Farm drainage / The Principles, Processes, and Effects of Draining Land with Stones, Wood, Plows, and Open Ditches, and Especially with Tiles

by Henry F. French

These are only the public lands, and in the new States. In every township in New England, there are hundreds of acres of swamp land, just beginning to be brought to the notice of their owners, as of sufficient value to authorize the expense of drainage.

To say that these swamps are the most fertile and the most valuable lands in New England, is but to repeat the assertion of all who have successfully tried the experiment of reclaiming them.

In their natural state, these swamps are usually covered with a heavy growth of timber; but the greater portion of them have been partially cleared, and many of them are mowed, producing a coarse, wild, and nearly worthless grass.

The soil of these tracts is usually a black mud or peat, partly the product of vegetable growth and decay on the spot, and partly the deposit of the lighter portion of the upland soil, brought down by the washing of showers, and by spring freshets. The leaves of the surrounding forest, too, are naturally dropped by the Autumn winds into the lowest places, and these swamps have received them, for ages. Usually, these lands lie in basins among the hills, sometimes along the banks of streams and rivers, always at the lowest level of the country, and not, like Irish bogs, upon hill-tops, as well as elsewhere. Their surface is, usually, level and even, as compared with other lands in the old States. Their soil, or deposit, is of various depth, from one foot to twenty, and is often almost afloat with water, so as to shake under the feet, in walking over it.

The subsoil corresponds, in general, with that of the surrounding country, but is oftener of sand than clay, and not unfrequently, is of various thin strata, indicating an alluvial formation. Frogs and snakes find in these swamps an agreeable residence, and wild beasts a safe retreat from their common foe. Notoriously, such lands are unhealthful, producing fevers and agues in their neighborhood, often traceable to tracts no larger than a very few acres.

In considering how to drain such tracts, the first inquiry is as to the source of the water. What makes the land too wet? Is it the direct fall of rain upon it; the influx of water by visible streams, which have no sufficient outlet; the downflow of rain and snow water from the neighboring hills; or the bursting up of springs from below?

Examine and decide, which and how many, of these four sources of moisture, contribute to flood the tract in question. We assume, that the swamp is in a basin, or, at least, is the lowest land of the neighborhood. The three or four feet of rain water annually falling upon it, unless it have an outlet, must make it a swamp, for there can usually be no natural drainage downward, because the swamp itself is the lowest spot, and no adjacent land can draw off water from its bottom. Of course, there is lower land towards the natural outlet, but usually this is narrow, and quite insufficient to allow of drainage by lateral percolation. Then, always, more or less water must run upon the surface, or just below it, from the hills, and usually, a stream is found in the swamp, if none pours into it from above.

The first step is a survey, to ascertain the fall over the whole, and the next, to provide a deep and sufficient outlet. Here, we must bear in mind a peculiarity of such lands. All land subsides, more or less, by drainage, but the soils of which we are speaking, far more than any other. Marsh and swamp lands often subside, or settle, one or two feet, or even more. Their soil, of fibrous roots, decayed leaves, and the like, almost floats; or, at least, expands like a sponge; and when it is compacted, by removing the water, it occupies far less space than before. This fact must be kept in mind in all the process. The outlet must be made low enough, and the drains must be made deep enough, to draw the water, after the subsidence of the soil to its lowest point.

If a natural stream flow through, or from, the tract, it will usually indicate the lowest level; and the straightening and clearing out of this natural drain, may usually be the first operation, after opening a proper outlet. Then a catch-water open drain, just at the junction of the high and low land, entirely round the swamp, will be necessary to intercept the water flowing into the swamp. This water will usually be found to flow in, both on the surface, and beneath it, and in greater or less quantities, according to the formation of the adjacent land. This catch-water is essential to success. The wettest spot in a swamp is frequently, just at its edge, because there the surface-water is received, and because there too, the water that has come down on an impervious subsoil stratum, finds vent. It is in vain to attempt to lay dry a swamp, by drains, however deep, through its centre. The water has done its mischief, before it reaches the centre. It should be intercepted, before it has entered the tract, to be reclaimed.

This drain must be deep, and therefore, must be wide and sloping, so that it may be kept open; and it should be curved round, following the line of the upland to the outlet. Often it has been found, in England, that a single drain, six or eight feet deep, has completely drained a tract of twenty or thirty acres, by cutting off all the sources of the supply of water, except that from the clouds. This kind of land is very porous and permeable, and readily parts with its water, and is easily drained; so that the frequent drains necessary on uplands, are often quite unnecessary. Many instances are given, of the effect of single deep drains through such tracts, in lowering the water in wells, or entirely drying them, at considerable distances from the field of operation.