Page images
PDF
EPUB

INTRODUCTION OF FERTILITY.

103

of the plants. A fertile soil, cultivated so as to exhibit its fertility in the most profitable manner, has growing upon it crops whose habit and specific character are adapted to the climate in which they are placed, and to the character of the soil itself. It yields these crops in the order in which each, succeeding to the cultivation of its predecessor, shall find the soil, chemically as regards its contents, and mechanically as regards its texture, and practically as regards consequent cleanness of the land, and the fitness of their respective times of cultivation to one another, in best condition for the supply of the wants of the crop in question. It is annually manured and cultivated so as best to meet the current wants of the plants raised upon it; but it is especially dependent for all its powers to bring these crops to a fruitful maturity upon the fact that there is, during and after every shower of rain, a continual current of water and of air passing throughout its substance. This current should not be too rapid, lest its soluble parts should be washed to water; indeed, it is hardly possible that it should be too slow; slow enough, however, to dissolve from the soil whatever it contains of food for plants, and fast enough to be continually bringing fresh supplies by every mouth which the absorbing extremities of the roots present.

"All these purposes of warming the soil, of introducing substances into it which shall operate

104

WHAT LANDS REQUIRE DRAINAGE.

chemically upon its minerals, and of converting it into an efficient vehicle of the matter which it contains, are answered by the percolation of water through the soil. You must not think, then, of drainage as a contrivance for getting rid of water from the land as an enemy; nor must you think of a wet and ill-drained field as being merely an illustration of the injury done by water in excess, as it is called. Water need hardly ever be an enemy, and need rarely be in excess. Drainage is a contrivance for making use of it as a friend, and an ill-drained field is an illustration of the mischief done by water, whether there be little of it or much, when not in motion."

We desire, then, to promote the percolation of the water through the soil, and to do this we lay conduits beneath its surface to carry away the surplus moisture, and to produce currents of water and of air. We intend to enumerate several points which are of importance to its accomplishment.

1. What lands require drainage? That it is necessary in land where water stands upon its surface in summer, is evident to every one; but that soils where the evil is hidden are as much in need of it, is difficult for the uninitiated to comprehend. If rushes, or any aquatic plants make their appearance, it is a sure sign of the necessity of drainage; for all the fruit-growing plants flourish alone upon dry

DIRECTION OF THE DRAIN.

105

land, and these water-loving weeds would not appear did not the wetness of the soil encourage them. If the earth is wet and clammy in the spring, so that it is impossible to cart muck upon it, or prepare the ground properly for the crop until late in the season, it is manifest that to gain a week or ten days in this most important time is a very decided advantage. When trees or grain heave badly during the thaws of winter, or generally when the foliage of plants is pale and sickly during the summer, it is an index of the necessity of thorough drainage.

2. The direction of the drains. While there are some general rules applicable in most cases, yet it is sometimes necessary to vary them with reference to the outlet and the undulating character of the ground.

"In many subsoils there are thin partings, or layers, of porous materials, interspersed between the strata, which, though not of sufficient capacity to give rise to actual springs, still exude enough water to indicate their presence. These partings occasionally crop out, and give rise to damp spots, which are to be seen diversifying the surface of fields, when the drying breezes of spring have begun to act upon them. In the following cut the light lines represent such partings.1

66

Now, it will be evident, in draining such land, that if the drains be disposed in a direction trans

1 Cyclopedia of Agriculture, by Girdwood.

106

DIRECTION OF THE DRAINS.

verse or oblique to the slope, it will often happen that, no matter how skilfully planned, they will not reach these partings at all, as at (a). In this case, the flow will continue in its accustomed channel, and discharge its waters at (b). But again,

[ocr errors][ocr errors][merged small]

even though it does reach these partings, as at (c), a considerable portion of water will escape from the drain itself, and flow to the lower level of its old point of discharge at (d). Whereas, a drain cut in the line of the slope, as from (d) to (e), intersects all these partings, which furnishes an outlet to them at a lower level."

Mr. French in his "Land Drainage," in remarking on this description by Mr. Girdwood, says: "The line of the greatest fall is the only one in which a drain is relatively lower than the land on either side of it. Whether we regard the surplus water as having recently fallen upon the field, and as being stopped near its surface by an impervious stratum, or as brought down on these strata from above, we have it to be disposed of, as it rests

THE LINE OF DESCENT.

107

upon this stratum, and as borne out by it to the surface.

"A drain down the slope gives to the water borne up by these strata an outlet of the depth of the drain. If it be four feet, it cuts the water-bearing strata each at that depth, and takes off the water. In these cases the different layers of clay, or other impervious partings, are like the steps of a huge staircase, with the soil filling them up to a regular grade. The ditch cuts through these steps, letting the water that rests on them fall off at the ends, instead of running over the edges.

66

Now, looking at the operation of drains across the slope, and supposing that each ditch is draining the breadth next above it, we will suppose the drain to be running full of water, what is there to prevent it from passing out of that drain in its progress at every joint of the tile, and so saturating the breadth below it? Drain-pipes afford the same facility for water to soak out at the lower side as to enter on the upper, and there is the same law of gravitation to operate in each case.

"Mr. Denton says: With respect to the direction of drains, I believe very little difference of opinion exists. All the most successful drainers concur in the line of the steepest descent as essential to efficiency and economy.'

"To produce perfect drainage of a portion of this land, which we will suppose to be a gentle slope,

« PreviousContinue »