VII. PREPARATION OF THE LAND FOR TILLAGE OPERATIONS
When Required. Draining.
Before those simple tillage operations which are necessary in every instance of committing seeds to the earth can be gone about, there are more costly and elaborate processes of preparation which be encountered in certain circumstances, in order to fit the soil for bearing cultivated crops. It is now only in exceptional cases that the British agriculturist has to reclaim land from a state of nature. The low-country farmer does occasionally meet with a patch of woodland, or a bank covered with gorse or brushwood, which be sets about converting into arable land. It is in the higher districts that, from the facilities now afforded for readily enriching poor soils y portable manures, the plough still frequently invades new portions of muir and bog, and transforms tem into fields. The occupiers of land in these upland districts are accordingly still familiar with the processes of paring and burning, trenching, removing earth-fast stones, an leveling inequalities of surface. In breaking up land that has been for a course of years under pasturage, paring and burning are also frequently resorted to in all parts of the country. The grand improvements of all, thorough underground drainage, is common to every district and class of soils.
From the moist-climate of Britain, draining is undoubtedly the all-important preliminary operation in setting about the improvement of the soil.
To drain land is to rid it of its superfluous moisture. The rivers of a country with their tributary brooks and rills are the natural provision for removing the rain water which either flows directly from its surface, or which, after percolating through porous strata to an indefinite depth, is again discharged at the surface by spring. The latter may thus be regarded as the outlets of a natural underground drainage. This provision for disposing of the water that falls from the clouds is usually so irregular in its distribution, and so imperfect in its operation, that it leaves much to be accomplished by human labour and ingenuity. The art of the drainer according consists. ---
1st, In improving the natural outfalls by deepening, straightening, or embanking rivers; and by supplementing these, when necessary, by artificial canals and ditches: and,
2nd , In freeing the soil and subsoil from stagnant water, by means if artificial underground channels.
The first of these operations, called trunk drainage, is the most needful; for until, it be accomplished there are extensive tracts of land, and that usually of the most valuable kind, to which the secondary process either cannot be applied at all, or only with the most partial and inefficient results. Very many of our British rivers and streams flow with a sluggish and tortuous course valleys of flat alluvial soil, which, as the coast is approached, expand into extensive plains, but little elevated above the level of the sea. Here the course of the river is obstructed by shifting shoals and sand-banks, and by the periodic influx of the tides. The consequence is, that immerse tracts of valuable land are at all times in a water-logged and comparatively worthless state, and on every recurrence of a flood are laid entirely under water. In a subsequent chapter on "Waste Lands" some account shall be given of the extent of this evil, and of the efforts that have been successfully devoted to its remedy. Some of these fen0land and estuary drainage works have been accomplished in the face of natural obstacles of the most formidable character, and constitute trophies of engineering talent of which the country may well be proud. Great as the natural difficulties are which have to be encountered in such cases, there are other, of a different kind which have often proved more impracticable. It has been found easier to exclude the sea and restrain land-floods, than to overcome the prejudices and reconcile the conflicting interest of navigation companies, commissioners of sewers, owners of mills, and landed proprietors. Although all these classes suffer the most serious losses and inconveniences from the defective state of many of our rivers, it is found extremely difficult to reconcile their conflicting claims, and to allocate to each his proper share of the cost of improvements by which all are to benefit. A most interesting and instructive illustration of the urgent necessity for improving the state of our rivers, of the difficulties to be encountered in doing so, and of the incalculable benefits thus to be obtain, has been given in an essay on Trunk Drainage, by John Algernon Clarke, Esq., published in vol. xv. (part first) of the Journal of the Royal Agricultural Society of England. Mr. Clarke, after some most important observations on trunk drainage, described in detail works projected under powers granted in an Act of Parliament, passed in 1852, "constituting commissioners for the improvement of the river Nene and the navigation thereof."
There is not a district of the kingdom in which works similar in kind are not absolutely indispensable, before extensive tracts of valuable land can be rendered available for profitable cultivation by means of underground drainage. It is interesting to know that the necessity for truck drainage, and the means of accomplishing it, were distinctly set before the public 200 years ago by a practical draining engineer, to whose writing the attention of the agricultural community has been frequently directed of late by Mr. Parkes, Mr. Gisborne, and others. From the third edition (1652) of the The Improver Improved, by Walter Blithe, the author referred to, in which the true principles of land drainage are stated as distinctly, and urged as earnestly, as by any our modern writer, we here quote the following remarks: ----
"A strait water-course, cut a considerable depth, in a thousand parts of this nation, would be more advantageous than we are aware of, or will task myself here to dispute further. And though many persons are interested therein, and some will agree, and others will oppose; one creek lyeth on one side oft h river, in one lords manor, and another lyeth on the other side, and divers men own the same; why may not one neighbour change with another, when both are gainers? If not, why may they not be compelled for their own good and the commonwealths advantage? I daresay thousands of acres of very rich land may herby be gained, and possibly as many more much amended, that are almost destroyed; but a law is wanting herein for the present, which I hope will be supplied if it may appear advancement to the public; for to private interest is its not possible to be the least prejudice, when every man hath benefit, and each man may also have an equal allowance if the least prejudiced.
"But a word of two more, and so shall conclude this chapter and it is a little to further this improvement through a great destruction (as some may say); it is the removing or the destroying of all such mills, and none else, as drown and corrupt more lands than themselves are worth to the commonwealth, and they are such as are kept up or dammed so high as that they boggyfie all the lands that lye under their mill-head. Such mills as are of little worth, or are constant great charges maintained, I advise to be pulled down; the advance of the land, when the water is let run his course and not impounded will be of far greater value many times. But in case the mills should be so necessary and profitable too, and far more, than the lands they spoil, I shall then advice, that under they mill-dam, so many yards wide from it as may prevent breaking through, thou make a very deep trench all along so far as thy lands are putrefied, and there into receive all the issuing, spewing water, and thereby stop or cut off the feeding of it upon they meadow, and carry it away back into thy back-water or false course, by as deep a trench, cut through the most low and convenient part of they meads. But put case that thou shouldst have no convenient fall on that side thy mill-dam, then must make some course, or plant some trough under thy mill-dam, and so carry it under into some lower course that may preserve it from soaking thy meadows or pastures under it; and by this means thou maist in a good measure reduce thy land to good soundness, and probably wholly cure it, and preserve thy mill also."
It is painful to reflect that after the lapse of two centuries, we should still see, as Blithe did, much "gallant land" ruined for want of those draining operations which he so happily describes.
A clear outfall of sufficient depth being secured, the way is open for the application o underground draining. And here it may be proper to state, that there is very little of the land of Great Britain naturally so dry as not to be susceptible o9f improvement by artificial draining; for land is not in a perfect condition with respect to drainage, unless all the rain that falls upon it can sink down to the minimum depth required for the healthy development of the roots of cultivated crops, and thence find vent, either through a naturally porous subsoil or by artificial channels. Much controversy has taken place as to what this minimum depth is. Suffice it to say, that opinion is now decidedly in favour of a greater depth than was considered necessary even a few years ago, and that the best authorities concur in stating it at from three to four feet. There are persons who doubt whether the roots of our ordinary grain or green crops ever penetrate to such a depth as has now been specified. A careful examination will satisfy any one who makes it, that minute filamentary rootlets are sent down to extraordinary depts., whatever they are not arrested by stagnant water. It has also been questioned whether any benefits accrues to crops from this deep descent of their roots. Some persons have been asserted that it is only when they do not find food near at hand that they thus wander. But it must be borne in mind that plants obtain moisture as well as nourishment by means of their roots, and the fact is well known that plants growing in a deep soil resting on a porous subsoil seldom or never suffer from drought. It is instructive, too , on this point, to observe the practice of the most skilful gardeners, and see the importance which they attach to trenching, the great depth at which they often deposit manure, and the stress which they lay upon thorough drainage, On the other hand, it is well known that soils which soonest become saturated, and run from the surface in wt weather, are precisely those which parch and get chapped the soonest in drought. The effectual way to secure our crops at once from drowning and parching, is to put the land in a right condition with respect to drainage.
All soils posses more or less the power of absorbing and retaining water. Pure clays have it in the greater degree, and gritty siliceous ones in the smallest. In dry weather this power of attracting moisture is constantly operating to supply from below the loss taking place by evaporation at the surface. In heavy rains, as soon as the entire mass has drunk its fill, the excess begins to flow off below; and therefore a deep stratum, through which water can percolate, but in which it can never stagnate --- that is, never exceed the point of saturation --- is precisely that in which plants are most secure from the extremes of drought and drowning.
In a perfect condition of the soil with respect to drainage is of importance for its influence in preserving it in a right condition as respects moisture, it is still more so for its effects upon its temperature. All who are conversant with rural affairs are familiar with that popular classification of soils in virtue of which as are naturally dry are also invariably spoken of as warm and early; and conversely, that wet soils are invariably described as being cold and late. This classification is strictly accurate, and the explanation of it is simple. An excess of water in soil keeps down its temperature in various ways. In passing into the state of vapor it rapidly carries off the heat which the soil has obtained from the suns rays. Water possesses also a high radiating power; so that, when present in the soil in excess, and in a stagnant state, it is constantly carrying off heat by evaporation and radiation. On the other hand, stagnant water conveys no heat downwards; for although the surface is warmed, the portion of water thus heated being lightest, remains floating on the surface, and will give back its heat to the atmosphere, but conveys none downwards. When the surface of stagnant water becomes colder than the general mass, the very opposite effect immediately ensures; for as water cools its density increases, and thus causes an instant sinking of the portion that has been cooled, and a rising of a warm portion from below to take its place this movement continuing until the whole has been lowered to 40°, at which point water reaches its maximum density, while, if he temperature be reduces a few degrees more, water will begin to freeze. It is thus that soil surcharges with water is kept at a lower temperature than similar soil that has a sufficient natural or artificial drainage.
But while the presence of stagnant water in a soil has this injurious power of lowering its temperature, a very different effect ensues when rains water can sink freely into it to a depth o several feet, and then find a ready exit by drainage; for in this case the rain water carries down with it the heat which it has acquired from the atmosphere and from the sun-heated surface, and imparts it to the subsoil. There is as yet a lack of published experiments to show the ordinary increase of temperature at various depts. And in different soils, as the result of draining wet land. Those conducted by Mr. Parkes, in a Lancashire bog in June 1837, showed, as the mean of thirty-five observations, that the drained and cultivated soil at seven inches from the surface was 10° warmer than the adjoining undrained bog in its natural state at the same depth. It is understood that later experiments conducted by the same gentleman on an extended scale fully establish the fact, that an increased temperature of the soil is an unfailing accompaniment of thorough draining. The importance of this result cannot well be over-rate. The temperature and other conditions of the atmosphere, which we call climate, are placed beyond human control; but this power of raising the temperature of all wet, and consequently cold soils, becomes tantamount in some of its results to a power of improving the climate. There are, accordingly, good grounds for stating that in numerous cases grain crops have ripened sooner by ten or twelve days than they would have done but for the draining of the land on which they grew.
The points which we have thus briefly touched upon are so essential to an intelligent appreciation of the subject, that we have felt constrained to notice them, however meagerly. But our space forbids more than a mere enumeration of some of the many evils inseparable from the presence of stagnant water in the soil, and of the benefits that flow from its removal. Wet land, id in grass, produces only the coarser grasses, and many sub-aquatic plants and mosses. Which are of little or no value for pasturage, its herbage is late of coming in spring, and fails early in autumn; the animals grazed upon t are unduly liable to disease, and sheep, especially, to the fatal rot. When land is used as arable, tillage operations are easily interrupted by rain, and the period always much limited in which they can be prosecuted at all; the compactness and toughness of such land renders each operation more arduous, and more of them necessary, than in the case of try land. The surface must necessarily be thrown into ridges, and the furrows and cross-cuts duly cleared out after each process of tillage, on which surface expedients as much labour has probably been expended in each thirty years as would now suffice to make drains enough to lay it permanently dry. With all these precautions the best seed-time is often missed, and this usually proves the prelude to a scanty crops, or to a late and disastrous harvest. The cultivation of the turnip and other root crops, which require the soil to be wrought to a deep and free tilth, either becomes altogether impracticable, and must be abandoned for the safe but costly bare fallow, or is a carried out with great labour and hazard; and the crop, when grown, can neither be removed from the ground, nor consumed upon it by sheep without damage by poaching. The dung, lime, and other manure, that is applied to such land is in a great measure wasted; and the braking of the subsoil and general deep tillage, so beneficial in other circumstances, is here positively mischievous, as it doe but increase its power of retaining water. Talking into account the excessive labour, cost and risk, inseparable from the cultivation of wet land, and the scanty and precarious character of the crops so obtained, it would ion many cases be wiser to keep such lands in grass, than to prosecute arable husbandry under such adverse circumstances. These very serious evils can either be either be entirely remove, or, at the least, very greatly lessened by thorough draining. If often happens that naturally porous soils are so soaked by spring, or so water-logged by resting upon an impervious subsoil, or, it may be, so drowned for want of an outfall in some neighboring river or steam, that draining at once effects a perfect cure, and places them on a par with best naturally dry soils. In the case of clay soils, the improvement effected by draining is in some respects greater than in any other class, but sill it cannot change the inherent properties of clay. This has sometimes been overlooked by sanguine improvers, who, hastily assuming that their strong land, when drained, would henceforward be as friable and sound as the more porous kinds, have proceeded to treat clay, however well drained, will still get into mortar and clods, if it is tilled or trodden on too soon after rain. It is entirely owing to such rash and unskilful management that an opinion has sometimes got abroad, that clay lands are injured draining. They merely retain the qualities peculiar to clay, and when they are treated judiciously show as good a comparative benefit from draining as other soils. The only instances in which even temporary injury arises from draining is the case of some peaty and fen lands, which are so loose that they suffer from drought in protracted dry weather. As such lands are usually level and have water-courses near0tehm, this inconvenience admits of an easy remedy by shutting up the main outlets, and then admitting water into the ditches. The drains in this way become ready channels for applying the needed moisture by a kind of subterraneous irrigation.
The beneficial effects of thorough draining are of a very decisive and striking kind. The removal of stagnant water from a stratum of 4 feet in depth, and the establishing of a free passage for rain water and air from the surface to the level of the drains, speedily effects most important changes in the condition of the soil and subsoil. Ploughing and other tillage operations are performed more easily than before in consequence of amore friable state of the soil. Moderate rains which formerly would have sufficed to arrest these operations do so no longer, and heavy falls of rain cause a much shorter interruption of these labours than they did when the land was in its natural state. Deep tillage, whether by the common or subsoil plough (which formerly did harn), now aids the drainage, and is every way beneficial. Ridges and surface furrows being no longer needed the land can be kept flat, with great benefit to crops and furtherance to filed operations. An earlier seed-time and harvest, better crops, a healthier live stock , and an improved style of husbandry, are the usual and well known sequent of judiciously conducted drainage operations. In short, the most experienced and skilful agriculturist now declare with one consent that good drainage is an indispensable preliminary to good cultivation.
Although it has been reserved to the present times to see land draining reduced to a system based on scientific principles, or very great improvement effected in its details, it is by no by means a modern discovery. The Romans were careful to keep their arable lands dry by means of open trenches, and there are even some grounds for surmising that they used covered drains for the same purpose. Indubitable proof exits that they constructed underground channels by means of tubes of burned earthenware; but it seems more probable that these were designed to carry water to their dwellings, &c., than that they were used simply as drains. Recent inquiries and discoveries have also shown that it is at least several centuries since covered channels of various kinds were in use by British husbandmen for drying their land. It is, at all events, two centuries since Captain Walter Blithe wrote as follows: ----
"Superfluous and venomous water which lyeth in the earth and much occasioneth bogginesse, mirinesse, rushes, flags and other filth, is indeed the chief cause of barrenesses in any land of this nature
.. Drayning is an excellent and chiefest means for their reducement; and for the depth of such draynes, I cannot possibly bound, because I have not time and opportunity to take in all circumstances
.And for thy draying trench, it must be made so deepe that it goe to the bottome of the cold, spewing moyst water, that feed the flagg and the rush; for the widenesse of it, use thine owne liberty, but be sure to make it so wide as thou mayest goe to the bottome of it, which must be so low as any moyture lyeth, which moisture usually lyeth under the over and second swarth of the earth, in some fravel or sand, or else, where some greater stones are mixt with clay, under which thou must goe halfe one spade graft deepe at least; yeam suppose this corruption that feeds and nourisheth the rush or flagg should lie a yard or foure foot deepe, to the bottome of it thou must goe, if ever thou wilt drayne it to purpose
.. And for the drying trench be sure thou indeavour to carry it as neare upon a straight line as possible
.. To the bottome where the spewing spring lyeth thou must goe, and one spades depth or graft beneath, how deep so ever it be, if thou wilt dryane thy land to purpose. I am forced to use repetitions of some things, because, of the suitableness of the things to which they are apllyed; as also because of the slownesse of peoples apprehensions of them , as appears by the non-practice of tem, the which wherever you see draying and trenching you shall rarely find new or none of them wrought to the bottome
..Go to the bottome of the bog, and there make a trench in the sound ground, or else in some old ditch, so low as thou veruly conceivest thy selfe assuredly under the level of the spring or spewing water, and then carry up thy trench into thy bogg straight through the middle of it, or foot under that spring;
.. but for these common and many trenches, oft times crooked too, that men usually make in their boggy grounds, some one foot, some two, never having respect to the cause or matter that maketh the bogg to take that way, I say away with them as a great piece of folly, lost labour and spoyle
After thou has brought a trench to the bottom of the bog, then cut a good substantial trench about thy log; and when thou hast so done make one work or two just over-thwart it, upwards and downwards, all under the matter of the bog. The thou must take good green faggots, willow, alder, elme, or throne, and thorne, and lay in the bottome of thy works, and then take thy turfe thou tookest up in th top of thy trench, and plant upon them with the green sward downwards; or take great pebbles, stones, or flint stones, and so fill up the bottome of thy trench about fifteen inches high, and take thy turfe and plant it as aforesaid, being cut very fit for the trench, as it may join close as it is layd downe, and thenm having covered it all over with earth, and made it even as they other ground, waite and expect a wonderfull effect through the blessing of God."
These sagacious arguments and instructions were doubtless acted upon by some persons in his own times and since; but still they had never attained to general adoption, and were ultimately forgotten. Towards the close of last century, Mr. Elkington, a Warwickshire farmer, discovered and promulgated a plan of laying dry sloping land that is drowned by the out bursting of spring. When the higher lying portion of such land is porous, rain falling upon it sinks down until it is arrested by clay or other impervious matter, which causes it again to issue at the surface and wet and lower-lying ground. Elkington showed that by cutting a deep drain through the clay, aided when necessary by well s or augur holes, the subjacent bed of sand or gravel in which a body of water is pent up by the clay, as in a vessel, might be tapped, and the water conveyed harmlessly in the covered drain to the nearest ditch or stream. In the circumstances to which it is applicable, and in the hands of skilful drainers, Elkingtons plan, by bringing into play the natural drainage furnished by porous strata, is often eminently successful. His system was given to the public in a quarto volume, edited by a Mr. John Johnston of Edilburgh, who does not seem to have shared the engineering talents of the man whose discoveries he professes to expound. During the thirty or forty years subsequent to the publication of this volume, most of the draining that took place was on this sytem, and an immerse capital was expended in such works with very varying results, Things continued in this position until about the year 1823, when the late James Smith of Deanston, having discovered anew those principles of draining as long before indicated by Blithe, proceeded to exemplify them in his own practice, and to expound them to the public in a way that speedily effected a complete revolution in the art of draining, and marked an era in our agricultural progress. Instead of persisting in fruitless attempts to dry extensive areas by a few dexterous cuts, he insisted on the necessity of providing every field that needed draining at all with a complete system of parallel underground channels, running in the line of the greatest slope of the ground, and so near to each other that the whole rain falling at nay time upon the surface should sink down and be carried off by the drains. The distances between drains be showed must be regulated by the greater or less retentiveness of the ground operated upon, and gave 10 feet as the minimum, and 40 feet as the maximum of these distances was 30 inches, and these were to be filled with 12 inches of stones small enough to pass through a 3-inch ringin short, a new edition of Blithes drain. A man receiving-drain was to be carried along the lowest part of the ground, with sub-mains in every subordinate hollow that the ground presented. There receiving drains were directed to be formed with a culvert of stone work, or of tiles, of waterway sufficient to contain the greatest volume of water at any time requiring to be passed from the area to which they respectively supplied the outlet. The whole cultivated lands of Britain being disposed in ridges which usually lie in the line of greatest ascent, it became customary to form the drains in each furrow, or in each alternate, or third, or fourth one, as the case might require or views of economy dictate, and hence the system soon came to be popularly called furrow draining. From the number and arrangement of the drains, the terms frequent and parallel were also applied to it. Mr. Smith himself more appropriately named it , from its effects, thorough draining. The sound principles thus promulgated by him were speedily adopted and extensively carried into practice. The great labour and cost incurred in procuring stones in adequate quantities and the difficulty of carting them in wet seasons, soon led to the substitution of tiles and soles of burned earthenware. The limited supply and high price of these tiles for a time impeded the progress of the new system of draining; but the invention of the making machines by the Marquis of Tweddale and others, removed this impediment, and gave a mighty stimulus to this fundamental agricultural improvement. The substitution of cylindrical pipes for the original horseshoe tiles has still further lowered the cost and increased the efficiency and permanency of drainage works.
The system introduced and so ably expounded by Smith of Deanston has now been virtually adopted by all drainers. Variations in matters of details 9having respect chiefly to the depth and distance apart of the parallel drains) have indeed been introduced; but the distinctive features of his system are now recognized and acted upon by all scientific drainers.
In setting about the draining of a field, or farm, or estate, the first point is to secure, at whatever cost, a proper outfall. The lines of the receiving drains must next be determined, and then the direction of the parallel drains, The former must occupy the lowest part of the natural hollows, and the latter must run in the line of the greatest ascent of the ground. In the case of flat land, where a fall is obtained chiefly by increasing the depth of the drains at their lower ends, these lines may be disposed in any direction that is found convenient but in undulating ground a single field may required several distinct sets of drains lying at different angels, so as to suit its several slopes of the ground, there is an obvious convenience on adopting the furrows as the site of the drains; but wherever this is not the case the drains must be laid off to suit the contour of the ground, irrespective of the furrows altogether. When parts of a filed are flat, and other parts have a considerable acclivity, it is expedient to cut a receiving drain near to the bottom of the slopes, and to give the flat ground an independent set of drains, In lying off receiving drains it is essential to give hedge-rows and trees a good offing, lest the conduit should be obstructed by roots. When a drain must of necessity pass near to trees, we have found it practicable to exclude their roots from it by the use of coal-tar. In our own practice, a drain carried through the corner of a plantation has by this expedient remained free from obstruction for now fourteen years. In this instances the tar was applied in the following manner: --- Sawdust and coal-tar being mixed together to the consistency of ordinary mortar, a layer of this was laid in the bottom of the trench; the drain-pipes were then laid, and completely coated with the same mixture to the thickness of an inch, and the earth carefully replaced in the ordinary way. When a main drain is so placed that parallel ones empty into it from both sides, care should be taken that the inlets of the latter are not made exactly opposite to each other. Indeed, we have found it expedient in such cases to have two receiving drains parallel to each other, each to receive the subordinate drains from its own side only. As these receiving drains act also as ordinary drains to the land through which they pass, no additional cost is incurred by having two instead of one, provided they are as far apart as the other drains in the field. Much of the success of draining depends on the skillful planning of these main drains, and in making them large enough to discharge the greatest flow of water to which they may be exposed. Very long main drains are to be avoided. Numerous outlets are also objectionable, from their liability to obstruction. An outlet to an area of from ten to fifteen acres is a good arrangement. These outlets should be faced with mason work, and guarded by iron gratings.
The depth of the parallel drains must next be determined. In order to obtain proper data for doing so, the subsoil must be carefully examined by digging test-holes in various places, and also by taking advantage of any quarries, deep ditches, or other cuttings in the proximity, that afford a good section of the ground. We have already expressed an opinion that the drains should not be less than four feet deep; but it is quite possible that the discovery at a greater depth than four feet of a seam gravel, or other very porous material charged with water, underlying considerable portions of the ground, may render it expedient to carry the drains so deep as to reach this seam. Such a seam, when furnished with sufficient outlets, supplies a natural drain to the whole area under which it extends. When such exceptional cases are met with, they are precisely those in which deep drains, at wide intervals, can be trusted to dry the whole area. When the subsoil consists of a tenacious clay of considerable depth, it is considered by many persons that a greater depth than three feet is unnecessary. The greater depth is, however, always to be preferred; for a drain of four feet, if it works at all, not only does all that a shallower one can do, but frees from stagnant water a body of subsoil on which the other has no effect at all. It has indeed been alleged that such deep drains may get so close over by the clay that water will stand above them. If the surface of clay soil is wrought into puddle by improper usage, water can undoubtedly be made to stand for a time over the shallowest drains as easily as over the deepest. But the contraction which takes place in summer in good alluvial clays gradually establishes fissures, by which water reaches the drains. In such soils it is usually a few years before the full effect of draining is attained. This is chiefly due to the contraction and consequent cracking of clay soils in summer just referred to, and partly, as Mr. Parkes thinks, to the mining operations of the common earth-worm. Both of these natural aids to drainage operate with greater force with drains four feet deep than when they are shallower. The tardy percolation of water through clay soils seems also a reason why in such cases it should get the benefit of a greater fall, by making the drain deep.
Draining is always a costly operation, and it is therefore peculiarly needful to have it executed in such a way that it shall be effectual and permanent. We advocate a minimum depth of four feet, because of our strong conviction that such drains carefully made will be found to have both these qualities. And this opinion is the result of dear-bought experience, for we have found it necessary in our own case to re-open a very considerable extent of 30-inch drains in consequence of their having totally failed to lay the land dry, and to replace them by four feet ones, which have proved perfectly efficacious. In doing this we have seen a 30-inch drain open up and found to be perfectly dry, and yet when the same trench was deepened to four feet there was quite a run of water from it. Now also that steam power has become available for the tillage of the soil, and is certain, at no distant day, to be in general requisition for that purpose, it is peculiarly expedient to have the drains laid at such a depth as to admit of that potent agency being used for loosening the subsoil to depths hitherto unattainable, not only without hazard to the drains, but with the certainty of great augmenting their efficiency. Therefore we earnestly dissuade all parties who are about to undertake drainage works from giving ear to representations about the sufficiency and economy of shallow drains. These, doubtless, cost somewhat less to begin with, but in thousands of cases they fail to accomplish the desired end, and the unfortunate owners, after all their outlay, are left to the miserable alternative of seeing their land imperfectly drained, or of executing the works anew, and thus losing the whole cost of the first and inefficient ones. The extreme reluctance with which the latter alternative is necessarily regarded will undoubtedly operate for a long time in keeping much land that has been hastily and imperfectly drained from participating in the benefits of thorough drainage. The distance apart at which the drains should be cut must be determined by the nature of the subsoil. In the most retentive clays it need not be less than 18 feet. On the other hand, this distance cannot safely be exceeded in the case of any subsoil in which clay predominates, although it should not be of the most retentive kind. In all parts of the country instances abound in which drains cut in such subsoils, from 24 to 30 feet apart, have totally failed to lay the land dry. When ground is once pre-occupied by drains too far apart, there is no remedy but to form a supplementary one betwixt each pair of the first set; and thus, by exceeding the proper width at first, the space betwixt the drains is unavoidable reduced to 12 or 15 feet, although 18 feet would originally have sufficed. It is only with a decided porosity in the subsoil, and in proportion to the degree of that porosity, that the space between drains can safely be increased to 24, or 30, or 36 feet. In those exceptional cases in which drains more than 36 feet apart prove effectual, their success is due to the principle on which Elkingtons systems is found. A few years ago an opinion obtained currency, that as the depth of drains was increased their width apart might with safety be increased in a corresponding ratio. And hence it came to be confidently asserted, that with a depth of 5 or 6 feet a width of from 40 to 60 feet might be adopted with a certainty of success, even in the case of retentive soils. We believe that experience has already demonstrated the unsoundness of its opinion. At all events, in recommending a minimum depth of 4 feet, we do so on the ground that (other things being equal) the whole benefits of drainage are more fully and certainly secured by drains of this depth than by those of 2_ or 3 feet. In ordinary cases an increase of depth does not compensate for an increase of the width of the drains. Draining can be carried on at all seasons, but is usually best done in summer or autumn. The diggings is usually paid for by task work and the setting of the pipes by days wages. A thorough trustworthy and experienced workman is selected for the latter work, with instructions to set no pipes until he is satisfied that the depth of the drains and level of the bottoms are correct. When the soil is returned into the drains all defects are of course buried, and it therefore behoves the landlord, or his substitute, whether tenant or bailiff, to exercise a vigilant oversight of draining operations. Unless carefully executed they cannot be efficient; and without efficient drainage all other agricultural operations must be carried on under grievous disadvantages. The extent of land in Great Britain naturally so dry as not to need artificial drainage is very much less than even practical farmers, who have not studied the subject, are at all aware of.
Cylindrical pipes with collars are undoubtedly the best draining material that has yet been discovered. The collars referred to are simply short pieces of pipe, just so wide in the bore as to admit of the smaller pipes which form the drain passing freely through them. In use, one of these collars is so placed as to encase the ends of each contiguous pair of tubes, and thus forms a loose fillet around each joining. The ends of these pipes being by this means securely kept in contact, a continuous canal for the free passage of water is infallibly insured, the joinings are guarded against the entrance of mud or vermin, and yet sufficient space is left for the admission of water. Pipes of all diameters, from 1 inch to 16 inches, are now to be had; those from 1 to 2 inches in the bore are used for subordinate drains; the larger sizes for sub-main and main receiving drains. Collars are used with the smaller sizes only, large pipes not being so liable to shift their position as small ones. In constructing a drain, it is of much importance that the bottom be cut out just wide enough to admit the pipes and no more. Pipes, when thus accurately fitted in, are much less liable to derangement than when laid in the bottom of a trench several times their width, and into which a mass of loose earth must necessarily be returned. This accurate fitting is now quite practicable in the case of soils tolerably free from stones, from the excellence of the draining tools that have lately been introduced. The following cut represents the most important of these tools.
If a quicksand is encountered in constructing a drain, it will be found expedient to put a layer of straw in the bottom of the trench, and then, instead of the ordinary pipes and collar, to use at such a place a double set of pipes --- one within the other --- taking care that the joinings of the inner set are covered by the centers of the outer ones. By such precautions the water gets vent, and the running sand is excluded from the drain. When a brook has been diverted from its natural course for mill-power or irrigating purposes, it often happens that portions of land are thereby deprived of the outfall required to admit of their being drained to a proper depth. In such cases it is frequently practicable to obtain the needed outlet by carrying a main drain through below the water-course, by using at that point a few yards of cast-iron pipe, and carefully filling up the trench with clay puddle, so that there may be no leakage from the water-course into the drain. While this is being done the water must either be turned off or carried over the temporary gap in a wooden trough.
The cost of draining is so much influenced by the ever varying price of labour and materials, and by the still more varying character of the land to be operated upon, that it is impossible to give an estimate of the cost that will admit of general application. The following tabular data, taken chiefly from Mr. Bailey Dentons valuable treatise, are presented to aid those who wish to form such an estimate: ---
TABLE I. --- Showing the number of rods of drain per acre at given distances apart, and the number of pipes of given lengths required per acre.
== TABLE ==
TABLE II. ---- Showing the cost of draining per acre at different intervals between the drains.
== TABLE ==
Various attempts have from time to time been made to lower the cost of draining land by the direct application of animal or steam power to the work of excavation. The most successful of there attempts is the steam-draining apparatus invented by Mr. John Fowler of Bristol, usually called Fowlers draining plough. A six-horse portable steam-engine is anchored in one corner of the filed to be drained. It gives motion to two drums, to each of which a rope 500 yards long is attached, the one uncoiling as the other is wound up. There ropes pass round blocks which are anchored at each end of the intended line of drain, and are attached one to the front and the other to the hinder end of the draining apparatus. This consists of a frameworks, in which is fixed, at any required depth not exceeding 3 _ feet, a strong coulter terminating in a short horizontal bar of cylindrical iron, with a piece of rope attached to it, on which a convenient number of drain pipes are strung. This frame being pulled along by the engine, the coulter is forced through the soil at a regulated depth, and deposits its string of pipes with unerring accuracy, thus forming, as it proceeds a perfect drain. The supply of pipes is kept up by means of holes previously dug in the line of the drain, at distance corresponding to the length of the rope on which they are strung. This machine as subjected to a very thorough trial at the meeting of the Royal Agricultural Society of England at Lincoln in 1854, on which occasion a silver medal and very high commendation were awarded to it. In March 1855 it was publicly stated that five of these implements are now at work in different parts of England, and that already 10,000 acres of land have been drained by means of them. At the Lincoln trial it was satisfactorily proved that this implement could work at a depth of 3 _ feet. As it moved along, the soil on each side, to the width of 2 or 3 feet, seemed to be loosened. It is therefore probable that this implement, or at least on propelled on the same principle, may yet be used as a subsoil disintegrator.
A great stimulus has recently been given to the improvement of land by the passing of a series of Acts of Parliament, which have removed certain obstacles that effectually hindered the investment of capital in works of drainage and kindred ameliorations. By the first of these Acts, passed in 1846, a sum of £4,000,000 of the public money was authorized to be advanced to landowners to be expended in draining their lands. The Enclosure Commissioners were charged with the allocation of this money and the superintendence of its outlay. The most important provisions of this Act are that it enables the possessors of entailed estates (equally with others) to share in the benefits of this fund. That it provides, on terms very favorable to the borrower, for the repayment of the money so advanced, by twenty-two annual installments; that before sanctioning the expenditure of these funds on drainage works, the commissioners must have a report from a qualified inspector, to the effect that they are likely to prove remunerative; and finally, that the works much be performed according to specifications prepared by the inspector, and approved by the commissioners, who gave seldom allowed of a less depth of drain than 3 _ feet. By the end of the year 1854 the whole of this money was allocated, and more than half of it actually expended. Scottish landowners were so prompt to discern, and so eager to avail themselves of this public fund, that more than half of it fell to their share. The great success of this measure, and the rapid absorption of the fund provided by it, soon led to further legislative Acts, by which private capital has been rendered available for the improvement of land, by draining and otherwise, on conditions similar to those just enumerated. These Acts are ---
1st, The Private Moneys Drainage Act (12 and 13 Vict. c. 100), limited to draining.
2d. The West of England, or South-West Land Draining Companys Act (11 and 12 Vict., c 142), for the purpose of draining, irrigation and warping, embanking, reclaiming and enclosing, and road-making.
3d, The General Land-Drainage and Improvement Companys Act (12 and 13 Vict. c. 91), for the purposes of draining, irrigating and warping, embanking, reclaiming and enclosing, road-making and erecting farm-building.
4th, The Lands Improvements Companys Act (16 and 17 Vict. c. 154), for the same purposes as the above, with the addition of planting for shelter. This companys powers extend to Scotland.
By these Acts ample provision is made for rendering the dormant capital of the country available for the improvement of its soil. To the owners of entailed estates they are peculiarly valuable, from the power which they give to them of charging the cost of draining, &c., upon the inheritance. If such owners apply their own private funds in effecting improvements of this kind, They are enabled, through the medium of these companies, to take a rent-charge on their estates for repayment of the money they so expend, over which they retain personal control, so that they can bequeath as they choose the rent-charge payable by their successor. Beside their direct benefits, these Drainage Acts have already produced some very important indirect fruits. They have led to many improvements in the manner of accomplishing the works to which they relate, to the wide and rapid dissemination of the improved modes of draining, &c., and, in particular, they have had the effect of creating, or at least of greatly multiplying and accrediting, a staff of skilful and experienced draining engineer, of whose services all who are about to engage in draining and similar works will do well to avail themselves.
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