Book III. IRRIGATION OF ARABLE LANDS. 733 



121. or 15t. the acre, according to Young, and in most instances it must be greatly below 

 such estimates. 



4+58. That no estimate ean be made without viewing the situation of the lands to be warped, and the 

 course and distance it will be necessary to carry the warp to such lands, is remarked by Day, in the Agri. 

 cultural Survey of the same district. 1st, The situation of the lands must be considered ; L'd, The quantity 

 of land the same drains and doughs will be sufficient to warp ; 3d, The expense of building the doughs, 

 cutting the drains, embanking the lands, &c. An estimate of these expenses being made, it will then be 

 necessary to know the number of acres sucli doughs and drains will warp, before any estimate can be 

 made ; as the greater the quantity of land the same doughs and drains will warp, the lighter the expense 

 will be per acre. In Day's opinion, there is a great deal of land in the country capable of being warped 

 at so small an expense as from 4/. to 81. per acre, which is nothing in comparison to the advantages which 

 •arise from it. He has known land raised in value by warping, from 51. to upwards of 40/. and M)l. per 

 acre. The greatest advantages arise upon the worst land, and the more porous the soil the better, as the 

 wet filters through, and it sooner becomes fit for use. The advantages of warping are very great ; as, 

 after lands have been properly warped, they are so enriched thereby that they will bring very large crops 

 for several years afterwards without any manure; and, when it is necessary, the lands might be warped 

 again, at a very trifling expense, by opening the old drains, and would bring crops ip succession for many 

 years, with very little or no tillage at all, if the lands were kept free from quick grass and other weeds, 

 which must be the case in all properly managed lands ; besides, the drains which are made for the pur. 

 pose of warping are the best drains that can be constructed for draining the lands at the time they are not 

 used for warping, which is another very great advantage in low lands. 



4459. The best mode of cultivating new-warped land must depend principally on the 

 nature of the warp and of the subsoil. In the Code of Agriculture it is recommended to 

 sow it with clover, and to let it lie under that crop for two years, in order that it may be 

 brought into a state fit for corn. Even though fallowed, it does not answer to sow land 

 with wheat immediately after it is warped ; but after white or red clover for two years, 

 a good crop of wheat may generally be relied on. Nor is it proper, when land is warped, 

 to plant it with potatoes, or to sow it with flax, being at first of too cold a nature ; though, 

 if the land be not too strong for potatoes, these crops may answer, after it has been for 

 two or three years in cultivation. In the quality of warped land, there are most essential 

 differences ; some will be very strong, and in the same field some will be very friable. 

 The land nearest the drain is in general the lightest, owing to the quantity of sand that 

 is deposited as soon as the water enters the field : the land farthest from the drain is in 

 general the best. The produce of warped land varies much, but in general it may be 

 stated as abundant. {Code, 315) 



Subsect. 1. Irrigation of Arable Lands, and Subterraneous Irrigation. 



4460. The irrigation of arable lands is universal in warm countries, and even in the 

 south of France and Italy. The land is laid into narrow beds, between which the 

 water is introduced in furrows during the growth of the crop, and absorbed by the soil. 

 In other cases the crop is grown in drills, and the water introduced in the furrow be- 

 tween each row. In this mode of irrigation no collecting drains are required, as the 

 whole of the water laid on is absorbed by the soil. The principal expense of the opera- 

 tion is that of preparing the lands by throwing the surface into a proper level or levels. 

 The main or carrier is conducted to the higher part of the field, and the rest is easy. 

 A particular description of the practice, as carried on in Tuscany, is given by Sigismondi. 

 (Agr. de la Toscane-} Some account also of the practice in Italy and the East Indies 

 will be found in our outline of the agriculture of these countries. (267 and 921.) In 

 the General Report of Scotland, vol. iii. p. 361. it is stated, that a field of waste land, which 

 had been flooded during winter with stagnant water, was thus, without manure, rendered 

 capable of yielding a good crop of oats; but this is more of the nature of warping than 

 of that description of irrigation which is practised in warm countries on arable lands, 

 during the growth of the crop. 



4461. Subterraneous irrigation appears to have been first practised in Lombardy, and 

 first treated of by Professor Thouin. {Annates du Musee, &c.) It consists in saturating 

 a soil with water from below, instead of from the surface, and is effected by surround- 

 ing a piece of ground by an open drain or main, and intersecting it by covered 

 drains communicating with this main. If the field is on a level, as in most cases where 

 the practice is adopted in Lombardy, nothing is more necessary than to fill the main, and 

 keep it full till the lands have been sufficiently soaked ; but if it lies on a slope, then the 

 lower ends of the drains must be closely stopped, and the water admitted only into the 

 main on the upper side: this main must be kept full till the land is soaked, when the 

 mouths of the lower drains may be opened to carry off the superfluous water. The 

 practice is applicable either to pasture or arable lands. 



4462. In Britain, subterraneous irrigation has been applied in a very simple manner 

 to drained bogs and morasses, and to fen lands. All that is necessary is to build a 

 sluice in the lower part of the main drain where it quits the drained grounds, ami in 

 dry weather to shut down this sluice, so as to dam up the water and throw it back into 

 all the minor open drains, and also into the covered drains. This plan has been adopted 

 with success, first, as we believe, by Smith, of Swineridge Muir, in Ayrshire, and subse- 

 quently by Johnston, in the case of several bog drainages executed by him in Scotland. 



