QUANTITY OF WATER APPLIED. 447 



ture it ranges from 27 or 28 to 60 inches, while in smaller crops, 

 tilled by hand-labor, it is sometimes carried as high as 300 inches* 



delle Aoque, Firenze, 1843, 3 v. 8vo, and Trattato delta Region Civile delle 

 Acque, Firenze, 1834, 8vo. Also, particularly on the economical question, 

 Cattanko, D'acune Instituzioni Agrarie dell' Alia Italia, in Memorie di Eco- 

 nomia Pubblica, vol. 1., Milano, 1860. 



* NiEL, Agriculture des Etats Sardes, p. 237. Lombardini's computation 

 just given allows eighty-one cubic metres per day to the hectare [two hun- 

 dred and sixty cubic yards to the acre], which, supposing the season of irriga- 

 tion to be one hundred days, is equal to a precipitation of thirty-two inches. 

 But in Tjombardy, water is applied to some crops during a longer period than 

 one hundred days ; and in the marcite it flows over the ground even in winter. 

 According to Boussingault {Economie Rurale, ii., p. 246) grass-grounds ought 

 to receive, in Germany, twenty-one centimetres of water per week, and with 

 less than half that quantity it is not advisable to incur the expense of supply- 

 ing it. The ground is irrigated twenty-five or thirty times, and if the full 

 quantity of twenty-one centimetres is applied, it receives more than two hun- 

 dred inches of water, or six times the total amount of precipitation. Puvis, 

 quoted by Boussingault, after much research comes to the conclusion that a 

 proper quantity is twenty centimetres [eight inches] applied twenty-five or 

 thirty times, which corresponds with the estimate just stated. Puvis adds — 

 and, as our author thinks, with reason — that this amount might be doubled 

 without disadvantage. — Ibidem, ii., pp. 248, 249. In some parts of France this 

 quantity is immensely exceeded, and it is very important to observe, with 

 reference to the employment of irrigation in our Northern States, that water 

 is most freely supplied in the colder provinces. Thus, in the Vosges, meadows 

 are literally fiooded for weeks together, and while in the department of Vau- 

 cluse a meadow may receive, in five waterings of six and a half hours each, 

 twenty-one inches of water, in the Vosges it might be deluged for twenty- 

 four hundred hours in six applications, the enormous quantity of thirteen 

 hundred feet of water flowing over it. See the important work of Herte 

 Mangon, Sur I'emploi des eaux dans les Irrigations, chap. ix. 



Boussingault observes that rain-water is vastly more fertilizing than the 

 "water of irrigating canals, and therefore the supply of the latter must be 

 greater. This is explained partly by the different character of the substances 

 held in solution or suspension by the waters of the earth and of the sky, partly 

 by the higher temperature of the latter, and, possibly, partly also by the mode 

 of application — the rain being finely divided in its fall or by striking plants on 

 the ground, river-water flowing in a continuous sheet. 



The temperature of the water is thought even more important than its com- 

 position. The sources which irrigate the viarcite of Lombardy — meadows so 

 fertile that less than an acre furnishes grass for a cow the whole year — are 

 very warm. The ground watered by them never freezes, and a first crop for 

 soiling is cut from it in January or February. The Canal Cavour — which 

 takes its supply chiefly from the Po at Chivasso, fourteen or fifteen miles be- 

 low Turin — furnishes water of much higher fertilizing power than that de- 



