affected too greatly by the alternations of dryness and moisture. And if, again, a shallow soil rest upon a porous subsoil, the moisture of the soil is too easily acted upon and exhausted by heat.

A subsoil, in so far as mere texture is concerned, should be neither too retentive nor too porous. But although this intermediate condition is, in most cases, the best, yet, in a very cold and moist country, a free or porous subsoil is, for the most part, to be preferred to one which is close and retentive. The soil, besides being affected by the texture of the subsoil, is sometimes also affected by the nature of the mineral substances of which the subsoil is formed.

If the subsoil be rocky, it is desirable that it be calcareous rather than silicious; chalk or limestone, for example, rather than quartz. Sometimes the subsoil contains matter which is directly injurious to the growth of plants. This matter is generally found to be the oxydes of metals in combination with acids. Subsoils of this kind are usually distinguished by deepness of colour.

Soils, then, it is seen, are affected in their properties not only by their own texture and composition, but by the texture and composition of the subsoil; and they are divided into the stiff or clayey, and the light or free.

The clayey soils have, as their distinguishing character, the adhesiveness of their parts; and this property alone will enable even the inexperienced to discriminate them. A stiff clay, when dried either by natural or artificial heat, becomes so hard as to resist a considerable mechanical pressure. On account of the tenacity of such soils, they are tilled with more difficulty than the freer soils. They require, to fertilize them, a larger proportion of manures; but they retain the effects of these manures for a longer time. They are better suited to the cultivation of plants with fibrous, than with

Soils of this class, as of

tuberous or bulbous roots. every other, possess many degrees of natural fertility. The poor clays form, for the most part, a very unprofitable soil, because, while their powers of production are inconsiderable, the expenses of tilling them are large. The clay soils of this character are generally of little depth, and rest upon a retentive subsoil. The natural herbage they produce is coarse and little nutritious, and they are not well suited to the production of the cultivated grasses and other herbage plants. They are little fitted for the growth of turnips or other plants with bulbous and tuberous roots. Such soils have everywhere local names which sufficiently denote their qualities. They are termed, by a not improper figure, cold soils; and sometimes they are classed under the general name moor, which term is often used to denote soils, whatever be their nature, of a low degree of fertility.

Very different in their value and nature are the richer clays. These bear weighty crops of all the cultivated kinds of corn:* they do not excel the better soils of other classes so greatly in the production of oats, and still less in that of barley, in which lighter soils loams may surpass them; but they are unequalled for the production of wheat, and in many places derive their descriptive appellation from that circumstance, being termed wheat soils. They are well suited for the growth of the bean,t a plant with a weighty stem, and requiring a stiff soil to support it. They will yield large returns of the cultivated grasses and leguminous herbage plants, though they are not so quickly covered with the natural herbage plants of the soil, when laid down to perennial pasturage, as the lighter soils.

* This term applies, in Europe, to wheat, barley, and the other small grains, and not to Indian corn, as in the United States.

The bean here alluded to is the horsebean, little cultivated here, and not the kidney-bean which we grow.

As pease, beans, &c.

Clays, like other soils, approach to their most perfect condition as they advance to that state which has been termed loam. The effect of judicious tillage, and of the application of manures, is to improve the texture of such soils as well as to enrich them. Thus, clays in the neighbourhood of cities become dark in their colour, and less cohesive in their texture, from the mixture of animal and vegetable matter, and thence acquire the properties of the most valued soils of their class.

Natural changes, however, yet more than art, have furnished the rich soils of clay. The best, for the most part, of the soils of clay, are those which are formed from the depositions of rivers or the sea. The finest natural soils of this and other countries are those which are thus formed. The deposition of rivers, indeed, are not always of a clayey nature. In mountainous districts, they generally form soils of the lighter kinds. Where the sea, however, is the agent, or where both the rivers and the tides combine their action, the depositions generally partake of the nature of clay. Such alluvial soils have everywhere local terms to mark their character and fertility. On the great rivers and estuaries in England, and what are termed carses in Scotland, fine and extensive districts of this kind exist. The next class of soils is the light or free. These are readily distinguished from the last by their smaller degree of tenacity. They are less suited for the production of wheat and beans than the clays, but they are better suited for the production of plants cultivated for their bulbs and tubers, as the turnip and the potato.

This class of soils may be divided into two classes or sub-classes, differing from each other in certain characters, but agreeing in the common property of being less tenacious in their parts than the clays.

The first of these sub-classes of the lighter soils has been termed the sandy.

The sandy soils are of all the degrees from barrenness to fertility. When wholly without cohesion in their parts, they are altogether barren, and are only rendered productive by the admixture of other substances. The cultivated sands part readily with their moisture on the application of heat. They do not become hard like the clays, and, making no considerable resistance to external pressure, they are tilled with little labour.

The poorer sands are almost always marked by the scantiness of their natural herbage. This character they possess in common with the poorer gravels. Other soils, even the poorest, may be thickly covered with the plants peculiar to them; but the poorer sands and gravels put forth their natural herbs with a sparingness which denotes the absence of vegetable nourishment.

But sand, without losing its distinctive characters as a soil, may possess a greater cohesiveness in its particles, and be fertile by nature, or rendered so by art, and then the soils denominated sandy become of deserved estimation. Rich sands are early in maturing the cultivated plants, and thence they are familiarly termed kindly soils. They are fit for the production of every kind of herbage and grain. They yield to the richer clays in the power of producing wheat, but they surpass them in the production of rye and barley. They are well suited to the growth of the cultivated grasses; and, when left in perennial pasture, they are quickly covered with the natural plants of the soil. But their distinguishing character is their peculiar adaptation to the raising of the plants cultivated for the bulbs and tubers of their roots.*

The next division of the lighter soils, and allied in the character to the sandy, is the gravelly. Sands will frequently be found to be the produc* And to the culture of Indian corn. VOL. I.-D

tion of flat countries, gravels of the mountainous and rocky. The characteristic of the gravelly soils is the quantity of loose stones which they contain. These stones will be found to consist of those varieties of rock which the mountains of the country afford; and the nature of these rocks will frequently indicate the character of the soil; thus soils, of which the stony matter is very silicious, are generally found to be barren, while those of which it is calcareous are found to be fertile.

Sands, upon examination, will be found to consist of small particles of stony matter, and thus sands may be said to differ only from gravels in the more minute division of their parts. Yet, in this minuteness of division, there is generally sufficient to distinguish the two kinds of soils. The stony matter of the sand forms its principal component part, while the larger stones in the gravel, which give to it its name and its character, seem only to be mixed with the other necessary parts of the soil. The stone of the one has undergone a considerable mechanical division, while much of that of the other has only been loosened, in sensible masses, from its native bed. Any light soil, mixed with a sufficient portion of stones, is gravel and gravel, therefore, is nothing else than the different kinds of light soils, mixed with a greater or less proportion of stones.

Gravels, like sands, have all the gradations of quality, from fertility to barrenness. The loose soils of this nature, in which the undecomposed material is great, and the intervening soil silicious, are held to be the worst of their kind. These are, in some places, termed hungry gravels, not only to denote their poverty, but their tendency to devour, as it were, manure, without any corresponding nourishment to themselves. As the texture and quality of the ir tervening earth improve, so does the quality of the entire soil; and gravels, like sands