ALFALFA 133 



tance too near the surface, the best crops by far are 

 usually grown on irrigated lands. This arises, first, 

 from the ability to adjust the supplies of water to 

 meet the needs of the plants, and second, from the 

 congenial character of the soil and subsoil. Next 

 to these the best crops are grown where congenial 

 soils are underlaid with ground water, not too near 

 nor too distant from the surface. On these soils the 

 plants are largely supplied with moisture from the 

 water below ascending on the principle of capillary 

 attraction. How near or how distant such water 

 should be will depend somewhat on subsoil condi- 

 tions. It would seem correct to say that it ought 

 never to come nearer to the surface than 3 feet, nor 

 should it be more than 20 feet down. The most suit- 

 able distance would be, say, 8 to 16 feet. When the 

 roots of alfalfa reach water at too short a depth they 

 will die. 



Alfalfa may sometimes be grown satisfactorily on 

 soils subject to overflow, but usually there is hazard 

 in growing it on these. If the overflow occurs com- 

 paratively early in the season, if it is not of great 

 depth, if it is of short duration, and if the waters 

 quickly drain out of the subsoil possessed by the al- 

 falfa, it may receive little or no harm from such 

 overflow. Instances are on record wherein ice has 

 formed on alfalfa and yet the plants survived, but 

 such a condition will usually prove fatal to them. 

 But should the overflow take place in hot weather, 

 . usually it will injure the plants seriously, and may, 

 indeed, completely destroy them. So great is such 

 hazard, that care must be taken against the applica- 



