THOUGHTS ON DRAINING.

To the Editor of the Quarterly Journal of Agriculture.

An eminent civil engineer once remarked to me, that he had never met with a farmer who could give him a satisfactory définition of draining. He also stated it as his opinion, that, so far as he was able to judge from observation, a great deal more had been said in praise of draining than it really deserved; and he was convinced much money had been thrown away upon it, which might have been more beneficially expended otherwise on the farm. I certainly do not concur in these sweeping observations, although the last of them may contain some truth.

Definitions are at best metaphysical; but, it must be confessed, that no satisfactory theory of draining has ever been proposed. The theory offered is, that water remaining in the arable part of the soil longer, and in greater quantity, than the cultivated plants or natural grasses will use, it becomes hurtful to their growth'; and to remove this injurious cause, it is necessary to drain the ground. This theory, as it is called, amounts to no more than a statement of the fact, that too much moisture is injurious to the vegetation of useful plants. We cannot, it is true, in general, remove this superabundant moisture except by drains; but the reason why a mere excess of moisture should be so injurious to vegetation still remains unexplained. The fact is, until we are better acquainted with the physiology of plants we cannot satisfactorily explain it. When we see a change produced in any given chemical solution, by the admixture of another given chemical agent, we can explain it satisfactorily, by referring to the principles of chemical affinity; but our present state of knowledge does not yet clearly comprehend that principle in vegetable physiology, which could explain the injurious effects of wet land on vegetation.

If too much moisture is injurious to vegetation, too much drought is as injurious to it; and if we drain to counteract the effects of the former, what can we do to counteract the effects of the latter? Do not the drains aggravate those effects prodigious

ly in a dry season? Certainly they do. It is the nature of the climate then, that regulates the necessity for draining; and as the humid seasons greatly outnumber the dry ones in this coun-. try, we must therefore adopt that necessity.

Had our climate been like that of Italy, not only no draining would have been in general necessary; but our rivers, like hers, would have been directed into channels to irrigate our lands, in order to preserve to them that pleasant verdure in the height of summer, on which the eye gazes with so much delight, amid the rich luxuriance of the plains of Lombardy. Or even had the alluvial crust of the earth been of equal depth, and homogeneous throughout, no draining would have been necessary; for the rains and dews would then have been absorbed by the soil, and they would have flowed in the shape of tiny streams between it and the rocky strata which form the basis of the alluvial crust. Water would then have been found by digging wells to the rocky strata. But as the alluvial crust is really formed of a heterogeneous mass of different kinds of earth, which possess different capacities for water, the rains and dews which permeate them, are partly absorbed by the porous, and partly reflected by the retentive, kinds to the surface of the ground at a lower level. Hence the origin of springs, and moist spots on the surface of the earth.

The subsoil, on which the arable part of the soil rests, is, in general, of a different structure from the upper soil. It may be composed chiefly of gravel or sand, or a mixture of both, which being porous, and absorbing all the excess of moisture that may have fallen upon it, prevent the appearance of any moist spots; and of course no drains are necessary in such subsoils. On the other hand, it may be composed of clay, through, which moisture cannot easily permeate, and in this case the assistance of drains is necessary to draw off the superfluous moisture. This necessity for draining in this kind of subsoil was known to our forefathers, as the remains of ancient drains found in soil resting on such subsoils testify. But in the old method of draining in this country, the depth of the drain depended on the depth of the arable soil alone; but as the depth of the arable soil, when it is of a different structure from the subsoil, is never very great, the drains were necessarily shallow; and as expe

rience would soon teach men the impropriety of placing the stones in the drains within reach of the operation of the plough, few stones were placed in them,-often not exceeding three in number, one on each side of the cut and another above them, forming a sort of conduit.

As these conduits were so near the surface, and of small areas, an extra quantity of water, or moles digging along their sides, soon placed such obstructions in them as to prevent entirely the flow of the water. They then became receptacles of water, and produed the very mischief they were intended to obviate. Many of these old-fashioned drains are daily to be met with in the soil, and they have all been uniformly formed on the notion, that a conduit to convey the water at the point of junction between the arable and subsoils, was sufficient to render the soil permanently dry. These drains are often found in all soils whose structure is different from that of the subsoil; but I have never heard whether they have ever been found in purely clay soils. Such drains could only be useful in conveying away surface water, that water which could only permeate the upper soil.

A better knowledge of the relative positions of the alluvial earths, which form the crust of the earth, dictated a more efficient mode of extracting the superfluous moisture of the subsoil, to a considerable depth. To dig into the subsoil, would not only grant all the advantages which could accrue from the old-fashioned drains; but it would, at the same time, by conveying away the permanent moisture which lodged in the subsoil itself, ameliorate the nature, and thereby confer a capacity for improvement, of the arable soil. In deep arable soils, where the influence of moisture must be remote, draining at all, or at least deep draining, must be unnecessary. It is more necessary in thin arable soils, as the proximate relation of the subsoil to them, in regard to a state of wetness or dryness, has a direct influence on the productive powers of the soil. Manures and stimulants can never impart their peculiar benefits to any soil which rests continually on a wet bottom,-the operations of husbandry can never be accomplished in due season, and the produce is never abundant, or of good quality, in such circumstances. Draining removes all these evils. It may be described, ac

cording to Pliny, an operation which-utilissimum est. In truth, too much praise cannot be bestowed on an operation, which has formed the basis of all the improvements that have been introduced into the husbandry of these islands for the last hundred years.

The inefficiency of these small drains, which were only made in the arable part of the soil, at length exhibited itself. The subject was first broached to the agricultural world by Mr Elkington, a farmer, about the middle of the last century; and who, by his own practice, pointed out the utility of digging drains into the substance of the subsoil. Since then deep draining has been most scrupulously followed; and under that practice a great improvement is apparent on the face of our country, even during the period of a lifetime.

Deprecating all intention of derogating, in the smallest degree, from the general principle of deep draining, by means of which I verily believe, the most substantial of the improvements in our husbandry have been effected, I am, nevertheless, inclined to agree with our engineer, that much more money has been expended in the indiscriminate application of that principle to every class of soils than is generally imagined. I believe that, in numberless instances, drains have been dug deep, where shallower ones would have served the same purpose; and this has arisen in many cases, I am afraid, not from a conviction in the operator of the excellence of their nature, because he might not have been able to judge of the relative values of both from experience, but merely because he must follow the general practice of the country. I do not assert that the money thus expended has been absolutely thrown away; for success-decided improvement has followed almost every attempt at draining; as no one, however incapable he might be of directing the operation aright, would even make the attempt, unless he experienced the obvious injury arising from wet land.

But, at the same time, it must be confessed, that many of these improvements have been purchased at a greater cost than was necessary to accomplish the end proposed. It must be confessed, many men have attempted to drain land, who did not know when to apply the general principle to the best advantage, and the outlay of whose money was of course ill directed. In

this way much money has been imprudently squandered. Had the mischief only been to this extent, its consequences might have been remedied by better management in the other operations of the farm; but the sinking of so much capital in injudicious draining, deprives the farmer of means to pursue his general improvements, and thus prevents his reaping all the advantages derivable from the draining itself. Had the money, which was more than necessarily expended in this way, been at the command of the farmer, it would have most probably been laid out in maintaining his farm in the highest condition; for such is the general character of our farmers, as promoters of improvements, that they cannot be accused of hoarding up their riches, through the love of money, so long as there is any change for the better, within their reach, to be made on the state of their farms, though it may not ultimately yield advantage to themselves.

Were draining an operation which could be executed at little trouble and cost, it would be of less importance to urge economy in conducting it; but as it is an expensive one, when conducted even in the most economical manner, much thought is requisite before attempting to break up the ground to a great extent. Had the structure of the upper strata been known as scientifically at the period when deep draining received an impulse, and was exhibited as an example to all future drainers, as it is now, it is probable its knowledge would have exerted a beneficial influence, at its outset, on this art. That knowledge may now be acquired by any one. Let us therefore contemplate the facts it unfolds to our view, and endeavour, through them, to acquire that wisdom which will direct us to expend our money in draining, with prudence as well as skill. Some remarks on the nature and structure of the different kinds of soil, which present themselves to our notice, as agriculturists, will assist us much in ascertaining what are the kinds which admit of deep draining, and what kinds may be treated equally well, under a different management. Inattention to this distinction has given rise to the inordinate application of that general principle, which, as a general principle, but subject to necessary limitations, must ever receive the approbation of every man, who knows and feels the importance of these improvements in husbandry.