272 On Irrigation. 



weeds, which delight in a dry soil ; and, as a mere element 

 it is beneficial, more especially in dry seasons ( 401! ). 



Water, as a carrier, likewise conveys other substances to 

 the soil, by which it is enriched. This is, obviously, the 

 case when land is irrigated by muddy waters, which leave 

 behind them rich mould, and other substances. If lime or 

 marl be held in solution, the waters become highly enrich- 

 ing. Other soluble and nutritive substances are also capa- 

 ble of being conveyed by water in the same manner, on pass- 

 ing through fertile tracts. 



Meadow plants, cut green, without any external moisture 

 on their stalks or leaves, and afterwards dried, lose by ex- 

 siccation, from 66 to 70 parts out of 100. This very large 

 proportion of moisture, (though water is perhaps not the 

 only substance carried off), is a direct proof, that water it- 

 self enters largely into the composition of these vegetables. 

 Water is likewise of use, by the more equable diffusion of 

 nutritive matter in the soil, which it necessarily occasions. 



The system of watering land however, can never be car- 

 ried to perfection, unless when accompanied by drainage and 

 inclosure. Stagnant water, and impetuous torrents, do es- 

 sential injury ; but if water is entirely under command, so 

 that it may be laid on, or taken off at pleasure, it may be- 

 come a most useful instrument, in the hands of a skilful 

 husbandman. Drainage is therefore a necessary preparation 

 for irrigation ( 4 *). 



With respect to inclosure, it can be of little real use to 

 water lands, unless they are previously secured, by suitable 

 fences, from poaching and trespass. Indeed these are ne- 

 cessary, not only for the advantage of the grass, but for the 

 safety of the stock, as sheep cannot be suffered to resort to 

 lands flooded in summer, from the risk of rot. 



2. Corn. In the East Indies, not only rice, but wheat 

 and barley, are raised by means of irrigation ; and it has 

 long been a practice in some parts of Scotland, to enrich 

 the soil for crops of grain, by the same means. Mr Scrym- 

 soure of Tealing, a gentleman in Forfarshire, followed the 

 practice for nearly fifty years, and with such success, that 

 an inclosure, which had got into an exhausted state, was so 

 enriched by it, that it preserved an uncommon degree of fer- 

 tility for a succession of crops, (one of them wheat), without 

 fallow, lime, or marl, and with very moderate assistance from 

 dung( 4 3 ). The common method was very different. After 

 watering for one or two seasons, they ploughed for oats, 

 and by taking two or three successive crops, the soil was 



