ADAPTATION OF SOILS
To Varieties of Vegetation, and Its Application to Indoor Cultivation
By Gustavus B. Maynadier,
Bureau of Soils, U. S. Dept. of Agriculture.
This paper in conjunction with that of Mr. Valentine's received marked attestion.
The whole work of the Department of Agriculture is apportioned, according to the character of the problem, among the various bureaus of which the Department is made up, one of these being the Bureau of Soils.
This Bureau has allotted to it the duty of surveying and mapping the soils of the United States and of making all investigations concerning them. The problems with which it deals are by no means the simple affairs, that many who fail to appreciate what the soil is, what it does and how it does it are inclined to think. To them the soil is so much dirt. It is to them a lifeless inert mass. It is necessary to be sure, and therefore to be tolerated.
We who take a deeper interest, however, know the soil as it really is. whether we are accustomed to study it in the laboratory or to use in the field, the garden or the greenhouse, we know that far from being just so much dirt that it is a highly complex body. Far from being an inert lifeless mass, it is most emphatically a thing of life. For every living thing, bush, tree or shrub that we see upon its surface, myriads exist within the soil itself. One of the duties of this bureau is to study these soil organisms and to find out what functions they perform.
Soils also vary in composition, and there may be present substances actually harmful to plants, or some of the essentials for plant growing may be wanting, hence they must be studied from the chemical standpoint.
Soils possess also certain physical properties such as weight, fineness of division, arrangement of particles. They bear certain relations to heat and moisture. In the physical laboratory of this Bureau is determined the influence of these attributes upon the soil and their effect upon its productiveness.
The causes of infertility in certain soils, the restoration of the so-called worn out soils, the presence of poisonous substances in the soil as the result of excretion from the roots of living plants, all these demand special lines of investigation, each line being in the hands of specially trained men.
Following these strictly scientific technical investigations of the soil comes the study of soil utilization and management. This comprises the application of these laboratory results to conditions as they exist, dealing with problems of drainage, methods of tillage, the effect of fertilizers and special adaption of soils to certain crops.
For you may rest assured that the field operation must be based on correct scientific principles or they will be of no avail. However frequently existing conditions demand that these principles be modified, yet they can never be disregarded or opposed or disaster will surely follow.
In the work of the Bureau of Soils in the field one of the most striking soil characteristics observed is the special adaption or fitness of certain soils for certain classes of crops.
That certain classes of soils are peculiarly adapted to the growth and production of certain crops has been recognized by agriculturalists of all lands, and in the writings of some of the highest authorities on agricultural topics such expressions as good "corn soil" or "wheat soil" are frequently to be met with. Not only is this adaptation for certain crops observed, but in addition a special adaptation for certain varieties of the same crop.
While it is no doubt true that there are other factors which perhaps are to be considered in field practice, yet we feel assured from our observations in this direction that no single factor is of as great importance as the soil.
In regions where uniform soil and climate abound there is frequently to be found one particular variety of a crop that gives far better results than any other variety, though it is agreed on all sides that the soil is a good one for the crop generally speaking. Moreover when two sections are situated so as to be embraced within the same climatological zone it frequently happens that the predominating soils are quite different. In such cases it is usually observed that the successful planters upon each soil type are growing the same or closely related varieties. There will, however, be found a considerable difference between the varieties grown on the different soil types. Not alone with field crops is this mutual agreement of soils and specific varieties to be observed but with fruits and vegetables.
As specific instances I may mention a few of the many cases that have been observed in the field and garden crops, fruits, etc.
The "Drake Cluster," a very high grade and highly productive variety of cotton, has been grown and kept pure on the upland soils of Alabama, where it is noted for its superior qualities. This variety when grown on the bottom lands produces but little lint, the plant "going to weed," as it is called.
With some varieties of tobacco it is possible it grow on the sandy soils of certain localities cigar wrappings of the highest quality, when these same varieties are grown on the clay soils the product is suitable only for fillers, the quality of which is none too good. With fruits we find much additional evidence of the adaptation of soils to varieties and in those sections where orange growing is carried on it is now recognized that it is absolutely necessary to select the particular variety to which the soil is most adapted.
With the apple this adaptation is well illustrated by the Newtown Pippin which reaches its highest state of perfection only when grown on the same class of soils, whether in New York or in Virginia. Again, the Baldwin, which also ranks high as a commercial apple in this same eastern region is specially adapted to a much lighter class of soils.
The sandy and gravelly soil in Steuben County, New York, is especially adapted to the Carman potato, while on the light loams of the southwestern section of New Jersey, Irish Cobbler and Green Mountain produce the best crops. On the clay loams in northwestern Ohio we find such late varieties as Iona and Rural New Yorker best suited to prevailing conditions, while Bliss' Triumph is especially adapted to the black prairie soils.
In those localities where truck growing is carried on commercial success depends very largely on the proper observance of this intimate and important inter-relationship.
In a majority of the cases observed it was found that varieties not only were better suited to certain soils, but that the class of soils specially adapted for their growth was similar to that upon which the variety was developed.
This is because the plant is in no sense a fixed unchangeable organism restricted to a definite form. On the contrary it is highly plastic, capable of being changed or modified in all of its parts. We can by cultural methods alone effect many changes, and it is just as certain that as many more will occur through natural agencies. The effect of climate, the character of the soil whether dry or moist, sandy or clay, all exert an influence tending to change or modify plant characters.
We see then that in the development of varieties the effect of soil is manifested, and that to keep a variety pure by freedom from cross fertilization, is not always sufficient to maintain its varied characteristics. To keep it up to the ideal established by the originator it is necessary to provide an environment quite similar to that in which it was developed. For it is now thoroughly understood that a change in environment is accompanied by an attempt on the part of the plant to readjust itself to meet the new conditions. If the change is within the limits of the readjustment the plant responds by changing its physical structure sufficiently to meet the new conditions. If the change is too great the plant dies. Originators of new varieties seldom think it necessary to mention the class of soils upon which the varieties were produced. never perhaps considering the influence that it may exert upon the future of the plants. And I believe that many new varieties which are introduced only to be as suddenly cast aside, disappear from cultivation because their habit is such that there are but few soils really well adapted to their culture.
By environment is meant those conditions that surround the growing plant. and may be considered under two heads, climate and soil.
In climate we include the combined effects of light, heat, moisture, etc. In the field these conditions are always subject to variation, and it is quite impossible for a single growing season to pass without the plants being subjected to climatic conditions more or less hindering their development.
In the soil we have not only the supply of mineral plant food, but seemingly there is in it also forces, not yet understood, that exert powerful influence on the habits of the plant, controlling to a great extent its thrift, characteristics and fruitfulness. And the effect of this influence appears whether the plant is cultivated for its foliage, its flowers or its seed.
In a change of environment may or may not be included a change of climatic conditions. A change of soils type alone has been shown to be quite sufficient to bring about changes in the plant that in many instances are so marked as to greatly effect many varietal characteristics.
If with our field and garden crops where the climatic influences have necessarily such a wide variation the soil proves itself to be so important in maintaining varietal characteristics and habits, is it not reasonable to suppose that with in-door conditions these factors are under control that the relative influence of the soil is increased.
From my own observations and from the testimony of others I believe this to be the case.
It is this phase of soil adaptation that concerns the indoor grower and which is now being investigated, particularly in regard to the soils used In the production of the different varieties of carnations and roses.
In our modern greenhouses we have eliminated climatic variations.
We control the temperature by the turn of a valve. Rainfall is displaced by the hose. Ventilation is accomplished without subjecting our plants to damaging winds. In short, it is our business to provide the most suitable climatic conditions for the development of our plants.
It is clear then that the only change in environment given the plants in a house where light and loamy soil is used, compared with one in which the benches are filled with a clay soil, is the soil itself.
Yet with this difference in the soil only, we frequently observe that there is a considerable variation in the size, brilliancy of color, and other characters of the bloom of the same variety.
A visit to the flower markets of our large cities affords many illustrations of these differences, when the products of the various establishments are seen side by side.
It is not to be expected that the soil adaptation is equally well defined with all varieties. Some being more fixed offer a greater resistance to change than others, nor should we expect to find the modifications that arise to be always in the same direction.
Not only in the character of bloom may the influence of the soil appear, but in many cases it will be found to effect the habit of the plant itself. It does so in the field with outdoor crops, and it is reasonable to think that it exerts a similar influence on plants grown under glass.
A partial examination of the soils used by a few of our rose growers has already been made, and it discloses the great variety of soil types that are being used in the production of this crop alone. Ranging in texture from dense clay loams to porous sandy loams practically all intermediate grades are represented. Yet in many instances two very widely differing soil types are being used for the production of the same variety, resulting perhaps in a depreciation of the quality or quantity of bloom of one variety or the other
I recently visited a rose house where I found one of the most popular varieties, a rose of great merit, giving such poor results that its cultivation is to be abandoned after this season. In this instance the size of the blooms was materially effected, though in other respects the general appearance of the plants was comparable in every way with those of the other varieties grown.
A recent experiment carried on to determine the effect of various fertilizers on carnations is particularly interesting when viewed from the standpoint of soil adaptation.
In this experiment two soils were used, various fertilizers being applied to each, comparison being with the soils to which stable manure alone was added. As it is no part of my present purpose to discuss the relative efficiency of fertilizers, I will consider only the results obtained from the use of stable manure. These soils were planted to four varieties of carnations of undoubted merit: and were grown in a range of three even spans houses without interior walls making it practically one house. Particular attention was paid to the maintenance of favorable conditions so that the only point of difference was in the soil in which the plants were grown, the same number of plants of each variety being grown in each of the soils used.
Enchantress gave only eighty-five per cent. as many blooms on soil No. 2 as on soil No. 1, Lawson eighty-seven per cent., and Robert Craig but seventy-eight per cent. on the corresponding soils. Peary somewhat reversed conditions and on soil number two produced four per cent. more blooms than on soil number one.
We have then three varieties out of four that showed a very decided falling off accompanied by a difference in soil only—all other conditions being the same. In one case the results are to all intents equal in each soil. Now I take it that such results are not due to chance. There must be a reason. And I do not think it too much to offer the difference in soils to this reason.
Lawson, Enchantress and Craig found one of the soils far more adapted to their special requirements. With Peary the reverse was true, though the adaptation was not so marked. Nor is this illustrative of adaptation of soils to a whole race of plants, but to specific varieties.
It shows also the impropriety of attempting to draw definite conclusions as to the relative merits of different varieties, unless it can be shown that the soil type is equally well adapted to all of the varieties grown. It is, however, in determining the varieties that will likely prove most remunerative to the individual grower that such tests have their real value. For with a single bench, in one season, information of vast importance for his future guidance is readily obtained.
Just what determines the peculiar fitness of a soil for the growth of certain plants or varieties of these plants is yet to be determined.
The books on rose culture state generally that the proper soil to use is a well drained loam; many authors adding that it should have a smooth or greasy feeling. This description, while somewhat vague, is yet helpful, for it cautions us to beware of heavy clays and coarse sands and brings before us the necessity of good drainage. But the term loam, even in its technical sense, is a very elastic one, and soils may be very different in some of their most important features and still be properly classed as loams. The provision that it should have a smooth or greasy feeling somewhat restricts the original description and brings it within the limits of the class of soils known as silt loams. The smooth or greasy feeling that is found in a soil when pressed between the thumb and finger, is a consequence of the presence of silt, the finest particles excepting clay that go to make up a soil. The amount present may vary to a considerable degree without altering the feeling, although materially affecting the character of the soil. This variation in the relative proportions of the different sized soil particles is the basis of soil classification. Upon it also depends the permeability to air and to water, responses to changes in temperature, retention of moisture, and other physical properties of a soil. It is an important factor in determining the general adaptation of a soil, and there can be but little doubt that modifications in texture greatly affect the adaptation of a soil to varieties. There are other conditions to be taken into account, however, and we must carry our investigations on from a number of standpoints in order to arrive at a solution of this problem.
In carrying out the investigation of this interesting and important soil problem it is planned to secure samples of soil from various growers with whom the cultivation of certain varieties is made a specialty and to obtain from them the necessary information to enable us to understand the conditions under which their plants are grown. To this end a circular letter has been sent a number of growers requesting the samples and information desired. While our studies have not been carried on far enough to warrant our drawing any conclusions at the present time, yet the outlook is most encouraging and we have every reason to believe that before long we will be able to state a definite relation between some of the soils and varieties.
In this matter we must have the cooperation of the growers, and I am glad to say that we have found them ready and willing to supply the information and samples necessary to insure the success of this investigation.