IRRIGATION AND DRAINING. 83 



the disease is common, sheep are more liable to rot upon 

 irrigated and marshy lands, than on such as are free from 

 excessive moisture. 



The kind of Soils suited to Irrigation Light porous 

 soils, and particularly gravels and sands, are the most bene- 

 fitted by irrigation. Tenacious and clay soils are but slight- 

 ly improved by it, unless first made porous by underdraining. 

 It is not only important that water be brought on to the 

 ground, but it is almost equally important, that it should pass 

 off immediately after accomplishing the objects sought. 



The increase from the application of water, is sometimes 

 fourfold, when the soil, the season and the water are all 

 favorable, and it is seldom less than doubled. Many fields, 

 which in their natural condition, scarcely yield a bite of 

 grass for cattle, when thoroughly irrigated, will give a good 

 growth for years, and without the aid of any manures. 



UNDER DRAINING HEAVY AND TENACIOUS CLAY LANDS. 



The advancement of agriculture in this country during 

 the few last years, and the high price of farming lands and 

 their products, within convenient distances of our larger 

 markets, fully justify the commencement of an intelligent 

 system of draining on such lands as require it. This system 

 has for many years been introduced and largely practiced in 

 England and Scotland, and has resulted in the most signal 

 success,. 



The plan first adopted was, to excavate the land in paral- 

 lel lines, at intervals of 16 to 25 feet, and to a depth of two 

 or three feet, forming a slightly-inclined plane on the bottom, 

 which was from three to six inches wide, and gradually en- 

 larging as it approached the surface. The narrowest drains 

 were arched with inverted turf and clay, at such distance 

 from the bottom, as would leave the requisite space for the 

 escape of whatever water might filter through the soil. 

 Others were formed with continuous arched tiles, laid on a 

 sole, (a flat tile of the same material,) or on a board placed on 

 the bottom, forming an uninterrupted conductor. Larger 

 ditches were filled with rubble-stone, in some instances 

 brush, to a sufficient depth, and then covered with soil. In 

 all cases, the smaller ones communicated by their outlets, 

 with a large, open drain, which led the water from the field. 

 These drains were always below the reach of the plow, thus 

 leaving the whole surface of the lands free from any obstruc- 

 tion to cultivation 



