How crops grow. A treatise on the chemical composition, structure and life of the plant, for students of agriculture. With numerous illustrations and tables of analyses

Front matter

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Preface

The original edition of this work, first published in 1868, was the result of studies undertakenin preparing instruction in Agricultural Chemistry which the Author has now been giving for three and thirty years. Together with the companion volume, "How Crops Feed," it was intended to present concisely but fully the then present state of Science regarding the Nutrition of the higher Plants and the relations of the Atmosphere, Water, and the Soil, to Agricultural Vegetation. Since its first appearance, our knowledge of the subject treated of in the present volume has largely participated in the remarkable advances which have marked all branches of Science during the last twenty years and it has been the writers' endeavor in this revised edition to post the book to date as fully as possible without greatly enlarging its bulk or changing its essential character. In attempting to reach this result he has been doubly embarassed, first, by the great and rapidly increasing amount of recent publications in which the materials for revision must be sought, and, second, by the fact that official duties have allowed very insufficient time for a careful and comprehensive study of the literature. In conclusion, it is hoped that while the limits of the book make necessary the omission of a multitude of interesting details, little has been overlooked that is of real importance to a fair presentation of the subjects discussed, in

Table Of Contents

DIVISION I.— CHEMICAL COMPOSITION OF THE PLANT.

Chap. I.— The Volatile Part of Plants 12

§ 1. Distinctions and Definitions . . 12

§ 2. Elements of the Volatile Part of Plants 14

§ 3. Chemical Affinity 29

§4. Vegetable Organic Compounds or Proximate Elements 36

2. Carbhydrates 39

3. Vegetable Acids 75

4. Fats 83

5. Albuminoids and Ferments 87

6. Amides 114

7. Alkaloids 120

8. Phosphorized Substances 122

Chap. II.— The Ash of Plants 126

§ 1. Ingredients of the Ash 126

Non-metallic Elements 127

Carbon and its Compounds 128

Sulphur and its Compounds 129

Phosphorus and its Compounds 132

Chlorine and its Compounds 132

Silicon and its Compounds 134

Metallic Elements . . 138

Potassium and its Compounds 138

Sodium and its Compounds 139

Calcium, and its Compounds 139

Magnesium and its Compounds 140

Iron and its Compounds -. 141

Manganese and its Compounds 142

Salts 143

Carbonates 144

Sulphates 146

Phosphates 147

Chlorides 149

Nitrates 149

§ 2. Quantity, Distribution, and Variations of the Ash 151

Table of Proportions of Ash in Vegetable Matter — 152

§ 3. Special Composition of the Ash of Agricultural Plants 161

1. Constant Ingredients 161

2. Uniform composition of normal specimens of

given plants 161

Table of Ash-analyses 164

3. Composition of Different parts of Plant 171

4. Like composition of similar plants 173

5. Variability of ash of same species 174

6. What is normal composition of the ash of a plant? 177

7. To what extent is each ash-ingredient essential

or accidental 180

Water-culture 180

Essential ash-ingredients 186

Is Sodium Essential to Agricultural Plants ? 186

Iron indispensable 192

Manganese unessential 193

Is Chlorine indispensable ? 194

Silica is not essential 197

Ash-ingredients taken up in excess 201

Disposition of superfluous matters 203

State of Ash-ingredients in plant 207

44. Functions of the Ash-ingredients 210 1. Quantitative Relations among the Ingredients of

§ 2. Composition of the plant in successive stages of

growth 222

Composition and Growth of the Oat Plant : 223

V

VI TABLE OF CONTEXTS.

DIVISION II.— THE STRUCTURE OF THE PLANT AND OFFICES OF ITS ORGANS.

Chap. I.— Generalities 241

Organism, Organs 242

Chap. II.— Primary Elements of Organic Structure 243

§ 1. The Vegetable Cell 243

§ 2. Vegetable Tissues 254

Chap. III.— Vegetative Organs 256

§ 1. The Root 256

Offices of Root 260

Apparent Search for Food 263

Contact of Roots with Soil 266

Absorption by Root 269

Soil Roots, Water Roots, Air Roots 273

§ 2. The Stem 282

Buds 283

Layers, Tillering 286

Root-stocks 287

Tubers 288

Structure of the Stem 289

Endogenous Plants 290

Exogenous Plants 296

Sieve-cells 303

Leaf Pores « 309

Exhalation of Water Vapor 311

Offices of Foliage 314

Chap. IV.— Reproductive Organs 315

§ 1. The Flower 316

Fertilization 319

Hybridizing 324

Species. Varieties 326

Seed 332

Embryo 333

§ 3. Vitality of seeds and their influence on the Plants

they produce 335

Duration of Vitality 335

Use of old and unripe seeds 338

Density of seeds 339

Absolute weight of seeds 340

Signs of Excellence 345

Ancestry. Race-vigor 346

DIVISION III.— LIFE OF THE PLANT.

Chap, l.— Germination 3ii>

§ 1. Introductory 34!)

§ 2. Phenomena of Germination 350

§ 3. Conditions of Germination 351

Proper Depth of Sowing 355

§ 4. Chemical Physiology of Germination. 357

Chemistry of Malt .' 358

Chap. II. — 5 1. Food of the Plant when independent of the Seed 366

§ 2. The Juices of the Plant. Their Nature and Movements369

Flow of Sap 370

Composition of Sap 376

Kinds of Sap 378

Motion of Nutrient Matters 379

§ 3. Causes of Motion of the Juices 385

Porosity of Tissues 385

Imbibition 386

Liquid Diffusion 390

Osmose or Membrane Diffusion 393

Root Action 399

Selective Power of Plant 401

§ 4. Mechanical effects of Osmose 406

Appendix

Table.— Composition of Agricultural Products 409

HOW CROPS GROW.

Introduction

The object of agriculture is the production of certain plants and certain animals which are employed to feed, clothe and otherwise serve the human race. The first aim, in all cases, is the production of plants.

Nature has made the most extensive provision for the spontaneous growth of an immense variety of vegetation ; but in those climates where civilization most certainly attains its fullest development, man is obliged to employ art to provide himself with the kinds and quantities of vegetable produce which his necessities or luxuries demand. In this defect, or, rather, neglect of nature, agriculture has its origin.

The art of agriculture consists in certain practices and operations which have gradually grown out of an observation and imitation of the best efforts of nature, or have been hit upon accidentally, or, finally, have been deduced from theory.

The science of agriculture is the rational theory and systematic exposition of the successful art.

Strictly considered, the art and science of agriculture are of equal age, and have grown together from the earliest times. Those who first cultivated the soil by digging, planting, manuring and irrigating, had their sufficient reason for every step. In all cases, thought goes before work, and the intelligent workman always has a theory upon which his practice is planned. ~No farm was ever conducted without physiology, chemistry, and physics, any more than an aqueduct or a railway was ever built without mathematics and mechanics. Every successful farmer is, to some extent, a scientific man. Let him throw away the knowledge of facts and the knowledge of principles which constitute his science, and he has lost the elements of his success. The farmer without his reasons, his theory, his science, can have no plan ; and these wanting, agriculture would be as complete a failure with him as it would be with a man of mere science, destitute of manual, financial and executive skill.

Other qualifications being equal, the more advanced and complete the theory of which the farmer is the master, the more successful must be his farming. The more he knows, the more he can do. The more deeply, comprehensively, and clearly he can think, the more economically and advantageously can he work.

That there is any opposition or conflict between science and art, between theory and practice, is a delusive error. They are, as they ever have been and ever must be, in the fullest harmony. If they appear to jar or stand in contradiction, it is because we have something false or incomplete in what we call our science or our art ; or else we do not perceive correctly, but are misled by the narrowness and aberrations of our vision. It is often said of a machine, that it was good in theory, but failed in practice. This is as untrue as untrue can be. If a machine has failed in practice, it is because it was imperfect in theory. It should be said of such a failure — the machine was good, judged by the best theory known to its inventor, but its incapacity to work demonstrates that the theory had a flaw.

But, although art and science are thus inseparable, it must not be forgotten that their growth is not altogether parallel. There are facts in art for which science can, as yet, furnish no adequate explanation. Art, though no older than science, grew at first more rapidly in vigor and in stature. Agriculture was practiced hundreds and thousands of years ago, with a success that does not compare unfavorably with ours. Nearly all the essential points of modern cultivation were regarded by the Romans before the Christian era. The annals of the Chinese show that their wonderful skill and knowledge were in use at a vastly earlier date.

So much of science as can be attained through man's unaided senses, reached considerable perfection early in the world's history. But that part of science which relates to things invisible to the unassisted eye, could not be developed until the telescope and the microscope had been invented, until the increasing experience of man and his improved art had created and made cheap the other inventions by whose aid the mind can penetrate the veil of nature. Art, guided at first by a very crude and imperfectly-developed science, has, within a comparatively recent period, multiplied those instruments and means of research whereby science has expanded to her present proportions.

The progress of agriculture is the joint work of theory and practice. In many departments great advances have been made during the last hundred years ; especially is this true in all that relates to implements and machines, and to the improvement of domestic animals. It is, however, in just these departments that an improved theory has had sway. More recent is the development of agriculture in its chemical and physiological aspects. In these directions the present century, or we might almost say the last fifty yeai*3, has seen more accomplished than all previous time.

The first book in the English language on the subjects which occupy a good part of the following pages, was written by a Scotch nobleman, the Earl of Dundonald, and was published at London in 1795. It is entitled: " A Treatise showing the Intimate Connection that subsists between Agriculture and Chemistry." The learned Earl, in his Introduction, remarked that "the slow progress which agriculture has hitherto made as a science is to be ascribed to a want of education on the part of the cultivators of the soil, and the want of knowledge in such authors as have written on agriculture of the intimate connection that subsists between the science and that of chemistry. Indeed, there is no operation or process, not merely mechanical, that does not depend on chemistry, which is defined to be a knowledge of the properties of bodies, and of the effects resulting from their different combinations. " Earl Dundonald could not fail to see that chemistry was ere long to open a splendid future for the ancient art that always had been and always is to be the prime support of the nations. But when he wrote, how feeble was the light that chemistry could throw upon the fundamental questions of agricultural science ! The chemical nature of atmospheric air was then a discovery of barely twenty years' standing. The composition of water had been known but twelve years. The only account of the composition of plants that Earl Dundonald could give was the following: '"Vegetables consist of mucilaginous matter, resinous matter, matter analogous to that of animals, and some proportion of oil. * * Besides these, vegetables contain earthy matters, formerly held in solution in the newly-taken-in juices of the growing vegetable." He further explains by mentioning on subsequent pages that starch belongs to the mucilaginous matters, and that, on analysis by fire, vegetables yield soluble alkaline salts and insoluble phosphate of lime. But these salts, he held, were formed in the process of burning, their lime excepted, and the fact of their being taken from the soil and constituting the indispensable food of plants, his Lordship was unacquainted with. The gist of agricultural chemistry with him was, that plants are "composed of gases with a small proportion of calcareous matter;" for "although this discovery may appear to be of small moment to the practical farmer, yet it is well deserving of his attention and notice, as it throws great light on the nature and food of vegetables." The fact being then known that plants absorb carbonic acid from the air, and employ its carbon in their growth, the theory was held that fertilizers operate by promoting the conversion of the organic matter of the soil or of composts into gases, or into soluble humus, which were considered to be the food of plants.

The first accurate analysis of a vegetable substance was not accomplished until fifteen years after the publication of Dundonald's Treatise, and another like period passed before the means of rapidly multiplying good analyses had been worked out by Liebig. So late as 1838, the Gottingen Academy offered a prize for a satisfactory solution of the then vexed question whether the ingredients of ashes are essential to vegetable growth. It is, in fact, during the last fifty years that agricultural chemistry has come to rest on sure foundations. Our knowledge of the structure and physiology of plants is of like recent development. What immense practical benefit the farmer has gathered from this advance of science ! Chemistry has ascertained what vegetation absolutely demands for its growth, and points out a multitude of sources whence the requisite materials for crops can be derived. Cato and Columella knew indeed that ashes, bones, birddung and green manuring, as well as drainage and aeration of the soil, were good for crops ; but that carbonic acid, potash, phosphate of lime, and compounds of nitrogen are the chief pabulum of vegetation, they did not

G HOW CROPS GROW.

know. They did not know that the atmosphere dissolves the rocks, and converts inert stone into nutritive soil. These grand principles, understood in many of their details, are an inestimable boon to agriculture, and intelligent farmers have not been slow to apply them in practice. The vast trade in phosphatic and Peruvian gnano, and in nitrate of soda ; the great manufactures of oil of vitriol, of superphosphate of lime, of fish fertilizers ; and the mining of fossil bones and of potash salts, are industries largely or entirely based upon and controlled by chemistry in the service of agriculture.

Every day is now the witness of new advances. The means of investigation, which, in the hands of the scientific experimenter, have created within the writer's memory such arts as photography and electro-metallurgy, and have produced the steam-engine, the telegraph, the telephone and the electric light, are working and shall evermore continue to work progress in the art of agriculture. This improvement will not consist so much in any remarkable discoveries that shall enable us to ' * grow two blades of grass where but one grew before;" but in the gradual disclosure of the reasons of that which we have long known, or believed we knew ; in the clear separation of the true from the seemingly true, and in the exchange of a wearying uncertainty for settled and positive knowledge.

It is the boast of some who affect to glory in the sufficiency of practice and decry theory, that the former is based upon experience, which is the only safe guide. But this is a one-sided view of the matter. Theory is also based upon experience, if it be worth the name. The fancies of an ignorant and undisciplined mind are not theory as that term is properly understood. Theory, in the strict scientific sense, is always a deduction from facts, and the best deduction of which the stock of facts in our possession admits. It is therefore also the interpretation of facts. It is the expression of the ideas which facts awaken when submitted to a fertile imagination and well-balanced judgment. A scientific theory is intended for the nearest possible approach to the truth. Theory is confessedly imperfect, because our knowledge of facts is incomplete, our mental insight weak, and our judgment fallible. But the scientific theory which is framed by the contributions of a multitude of earnest thinkers and workers, among whom are likely to be the most gifted intellects and most skillful hands, is, in these days, to a great extent worthy of the Divine truth in nature, of which it is the completest human conception and expression.

Science employs, in effecting its progress, essentially the same methods that are used by merely practical men. Its success is commonly more rapid and brilliant, because its instruments of observation are finer and more skillfully handled ; because it experiments more industriously and variedly, thus commanding a w T ider and more fruitful experience ; because it usually brings a more cultivated imagination and a more disciplined judgment to bear upon its work. The devotion of a life to discovery or invention is sure to yield greater results than a desultory application made in the intervals of other absorbing pursuits. It is then for the iuterest of the farmer to avail himself of the labors of the man of science, when the latter is willing to inform himself in the details of practice, so as rightly to comprehend the questions which press for a solution.

Agricultural science, in its widest scope, comprehends a vast range of subjects. It includes something from nearly every department of human learning. The natural sciences of geology, meteorology, mechanics, physics, chemistry, botany, zoology and physiology, are most intimately related to it. It is not less concerned with social and political economy. In this treatise it will not be attempted to touch, much less cover, all this ground, but some account will be given of certain subjects whose understanding will be of the most direct service to the agriculturist. The Theory of Agriculture, as founded on chemical, physical and physiological science, in so far as it relates to the Chemical Composition, the Structure and the Life of the Plant, is the topic of this volume.

Some preliminary propositions and definitions may be serviceable to the reader.

Science deals with Matter and Force.

Matter is that which has weight and bulk.

Force is the cause of changes in matter — it is appreciable only by its effects upon matter.

Force resides in and is inseparable from matter.

Force manifests itself in motion and change.

All matter is perpetually animated by force — is therefore never at rest. What we call rest in matter is simply motion too fine for our perceptions.

The different kinds of matter known to science have been resolved into some seventy chemical elements or simple substances.

The elements of chemistry are forms of matter which have thus far resisted all attempts at their simplification or decomposition.

In ordinary life we commonly encounter but twelve kinds of matter in their elementary state, viz. :

Mercury,

Tin,

Iron,

Copper,

Silver,

Sulphur,

Zinc,

Lead,

Gold.

The numberless other substances with which we are familiar, are mostly compounds of the above, or of twelve other elements, viz. :

Silicon,

Calcium,

Manganese,

Potassium.

Magnesium,

Chromium,

Sodium,

Aluminum,

Nickel.

INTRODUCTION.

So far as human agency goes, these chemical elements are indestructible as to quantity, and not convertible one into another.

We distinguish various natural manifestations of force which, acting on or through matter, produce all material phenomena. In the subjoined scheme the recognized forces are to some extent classified and defined, in a manner that may prove useful to the reader.

Act at sensible and insensible distances

Act only at insensible distances

Repulsive Attractive

and Repulsive

Attractive

LIGHT HEAT

ELECTRICITY Magnetism

r GRAVITATION

COHESION

Crystallization

ADHESION

Solution

Osmose [AFFINITY

VITALITY

J Radiant

> Inductive Cosmical

Molecular

Atomic Organic

►Physical

Chemical Biological

Within human experience the different kinds of force are mostly convertible each into the others, and must therefore be regarded as fundamentally one and the same. Force, like matter, is indestructible. Force acting on a body may either increase its Kinetic Energy, or be stored up in it as Potential Energy. Kinetic (or actual) energy is the energy of a moving body. Potential (or possible) energy is the energy which a body may be able to exert because of its state or position. A falling stone or running clock gives out actual energy. The stone while being raised, or the clock while winding, acquires and stores potential energy. In a similar manner kinetic solar energy, reaching the earth as light, heat and chemical force, not only sets in operation the visible activities of plants, but accumulates in them a store of potential energy which, when they serve as food or fuel, reappears as kinetic energy in the forms of animal heat, muscular and nervous activity, or as fire and light.

The sciences that more immediately relate to agriculture are Physics, Chemistry and Biology.

Physics, or "natural philosophy," is the science which considers the general properties of matter and such phenomena as are not accompanied by essential change in its obvious qualities. All the forces in the preceding scheme, save the last two, manifest themselves through matter without destroying or masking the matter itself. Iron may be hot, luminous, or magnetic, may fall to the ground, be melted, welded, and crystallized ; but it remains iron, and is at once recognized as such. The forces whose play does not disturb the evident characters of substances are physical.

Chemistry is the science which studies the properties peculiar to the various kinds of matter, and those phenomena which are accompanied by a fundamental change in the matter acted on. Iron rusts, wood burns, and both lose all the external characters that serve for their identification. They are, in fact, converted into other substances. Chemical attraction, affinity, or chemism, as it is variously termed, unites two or more elements into compounds, unites compounds together into more complex compounds ; and, under the influence of heat, light, and other agencies, is annulled or overcome, so that -compounds resolve themselves into simpler combinations or into their elements. Chemistry is the science of composition and decomposition ; it considers the laws and results of affinity.

BicUogy, or physiology, unfolds the laws of the propagation, development, sustenance, and death of living organisms, both plants and animals.

When we assert that the object of agriculture is to develop from the soil the greatest possible amount of certain kinds of vegetable and animal produce at the least cost, we suggest the topics which are most important for the agriculturist to understand.

The farmer deals with the plant, with the soil, with manures. These stand in close relation to each other, and to the atmosphere which constantly surrounds and acts upon them. How the plant grows, — the conditions under which it flourishes or suffers detriment, — the materials of which it is made, — the mode of its construction and organization, — how it feeds upon the soil and air, — : how it serves as food to animals, — how the air, soil, plant, and animal stand related to each other in a perpetual round of the most beautiful and wonderful transformations, — these are some of the grand questions that come before us ; and they are. not less interesting to the philosopher or man of culture, than important to the farmer who depends upon their practical solution for his comfort ; or to the statesman, who regards them in their bearings upon the weightiest of political considerations.

DIVISION 1.

CHEMICAL COMPOSITION OF THE PLANT.