40 THE SOIL OF THE FARM. 



long before the grass throws up a flower stem. When 

 kept for hay, immediately after the grass is cut, the 

 water may be let in as occasion requires, during the 

 drouth of summer ; and pastures may be irrigated from 

 time to time as the weather may demand, throughout the 

 entire season. 



Qmantity of Water Required for Irrigation.— As to 



the quantity of water, it necessarily varies with the 

 nature and condition of the soil, with the character of 

 the subsoil, with the inclination of the surface, and with 

 the crops cultivated. In Italy, it is generally held that 

 the continued discharge of one cubic foot per second 

 during twenty-four hours, is sufficient for the irrigation 

 of four acres of meadow land. Hence, as the total volume 

 discharged in that time amounts to eighty-six thousand 

 four hundred cubic feet, and the area watered to one 

 hundred and seventy-four thousand two hundred and 

 forty square feet, it appears that a stratum of water equal 

 to nearly six inches in depth is in this, case spread over 

 the surface of the meadow. Twelve waterings are given 

 during the season, at intervals of fourteen days. The 

 above calculations assume, however, that the w^hole water 

 is absorbed by the soil, which is never the case. The 

 absorption in each watering in that case probably ranges 

 from half to one-third of the total quantity of water 

 em.ployed. 



In English water-meadows the amount of water poured 

 over the land far exceeds this amount ; and the best effect, 

 when the water itself brings not only warmth but food, 

 is obtained where there is a continually moving thin layer 

 of water over the wdiole surface in addition to the quan- 

 tity which passes through the substance of the land to 

 the drains in the subsoil. 



SewasfC Irrigation, by Avhich the greatest luxuriance 



