72 AMERICAN AGRICULTURE. 



proper guide in this, as in most of the operations of the 

 fanner ; and it will be seen how careful she is in ordinary 

 seasons, to provide an affluence of rains for the commence- 

 ment of vegetation, while she as carefully withholds them 

 when it approaches maturity. After the grass is cut, the 

 water may be again let on to flood the meadows. Pastures 

 may be irrigated at proper intervals, throughout the year. 



THE MANNER OF IRRIGATING. This must depend on the 

 situation of the surface and the supply of water. Sometimes 

 reservoirs are made for its reception from rains or inunda- 

 tions, and sometimes they are collected at vast expense from 

 springs found by deep excavations, and led out by extensive 

 subterraneous ditching. The usual source of supply however, 

 is from streams or rivulets, or copious springs which dis- 

 charge their water on elevated ground. The former are 

 clammed up to turn the water into ditches or aqueducts, 

 through which it is conducted to the fields where it is divided 

 into smaller rills till it finally disappears. When it is desira- 

 ble to bring more water on to meadows than is required 

 for saturating the ground, and its escape to fields below is to 

 be avoided, other ditches should be made on the lower sides, 

 to arrest and convey away the surplus water. 



The advantages of irrigation are so manifest, that they 

 should never be neglected when the means for securing them 

 are within economical reach. To determine what economy 

 in this case is, we have to estimate from careful experiment, 

 the equivalent needed in annual dressing with manures to 

 produce the same amount of grass as would be gained by irri- 

 gation ; and to offset the cost of the manure, we must reckon 

 the interest on the permanent fixtures of dam, sluices, &c., 

 and the annual expense of attention and repair. 



The quality of grass fr&m irrigated meadows is but slightly 

 infrior to to that grown upon dry soils ; and for pasturage it 

 is found that animals do better in dry seasons upon the former, 

 and in wet upon the latter. In Europe, where the disease in 

 common, sheep are more liable to rot upon irrigated and 

 i arshy 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- 

 lited by irrigation. Tenacious and clay soils arc but slightly 

 improved by it unless first made porous by* underdrainins. 

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



