its usual air dry condition — and thus disengages hydrogen, which can easily combine with the nitrogen disengaged in the combustion of nitrate of potash present in the leaves, and so form ammonia. But there are other circumstances which tend to favor the belief, in a much stronger manner, that ammonia does enter into the circulation of plants in many cases. Experience has shown that plants grow most rapidly and luxuriantly when liberally supplied with manures con- taining animal substances. Dried blood ; fish scrap ; guano ; the dung of fowls ; decomposed urine and night soil; are all rich in ammonia and are the most efficacious of manures. The same is true of the salts of ammonia. These substances are used when in a state of decomposition and when the evolution of ammonia is in most active progress. Flowering plants also grow with greater luxuriance when a small quantity of ammonia is added to the w ater given to them. In 90 THE CULTURE OF FARM CROPS. the writers garden at the present time is a bed of red cab- bage; through the center of which flows a drain from the yard in which the manure from the horse stable is kept. On both sides of this drain, for about 3. feet, the red cabbages are blue : and their growth is far more luxuriant than that of other plants distant from the drain. Is not this a dis- tinct illustration of the fact that the ammonia from the li- quid manure; in which it is shown to be abundant by the litmus paper test ; is absorbed by the cabbages and acts up- on the coloring matter with its usual effect? In all these cases however the proof is not decisive; but it is quite sufficient to make it appear that the probabilities are all in favor of the belief that ammonia does enter into the tissues of plants when brought in solution in water to the roots and to justify us in holding this belief. But ac- tual proof is wanted before this can be asserted as a fact. The changes which occur in nature are so involved ; so in- tricate ; so sudden ; and so unexpected when experience is at fault ; that we should hesitate to found a belief upon any but the strongest evidence, or to base a principle, or a law for our guidance, upon anything but accurate and well de- termined knowledge. So far as the question under consid- eration is concerned this knowledge is wanting ; but a mass- of observed facts tending thereto is all that we possess. Other soluble compounds of nitrogen are formed during the . decay and oxidation of animal substances and actually ex- ist in the liquid manures of the stable and yards, and they are likely to be absorbed by the roots of plants when ap- plied to the soil. Thus urea, a compound of carbon, hy- drogen, nitrogen and oxygen, and containing about one- third of its weight of nitrogen, exists abundantly in urine^ and by its decomposition produces carbonate of ammonia. Being very soluble this substance may enter with water in- to the roots of plants and be decomposed within the tissues and made to give up its nitrogen. The same may be ap- plied to other compounds of nitrogen ; so that while the fact that animal manures are very beneficial to the growth of plants, may be considered as favoring the probability that EFFECTS OF NITRIC ACID UPON VEGETATION. 91 the ammonia ccntained in such manures enters into th& substance of plants and yields up nitrogen to them, it must also be considered that a portion of the nitrogen contained in plants and procured from decaying animal substances, may be obtained from other compounds of it than ammonia,, and in which ammonia may not exist. Nitric acid is invariably present in the juices of plants in combination with potash, soda, lime, and magnesia. Therefore all the evidence afforded by the facts above noted are also applicable to the belief that this acid is one of the sources, at least, from whence the nitrogen of plants is de- rived. This acid has been detected in tobacco, and the sun- flower, and in the grain of barley in the form of nitrate of soda. If we were therefore to infer from these fa6ts that this acid really enters the roots of plants we might draw a certain conclusion. Like other compounds of nitrogen, it may have been formed in the interior of plants during the many changes there effected, and hence its presence proves no more in regard to a solution of the question at issue than the presence of ammonia. The same uncertainty would still exist. But the most recent investigations go to show that of all the forms in which nitrogen enters into plants, nitric acid is the most probable one. It exerts a powerful in- fluence upon growing crops of grass and grains. It changes the color of the leaves to an intense green in a short time ; and largely increases the quantity of nitrogenous matter in grain, as well as the yield of the crop. For instance it has been found that a dressing of nitrate of soda has increased the amount of gluten in wheat from 19 to 23 i percent, reducing the starch from 55^ to 49* per cent. Many other similar instances are recorded, all tending to show the fav- orable effect of nitric acid upon the growth of vegetation. Heretofore a still more striking instance has been given of similar results from the use of manures rich in ammonia. But recent researches of the leading investigators espec- ially those at the Rothampstead farm in England under the supervision of Sir J. B. Lawes, aided by a most eflicient ^2 THE CULTURE OF FARM CROPS. corps of assistants, have shown that there is much reason to believe that ammonia is oxidized and changed to nitric acid and in this form it is that the nitrogen enters into the circulation of plants. To sum up the conclusions in regard to this question, of such surpassing interest to farmers, which are presented by a consideration of the facts known in this connection, the following propositions result. First — That uncombined nitrogen of the atmosphere may- enter into the circulation to a small extent, either in its natural form of a gas or in solution in water ; and this prob- ably does happen. But the quantity so gained by plants is very small and is wholly insufficient for their needs and only a small proportion of that which vegetables actually contain. Second. — That ammonia has the power of entering into plants and of yielding nitrogen to them to a very large ex- tent and actually in excess of their necessities so that the normal quantity of nitrogen in the product is largely in- creased ; and it does appear, but is not proved, that plants do derive nitrogen from this source. Third. — That in like manner nitric acid has the power of entering into plants and of yielding nitrogen to them to a larger extent than they need to produce a normal product and there is reason to believe that plants do derive the largest portion of the nitrogen they contain from this source. Fourth. — But there is also reason to believe that ammo- nia is changed to nitric acid in the soil, and perhaps in the plants, and in this combination it is that nitrogen enters the roots of plants and contributes to their substance. THE INOEGAlfIC ELEMENTS OF PLANTS. PART SECOND. CHAPTER XV. THE INORGANIC ELEMENTS OF PLANTS. When any vegetable substances are burned in the air,, the whole of the organic elements disappear, and a small quantity of ash remains. The proportion of the substance which has disappeared varies from 88 to 99 per cent. This has all been derived from the air, and is made up of the four elements which have occupied our attention up to this point. The small remnant left after complete combustion constitutes the inorganic elements of plant growth. These are now to be studied. The results of recent investigations have wholly exploded the notions which formerly prevailed, to the effect that this inorganic matter was of no serious importance to the crops, and was a mere accidental circumstance, and might be ab- sent without any serious detriment to the growth of the plants. It was discovered in course of careful experiments that this ash of the plants represented exactly the various mineral substances which were taken from the soil, and that these, to the smallest proportion, were of vital necessity to the plants. The results of long continued study, finally gathered into systematic order, showed that on whatever soil a plant might be growii and mature its seed fully, the quantity and char- acter of the ash is nearly the same ; and that though grown on the same soil, plants of different species and character leave an ash entirely unlike; the ash varying characteristic ■94 THE CULTURE OF FARM CROPS. <3ally with the species. Moreover it was found that when a plant was grown out of the soil ; and with its roots envel- oped only in water; it grew with equal luxuriance as if grown in the soil, provided that the water held in solution the same mineral substances which were found in the ash of the same species, together with the needed quantity and variety of its organic elements. Thus the soil was found to possess functions of more importance to plant growth than the mere mechanical support for its roots, and really sup- plied to the plant a number of constituents without which, or any one of which, the growth was enfeebled or wholly failed. Hence there was no longer any doubt that the ash of plants represented really essential portions of their nutri- ment, and the farmer then was able to understand the whole secret of the art of manuring ; viz ; that to grow abundant crops every constituent part of the plants must be present in the soil, or if not, they must be supplied to it in the form of manures or fertilizers. This discovery necessarily modi- fied the notions held by farmers, and regulated the prac- tices of agriculture in every branch. One of the most use- ful reforms in thought and practice was to abolish the idea which was prevalent among unintelligent farmers, viz, that books and other literature were totally useless to them, and that the only way to become good farmers w^as to spend a life time in copying the ways and methods of older men, and learning from them what they knew of their art. We have now learned that while this is all useful, there is some- thing else which is pre-eminently necessary ; viz ; to study the laws of plant growth and with the knowledge thus gained from books and other sources to give careful and in- telligent consideration to the nature of the soil ; the princi- ples upon which its proper culture are based ; the most perfect machinery for this culture; the ait of manuring; the nature and use of artificial fertilizers; and the produc- tion of manure, made richer in the needed elements of pl^nt growth by feeding cattle. And for the purpose of encouraging this study and of spieading abroad the neces- sary information for it ; a special literature devoted to agri- THE FEEDING FUNCTIONS OF PLANTS. 95 <;iilture, consisting of books and periodical journals, sprang into existence, and was eagerly procured and read; and lastly special schools for teaching the science and art of farming were established jointly with farms and laboratories for experimental culture and chemical investigations. Thus step by step the art of growing farm crops became an intelli- gent industry, and farmers are respected in proportion to the importance and dignity of their vocation. For all this we are indebted to numerous pains-taking men, who with unusual self-denial, patience, and per- severance, have spent their lives in industrious retirement ; heard of by few and known by less; busy in their fields and experimental plots, or hidden in their laboratories; gradually building up, fragment by fragment, the grand edifice of knowledge which now represents what every man who desires, may know of the culture of farm crops. One very important point of this knowledge is the fact that vegetables feed — that is, absorb and assimilate or build up their substance — upon mineral substances, as well as up- on the remains of vegetable matter. That while these re- mains in the shape of completely decomposed farm manure, or animal matters, contain the various inorganic compounds which are found in the ashes of plants, and which are known to be necessary to their growth, yet j;he same com- pounds drawn from a mineral origin, are equally serviceable as plant food. Thus, lime procured from the lime kilns; potash from the rocks of which it forms a part; gypsum or plaster; phosphate of lime; soda in the form of salt, or as nitrate of soda ; sulphate of magnesia; and other mineral substances; when finely ground, and made soluble, produce precisely the same results when used as fertilizers as the same substances in the ashes of plants, or in their decayed remains. They are absorbed by plants with equal facility, and are utilized in the same way and to the same extent, in forming the tissues of the plants. They are in fact plant food. Hence the common idea that these fertilizing sub- stances are stimulants only, and merely encourage the crops to put forth some unusual efifort, so to speak, by which 96 THE CULTURE OF FARM CROPS. some unnatural and excessive product is yielded, is a wholly wrong and mistaken one. Wrong terms and ideas are in- jurious, notwithstanding that a name has no effect in chang- ing the nature of anything; for they lead to wrong prac- tices and grave errors in the management of the crops, and these cannot fail to result in loss. The inorganic substances upon which plants feed and which they extract by their roots from the soil, have been mentioned in a previous chapter, but they may be conven- iently repeated. They are lime; potash; soda; magnesia; sulphur and sulphuric acid; phosphoric acid; silica and chlorine. These, with the exception of sulphur and chlor- ine, which are elements, are the oxides of metals which are elementary substances. The first four are usually found in the ashes of plants combined with carbonic acid as carbon- ates; lime however is found ae a sulphate being combined with sulphuric acid in the ashes of clover and a few other plants. There are a few other substances of inorganic ori- gin which are occasionally found in plants, such as iron, manganese, iodine, &c. but these are evidently accidentally absorbed with the water in Avhich they happen to be in sol- ution, and being innoxious do not interfere with the devel- opment of the plants, but are not strictly plant food. The proportion of the various mineral elements of plant growth varies greatly in the different species of vegetables; so much so as to become a leading characteristic with them. Thus there are what may be called potash plants; lime plants; soda plants, &c.; and these dominant elements will be found to have a considerable bearing upon the question of fertilizing crops, to be hereafter treated. Thus on refer- ence to the tables given in the next chapter, it will be seen that the ash of the stems and leaves of potatoes contain from 39 to 46 per cent, of lime and 16 to 22 per cent, of mag- nesia; pea straw cantains 38 per cent, of lime; but wheat straw only 6 per cent.; and the tubers of potatoes only 2t per cent.; while the ash of the last mentioned contains 60 per cent, of potash; that of turnips 50 per cent., clover 35 to 50 per cent.; of young grass 56 per cent.; and of tobacco- THE LAWS OF PLANT GROWTH. 97 27 i per cent. The dried tobacco plant has 24 per cent, of ash while the whole wheat plant has but 3 J per cent. It must not be supposed that these peculiarities are of no im- portance to the farmer, and that the fact that the ash of beets, turnips, and carrots, including leaves and roots to- gether, contains from 12 to 24 J per cent, of soda, and from 6 to 11 per cent, of chlorine; while that of most other plants contain a very insignificant quantity of these sub- stances; or that the ash of clover contains along with the large quantity of lime a considerable amount of sulphuric acid, and that this acid exists in the ash of turnips, cabbage, rape and kolil-rabi, mustard and other plants of the Oru- cijerce family to the enormous extent of from 8 to 16} per cent. For these facts explain the reason why an applica- tion of salt (chloride of sodium) and of gypsum (sulphate of lime) furnishes these elements to the crops mentioned, and thus supplies necessary food without which they could not grow. It results, in fact, that the soil must contain all these substances, which are found in their ashes, in such quantity and in such form as to yield easily to each crop as much of each, as the plant specially requires. This is the first grand law which controls the culture of farm crops. The second is that the soil must be brought into such a proper condition by tillage, as to enable the roots of plants to avail themselves of the needed food which it contains. A special study should be made of the tables given in the next chapter and specially placed by themselves that they may attract the notice which they demand. For a third law controlling the growth of plants is, that if one of these necessary substances is wanting in the soil, or is existing there in deficient quantity, the crop will prove a failure; it will either be weak and diseased (for it is the weak and ill nour- ished plants — and animals equally — which are subject to disease) or it will fail to grow at all. The intelligent farmer will then naturally ask what are these mineral or inorganic substances upon which plants depend for their successful growth, and in what proportion do they require them; and further, in what proportions do 98 THE CULTURE OF FAEM CROPS. these needed mineral substances exist in the soil; and ^vlien any of them are deficient, how can they be supplied in the easiest, most advantageous and most economical manner? The first of these questions will be answered by the tables given in the next chapter and the others will be considered in their turn. THE ASH, OR MINERAL PARTS OF PLANTS. CHAPTEK XVI. THE ASH OF CULTIVATED PLANTS AND ITS VARIED COMPOSITION. In the following tables collected from various sources in which the results of thousands of experiments by the most noted agricultural chemists and investigators have been published, will be found the average composition of the ash of the plants named. These plants have been gathered from the crops grown under ordinary circumstances, and when there has been any unusual variation in any samples, a large number of analyses have been made and an average taken. These analyses have been verified so often by more recent examinations that they have been accepted as the standard, and are used for all purposes, and for reference in all recent agricultural study. They may therefore be ac- cepted by students with the utmost confidence and reliance. They are given in full because hereafter frequent allusions and references will be given to them in future chapters. Composition of the Ash of Agricultural Products. o Substances. S| ^ ^ F .§ p-'S ll ;§ § 0, S g CO o HAY AND GRASS. Ordinary hay 7.78 25.6 7.0 4.9 11.6 6.2 5.1 29.6 8.0 Young grass 9.32 56.2 1.8 2.8 10.7 10.5 4.0 10.3 2.0 Ripe hay 7.73 7.6 2.9 3.4 12.9 4.4 0.7 63.1 5.7 Timothy 7.1 28.8 2.7 3.7 9.4 10.8 3.9 35.6 5.0 Hungarian 7.23 37.4 8.0 10.8 5.4 3.6 29.1 6.4 CLOVER AND FODDER PLANTS. Red Clover 6.72 34.5 1.6 12.2 34.0 9.9 3.0 2.7 3.7 White Clover 7.16 17.5 7.8 10.0 32.2 14.1 8.8 4.5 3.2 Lucorn 7.14 25.3 1.1 5.8 48.0 8.5 6.1 2.0 1.9 Alsike clover 5.53 33.8 1.5 15.3 31.9 10.1 4.0 1.2 2.8 Green pea (in flower) 7.40 40.8 0.2 8.2 28.7 13.2 3.5 2.6 1.8 Green rape 8.97 32.3 3.8 4.5 23.1 8.7 16.3 3.2 7.6 100 THE CULTURE OF FARM CROPS. ROOT CROPS (Roots.) Potatoes 3.74 59.8 1.6 4.5 2.3 Beets 6.8G 53.1 14.8 5.1 4.6 Sugarbeets 4.35 49.4 9.6 8.9 6.3 Turnips 8.28 39.3 11.4 3.9 10.4 Rutabagas 7.68 57.2 6.7 2.6 9.7 Carrots 6.27 36.7 22.1 5.3 10.7 ROOT CROPS (Leaves and Stems. Potatoes (green) 8.92 14.5 2.7 16.8 39.0 (ripe) 5.12 6.3 0.8 22.6 46.2 Beets 15.90 29.1 2L0 9.7 11.4 Sugar beets 17.49 22.1 16.8 18.3 19.7 Turnips 13.68 22.9 7.8 4.5 32.4 Carrots 13.57 14.1 23.1 4.6 33.0 Cabbage. 10.81 48.6 3.9 3.3 15.3 STRAW. Winter wlieat 4.96 11.5 2.9 2.6 6.2 Winter rye 4.81 18.7 3.3 3.1 7.7 Springrye 5.55 23.4 2.8 8.9 Barley 5.10 21.6 4.5 2.4 7.6 Oats 5.12 22.0 5.3 4.0 8.2 Corn 5.49 35.3 L2 5.5 10.5 Peas 5.74 2L8 5.3 7.7 37.9 Beans 7.12 44.4 3.8 7.8 23.1 Buckwheat 6.15 46.6 2.2 3.6 18.4 Rape 4.58 25.6 10.3 5.7 26.5 CHAFF. Wheat 10.73 9.1 L8 1.3 L9 Barley 14.23 7.7 0.9 1.3 10.4 Oats 9.22 13.1 4.8 2.6 8.9 Corn (cobs) 0.56 47.1 1.2 4.1 3.4 FIBER PLANTS. Flax (entire) 4.30 34.2 4.8 9.0 15.5 Hemp " 4.60 18.3 3.2 9.6 43.4 Hops " 9.87 26.2 3.8 5.8 16.0 Tobacco 24.08 27.4 3.7 10.5 37.0 LITTER. Heath 4.51 13.2 5.3 8.4 18.8 Fern 7.1 42.8 4.5 7.7 14.0 Sea-weeds 14.39. 14.5 24.0 9.5 13.9 Beech leaves 6.75 5.2 0.6 6.0 44.9 Oak " 4.90 3.5 0.6 4.0 48.6 White pine " 1.40 10.1 9.9 41.4 Red pine " 5.82 1.5 2.3 15.2 Salt black grass 5.30 36.6 6.6 6.4 9 5 Salt marsh grass 8.08 33.2 7.3 4.2 5.3 GRAINS AND SEEDS. Wheat 2.07 31.1 3.5 12.2 3.1 Rye 2.03 30.9 1.8 10.9 2.7 Barley 2.55 21.9 2.8 8.3 2.5 Oats.! 3.07 15.9 3.8 7,3 3.8 Com 1.42 27.0 1.5 14.6 2.7 19.1 6.6 2.3 2.8 9.6 3.3 3.3 6.6 14.3 4.7 3.5 2.0 13.3 14.3 2.4 4.1 15.3 8.4 0.5 5.1 12.5 6.4 2.0 3.2 .) 6.1 5.6 8.0 4.6 5.5 5.5 4.2 3.0 5.1 7.4 4.8 11.3 7.4 8.0 3.1 5.7 8.9 9.9 3.8 8.2 4.7 7.9 5.6 7.1 15.8 8.5 L2 2.5 5.4 2.9 66.3 4.7 L9 58.1 6.5 2.6 55.9 4.3 3,7 53.8 4.2 3.5 48.7 8.1 5.2 38.0 7.8 5.6 5.7 6.1 7.0 0.2 5.4 13.1 11.9 5.3 5.5 7.7 7.0 7.1 6.7 12.4 4.3 81.2 2.0 3.0 70.8 0.3 2.5 59.9 4.4 L9 26.4 23.0 4.9 2.6 5.& 1L6 2.8 7.6 2.5 12.1 5.4 2.5 4.6 3.6 3.9 9.6 4.5 5.1 4.4 35.2 2.1 9.7 5.1 6.1 10.2 3.1 24.0 1.7 10.1 4.2 3.7 33.9 0.4 8.1 4.4 30.9 16.4 4.4 13.1 4.4 8.2 2.8 70.1 6.4 8.7 10.9 14.2 6.7 3.3 31.5 5.Q. 46.2 2.4 L7 47.5 2.3 1.5 32.8 2.3 27.2 20.7 1.6 46.4 44.7 LI 2.2 COMPOSITION OF FAEM CROPS. 101 Rice 7.84 18.4 4.5 8.6 5.1 47.2 0.6 0.6 Millet 4.49 11.9 1.0 8.4 1.0 23.4 0.2 52.3 Sorghum 1.86 23.0 3.3 14.8 1.3 50.9 7.5 Buckwheat 1.07 23.1 6.2 13.4 3.3 48.0 2.1 1.7 Rape 4.24 23.5 1.1 12.2 13.8 43.9 3.6 1.1 0.3 Cotton 7.80 37.42 8.6 16.10 3.0 33.16 0.27 2.8 0.2 Flax 3.65 32.2 1.8 13.2 8.4 40.4 1.1 1.1 0.1 Hemp 5.48 20.1 0.8 5.6 23.5 36.3 0.2 11.8 0.1 Mustard 4.30 15.9 5.8 10.2 18.8 39.0 4.7 2.4 0.4 Turnip 3.98 21.9 1.2 8.7 17.4 40.2 7.1 0.7 Carrot 8.50 19.1 4.8 6.7 88.8 15.8 5.6 5.3 3.3 Peas 2.81 40.4 3.7 8.0 4.2 36.3 3.5 0.9 2.3 Beans 3.45 40.5 1.2 6.7 5.2 39.2 5.1 1.2 2.9 Clover 4.11 37.3 0.6 12.2 6.2 33.5 4.7 2.4 1.3 WOOD. Grape 2.75 29.8 6.7 6.8 87.3 12.9 2.7 0.8 0.8 Birch 0.31 11.6 5.8 8.9 60.0 8.5 0.3 4.8 0.6 Beech 0.82 16.1 2.7 14.0 50.2 8.0 1.0 5.4 0.1 Oak 0.21 10.0 3.6 4.8 73.5 5.5 1.4 1.1 0.2 Willow 0.45 11.5 5.6 10.1 50.8 16.4 3.1 0.7 0.6 Elm 1.88 24.1 2.1 10.0 37.9 9.6 5.4 6.2 6.7 Linden.... 1.42 35.8 6.0 4.2 29.9 4.9 5.3 5.3 1.5 Apple 1.29 12.0 1.6 5.7 71.0 4.6 2.9 1.8 0.2 Red pine 0.25 5.2 26.8 6.2 47.9 5.1 3.0 2.0 4.0 White pine 0.28 15.3 9.9 5.9 50.1 5.5 3.0 6.0 0.2 Balsam fir 0.31 11.8 4.6 9.1 50.1 5.8 2.3 15.0 0,4 Larch (Tamarac) 0.32 15.3 7.7 24.5 27.1 3.6 1.7 3.6 0.6 LEAVES OF TREES. Walnut 7.01 26.6 9.8 53.7 4.0 2.7 2.0 0.8 Beech 6.75 5.2 0.6 6.0 44.9 4.2 3.7 33.9 0.4 Oak 4.90 3.5 0.6 4.0 48.6 8.1 4.4 30.9 Fir (Balsam) 1.40 10.1 9.9 4L4 16.4 4.4 13.1 4.4 Red pine 5.82 1.5 2.3 15.2 8.2 2.8 70.1 White pine 6.24 3.7 LI 12.1 8.5 L9 66.6 Maple 6.80 10.2 0.5 6.1 39.6 4.2 3.6 34i0 Elm 4.88 13.7 0.6 4.1 48.5 8.0 4.3 20.8 BARK. Oak 3.21 5.7 3.2 8.7 42.0 7.1 L5 21.0 1.5 Maple L37 15.0 3.1 9.0 46.1 6.7 1.4 110 Birch L33 3.8 5.4 8.2 45.6 7.3 L3 20.1 1.8 Beech 14.7 0.4 0.2 57.9 0.4 L3 18.0 Walnut 6.40 1L6 10.6 70.1 5.9 0.2 0.7 0.4 Elm 7.1 2.2 10.1 3.2 72.7 L6 0.6 8.9 Linden 8.5 16.1 5.7 8.0 60.8 4.0 0.8 2.3 1.2 Red pine 2.81 5.3 4.2 4.7 62.4 2.6 1.0 15.7 0.2 White pine 3.30 8.0 3.2 3.0 69.8 2.5 L6 8.4 1.0 Eir (Balsam) 2.01 3.0 1.0 1.4 43.7 8.3 0.8 3L1 0.1 Although the consideration of the organic substance of plants has been passed for the present, yet this being a con- Tenient place for a table showing the amount of organic matter contained in the common products of the farm, this 102 THE CULTURE OF FARM CROPS. is given here and will be frequently referred to hereafter. The organic matter is separated from the ash, and water> which are also given, and into two principal divisions, viz: that into which nitrogen chiefly enters, and which are com- monly referred to as nitrogenous matter; or albuminoids or protein compounds; and that commonly called carbo-hy- drates; the former consisting of carbon; oxygen; hydrogen and nitrogen; and the latter of carbon, oxygen and hydro- gen. These are often distinguished also as non-nitrogen- ous. Composition of Agricultural Products. Carbon & Hydro- gen compounds. HAY. Meadow Hay, poor 14.3 better 14.3 " " . medium 14.3 '• " very good 15.0 " " extra 16.0 Red Clover, poor 15.0 «' " medium 16.0 " " very good ....16.5 " " extra 16.5 White Clover, medium 16.5 Lucerne, medium 16.0 " very good 16.5 Swedish Clover 16.0 Hop Clover 16.7 Trefoil 16.7 Seradella 16.7 Fodder Vetch, medium 16.7 " " very good 16.7 Peas in bloom 16.7 Lupine, medium 16.7 " very good 16.7 Fodder Rye 14.3 Timothy 14.3 Italian Rye Grass 14.3 English Rye Grass.'. 14.3 French Rye Grass 14.3 Upland Grasses, average 14.3 Hungarian Grass 18.4 ' ^8 1 1 5.0 7.5 33.5 38.2 1.5 5.4 9.2 29.2 39.7 2 0 6.2 9.7 26.3 41.4 2.5 7.0 11.7 21.9 41.6 2.8 7.7 13.5 19.3 40.4 3.0 5.1 11.1 28.9 37.7 2.1 5.3 12.3 26.0 38.2 2.2 6.0 13.5 24.0 37.1 2.