ON THE INDICATIONS WHICH ARE GUIDES IN JUDGING OF THE FERTILITY OR BARRENNESS OF THE SOIL.
BY THE REV. WILLIAM THORP.
(Continued from No. 2.)

These three signs, viz., colour, consistence, and vegetation, are named by the Royal Agricultural Society as being pre-eminently indications of the value of lands; yet there are others of equal if not of greater consequence. For example:—

A knowledge of the geology of the land is of the first importance; that is, not only a knowledge of the range and extent of each formation and its subdivisions, which may be called geographical geology, but also how far and to what extent the various lands do depend upon the substratum for their soil, and the local variations in the chemical or mineralogical character of the substrata themselves, and which may be called the differential geology of soils. For not only do the qualities of land vary from one formation to another, but upon the same formation there is frequently considerable difference in the quality of land depending upon chemical difference in the substratum, or upon an intermixture of foreign debris derived from other strata.

A chemical investigation of the soil and subsoil will frequently afford most useful indications respecting the value of land. It may be laid down as an axiom that a soil to be fertile must contain all the chemical ingredients which a plant can only obtain from the soil, and chemistry ought to be able to inform us in unproductive soils what ingredients are wanting. It also is able to inform us if any poisonous substance exists in the soil, and how it may be neutralized; when lime, marl, and chalk are to be used, &c.[1]

The Royal Agricultural Society say that chemistry is unable to explain the productiveness of soils. But why is it unable? One reason is, that supposing everything required by the plant to be present in the soil, yet if the soil be either too wet, or too dry, too cohesive, or loose, the plant will not flourish; and chemical analysis does not declare this, for it affords no information respecting the mechanical division in which substances exist in the soil. Again, the chemical analysis of soils, to be worth anything, must be conducted with more rigid accuracy than those published by English writers. To detect one cwt. of gypsum in an acre there would be only one quarter of a grain in a pound of soil, or in 100 grains only three and a half thousandth of a grain (35/10000 or,00035 grs.), or to discover if sufficient alumina existed in a field for the production of red clover there must be ascertained if it contained (one hundred thousandth),00001 per cent. The analyses even by Sprengel do not afford us the quantity of nitrogen in each soil, or the capacity of the soil for this substance; while it is well known that most manures, as well as the different kinds of food, are valuable in proportion to the quantity contained by them, and it is highly probable, ceteris paribus, that the quantity of nitrogen found existing in soil, and the soil's capacity for containing that substance, would afford an easy indication of its immediate fertility, and also of its requiring great or small quantities of nitrogenous manures in its future cultivation.[2]

Chemistry, however, outsteps her province when it is attempted to explain how vegetable productions are formed in the plants by chemical forces; for the recent discoveries of Schwann, Henle, and Schleiden, prove that all the functions of the plant are performed by the means of simple vesicles and cells—that absorption, assimilation, fixation of carbon from the atmosphere, respiration, exhalation, secretion, and reproduction are all effected by single cells, of which the lower plants almost entirely consist—that the cell absorbs alimentary matters through the spongioles of the root, and that the fluid received thus undergoes the first steps of the organizing process—that the inorganic elements are changed into the simplest proximate principles by cells—so also are the further changes into the regular secretions of the plant, the result of cell-life—that gum and sugar are converted into the organizable portion of the nutritious sap by the cells of the leaves. The starchy fluid in the grains of corn is rendered capable of nutrition to the embryo by the development of successive generations of cells, which exert upon it their peculiar vitalizing influence. Albumen is converted into fibrine by the vital agency of cell life—i.e., cells are produced which do not form an integral part of any permanent structure in the plant, but which, after attaining a certain maturity, reproduce themselves and disappear; hence it may be stated that all the vegetable productions which are formed in the plant are effected by a series of vital actions through the agency of cells.

From the different transformations which these undergo all the different tissues in vegetables are formed; for instance, the spiral and dotted ducts, woody fibre, and so on. Schwann showed that the formation of tissues in animals went through exactly the same progress, a fact which has been confirmed by the microscopic observations of Valentin and Barry. Thus vessels, glands, the brain, nerves, muscles, and even bones and teeth are all formed from metamorphosed cells. Dr Bennett says—"If this be true, and there can be little doubt, it obliges us to modify our notions of organization and life. It compels us to confess that vegetables and animals are not simple beings, but composed of a greater or less number of individuals, of which thousands may exist in a mass not larger than a grain of sand, each having a vital centre and separate life, independent of those around it. Each of these individuals, or organized cells, should be regarded as a living being, which has its particular vital centre of absorption, assimilation, and growth, and which continues to vegetate, to increase, and undergo transformations as if it were an isolated individual. At all events, a knowledge of the existence of the cell-life of plants will explain several phenomena respecting the vegetation, growth, and ripening of corn, and may hereafter lead to some valuable practical results."

The climate, elevation, and exposure are not to be neglected. Upon the higher portions of the Wolds crops suffer, much from elevation and exposure, while in the western portion of Yorkshire, upon the moor edges, the harvest is usually a month later than in the central parts of the island.

A moderate depth of soil in general is a favourable sign, although some of shallow soils on the new red sandstone and on the Wolds are very good; to these signs are to be added locality, as respects markets, facilities of obtaining a supply of lime, or other tillage, the rates and outpayments peculiar to the district, &c. &c., all of which are to be taken into account when considering the value of any particular farm.

I shall now briefly apply these indications of fertility over the different geological formations of Yorkshire, and it will be found that each lends aid to the other, and that a person will be able to ascertain the value of land in proportion as he is able to appreciate the collective evidence afforded by them.

(To be continued.)

[1] Mr Brakenridge, of Bretton Lodge, who has extensive practice in land valuing, informs me that a mechanical analysis of the soil affords him much assistance; and he has found that in soils, whenever free from stagnant water, that in a mechanical analysis the larger the proportion which remains suspended in the water, the greater its powers of production will be found, and the less manure it will require. That the best soils are those which, when diffused and well stirred in water and allowed to stand for three minutes, from 20 to 30, say 25, per cent. is carried off with the water of decantation. When 30 per cent. and upwards is decanted off, the soil becomes retentive of water and consequently wet. When less than 20 per cent., say only 16 per cent. and under, is carried off, it becomes too porous; water passes through it too rapidly; its soluble matter is washed off into the substratum, and it has a strong tendency to become thin and sterile.[2] The celebrated black earth of Russia contains 2,45 per cent. of nitrogen.