On sheep pastures a still simpler mode of removing surface water is practised in some places. Wherever the water is apt to stagnate, a deep furrow is turned up with a stout plough. After this, a man with a spade pares off the loose soil from the inverted sod, and scatters it over the field. or casts it into hollow places. The sod thus pared, and brought to the thickness of about three inches, is restored to .ts orig.nal situation, with the grassy side uppermost, as it no lurruv hau been made. A pipe or opening is thus formed beneath it two or three inches deep ill the bottom of the furrow, which is suffi cient to discharge a considerable quantity of surface water, which readily sinks into it. These furrows, in deed, are easily choked up by any pressure, or by the growth of the roots ol the grass ; but they are also easily restored, and no surface is lost by means of them.
With regard to the duration of hollow drains, or the length of time that the water will continue to flow in them, and preserve the soil in a proper state of dryness, it must necessarily depend, in a great degree, upon the nature of the materials with which they are filled, and the care that has been taken to prevent their being choked up by any accession of soft soil. Independent of this last circumstance, a drain filled with stones, like the channel which supplies a natural spring, may endure for ever. Wood, with which many drains have of late years been filled, perishes at certain periods according to its nature ; but it does by no means follow, that the drain should lose its effect in consequence of the de struction of the wood. If the earth over it form itself into an arch, the water will still continue to flow. Ac cordingly, drains filled with bushes and straw have been known to run well after forty years.
Though many of the above methods of draining are confessedly of a superficial nature, and only calculated to serve for a short period, yet a proof is furnished from them, that agriculturists in every quarter consider drainage as a most useful and necessary measure. Per haps an over-abundance of water is no less pernicious to many plants than the total want of it. At all events, when water stagnates upon the soil, the roots of plants will be rotted and destroyed. Even a temporary stagna tion renders land unproductive ; and the merits of every farmer may be completely ascertained, by the degree of attention employed to prevent such an evil.
On Irritation, or the method of improving Land ing it with Water.
This mode of improving land was practised in Eng land so early as the clays of queen Elizabeth, and pro bably was brought from Italy, where it had long been successfully practised. It has been tried in Scotland to
a considerable extent, on the estates of that excellent nobleman the duke of Buccleugh ; and though the im provement made in consequence has not been so great as what attended similar attempts in England, yet a benefit has been derived sufficiently extensive, not only to defray the expenses incurred, but to afford a hand some return to the occupiers. These observations will be sufficiently understood from extracts from the paper of the rev. Dr Singers, Kirkpatrick-juxta, on the Prin ciples and Practice of Irrigation, and from his Report made to the Highland Society of Scotland in 1304, con cerning the watered meadows on or near the rivers Esk, Ewes, Teviot, Ettrick, and Yarrow. From these two papers the practical farmer may derive more informa tion than from any other source.
" The quality of the water," says Dr Singers, "may he ascertained by experiment. Let a small portion of land be floated with it for a month, about the latter end of harvest; and afterwards for a week or two, about the end of spring. The effects or this easy experiment will appear on the grass ; either in respect of quantity, or quality, or both : and the warmth of the water may be sufficiently discovered, by its power of resisting early frosts, a matter of importance in irrigation.
The appearance of the water is not sufficient to deter mine its qualities. Thick muddy rivers, enriched in their passage through towns, and fertile soils, are not So frequently to be met with in Scotland, as the friends of irrigation would wish. When these can be obtained, the operator may depend on their efficacy. But clear alpine streams differ essentially in their qualities ; and these arc safest and most certainly ascertained, by ob serving the effect of the water and the periods of its freezing, as recommended above. With regard to those waters which are known to flow through beds of marl, there is reason to believe that much advantage may be obtained from the use of them, in a sweet and rich ver dure, valuable for pasturage. Warm rivulets, contain ing great quantities of spring water, and resisting early frosts, may be expected to encourage an early pasturage, and probably also tolerable crops of hay. But mossy wa ters, darkened by the tincture of peat bogs, arc very unpromising for the purposes of irrigation; though it, is proper to give them a trial ; and if mixed with marl waters, or conducted upon soils abounding with calca reous matters, they may be productive of benefit.