HOW PLANTS AMU INFLUENCED 



343 



irrigate, we may hope to control very largely both the 

 quantity and quality of the crop. At present there is 

 so much confusion in this regard that we may find one 

 farmer using several times as much water as his neigh- 

 bor for the same kind of crop grown under the same 



198. Gorse: (a) leafy form, the result of growing in a saturated atmosphere, 

 (6) normal (leafless) form, the branches transformed to spines. 



gene^-al conditions. In general, crops cannot be grown 

 to advantage when the soil contains more than 50 to 

 60 per cent of the total amount it is capable of hold- 

 ing. The study of irrigation is bound to be of 

 increasing importance, since it is becoming evident 

 that it will pay to irrigate, even in regions where the 

 rainfall is now ordinarily regarded as amply sufficient 

 for crops (see pages 130 and 131). 



