Farming with green manures

Preface

TO FIRST EDITION

In publishing these pages I have two objects in view — the assistance of those who need advice and the instruction of my foreman on " My Farm," that he may understand the reason why he is required to do certain things. But how should I know any better than he does the laws of vegetable life and the best course to pursue to obtain remunerative crops ?

He is supposed to be practically acquainted with the whole art of agriculture. Now, the fact must be plain to every one that no man, in his short life, by his own experience and observation, can be come master of this art, because it takes a whole year to try one experiment. From this fact, his progress in knowledge must be very slow indeed.

Well, then, besides the actual trials on the farm to improve his mind, the next best thing to do is to study carefully the recorded experience of other farmers and the writings of the able investigators of the chemistry of plant-life. To do this with profit he should be acquainted, to a certain degree, with every science which has shed any light upon the subject.

Now, the working farmer is generally too much engaged to acquire this knowledge. Well, then, if he will please to lay aside all prejudice against me, we will read for him and report a few of the grand truths which we find scattered through the vast tomes of other times and the periodicals of our own rushing, busy century.

Whether I shall ever receive any thanks for this is a very small matter.

The consciousness of having done good to others will amply repay me for all my trouble.

4 PREFACE

I sincerely believe that he who tills the soil is helping God to feed the world, for without tillage the earth could not support one-tenth of its present population. Therefore, what I can do in this good and noble cause it is my duty to do. And I may as well confess that to me it is no tiresome labor, because I love the art; and ever have loved it from my boyhood to the present hour.

C. Harlan, M. D.

Preface To The Seventh Edition

The cordial reception given to the former editions of this book appear to call for a new edition. The editors have taken advantage of this occasion to have the book completely revised in light of the important scientific discoveries made since the earlier editions were issued. Although more than three decades have passed since the first edition of this book was published yet there is so much of permanent value to the original themes of the book that the subsequent findings of both science and experience have only added greater weight to their importance. The remarkable role which leguminous crops have come to play in assisting in the solution of the great problems of maintaining soil fertility has called for the addition of several of these leguminous crops to the list of those treated within the pages of the former editions. A few crops important at the time the early editions were issued have given way the others found to be more valuable and the discussion of these has been eliminated to make room for a more adaquate treatment of the more important crops for green manuring purposes. There have been some modifications in the accepted composition of the different crops as well as in the market values of the various fertilizer constituents. It has therefore been deemed wise to make such changes in these figures as to make them applicable to present day conditions. The illustrations in this book have been secured from various publications of the U. S. Department of Agriculture.

The importance of maintaining an abundant supply of humus in the soil is coming to be recognized more and more as being of prime importance to the up-to-date farmer who would restore and maintain the original fertility of his fields. The principal theme of Doctor Harlan in these pages has been to

6 PREFACE TO SEVENTH EDITION

point out how this maintenance of fertility can be brought about on the ordinary farm with the least possible outlay of labor and money. The general principles as laid down in the early editions have stood the test of time and experience and it is hoped that this edition will appeal with added force to the farmers of the country who have the permanent interests of their fa^s at heart.

Introduction

THE plowing under of green crops for the purpose of maintaining the fertility of the soil is almost as old as history itself. The ancient nations compelled to live for centuries upon the same land, realized the importance of green manure crops often to fuller degree than do we the inhabitants of our relatively new country. Here the problem of maintaining soil fertility is only beginning to be so serious as to call for the development of the best farm practices with reference to the use of these green manure crops. The subject must ever be a complex one calling for the proper adaptation and combination of green manures with commercial fertilizers and with crops that are to be fed upon the soil and the resulting manure spread back upon the fields. Different farms will require different systems of management. It is the province of the succeeding chapters to point out the special value of turning under green crops for the purpose of soil improvement.

Green manures may benefit the ground upon which they are grown in a number of different ways: (1) by adding vegetable matter or humus to the soil; (2) by utilizing and holding for succeeding crops much soluble plant food which would otherwise escape from the soil ; (3) plant food from the lower layers of the soil may be brought nearer the surface where it can be utilized to better advantage; (4) if the green manure crop be a legume there will be a considerable amount of nitrogen added to the soil through the fixation of nitrogen from the air.

There are two classes of green manures; namely, those that merely add humus to the soil together with what plant food materials they may have withdrawn from the soil itself, and those that in addition to the humus they return to the soil, are able to draw nitrogen from the air and thus directly increase the amount of this most valuable element in the soil. This last class is the family of plants known as the legumes. All the deep rooting green manure crops, both legumes and non-legumes are usually able to draw up out of the deeper layers of the subsoil, plant food which the succeeding shallower rooted crops would otherwise be unable to obtain. Such plants also permit the more feeble rooted plants to send their roots deeper into the soil since the deep feeding roots serve to break up the subsoil and aerate it properly for the best growth of the roots of the following crop.

The necessity of making some return to the soil to compensate it for the large removals from it in the form of crops is coming to be recognized even in the West where until recent years the soil was so new as to permit continued cropping and still produce satisfactory crops. There are still some sections in the more recently developed areas of the western half of the country where the soil has not yet become materially depleted, but it is only a question of time when all sections will be compelled to make some provision against the depletion of soil fertility. Commercial fertilizers have been used extensively for generations in the east and have the advantage in that they are easily applied. They do not, however, add any humus to the soil and in this respect do not furnish a complete solution of the problem of maintaining the fields in the proper condition.

One other method is to feed the crop on the farm and return the manure to the soil. This is the practice usually adopted on the dairy farms where grain brought in from outside sources increases the value of the manure returned to the ground. There are a number of points in which this method is not of universal application. In the first place, it is usually impossible to keep from losing nearly half of the original value of the manure

INTRODUCTION 13

by loss of much of the liquid portion, and by the leaching of fertilizing materials and escape of valuable gases into the air. Such farms can be only partially kept up by the use of manure produced from feed produced upon the farm itself. This means that the land from which this extra feed was secured must go without its quota of manure. Such a method is satisfactory for the individual farm, but it is apparent that all farms in the country could not be run in this manner as there would then be no lands from which feed for the extra manure could be obtained. In addition to this lack of universal application the labor incident to the scattering of the manure over the land is extremely great. In the green manure crops we have the scattering already accomplished by nature, and all that remains to do is to turn it under for the hungry soil. A ton of the green plant growth is about equal to a ton of manure as regards its fertilizing value and an ordinary growth of a green manure crop will produce quite as great a tonnage as is usually applied to the soil in the form of barn-yard or stable manure.

The principal disadvantage incident to the use of green manures is that the field cannot be utilized in producing a regular farm crop while it is producing its crop of green manure. Unless either the green manure or the regular crop can be seeded the same season, the use of the land is lost for the entire season. The greatly increased yield of the succeeding crop is the justification of such a practice. It is considered quite as profitable to crop one half the acreage if enough more than double the yield can be secured by this method, to pay for the seed and labor attending the use of the green manure crop. In deciding which green manure crop should be used for a specific purpose a number of points should be taken into consideration. Choice may be made between those that make most of their growth in the fall, winter and early spring and those that grow only in the summer time. The former class has the advantage in that a summer growing cash crop can usually be planted after a winter growing crop has been turned under in the spring. Preference should be given a leguminous crop if it be available as such a crop will in addition to its other benefits, naturally increase the nitrogen content of the soil. Other points that are of more or less moment are the cost of the seed, the deep or shallow rooting qualities of the plants, their ability to compete with the weeds and the ease with which the crop may be turned under. The supplemental value as pasture or as hay in emergency should also be considered. If pastured and the stock kept continually upon the land the net loss to the land is not great, while if cut for hay there will still be the stubble and roots available for soil improvement purposes. Even weeds are valuable as green manures if plowed under before they mature their seed. Their value is frequently as great as that of a light application of ordinary barnyard manure.

Liming may be necessary to correct any acidity due to the decay of the green crop. This may be best applied before turning under the crop. It may even be applied before seeding the green manure crop, especially if it be a legume needing lime in the soil. The complete results from a green manure crop are not secured until it has completely decayed and assumed soluble form so as to be available to the succeeding crops. This may require two or three years so that the beneficial results from the plowing under of a green manure crop are usually manifest for more than one season. Tillage hastens the decay of organic matter and for this reason it is usually best to follow the green manure crop with some cultivated crop as corn, cotton or tobacco depending upon the locality.

Many of the green manure crops permit of their being left on the fields over winter either in the green state or matured. In either case they perform valuable service as a cover crop, preventing the soil from washing and assisting in holding the snow which might blow off the otherwise windswept fields.

If a complete system of green manuring be installed upon the farm, the doing away with the pasturing of stock, avoids the necessity of inside fences which are the source of a great deal of expense both as to original cost as well as maintenance. Under such a system the soiling of crops for the necessary livestock

INTRODUCriON^'l'^l 111:3 ^flS would be practiced to a much greater extent than is at present the case. This is, however, in line with the best practice since more than double the niunber of stock can be maintained on a given acreage where the green feed is cut and fed to the stock than where the cattle are allowed to trample it in pasturing it off for themselves. In fact the intensive farming of a few acres has been repeatedly shown to be quite as profitable as the ordinary treatment of a much greater acreage. The intelligent use of green manures will facilitate any endeavors to further the intensive culture and upbuilding of the farm.

Chapter II. Covering The Soil

WHEN green crops are raised to improve the land it is not indispensable that they should be ploughed in to accomplish this object. You need not turn them in till you are under the necessity of doing it to prepare the ground for a future crop. But if the green dressing should be Hungarian millet or white mustard, or anything that might seed the ground at an improper time, you can either plough it in or cut it down when in blossom, and it will improve the soil in proportion to its ability to shelter it. Cuthbert W. Johnson says: "An English farmer inadvertently left for some months a door in his fallow field; for several years after the crops were particularly luxuriant where the door had been lying — so much so that one would have said that some rich manure had been applied to that spot."

Anderson, an eminent Scotch writer, says in his Economy of Manures: "Every practical farmer knows or ought to know, for the facts are constantly before his observation, that land can be made exceedingly fertile without manure. He must have noticed that if any portion of the soil has been covered, either accidentally or designedly for some time, by water, stone, plank, logs, chips, brush, rails, corn-stalks, straw, buildings of every description, with hay or straw ricks, leaves or clover — and in fact, that under any and every substance which has covered surface closely — it (the surface soil) invariably becomes exceedingly fertile, and that the degree of this fertility is totally independent of the covering substance."

After reading these remarkable statements of Johnson and Anderson, both men of extensive observation and intelligence, we can more fully credit the experiments of Gurney in England upon his fields of grass.

COVERING THE SOIL 17

Green grass covered with straw gave him in one month five thousand eight hundred and seventy pounds per acre. The same kind of grass uncovered produced but two thousand two hundred and seven pounds. No rain fell during this experiment. Another plot gave in one month, when covered, three thousand four hundred and sixty pounds per acre, while the rival lot, not covered, yielded but nine hundred and seventy pounds. Clover that was covered grew six inches, while that uncovered grew but one inch and a half.

And where a certain quantity of stall dung would double the crop of grass the mulch spread on top of the manure would increase the crop six times. He used about one ton and a half of straw per acre.

"Boussingault found upon comparing water obtained by melting two portions of snow — one taken immediately as it fell upon a stone terrace, and the other (from the same fall), after it had lian for thirty-six hours upon the soil of a contiguous garden — that the second contained ten times as much ammonia as the other. It is well known that snow has a most beneficial effect upon soils, and, amongst other causes, Boussingault believes that it may act in preventing ammoniacal emanations from the soil." — Journal oftJie Royal Agricultural Society of England.

Now , we can believe there is much truth in the old proverb, that "Snow is the poor man's manure."

Not having straw nor any barnyard material to top-dress his wheat, he has often noticed that his crop was much better when kind Nature covered it for him.

Does not this investigation of the great chemist reveal to us one, if not more, of the deep and far-reaching causes why mulching is so beneficial to the land ?

Professor Johnson says: "The ammonia of the soil is constantly in motion or suffering change, and does not accumulate to any great extent. In summer the soil daily absorbs ammonia from the air, receives it by rains and dews, or acquires it by the decay of vegetable and animal matter. Daily, too, ammonia wastes from the soil by volatilization, accompanying the vapor of water which almost unceasingly escapes into the atmosphere." — How Crops Feed, p. 247.

This is a revelation of scientific truth which cannot be misunderstood or explained away . Was ever a stern necessity to do anything more clearly demonstrated to the world ? We must keep the soil covered to promote and retain its richness. But how often do we strip the ground naked, and then bake it in the ever-burning sun!

Col, Waring, of Ogden Farm, says: "I had read so much about top-dressing that it was determined to try it on this apparently forlorn hope, and the land was all covered before the heavy rains that fell early in May. The result was almost magical. While that portion which had looked so promising as to seem not to need manure did not yield 1000 pounds per acre of poor hay, ox-eyed daisy and red sorrel, this poorer part, solely as an effect of the top-dressing, produced fully 4000 pounds per acre of very fair hay."

Chapter III. Surface Manuring

NOT many years ago it was the universal custom to plough in manure the very day or hour that it was spread upon the field. Farmers became irritable and had butlittletosayif anything prevented immediate ploughing after the precious contents of the barnyard were spread broadcast before their eyes. It was a prevalent opinion that nearly all the richness would dry out in a few days if exposed to the weather.

They had often noticed that manure under cover was about twice as good as that which lay out of doors all summer, but they did not discover that the great injury which it had received was owing to the leaching rains, which dissolved and carried off its richest elements, and not to the sunlight which occasionally fell upon it.

When manure is spread it soon becomes dry, and then all chemical changes cease; fermentation is arrested; it will decay no more in that condition. And when the dews settle and the rains descend upon it, it will dissolve, day after day, and a peculiar dark rich coffee will effectually saturate the soil beneath it.

In the Genesee Farmer John Johnston says to Joseph Harris : "I am not surprised at your correspondent, Buckeye, being opposed to surface manuring. I would have been so myself had not experience taught me better. I have used manure only as a top-dressing for the last twenty-six years, and I do think one load used that way is worth far more than two ploughed under on our stiff land."

Nearly ten years after this was written he speaks, if possible, with even a stronger faith than ever in defence of his favorite practice.

Harris writes in Walks and Talks, No. 112, that "John Johnston, who has a far heavier clay soil than the deacon, says he has found by actual trial that one load of rotted manure applied as a top-dressing to grass-land in the autumn, and the land ploughed up and planted to corn in the spring, is worth as much as three loads of fresh manure ploughed under."

Major Dickinson, another able and extensive farmer, declares: "I hold that one load of manure on the surface is worth two loads ploughed in."

Charles B. Calvert, a distinguished farmer of Maryland, "is a strong advocate of the application of stable manures ujjon the surface, instead of ploughing them in." — Cultivator.

Mr. Bright writes in the Gardener s Monthly: "The practice of top-dressing or of surface manuring has long been the favorite method employed by all intelligent gardeners within the circle of my acquaintance. A piece of soil heavily shaded by surface manuring actually decomposes like a manureheap; that is, it undergoes a sort of putrefaction or chemical change which sets free its chemical constituents, unlocks, as it were its locked-up manurial treasures, and fits its natural elements to become the food of plants. Manure, then, I say, chiefly upon the surface. Do not waste your manures by mixing them deeply with the soil. Surface manuring and mulching are the true doctrines. I am sure of it."

In Todd's Young Farmer's Manual I find the following statement: "James M. Garnet, a Virginia farmer, an excellent writer on agriculture, says: T began penning my cattle late in the spring, and continued it until frost in pens of the same size, moved at regular intervals of time, and containing the same number of cattle during the whole period. These pens were alternately ploughed and left unploughed until the following spring, when all were planted in corn, immediately followed by wheat. The superiority of both crops on all the pens which had remained unploughed for so many months after the cattle had manured them was just as distinctly marked as if the dividing fences had continued standing; it was too plain even to admit of the slightest doubt."

SURFACE MANURING 21

"A near neighbor, a young farmer, had made the same experiment on somewhat different soil the year before, but with results precisely the same. Similar trials I have made and seen made by others with dry straw alternately ploughed in as soon as spread, and left on the surface until the next spring. In every case the last method proved best, so far as the following crop would prove it.

"The same experiment has been made by myself and others of my acquaintance, with manure from the horse-stables and winter farm -pens, consisting of much unrotted corn-offal, and without a solitary exception either seen by me or heard of the surface application after the corn was planted produced most manifestly the best crop.

"Upon these numerous concurrent and undeniable facts my opinion has been founded, that it is best to apply manure on the surface of the land."

An able writer in the Cultivator in 1843 says: "I have seen spots where cattle had been penned at night for a month or two; for six years afterward, the vegetation was double on those spots to any other part of the field, although all the manure had been carefully removed and scattered about. Now, nothing but the liquid could have gone into the earth, and yet the rains of six years never washed away the beneficial effects."

On steep slopes, however, when the rains run off too rapidly without sinking into the soil it may be best to turn under the manure. Of two evils choose the lesser. If plowed under too deeply however it will be so deep that the bacteria cannot work upon it to make it available to the succeeding crops.

Now, if the valuable material of the barnyard will not suffer waste when spread upon the oj)en fields, and is better there than anywhere else, then the green crop, whatever it may be, that is raised to improve the land, should be mown down in summer and in autumn, and should be left upon the surface as long as possible — to prevent evaporation, to disintegrate the soil, to retain moisture, to be leached by rains and dews, and finally to enrich the ground by its total decomposition.

CHAPTER rV.

WATER AS A SOLVENT.

THE mineral constituents of the bones of man and animals are but the asJies of our daily food.

Every year from the rock and soil these ashes come, decomposed and dissolved by water, carbonic acid and oxygen.

Green manures, by their ability to collect and preserve moisture on the surface and in the soil when cut down or ploughed in, render an immense assistance in the growth of the organic world. Water is the olood of vegetation. It carries nourishment from the ground to the stem, to the leaf, to the seed. In its solvent action rocks become the food of man.

When the soil is dry no mouldering down to a finer dust, no disintegration of minerals, no decay of any kind, can be discovered; every atom, apparently stationary, seems fixed and firm as adamant.

Travellers tell us that in the dry air of Egypt the old monuments erected thousands of years ago are just as fresh and smooth in outline as if the chisel had finished them but yesterday. But when some of these relics of the past were transported to Paris, in the moist climate of France they soon began to change, and atom by atom to crumble away.

Dr. Youmans says : 'It has been shown by extensive experiments that no species of rock whatever will resist the solvent action of water impregnated with carbonic acid." — Atlas of Chemistry, p. 50.

What an instructive lesson! How valuable to the farmer! Such knowledge, how exceedingly useful! — that in our daily effort to convert the earth upon which we tread into a flourishing vegetation we can combine and concentrate the forces of nature by covering the ground, that moisture and carbonic acid may do a great work for man.

WATER AS A SOLVENT 23

Yes, so vastly important is the benefit that may be derived from mulching with green manures that we not only see it in the augmentation of our crops and the improvement of our tillable soil, but it may be observed in the condition of the forests around us. Those that have a deposit of leaves undisturbed for years about their roots make an annual growth much greater than those which have been robbed of their carpet of dead foliage by the winds or by the hand of man.

"The fallen leaves," says Liebig, "contain such trifling quantities of potash and phosphoric acid in comparison to their mass that it is difficult to account for the injurious consequences arising from the raking up and removal of the fallen leaves in woods."

It is difficult only when we forget the conditions existing in the woods. There the protection of the soil, the perpetual moisture, and the carbonic acid constantly forming, work without ceasing beneath the mulch, crumbling and mouldering the minerals into an impalpable and soluble state, ready to be absorbed by plants or trees.

Liebig admits that "the injury is perhaps rather attributable to the fact that the remains of leaves and plants constitute a lasting source of carbonic acid, which, carried by the rain to the deeper layers, must powerfully contribute to disintegrate and decompose the earthly particles."

These substantial truths should establish the advantage, if not the necessity, of shelter and moisture to improve the soil, and also to promote the growth of our crops.

Yet there is no scarcity of water in our favored country.

We have a rainfall of four thousand tons per acre every year. But what becomes of it ?

Professor Johnson says: "According to the observations of Dickinson at Abbot's Hill, Hertfordshire, England, and continued through eight years, ninety per cent, of the water falling between April 1st and October 1st evaporates from the surface of the soil, only ten per cent, finding its way into drains laid three and four feet deep." — How Crops Feed, p. 197.

This , we presume, is about the amount of evaporation in the United States. Then what a magnificent prospect is here presented !

Mighty rivers are pouring, not down the deep valleys, but upward from our broad fields to the blue sky above us.

Yes, every square mile of territory sends a constant flood, rushing, though invisible, to the vast seas in the viewless air.

Could all the streams from a single State be concentrated into one torrent, it would outroar Niagara as it dashed against the clouds.

But what becomes of the poor little ten per cent, of water that goes sparkling down the ravines to its ocean home ? Is it allowed to depart in peace .'^ No; the farmer at great expense cuts channels along the hillside to irrigate the sloping plains, and the results prove that it pays to do it.

All this is done while the ninety per cent, of fluid is passing away without an effort made to save it. We do not need it all — no, not the half of it. We know by covering the land we can retain enough except in the arid sections, for all the wants of vegetation.