Field management and crop rotation

Preface

This book has been written with the hope that it will prove of wide usefulness as a textbook in agricultural schools and colleges; as a handy reference book for editors, publicists, and agricultural students; and as a popular treatise for farmers. It treats, in popular language, of the most important problem of modern times — the maintenance of soil productivity and the profitable use of capital and labor in agriculture — a problem worthy of much consideration by the American people in these days of high costs, diminishing agricultural exports, and increasing population.

Field management and crop rotation, as presented in this book, had their inception, so far as the author is concerned, in the class rooms of the Minnesota School of Agriculture under the tutelage of Professors Willet M. Hays and Harry Snyder. In large measure the subject matter of this book traces back to the investigational work of these men as well as to their classification of knowledge about field management and crop rotation. Furthermore, this book is the outgrowth of the author's own experience in crop rotation investigational work at the Minnesota Agricultural Experiment Station, in teaching crop rotation and the planning of farms to students in the Minnesota School and College of Agriculture, as well as in the surveying and platting of Minnesota farms in connection with the gathering of cost statistics and farm management data by the Minnesota Agricultural Experiment Station and the United States Department of Agriculture. Travel and observation of farming practice in many regions of the United States of

America, as well as in Japan, Korea, North China and Manchuria, have also had an influence on the author's presentation of the subject.

The author acknowledges that in this book there is a free use of many ideas and principles taken from Snyder's "Soils and Fertilizers" and "Chemistry of Plant and Animal Life," and also a free use of the ideas and principles relative to soil amendment with fertilizers as advocated by Dr. C. G. Hopkins in the bulletins of the Illinois Agricultural Experiment Station. The investigational work of these men is so important to a discussion of field management and crop rotation that no book on this subject would be complete without it.

Acknowledgment is made to Andrew Boss, Chief of the Division of Agronomy and Farm Management, and to A. D. Wilson, Director of Agricultural Extension and Farmers' Institutes, of the Department of Agriculture, University of Minnesota, for important suggestions and for correcting copy, also to F. J. Alway, Chief of the Division of Soils of the Department of Agriculture, University of Minnesota, for valued suggestions. Many other agricultural writers-^ and Experiment Station workers have given valued assistance in securing local facts about crop rotation plans.

The problems and practicums of this book have been prepared with the idea of calling attention to many of the important features of the text, and also to provide supplementary work relative to the subject matter. Where time permits, the problems demanding supplementary reading will be found of great value. The practicums, if carried out under local conditions, will add greatly to the students' interest in the subject.

The responsibility for the arrangement and presentation of the subject matter, as well as for the interpretation of

PREFACE 7

much of the investigational data, is with the author. The greatest possible care has been used by the author, as well as the publishers, to avoid error and the omission of valuable facts, and yet it is possible that errors or important omissions exist in the text. The author requests that he be apprised of any that may come to the attention of readers.

■ EDWARD C. PARKER.

St. Paul, Minn., February 4, 1915.

PART I— HISTORICAL REVIEW Page

Early Experience of Mankind in Agriculture 15

The Eariy Use of the Bare Fallow 18

Legume Crops in Agricultural History 19

The History of Soil Tillage Methods and Implements 24

The History of Crop Rotation 29

Crop Rotation, an Important Feature of Farm Management . . 33 The Effect of Cheap and High Priced Land on Agricultiiral

Methods 36

PART II— ROTATIONS AND PLANS Chapter

I Definition and Classification 39

Grain Crops, Grass Crops, Cultivated Crops, Catch Crops, Green Manure Crops, Cover Crops

II Effect of Cropping on Soil Properties 50

Humus Producing Crops, Humus Destroying Crops, Nitrogen Gathering Crops, Gross Feeding Crops, DeUcate Feeding Crops, Shallow and Deep Rooted Crops ni Effect of Continuous Cropping on Productivity, Plant

Diseases, Insects, and Weeds 64

Continuous Grain Crops, Continuous Cultivated Crops, Continuous Grass Crops, Available Supply of Plant Food, Crop Residues, Plant Diseases and Insect Pests

IV Advantages of Crop Rotation 71

General Results; Control of Weeds, Crop Diseases and Insect Pests; Relation of Live Stock to Fertility; Maintenance of Nitrogen, Phosphorus, and Potassium; Farm Labor and Business Management; Value of Land, and Farm Profits

V Field Management to Establish Crop Rotation 98

Meaning of Systematic Crop Rotation, Drainage and Clearing, Division of Fields, Reorganization of Old Farms

Chapter Page

VI Plans and Diagrams 124

Short Cycle Rotations, Long Cycle Rotations, Rotations for Live Stock Farming, Use of Catch Crops, Use of Green Manure Crops, Use of Cover Crops, Use of Alfalfa, Permanent Pastures, Plans without Pasture Lands for Intensive Systems of Live Stock Farming

VII Rotations for North Central States 164

General Statements, Small Grain Farming, Corn Farming, Potato or Sugar Beet Farming, Mixed Grain and Live Stock Farming, Tobacco Farming, Semi-arid Farming

VIII Rotations for North Atlantic States 183

General Statements, Dairy Farming, Potato Farming, Tobacco Farming, Mixed Grain and Live Stock Farming

IX Rotations for South Atlantic States 191

General Statements, Live Stock Farming, Mixed Grain and Live Stock Farming, Tobacco Farming, Cotton Farming, Miscellaneous Crop Farming, Rice Farming

X Rotations for South Central States 203

General Statements, Cotton Farming, Diversified Farming, Sugar Cane Farming, Tobacco Farming, Rice Farming, Grain Farming

XI Rotations for Western States 223

General Statements, Plans for Humid Regions, Plans for Non-irrigated and Semi-arid Regions, Plans for Arid and Semi-arid Irrigated Lands .

XII Practicability of Rotations and Field Plans 261

Chief Criticisms, Value of Field Plans and Maps in Farm Management

PART III— ROTATION AND COMMERCIAL FERTILIZERS I Relation of Fertilizers to Permanent Agriculture 267

Comparative Permanency of Agriculture, Subtraction of Plant Food, Unavoidable Losses of Plant Food, Fertility not Inexhaustible, Ultimate Permanency of Agriculture

II Limitations of Crop Rotation in the Maintenance of Productivity 264

Insufficiency of Crop Rotation, Sufficiency of Crop Rotation

CONTENTS 11

Chapter Page

III Need for Commercial Fertilizers 269

General Conditions, How to Determine Need, Profitableness

rV Phosphorus, the Key to Permanent Productivity 277

Dearth of Phosphorus, Geographical Variations, Importance

V Source and Value of Commercial Fertilizers 280

Acid Phosphate, Ground Bone Steamed, Sulphate of Potash, Muriate of Potash, Kainit, Wood Ashes, Dried Blood, Tankage, Sulphate of Ammonia, Nitrate of Soda, Complete Fertilizer

VI Economical Use of Commercial Fertilizers 294

Draft of Crops on Plant Food, Indiscriminate Use of Commercial Fertilizers, Conditions Warranting Use of Complete Fertilizers, Fertilizer Efficiency Dependent on Good Farming

VII Use and Application of Commercial Fertilizers 306

Lime Fertilizers, Phosphate Fertilizers, Potash Fertilizers, Nitrogen Fertihzers, Fertihzer Machinery

VIII Experiment Station Reports 321

Fertilizers for the Cut-over Lands of South Mississippi, Wheat Growing in Kentucky, Soil Fertihty Problems in Kentucky, Natural Rock Phosphate and Manufactured Acid Phosphate in Illinois, Complete Fertilizers in the Corn Belt (Illinois), Fertility in Illinois Soils, Fertihzer Experiments with Sugar Beets (Colorado), Summary

PART IV— EXPERIMENTAL EVIDENCE I Rotation and Farm Management Experiments — Minnesota.. 341

II Cropping Systems for Wheat — North Dakota 353

III Co-operative Rotation and Fertilizer Tests — Nebraska 363

IV Continuous and Rotation Cropping with and without Manure

or Commercial Fertilizers — Ohio 364

V Thu-ty Years of Crop Rotation — Illinois 375

VI Results of Scientific Soil Treatment— Illinois 381

PART V— REVIEW OF SOIL PRODUCTIVITY Chapter Page

I Lessons from Other Nations 386

II Depletion and Maintenance of American Soils 392

PART VI— ADDITIONAL FEATURES I Plowing Practice 405

All Soils Cannot Be Plowed Alike, SubsoiUng or Deep Tillage, Fall and Spring Plowing

II Soil Inoculation for Legume Crops 416

Bacteria Essential to Legume Growth, Frequent Lack of Bacteria, Species of Bacteria, Natural Means of Distribution, Artificial Methods of Inoculation, Other Conditions Necessary to Legume Growth

III Seed Selection 420

Heavy Seed is Good Seed, How to Select Good Seed, Special Care Necessary for Seed Corn

IV Improved Crop Varieties 424

Pure Seed Desirable, Value of Improved Varieties, Maintenance of Variety Productivity

V Fungus Diseases 428

Flax Wilt; Stinking or Covered Smuts of Wheat Barley, Oats, and Rye; Loose Smut of Oats, Wheat, and Bailey; Corn Smut; Kafir Corn Smut; Potato Scab; Potato BUght; Sweet Potato Black Rot and Stem Rot; Tobacco Root Rot and Bed Rot

VI Weed Eradication 436

Wild Mustard, Wild Oats, Kinghead or Giant Ragweed, Corn Cockle, Bull Thistle, Burdock, Canada Thistle, Quack Grass

CONTENTS 13

Appendix

Compendium of Facts and Statistics

Page Rules for Measuring Hay in Mows and Stacks, Grain and

Roots in Bins, Corn in the Crib, Grain and Ear Corn

in Wagon Boxes, and the Acreage of Fields 449

Legal Weights of Agricultural Products 452

Amounts of Seed per Acre. Depth to Plant. Methods

of Planting. Crops : Annual, Biennial or Perennial 454

Standard Grass Mixtures 458

Composition and Amounts of Manure Produced by Different

Kinds of Farm Animals 459

Amounts of Nitrogen, Phosphorus, and Potassium in Animal

Products 459

Annual Maintenance Costs for Dairy Cattle 460

Quantity of Milk Required to Cover Costs of Maintenance

of Cows of Different Values 462

Haecker's Feeding Standards 463

Wolff's Feeding Standards 477

Cost of Farm Horse Power 478

Fencing Costs 479

Work Capacity of Farm Machines 482

Depreciation in Value of Farm Machinery 484

Cost of Producing Corn, Wheat, Oats, Barley, and Potatoes

in the Various Geographic Divisions of the United States 486 Summary of the Cost of Producing Field Crops in Minnesota 490 Itemized Accounts of the Costs of Producing Corn, Hay,

Wheat and Potatoes in Minnesota 491 iiWii

FIELD MANAGEMENT

AND

CROP ROTATION

Part I Historical Review

Early Experience of Mankind in Agriculture. The evolution of agriculture among the various nations of the earth has proceeded along very similar lines since the dawn of history and, doubtless, for many centuries of the prehistoric age. Indeed such pioneer agriculture as exists in the twentieth century A. D. in portions of North America, South America, and Africa, closely resembles, in many particulars, the agricultural experiences of mankind in the earliest periods of history. The growing of food crops on cultivated land has never been the first plan of a tribe or pioneer community of men to satisfy their food requirements. Man's first recourse to obtain food has ever been the wild animals of the forest or plain, the fish of the lake or stream, supplemented by the roots, grains and fruits that nature yielded unaided. Sometimes the wild meat and fruits would

Note: Acknowledgment is here made to three treatises on the historical features of agriculture from which the author has freely dra^wn for the material of this part: Roman Farm Management, or treatises of Cato and Varro, translated by Fairfax Harrison, a Virginia Farmer; English Agricultural Writers from Sir Walter of Henley to Arthur Young, 1200-1800 A. D., by Donald McDonald; Historical Sketch of American Agriculture by T. N. Carver, Vol. IV Bailey's Cyclopedia of American Agriculture.

be supplemented with a cultivated cereal grown on small patches of virgin soil, but, even then, the main food reliance was the wild animal life of the country. The families and tribes were more or less migratory. Nature fed them and they wandered from one hunting or fishing ground to another.

As population increased, nature's supply of easily obtained food decreased. Then we find man taming and domesticating animals and guarding their young from the attacks of wild beasts that he might control his meat supply and increase it according to his needs. With his flocks and his herds he now sought the richest grazing lands for his habitation. Life was still migratory to a large extent, but not so much so as when entire dependence was placed on the natural supplies of food. Man had then become skilled as a shepherd or drover. He still hunted and fished, but the hunter had mainly given way to the flock-master and the cattle-drover.

In the early history of mankind, as well as in the agricultural history of many modern communities, the pastoral or grazing stage of animal husbandry was slowly merged with agriculture. Agriculture— the growing of food crops on cultivated land — originated from several causes, chief of which was the desire for a varied diet, the need of winter forage for live stock, and the ever increasing population that demanded more food supplies from the known regions of the Eartli than could be supplied from hunting, fishing, and grazing live stock. And so man chose from the wild plant life surrounding him the cereals and vegetables that best suited his taste, and the grasses and forage plants that produced most abundantly, and began to grow these crops on cultivated land where he could nurse and protect them as he had once learned to tame and protect the wild animals of his environment. Early agriculture did not displace the grazing of live stock, but merged with it. Animal husbandry came to rely more and more on the products of the cultivated fields to winter and fatten the animals. As long as two thousand years ago the farm breeding and feeding of live stock, as distinct from pastoral animal husbandry, was well developed among the Romans, and this same evolutionary process has taken place in the development of nearly all the agricultural regions of the Earth.

It was early learned that cultivated lands under crop gradually lost their producing power. When cultivated land lost

Plowing with oxen in Europe.

some of its producing power, it was abandoned to nature, and new land of virgin fertility was reclaimed from the forest or prairie. This was the natural and simple procedure under the circumstances. Rich, productive, virgin land was abundant and cheap. Labor was relatively scarce. There was little knowledge of the causes for the decrease of soil productivity or the methods for renovating worn out land, and so the farmer followed the lines of least resistance and abandoned the old land for new. This custom of abandoning partly worn land has been almost universal in the history of all nations and their agriculture. The English farmers of the eleventh to the fifteenth centuries grew considerable grain, and the preparation of virgin land every year was a regular part of the farmer's work, some of the old land being allowed to go back to grass or weeds every year. Early agriculture in the American colonies followed the same practice. The tobacco growers of old Virginia would clear virgin land, plant tobacco for three to eight years on it, and th^n abandon the land to nature. Agricultural communities in South America, Central America, and even North America may still be found where this practice is followed.

The Early Use of the Bare Fallow. Along with such agricultural experience as taught man that cultivated lands under crop soon lost their producing power came the knowledge that idle lands tend to recuperate their power to produce good crops. The experience of the farmers of many nations in many chmates- showed that idle, abandoned land would come back in its productivity. In man's early discovery of this principle we find the origin of the practice of "bare fallowing." As land became scarcer and as agriculture increased in importance the bare fallow became a systematic feature of agriculture, j Instead of working land to a condition of unproductivity and then abandoning it to nature, the farmer cropped the land continuously with regular fallow periods every second or third year.

The bare fallow was the basis of Roman agriculture for a long period, being systematically alternated with the field crops every second or third year. The English farmer of the thirteenth to the seventeenth centuries also placed a great deal of dependence on the bare fallow in his scheme of cropping. Writing in the early part of the seventeenth century and just prior to the spread of knowledge about clover in England, the Rev. John Laurence says : "Fallowing kills weeds by turning their roots to the air. It lays the land in ridges thereby better exposing it to receive the nitrous influence of frost, wind, sun and dew. These influences all tend to sweeten and mellow the land." Many agricultural regions of the United States of North America have made extensive use of the bare fallow in their methods of agriculture — in fact the bare fallow, as a method for increasing the productivity of land, may still be found in numerous agricultural regions of North America.

Modern agricultural science reveals the fact that, while the bare fallow acts as a temporary stimulus to soil productivity, it is a. practice that serves to hasten the ultimate unproductivity of a soil area. The green manure fallow, the annual pasture, and the legume meadow are the modern methods for "resting land," and the old bare fallow is disappearing except as a means for destroying noxious weeds and, in some regions, for conserving soil moisture.

Legume Crops in Agricultural History. While modern science has answered all the whys and wherefores about the bare fallow, the green manure legume crop, and the legume meadow crop, in their relation to soil productivity, the practices of green manure fallowing and seeding down land with legume crops did not originate in modern times. The value of the legume crop as a soil renovator was known many centuries before science discovered all the reasons why legume crops rest the land more than a bare fallow. In fact, the green manure fallow and the legume crop meadow came to supersede the bare fallow in Roman and English agriculture long before the scientific facts were known about legume crops and the nitrogen gathering bacteria or the function of humus in the soil. Early experience with legume crops, therefore, developed the art of rotating them with other field crops.

Two thousand years ago the Romans well knew that the seeding of lupines, beans and vetches on their cultivated lands greatly increased the yields of succeeding grain crops. Discussing the best plants for the Roman farmer to cultivate, Varro wrote, fifty years before Christ: "Field beans should be sown as much as possible in your corn land." Varro also wrote about green manure crops in a manner that needs no revision to-day. He says: "Certain plants are cultivated not so much for their immediate yield as with forethought for the coming year, because, cut and left lying, they improve the land. So, if land is too thin, it is the practice to plow in for manure lupines not yet podded, and likewise the field bean, if it has not yet ripened so that it is fitting to harvest the beans."

Alfalfa was one of the standbys of ancient agriculture. It was brought into Europe from Asia long before Christ and gradually spread all over Europe. It had become a standard farm crop in Roman agriculture about the time of Christ. Columella, a Roman author, writing about alfalfa in the early Christian era, says: "But of all the legumes, alfalfa is the best, because, when once it is sown, it lasts ten years; because it can be mowed four times and even six times in a year; because it improves the soil ; because all lean cattle grow fat by feeding upon it; because it is a remedy for sick beasts; and because two thirds of an acre of it will feed three horses plentifully for a year." Columella gives instructions about seed bed preparation, seeding, care of the new seeding, and methods for feeding, that can hardly be improved to-day.

Clovers, trefoil, and alfalfa were introduced into England from Spain, France and Flanders in the first part of the seventeenth century. About the middle of this century many observing writers began to discuss the public loss that arose from constant pasturing on one portion of the land and constant plowing and fallowing on another portion of the land. After the introduction of legume crops into England the benefits to succeeding grain crops from the use of legumes became quite well known. The practice of seeding legume crops with a nurse crop of grain developed during this period, and the rearing of cattle on arable land received a great impetus. Animal husbandry and grain growing were merged in England during this period largely because farmers discovered that

Plowing in North China with a steel pointed wooden plow, not inverted but merely cultivated into ridges.

The topsoil is legume crops yielded much more hay and pasture than their native grasses, as well as that they improved the productivity of arable land better than the bare fallow.

The prevalent ideas about legume crops in the middle of the seventeenth century in England are well illustrated by the writings of Andrew Yarranton, who, in 1663, wrote a book encouraging the growing of clover, entitled, "Great Improvement of Lands by Clover." He says in this book: "Six acres of clover are as good as thirty acres of natural grass for fattening cattle." "Clover doth so frame the land that.

being plowed, it will yield three or four years together a crop of wheat, and after that, a crop of oats," "Clover improves land by the roots' cleaning the soil, and by the shade of the leaves, beneath which an incipient decomposition is encouraged which mellows the surface of the ground and provides food for future crops." "Lime should be used to encourage the growth of clover."

Clover was the first important legume crop to be introduced into the United States of North America. It was introduced from England into the New England colonies in 1763. In the period 1790 to 1810 clover first began to have some importance in American agriculture, and was frequently used in rotation with grain in Pennsylvania and New York as a substitute for bare fallow. The use of legumes in American agriculture has not yet become widespread. The development of the great cotton growing industry in the Southern states in the years 1830 to 1860, the rapid extension of cattle and sheep grazing in the Western states in the years 1865 to 1885, and the rapid development of specialized wheat and corn culture on the extraordinarily fertile prairies of the Middle Western states in the years 1870 to 1890, built up three great special industries that have not yet given way entirely to the mixed type of farming with the use of legume crops and the rearing of live stock in connection with the special enterprise. The use of legume crops in American agriculture is on the increase, however. Progressive grain, corn, and cotton growers are fast learning that clover, alfalfa, cowpeas, soybeans, or some other legume is a necessity in any rational scheme of cropping that will maintain soil productivity. The American live stock feeder is also fast placing his chief dependence on the legume crops for fodder crops on account of their productivity and high nutritive value. The United States Department of Agriculture has literally combed the Earth to find legumes adapted to every soil and climate of the United States and to every need of farm management. As a result, the most profitable and productive legume crops of all nations and all climates have been brought to the United States, and the future will undoubtedly see a great increase in the use of legume crops in American agriculture.

It was not until 1888 that scientific investigators discovered the relationship that exists between legume crops and the nitrogen gathering bacteria (See page 57). This discovery cleared up the mystery of why legume crops had such unusual power as soil renovators, especially when used for green manure fallows. It settled for all time the hitherto vexed problem of nitrogen plant food in agricultural soils, for it showed that the legume crop, and the nitrogen gathering bacteria associated with it, were the farmer's key to an absolutely inexhaustible supply of nitrogen in the atmosphere. It also proved that the legume crop meadow or green manure was eminently superior to the bare fallow as a means for maintaining the productivity of the soil (See page 350). Scientific investigation since 1888 has added much to our knowledge of the soil bacteria associated with legume crops and of the methods that can be employed to inoculate soil with these bacteria so as to stimulate legume growth. (See page 415).

There is much that we may still learn about legume crops and their place in a permanent scheme of agriculture, but we know enough now to realize the unrivaled value of these crops as soil renovators. The Romans realized the value of these crops in relation to soil fertility two thousand years ago, and when one sees the thousands of acres of cotton, corn, and wheat in the United States still grown in a ruinous system of continuous cropping, one wonders if the Romans were not wiser farmers two thousand years ago than we are to-day in the twentieth century after Christ.

The History of Soil Tillage Methods and Implements. The tillage methods employed in the agriculture of ancient and medieval times were crude in comparison with the best tillage methods of modern times. The farmer of early times did not have at his command the steel moldboard plow, the disk harrow, the sub-surface packer, and the deep tillage plow, with which to invert and pulverize his soil easily and thoroughly. The plows employed in agriculture, prior to the middle of the nineteenth century, were crude and inefficient. As compared with the thorough pulverizing

Photo by courtesy "The Farmer."

In the disk harrow the modern farmer has an implement for smoothing and

fining the seed bed, closing air spaces in freshly plowed land, and killing noxious

weeds, that is far more efficient than any implement available to the farmer of

ancient and medieval times.

HT8T0RTCAL REVIEW 25

work of the modern plow they merely stirred the surface soil. Many of the earliest plow types were merely sharpened, hardened sticks of wood. Later, an iron point was attached. The ancient and medieval farmer usually ridged his land in order to form a seed bed of loose soil. Often the tillage was accomplished as much with the mattock and spade as with the oxen or horse drawn plow. Hand tillage was common in Roman and English agriculture, and was largely employed in the early days of colonial agriculture in North America. In the Virginia colony, which was mainly agricultural, there were but one hundred and fifty plows of any kind in use in 1649, the majority of the fields being hand tilled.

In spite of the tillage implement handicaps under which early agriculture was pursued the Romans learned from long experience the value of deep and thorough tillage. The Roman farmers worked their land deeply, thoroughly, and often. They learned the value of deep tillage in conserving soil moisture and practiced "dry farming" in Mesopotamia for generations.

The value of thorough soil tillage as a factor in crop production was not emphasized and brought completely to the light until the middle of the eighteenth century. The Romans undoubtedly understood the value of thorough soil tillage and practiced it themselves, but with the decay of Rome and of Roman civilization their knowledge of the art of agriculture passed temporarily into oblivion. Many centuries intervened before the European barbarian tribes developed the art of agriculture to a point approximately comparable to that of the Romans in the height of their civilization. English agriculture, for example, underwent all the elementary stages of agricultural evolution from the eighth to the eighteenth centuries, and not until the middle of the eighteenth century, or even the first part of the nineteenth century, had Enghsh agriculture sufficiently advanced to be in any way comparable to the agriculture of the Romans.

In the middle of the eighteenth century an Englishman named Jethro Tull made some discoveries about soil tillage that made his name famous, and that gave a great impetus to the study and practice of thorough soil tillage as one of the most important of all factors in crop production. Before TuU's time English lands were scantily tilled and the seed was thickly sown broadcast. Legume crops had come into quite common use as well as the rearing of live stock on arable land, but the tillage methods were poor and inefficient. During Tull's travels in France he noticed that the vineyards were not manured, but were very thoroughly tilled. This gave him the idea that field crops could be similarly grown without manure, if the soil were thoroughly pulverized. He invented a crude machine for sowing grain in drills that would permit inter-tillage, and he also improved the plows and tillage implements of his time. His experiments and observations showed that drill sowing required less seed than broadcast sowing, and that with inter-tillage the fold of crop from seed was greater than his neighbors were getting by the common methods of sowing and tillage.

Tull's experience led him to develop a theory of crop production which stated that "tillage is manure," and that "hoeing and pulverizing the soil might supersede the use of manure." In the later years of his life he came to realize that his tillage methods were but one important factor of crop production and not inclusive of all the essential factors. For many years, however, he advocated thorough soil tillage as the cure-all for lands of low productivity. Agriculture owes much to Jethro Tull. In his experiments and writing he gave us the first great and comprehensive lesson about the value of the inter-tilled crop and thorough soil pulverizing in the art of successful agriculture. Other men may have known of the value of these practices in the centuries before his time, but, if so, they failed to stamp their ideas permanently on the art of agriculture. Jethro Tull's ideas soon became incorporated in English agriculture, and, subsequently, in the modern agriculture of many nations. From Jethro TuU we have learned that thorough soil tillage is essential to maximum crop production and that the inter-tilled crop prepares the land for a succeeding crop as well as a bare fallow.