40 



a portion of the year when the amount of moisture 

 present is far below that required for the best 

 growth of plants. Yields are often quartered and 

 halved by a few days or weeks without rainfall at 

 critical periods of growth. 



Irrigation in these regions is coming to be appre- 

 ciated more and more every season, and is being 

 widely adopted by vegetable growers where the 

 intensive methods of cropping make a drouth es- 

 pecially destructive and expensive. It matters not 

 how thoroughly the soil has been prepared, how 

 much manure and commercial fertilizer has been 

 added, how good the seed and how thorough the 

 care has been with reference to cultivation, spray- 

 ing, etc., a few weeks of drouth, during which the 

 plants cannot secure the necessary moisture for 

 growth, may mean heavy losses instead of splendid 

 profits. Some system of irrigation proves an insur- 

 ance against these conditions, and year in and year 

 out eliminates one of the principal factors of loss in 

 commercial gardening. 



King in his various experiments has emphasized 

 the enormous quantity of water required by plants 

 under normal growth conditions. This amounted 

 to 385 pounds of water for each pound of dry matter 

 produced in case of the potato and 576 pounds in 

 the case of clover. While these relations vary from 

 season to season they will suffice to show how 

 important an abundant water supply is in the soil. 

 It is to be remembered also that these amounts are 

 only those that must pass through the plant aside 

 from that naturally lost by direct evaporation from 

 the soil and by surface and underground drainage. 

 It is a great satisfaction for the gardener to realize 

 that he is practically independent of the natural 



