Right Use of Lime in Soil Improvement.

by Alva Agee.

CHAPTER 1

INTRODUCTION

There is much in the action of lime in the soil that is not known, but all that we really need to know is simple and easily comprehended. The purpose of this little book is to set down the things that we need to know in order that we may make and keep our land friendly to plant life so far as lime is necessarily concerned with such an undertaking.

Intelligent men like to reason matters out for themselves so far as practicable, taking the facts and testing them in their own thinking by some truth they have gained in their own experience and observation, and then their convictions stay by them and are acted upon. The whole story of the right use of lime on land is so simple and reasonable, when we stick only to the practical side, that we should easily escape the confusion of thought that seems to stand in the way of action. The experiment stations have been testing the value of lime applications to acid soils, and the government has been finding that the greater part of our farming lands is deficient in lime. Tens of thousands of farmers have confirmed the results of the stations that the application of lime is essential to profitable crop production on their farms. The confusion is due to some results of the misuse of lime before the needs of soils were understood, and to the variety of forms in which lime comes to us and the rather conflicting claims made for these various forms. It is unfortunate and unnecessary.

The soil is a great chemical laboratory, but exact knowledge of all its processes doubtless would enrich the farmer's vocabulary more than his pocketbook. We are concerned in knowing that lime's field of usefulness is broad in that it is an essential plant food and provides the active means of keeping the feeding ground of plants in sanitary condition. We want to know how it comes about that our soils are deficient in lime, and how we may determine the fact that they are deficient. We wish to know the relative values of the various forms of lime and how we may choose in the interest of our soil and our pocketbook. The time and method of application are important considerations to us. There are many details of knowledge, it is true, and yet all fit into a rational scheme that shows itself to be simple enough when the facts arrange themselves in an orderly way in our minds.

Lime cannot take the place of nitrogen, nor phosphorus, nor any other of the essential plant foods. It is not a subst.i.tute for any other essential factor in plant growth. It would be folly to try to depend upon lime as a sole source of soil fertility. On the other hand, we have learned very definitely within the last quarter of a century that it is foolish to depend upon commercial fertilizers and tillage and good seeds for full production of most crops from great areas of our farming country that have a marked lime deficiency. The obvious need of our soils is the rich organic matter that clover and gra.s.s sods could furnish, and their fundamental need is lime. Most farms cannot possibly make full returns to their owners until the land's hunger for lime has been met. The only question is that regarding the best way of meeting it.

CHAPTER II

THE LIME IN SOILS

_Limestone Land._ Soil a.n.a.lyses are serviceable only within certain limits, and in the case of the normal soils that comprise the very great part of the entire humid region of the United States the practical man gives little heed to what special a.n.a.lyses might show him when deciding upon the purchase of a farm. He does know, however, that a limestone soil has great natural strength, and recovers from mistreatment more readily than land low in lime. It has staying powers, and is dependable, unless through natural processes the lime leaches out or loses availability. All limestone areas have gained reputation for themselves as producers of grain and gra.s.s.

_Other Calcareous Soils._ It is not only the limestone areas that stand high in esteem. There are types of soil with every varying percentage of lime down to clear sand or to peat, and some of the types are finely calcareous, containing such a high percentage of lime that nothing more could be desired.

The actual percentage is not the determining factor, a clay soil needing greater richness in this material than a loam, and a sandy soil giving a good account of itself with an even less total content of lime, but in its way the particular soil type must be well supplied by nature with lime if its trees and other vegetation bear evidences of its strength and good agricultural value.

_Natural Deficiency._ It is interesting to note the differences in evidences of prosperity that are a.s.sociated with lime percentages. The areas that are able to produce the vegetation characteristic of calcareous soils are obviously the most prosperous. The decidedly lime-deficient sections, advertising their state by the kind of original timber, and later by unfriendliness to the clovers, do not attract buyers except through relatively low prices for farms. Such areas are extensive and have well marked boundaries in places.

It does not follow that every farm in such limestone valleys as the Shenandoah, c.u.mberland, and Lebanon, or in the great corn belt having a naturally calcareous soil, is prosperous, or that a mult.i.tude of owners of such lime-deficient areas as the belt in a portion of southern New York and northern Pennsylvania, or the sandstone and shale regions of many states, have not overmatched natural conditions with fine skill. We treat only of averages when saying that a "lime country" shows a prosperity in its farm buildings and general appearance that does not come naturally and easily to any lime-deficient territory. In the latter a man rows against the current, and if livestock farming is not employed to furnish manure, and if the manure is not supplemented by tillage and drainage to secure aeration, or if lime is not applied, the land reaches such a degree of acidity that it loses the power to yield any profit.

_Nature's Short Supply._ The total area of lime-deficient soil is large, comprising certainly much more than half of all the land east of the semi-arid belt of the United States. No small part of this area was not deficient at one time, as the nature of the original timber indicates, and it is well within the knowledge of practical men that land which once produced the walnut and ash and sh.e.l.lbark hickory can be brought back to productivity with reasonable ease after very hard usage. It has a good inheritance. It is a disconcerting fact in our American agriculture that, fertile as our country is as a whole, very great areas were so deficient in lime before they came under man's control that the chestnut, pine, and the oaks of mean growth were fully at home. The gradation from low lime content to high, and its relation to soil type, give us all sorts of mixtures of lime-loving and acid-resistant varieties of trees in original forests, but our agriculture is hampered by the high percentage of land for which nature made no great provision of lime, and on this land farming lags.

_Effect of Irrational Farming._ Interest in liming might well have been due to the amendment of all this soil, but the rational use of lime that has been the subject of much study in the last quarter of a century concerns chiefly great areas that probably could have been kept in alkaline condition and friendly to the clovers for a long time despite a short natural supply as compared with the content of our limestone lands. The success of individual farmers in areas now admittedly acid as a whole is convincing on this point. Nature tries constantly to cure the ills of her soil through the addition of vegetable matter. An excess of water or a deficiency is atoned for in a degree by the leaves and rotted wood of her forests. Aeration is kept possible. The lime in the product of the soil goes back to it. A system of farming that involves the application of manure, thorough tillage, drainage where needed, and the free use of sods in some way, has kept portions of these non-calcareous soils out of the distinctly acid cla.s.s. Clover grows satisfactorily, gra.s.s sods are heavy, and there is no acute lime problem. Such farms are relatively few in the great stretches of land now cla.s.sed as acid soil, and probably the most of the lime that is being applied goes only on ground that once was sufficiently alkaline to grow the clovers. The loss of organic matter through failure to use the best methods of farming is responsible for no small part of the widespread need of lime today. This subtracts nothing from the urgency of its use to restore a condition favoring clover and gra.s.s sods, but it does teach a lesson of the highest value. The day of destructive soil acidity can be r.e.t.a.r.ded by good farming, but in the long run the inevitable losses of lime from most soils must be met by applications.

_Limestone Soils._ The old-time practice of making heavy applications of fresh burned lime to stiff limestone soils to make them friable, and to make their plant food available, led to disuse of all lime in some sections on account of the exhaustion that followed dependence upon these large amounts as a manure. Queerly enough, these original limestone soils have latterly been going into the acid cla.s.s through loss of their distinctive elements, and they, too, have become dependent upon means for the correction of acidity.

CHAPTER III

SOUR SOILS

_Loss of Lime._ Nature made the value of land as a producer of food utterly dependent upon the activity of lime, and at the same time gave it some power to s.h.i.+rk its work. In a normal soil is a percentage of lime that came from the disintegration of rock of the region or was transported by action of water on a huge scale. Possibly rarely would it be in insufficient amount to keep a soil in a condition friendly to plant life, and to feed the plant, if it stayed where nature placed it and kept in form available for the needs it was intended to meet. There is land that always was notably deficient in this material, and there is land that was known in the early history of the world's agriculture to be "sour," but the troubles of our present day in the case of the farming country in the humid region of the United States is less due to any natural absolute shortage than to combination that destroys value and to escape by action of water.

[Ill.u.s.tration: Clover and Timothy Unfertilized at the Pennsylvania Experiment Station Yielded 2460 Pounds per Acre]

[Ill.u.s.tration: Clover and Timothy with Fertilizer alone at the Pennsylvania Experiment Station Yielded 3900 Pounds per Acre]

_Prevalence of Acidity._ The results of experiment station and farm tests are conclusive that the soils of the greater part of all the humid region of the United States show lime deficiency. Formerly, acidity was a.s.sociated in our minds with wet, low-lying land, but within the last twenty years we have learned that it prevails in light seash.o.r.e sands along the Atlantic sh.o.r.e, in clays, loams and shales stretching to the Appalachian system of mountains, on top of mountain ranges and across foothills to our central states, and through them in stretches to the semi-arid lands of the west. While not all this land has fallen into the lime-deficient cla.s.s, and the great part of some states remains alkaline, the tendency toward acidity is continuous.

Crop production in great portions of the Mississippi valley is restricted by lack of lime in the soil, and some states to the eastward have one-half to nine-tenths of their acreage too low in lime for the best results. Calcareous soils have been losing their distinctive feature, and the immense areas of land naturally low in lime have remained hampered in ability to make full returns for labor, fertilizer and seed. It is this situation that brings the right use of lime on land to the front as a matter of fundamental importance to the farmer.

_Causes of Soil Acidity._ If any discussion of the causes of soil acidity would delay a decision to apply lime where needed, the time given to such discussion would be worse than wasted. It is much more important to be able to detect the presence of harmful acids and to neutralize them than it is to know why the soil should be in such plight that it could not supply the required lime and had become dependent upon its owner for a.s.sistance. On the other hand, some of us find it difficult to accept a fact without seeing a reason for it, and we may do well to consider several causes that may be at work to put a soil out of the alkaline cla.s.s.

_Leaching._ One cause that appears obvious and easy of acceptance is leaching. In the case of one Pennsylvania farm, lying in a limestone valley, the lime had been washed out by action of water so freely that caverns formed under the surface, and a test showed a marked deficiency in the top soil. This land ceased to grow clover, and plantain and sorrel abounded. This case, which is not an isolated one, showed an unusually rapid loss, but we always expect to find the water from wells and springs in a limestone country strongly impregnated with lime.

Drainage waters contain it. The draft by action of water is continuous, and in some types could easily account for sufficient loss to change the nature of the soil. We may place undue emphasis upon this factor, as other causes are at work, but leaching is a leading source of loss.

_Chemical Compounds._ A serious cause of lime exhaustion that is being studied by soil chemists is the presence of compounds in the soil that combine with the lime and rob it of ability to serve the soil when new acids form. The practical farmer accepts the statements of the chemists on this point, and probably would not have his interests served by any exact knowledge of the nature of these agents.

_Decaying Vegetation._ A cause of acid conditions that is widely known and accepted, and that may therefore stand out in our thinking with undue prominence, is connected with the decay of green vegetable matter in the soil. Many of us have seen fields rendered temporarily unproductive by the plowing down of a ma.s.s of immature plants in midsummer. All organic matter, indeed, in its decay makes a draft upon the lime content of the soil in which it may be buried.

_Removal in Crops._ Lime is taken out of land by plants, and the loss is a considerable item, but our interest is in the form of lime that can correct soil acidity, and we know that compounds of lime that are worthless for this purpose may be the chief source of the lime in our crops. A determination of the lime in the ash of a crop does not give data of much practical value.

[Ill.u.s.tration: Clover and Timothy with Lime Alone at the Pennsylvania Experiment Station Yielded 4900 Pounds per Acre]

[Ill.u.s.tration: Clover and Timothy with Fertilizer and Lime at the Pennsylvania Experiment Station Yielded 6290 Pounds per Acre]

CHAPTER IV

EVIDENCES OF ACIDITY

_Character of Vegetation._ The character of the original forests is determined much by the lime-content, and the practical man, when buying a farm, rates its productive power by the kinds of timber it has produced. The black walnut, ash, sh.e.l.lbark hickory, black and white oak, st.u.r.dily grown, evidence a soil rich in lime, while the pines, small blackjack and post oaks, and the chestnut are at home in non-calcareous soils. The latter cla.s.s of lands gains nothing in lime as time pa.s.ses, and the timber continues to be a sure index, but in the former cla.s.s the surface soil may have lost enough lime to limit crop production materially while the trees continue to find in the subsoil all that they need. It does not follow that the land has gone down in value to the naturally lime-deficient cla.s.s, but its power to produce is impaired, and will remain so until there has been restoration of its original alkaline state.

_Sorrel and Plantain._ We determine quite surely the state of the soil by observance of the vegetation that roots in the surface soil and the immediate subsoil. Sorrel is a plant popularly a.s.sociated with soil acidity, but this is not through any dislike for lime. It has been observed growing in the edge of a heap. Its presence suggests acidity because it can thrive in a sour soil that will not produce plants of value which on even terms could crowd the sorrel out. There is constant compet.i.tion among plants for food and water and s.p.a.ce, and some of our worst weeds are not strong compet.i.tors of clover and gra.s.s where soil conditions are not unfavorable to the latter.

Blue gra.s.s, the clovers and timothy give a good account of themselves in a contest with sorrel and plantain where lime is abundant. This does not mean that the seeds of these weeds may not be so numerous that an application of lime cannot cause the clover and gra.s.ses immediately to take the ground to the exclusion of other plants, but it is true that the crowding process will continue until the time comes in the crop rotation that these weeds cease to be feared, and clean sods can be made. It is the absence of lime that permits such weeds to maintain their reputation for good fighting qualities.

[Ill.u.s.tration: Limed and Unlimed Ends of a Plot at the Ohio Experiment Station]

[Ill.u.s.tration: Effect of Finely Pulverised Limestone on Clover in a Soil Having a Lime Requirement of 5200 Pounds of Limestone per Acre at the Pennsylvania Experiment Station]

_The Clovers._ Red clover can make growth in some soils that have a lime deficiency. If all other conditions are favorable, the lime requirement may exceed one-half a ton per acre of fresh burned lime and not affect the clover adversely, but farm experience throughout the country has demonstrated that when soil acidity is only slight and clover grows with difficulty, an application rarely fails to favor the clover in a marked degree. Experience has taught the land owners to fear soil acidity when red clover does not thrive where formerly it made good growth.

The prevalence of alsike clover in a farming region is indicative of lack of lime. This clover thrives in a calcareous soil, but is more indifferent to a small lime supply than is the red clover. As red clover seedings begin to fail, the alsike gains in popularity, and where a soil is decidedly sour the alsike is most in evidence. The latter has less value to the farmer, rooting nearer the surface of the soil, and making less growth of top, but it has gained in favor with farmers as soil acidity has increased.

_The Gra.s.ses._ Timothy is more resistant to acidity than red clover, but often fails to make a heavy sod where the deficiency in lime is marked. Rhode Island Bent, known as redtop, is less exacting, and where it thrives to the exclusion of timothy, or is in evidence in gra.s.s lands, the inference is fairly safe that a test would show that the soil is sour.

_When Production Decreases._ It is not a matter of any moment to the owner of a productive soil whether or not his soil would give an acid or an alkaline reaction under test. Returns from his labor are satisfactory. Some land in this cla.s.s is not strictly alkaline. The man most interested in the effects of lime applications is the one who is not satisfied with yields. The tests for acidity have been so many throughout our eastern and central states that the owner of land which is not productive has reason for the presumption that its percentage of lime is too low. There is danger of error, and a scientific test is surer, but in most cases the land which has been reduced from a fertile to an unproductive state has lost its alkaline nature.