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NATURAL SO YOU ALWAYS THE BEST

vi ill them.* ̈ But Mr. Smith observes: In our experience, we have never found any plans thrive by retaining it in its native scil, or in vũ ton tiosely resembling . If we could also imitate all the various indueness of simate that modify and control the growth of planta in their native icealities, it might then be proper for us to enitivate the Lace-bark tree in marly sci, like limestone; but our plants afford evidence that such soll is not required when they are grown in an artificially heated atmosphere. We have used good yellow kam, mixed with a little leaf-mould and sand. In this they have attained the height of 8 feet, and continue in a perfectly healthy state." This opinion is greatly supported by such facts as the fullowing, which show that great numbers of plants have no particular predilection for soil, or at least, that if they have we cannot show it to exist, and that there are facts in the relation between plants and soil which remain without explanation. Mr. Knight observed that varieties of the same species of fruittree do not succeed equally in the same soil, or with the same manure: the Peach in many soils acquires a high degree of perfection, where its variety, the Nectarine, is of comparatively little value; and the Nectarine frequently possesses its full flavour in a soil which does not well suit the Peach. The same remark is also applicable to the Pear and the Apple; and, as defects of opposite kinds occur in the varieties of every species of fruit, those qualities in the soil which are beneficial in some cases will be found injurious in others. In those districts where the Apple and Pear are cultivated for cider and perry, much of the success of the planter is found to depend on his skill or good fortune in adapting his fruits to the soil. (Hort. Trans., i. 6.) Rhododendrons and Kalmias are usually cultivated in peat earth mixed with sand, and yet they grow as well in fresh hazelly loam, without any mixture whatever; and, than these two kinds of soil, none can be apparently more dissimilar. The fine American cottons are grown in a calcareous sand, those of India in a deep black saponaceous earth; the American cotton will not thrive in the latter, nor that of India in the former, as has now been ascertained; and yet the species of Gossypium producing the two qualities have no organic differences which can, so far as has yet been ascer tained, explain in the smallest degree the necessity, under

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which it is evident that they labour, of being provided with different kinds of food. The Alnus glutinosa, or Common Alder, flourishes in wet clayey meadows; while Alnus incana, or Upland Alder, is equally suited to a dry and light land: we are totally ignorant of the reason of such a case as this. Rhododendron hirsutum and Erica carnea are, in their wild state, confined to calcareous soil; while Rhododendron ferrugineum grows exclusively on granite, and Erica vagans on serpentine. We are informed by Beyrich (Gardeners' Magazine, iii. 442) that "the Pine-apple, in its wild state, is found near the sea-shore; the sand accumulated there in downs serving for its growth, as well as for that of most of the species of the same family. The place where the best Pine-apples are cultivated is of a similar nature. In the sandy plains of Praya velha and Praya grande, formed by the receding of the sea, and in which no other plant will thrive, are the spots where the Pine-apple grows best. The cause of this lies evidently in the composition of the sand, which chiefly consists of salt, lime from decomposed shells, and a very little vegetable mould. Warmth, lime, salt, and moisture seem therefore to be the principal ingredients in which the Pine-apple thrives. Sand will take a very high and continued degree of warmth, being often heated by the sun so much as to scorch vegetation, and yet it seldom dries to a greater depth than from eight inches to one foot; sea salt is well known for its property of attracting the nocturnal damps, and retaining them a long time. The lime of the shells seems to be the principal manure, which has also been proved by the English here, who, by manuring their Pine-apples with a mixture of stamped oyster-shells and vegetable earth, produce very large fruit. The natural mould, usually slightly mixed with sand, is partly of a vegetable and partly of a mineral origin." But it is well known that the Pine-apples of England are much superior to those of South America, and yet English gardeners grow their plants neither in sand, nor saline, nor calcareous soil. Moreover we learn from Mr. Campbell Lees that in the Bahamas the Pine-apple will neither grow in decomposed Madrepore limestone, nor in light deep black vegetable soil; but that it thrives exclusively

538

STERILE SOILS UNACCEPTABLE TO PLANTS.

in a red soil, which Professor Edward Solly found to be chiefly remarkable for an unusually large proportion of oxide of iron. (Journ. of Hort. Soc. i. 126.)

On the other hand we know that salt plants, like Nitraria, will not thrive in the absence of the salt soil in which they naturally grow; and that others, such as Samphire, the garden Pink, the Red Valerian, the Sea Beet, are much improved in health by its presence, to say nothing of Salicornias, and other purely salt plants, which will not grow in saltless land. Chalk also appears to be fatal to the healthy growth of others, such as Rhododendrons, and some Conifers; while Beech and Box prefer it. Clay again, which is invaluable as a soil for Quercus pedunculata, is ill suited to Q. sessiliflora, and will not grow Heaths at all. Therefore the opinion that the soil which plants inhabit when wild is not necessary to them, requires a good deal of qualification.

In like manner plants grow naturally and remain healthy in places where no manure can reach them. But they are not benefited by the absence of such agents; on the contrary, even Mosses and Lichens flourish most where they are best fed, and plants inhabiting peat, sterile as that soil is, feed greedily and thrive greatly when well manured. striking instance is furnished by Bagshot heath.

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A more unpromising appearance than that originally belonging to the present American nursery at Bagshot, can scarcely be imagined. In its present improved state, it affords a good example of what can be done in the most sterile spots. The ground in question forms part of 50 acres, the whole of which is rated in the poor's-rate book at 8l. The soil, which is from 12 to 15 inches in depth, is a black sandy peat, resting upon a clayey subsoil very deficient in vegetable matter, and naturally incapable of producing any crop. With cultivation it has been rendered in the highest degree productive. The first operation was to drain it from 3 to 4 feet deep; it was then trenched 2 feet deep, and to every acre so treated, from 30 to 40 tons of good farm-yard manure was added; and as a precautionary measure, in order to exhaust the rankness attendant upon this treatment, it was deemed necessary to take off the land a root crop of Potatoes, Carrots, Turnips, and Mangel Wurzel. After this treatment, American plants were found to thrive amazingly; but, like all crops in very poor soils, they continue to be benefited by the application from time to time of suitable enriching materials.-Standish on American Plants.

CHAPTER XXI.

OF MANURE.

To manure a plant is to feed it artificially.

We see that plants and animals exist in a wild state without the aid of any other food than what is presented to them spontaneously. There is everywhere around us a bountiful provision for sustaining life. Providence has created animals and plants to be fed on by man, animals prey on animals and plants, plants subsist upon the decay of animals and plants; and these mutual relations are so nicely adjusted, that we have no reason to suppose that any one species has disappeared since the creation from want of food. When species have perished they have been exterminated by man.

But although plants are surrounded on all sides by the materials necessary to sustain life, yet when man invades their haunts and turns them to his peculiar purposes, natural circumstances no longer suffice. Water and air and what belongs to them remain indeed as before, but the food provided in the soil becomes exhausted; when the races of plants are altered by domestication they require more abundant nutriment; and to obtain from the earth a greater produce than it can yield spontaneously becomes a matter of the first necessity; hence arises the application of manure, which is to the vegetable kingdom what artificial feeding is to animals.

The object of manuring is either to increase the fertility of land, or, if fertile by nature, to keep it in that state by continually returning to it the substances which crops may have removed. If a tree advances in the course of time from a mere

540

NATURAL FERTILITY OF SOIL.

point till it acquires the weight of many tons, it does so by gradually absorbing from the earth and air such food suitable to its nature as is found there. What is derived from the air may be disregarded, the constituents of the atmosphere being ever renewed and inexhaustible; but inorganic matter, presented to our eyes by the ashes of the tree when burnt, is wholly derived from the soil, which is neither ever renewing nor inexhaustible. Should the tree perish where it stood and there decay, the soil would receive back all that it had given up, and no exhaustion would have taken place. But if the tree is felled and carried away, then the soil is robbed of all the inorganic matter which entered into the composition of the timber, and becomes pro tanto exhausted of its nutritive powers. The matter thus removed is restored by manure. And so of all plants else. Such is the inevitable result of cultivation.

Although it is unquestionable that all cultivated plants require manure, on account of the exhaustibility of all soils, sooner or later, yet it must be remembered that the rate of exhaustion depends upon the proper nature of soil, and the treatment it receives at the hands of the gardener. Sandy soils are rapidly rendered barren by cropping without manure; clayey and loamy soils much more slowly. And when the latter are skilfully cultivated crop after crop of certain kinds of plants may be taken from them with no apparent loss of fertility. This has been strikingly illustrated by the Rev. Mr. Smith, an accomplished agriculturist residing at Lois- Weedon, a remote village on the oolitic clay of Northamptonshire, where repeated crops of wheat, at the rate of 40 bushels an acre, have been obtained for many years successively, without manure, by mere spade cultivation. This gentleman thus succinctly describes his mode of tillage (the land being of course thoroughly drained) :

"At the outset I plough the whole field early in autumn an inch deeper than the staple, harrow, and roll, and harrow again-pulverising and preparing it, in short, as for Barley. I then get in my Wheat, leaving yard-wide fallow intervals between the rows. When the Wheat is up I begin to dig, which is done thus :-At the end of the interval I first throw out on the headland about 3 feet of soil to the entire depth I intend to go the first year, and, supposing the staple to be 6 inches, and the 4 inches of subsoil to be clay, this depth altogether will be 10 inches. The spadesman now, with a shallow spit, casts the 6 inches of staple to the bottom of the trench of this yard length of interval; and then, with another spit still shallower, throws the 4 inches of the subsoil lightly on the top, and so on all over the field.

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