IRRIGATION BY FLOODING AND FURROWS 231 



Avoids necessity of tearing up the crop to form large 

 irrigation furrows. 



The objections to its use are: (1) The large amount 

 of water required. (2) The danger of over-irrigation, 

 with the possible consequent injury from seepage, 

 and the appearance of alkali salts. (3) The impossi- 

 bility of conserving water by appropriate cultivation. 

 (4) On heavy soils possible injury from the crusting 

 and checking of the surface soil as a result of the lack 

 of tillage. (5) Direct injury from flooding some crops, 

 as the potato. 



104. Furrows. Furrow distribution, by which, as 

 the name implies, the water is not applied to the whole 

 surface but is distributed in furrows. The length, size 

 and arrangement of these depends directly on the 

 soil, chiefly its texture. This includes the subsoil as well 

 as the soil. In soils which are porous or easity eroded, 

 the furrows must be shorter than where the opposite 

 9onditio"ns prevail, in order that the water may reach 

 the further end of the field before over-wetting the por- 

 tion near the head ditch. That is, in loose, porous soil, 

 head or feeder ditches must be nearer together than on 

 dense, impervious soil. 



The furrow system is adapted to all intertilled crops. 

 Next to the flooding system, it is used on the largest 

 area, and is adapted to all intensively cultivated crops. 

 Its advantages are that: (1) It conserves water. (2) 

 It is especially adapted to inter-tilled crops. (3) It- 

 permits the conservation of water by appropriate cul- 

 tural practices. (4) It avoids injury to crops sensitive 

 to an excess of water. Water should not come in contact 



