180 IEBIGATION. 



ferable to any other method of applying water. All cul- 

 tivated crops should therefore be sown or planted in drills. 

 Any crops, that may be grown in ordinary cultivation, 

 may be raised by irrigation, but there are some that 

 flourish better under it than under ordinary culture. 

 These are generally the broad-leafed crops, leguminous 

 plants, and the grasses cultivated for fodder. Long tap- 

 rooted plants, clover, lucern, carrots, all species of beets, 

 and the cabbage tribe, especially thrive under irrigation. 

 Cereals generally need but very little water after their in- 

 florescence, and the quality of the grain is improved by 

 its absence after fertilization has taken place. It is 

 asserted by the French irrigators that the wheat crop is 

 frequently injured by any watering at the time of blos- 

 soming, and that at this critical season the water should 

 be withdrawn, and again applied, for only a very short 

 period, as the grain is swelling. Potatoes are injured in 

 quality by overwatering, and for this crop a soil of reten- 

 tive character should be specially avoided. The satura- 

 tion of the subsoil, during the period when the soil is 

 bare of crops, as in the Fall and Winter, not only aids 

 the Summer growth by furnishing a reservoir of moisture, 

 but irrigation at these seasons brings to the soil consider- 

 able access of fertility, especially when the water is deriv- 

 ed from mountain streams. On the other hand, when 

 the subsoil is strongly alkaline, as in some localities, con- 

 tinuous and copious Winter irrigation will remove much 

 of the excess of alkaline salts ; but alternate irrigation 

 will not have this effect, for much of the alkaline matter 

 will be brought back near the surface by capillary at- 

 traction. 



There are large tracts of land, the subsoil of which is 

 so thoroughly impregnated with alkali, as to render the 

 surface hopelessly barren, except so far as they may bear 

 a sparse vegetation of plants, the roots of which remain 

 near the surface, and the quality of which unfits them 



