PLANTS AND WATER 



43 



with cattle. In dry seasons this part is injured by 

 drought, and finally becomes entirely unproductive a 

 month sooner than does the cultivated abaca on poorer 



ground. 



IRRIGATION 



In spite of excellent 



Various Methods. In spite of excellent cultivation, 

 some lands are so dry, and some crops so dependent on 



u;. 32. Arid land in western America before irrigation 



water, that their profitable cultivation depends on irriga- 

 tion. There are various ways of putting water on land: 

 by hand, by windmills, by engines, and by gravity. 

 Human labor can be used only where a valuable crop 

 can be raised on a little ground, especially in gardens. 

 In these, the water should be put on the ground in the 

 late afternoon. \Yindmills, too, are used only for irriga- 

 tion on a small scale, raising crops so valuable that a 

 man needs but little land. Steam pumps are used in the 

 United States to irrigate great rice fields ; but in the 



