« AnteriorContinuar »
U advocate draining. We really should not have the face " to tell our readers that water, passing through soils con “ taining elements prejudicial to vegetation, would carry “ them off, but would leave those which are beneficial be " hind. We cannot make our water so discriminating; the “ general merit of water of deep drainage is, that it con"tains very little. Its perfection would be that it should "contain nothing. We understand that experiments are “in progress which have ascertained that water, charged “ with matters which are known to stimulate vegetation, “ when filtered through four feet of retentive soil, comes “out pure. But to return to our wheat. In the first case “it shrinks before the cold of evaporation and the cold of 6 water of attraction, and it sickens because its feet are “never dry; it suffers the usual maladies of cold and wet. “In the second case, the excess of cold by evaporation -“ is withdrawn; the cold water of attraction is removed “out of its way; the warm air from the surface, rushing “in to supply the place of the water which the drains re“move, and the warm summer rains, bearing down with “them the temperature which they have acquired from " the upper soil, carry a genial heat to its lowest roots. “ Health, vigorous growth, and early maturity are the « natural consequences. * * * * * * * * *
“The practice so derided and maligned referring to “ deep draining has advanced with wonderful strides. .66 We remember the days of 15 inches; then a step to 20; a :6 stride to 30; and the last (and probably final) jump to 50, a ;" few inches under or over. We have dabbled in them all, 6 generally belonging to the deep section of the day. We “have used the words “probably final,' because the first " advances were experimental, and, though they were jus “tified by the results obtained, no one attempted to ex “plain the principle on which benefit was derived from ** them. The principles on which the now prevailing "depth is founded, and which we believe to be true, go
“ far to show that we have attained all the advantages " which can be derived from the removal of water in “ordinary agriculture. We do not mean that, even in the “ most retentive soil, water would not get into drains “ which were laid somewhat deeper; but to this there “must be a not very distant limit, because pure clay, lying “ below the depth at which wet and drought applied at “surface would expand and contract it, would certainly "part with its water very slowly. We find that, in coal “mines and in deep quarries, a stratum of clay of only a “ few inches thick interposed between two strata of per. “ vious stone will form an effectual bar to the passage of “ water; whereas, if it lay within a few feet of the sur“ face, it would, in a season of heat and drought become “as pervious as a cullender. But when we have got rid “ of the cold arising from the evaporation of free water, “ have given a range of several feet to the roots of grass “and cereals, and have enabled retentive land to filter “through itself all the rain which falls upon its surface, “We are not, in our present state of knowledge, aware of “any advantage which would arise from further lowering " the surface of water in agricultural land. Smith, of “ Deanston, first called prominent attention to the fertilize “ing effects of rain filtered through land, and to evils pro“ duced by allowing it to flow off the surface. Any one “ will see how much more effectually this benefit will be “ attained, and this evil avoided, by a 4-foot than a 2-foot “ drainage. The latter can only prepare two feet of soil “for the reception and retention of rain, which two feet, " being saturated, will reject more, and the surplus must
run off the surface, carrying whatever it can find with it. “ A 4-foot drainage will be constantly tending to have four “ feet of soil ready for the reception of rain, and it will “ take much more rain to saturate four feet than two. “ Moreover, as a gimlet-hole bored four feet from the sur * face of a barrel filled with water will discharge much
..more in a given time than a similar hole bored at the
“ depth of two feet, so will a 4-foot drain discharge in a -“ given time much more water than a drain of two feet. “ One is acted on by a 4-foot, and the other by a 2-foot
If any single fact connected with tile-drainage is established, beyond all possible doubt, it is that in the stiffest clay soils ever cultivated, drains four feet deep will act effectually; the water will find its way to them, more and more freely and completely, as the drying of successive years, and the penetration and decay of the roots of successive crops, modify the character of the land, and they will eventually be practically so porous that,-so far as the ease of drainage is concerned, -no distinction need, in practice, be made between them and the less retentive loams. For a few years, the line of saturation between the drains, as shown in Fig. 11, may stand at all seasons considerably above the level of the bottom of the tile, but it will recede year by year, until it will be practically level, except immediately after rains.
Mr. Josiah Parkes recommends drains to be laid “ Al a minimum depth of four feet, designed with the two-fold object of not only freeing the active soil from stagnant and injurious water, but of converting the water falling on the surface into an agent for fertiliz. ing; no drainage being deemed efficient that did not both remove the water falling on the surface, and keep down the subterranean water at a depth exceeding the power of capillary attraction to elevate it near the surface.'”
Alderman Mechi says: “Ask nineteen farmers out of twenty, who hold strong clay laud, and they will tell you it is of no use placing deep four-foot drains in such soila -the water cannot get in; a horse's foot-hole (without an opening ander it) will hold water like a basin; and so on. Well, five minutes after, you tell the same farmers you propose digging a cellar, well bricked, six or eight feet decp; what is their remark? Oh! it's of no use your making an underground' cellar in our soil, you can't keep the water out!' Was there ever such an illustration of prejudice as this ? What is a drain pipe but a small cellar full of air? Then, again, common sense tells us, you can't keep a light fluid under a heavy one. You might as well try to keep a cork under water, as to try and keep air undes
water. “Oh! but then our soil is n't porons.' If not, how can it hold water so readily? I am led to these observations by the strong contro versy I am having with some Essex folks, who protest that I am mad, or foolish, for placing 1-inch pipes, at four-foot depth, in strong clays. It is in vain I refer to the numerous proofs of my soundness, bronght for ward by Mr. Parkes, engineer to the Royal Agricultural Society, and confirmed by Mr. Pusey. They still dispute it. It is in vain I tell them I cannot keep the rainwater out of socketed pipes, twelve feet deep, that convey a spring to my farm yard. Let us try and convince this large class of doubters; for it is of national importance. Four feet of good porous clay would afford a far better meal to some strong bean, or other tap roots, than the usual six inches; and a saving of $4 to $5 per acre, in drainage, is no trifle.
“The shallow, or non-drainers, assume that tenacious subsoils are im. pervious or non-absorbent. This is entirely an erroneous assumption. If soils were impervious, how could they get wet ?
“I assert, and pledge my agricultural reputation for the fact, that there are no earths or clays in this kingdom, be they ever so tenacious, that will not readily receive, filter, and transmit rain water to drains placed five or more feet deep.
“A neighbor of mine drained twenty inches deep in strong clay; the ground cracked widely; the contwaction destroyed the tiles, and the rains washed the surface soils into the cracks and choked the drains. He has since abandoned shallow draining.
“When I first began draining, I allowed myself to be overruled by my obstinate man, Pearson, who insisted that, for top water, two fea was a sufficient depth in a veiny soil. I allowed him to try the exper. ment on two small fields; the result was, that nothing prospered ; and I am redraining those fields at one-half the cost, fire and six feet deep at intervals of 70 and 80 feet.
“I found iron-sand rocks, strong clay, silt, iron, etc., and an enor mous quantity of water, all below the 2-foot drains. This accounted at once for the sudden check the crops always met with in May, when they wanted to send their roots down, but could not, without going into stag. nant water.”
“There can be no doubt that it is the depth of the drain which regtlates the escape of the surface water in a given time; regard being had, as respects extreme distances, to the nature of the soil, and a due capacity of the pipe. The deeper the drain, even in the strongest soils, the quicker the water escapes. This is an astounding but certain fact:
“That deep and distant drains, where a sufficient fall can be obtained, are by far the most profitable, by affording to the roots of the plants a greater range for food.”
Of course, where the soil is underlaid by rock, less thau four feet from the surface; and where an outlet at that depth cannot be obtained, we must, per force, drain lose
deeply, but where there exists no such obstacle, drains should be laid at a general depth of four feet,-general, not uniforin, because the drain should have a uniform inclination, which the surface of the land rarely has.
The Distance between the Drains.—Concerning this, there is less unanimity of opinion among engineers, than prevails with regard to the question of depth.
In tolerably porous soils, it is generally conceded that 40 or even 50 feet is sufficiently near for 4-foot drains, but, for the more retentive clays, all distances from 18 feet to 50 feet are recommended, though those who belong to the more narrow school are, as a rule, extending the limit, as they see, in practice, the complete manner in which drains at wider intervals perform their work. A careful consideration of the experience of the past twenty years, and of the arguments of writers on drainage, leads to the belief that there are few soils, which need draining at all, on which it will be safe to place 4-foot drains at much wider intervals than 40 feet. In the lighter loams there are many instances of the successful application of Professor Mapes' rule, that “3-foot drains should be “ placed 20 feet apart, and for each additional foot in “ depth the distance may be doubled; for instance, 4-foot “ drains should be 40 feet apart, and 5-foot drains 80 feet "apart.” But, with reference to the greater distance, (80 feet,) it is not to be recommended in stiff clays, for any depth of drain. Where it is necessary, by reason of insufficient fall, or of underground rock, to go only three feet deep, the drains should be as near together as 20 feet.
At first thought, it may seem akin to quackery to reo ommend a uniform depth and distance, without reference to the character of the land to be drained; and it is unquestionably true that an exact adaptation of the work to the varying requirements of different soils would be bene. Gcial, though no system can be adopted which will make