THE WATER-COST OF DRY MATTER 



147 



quantities of water and on a deep fertile soil, are shown 

 for four of the standard crops. The results are averages 

 of a large number of experiments, and may be accepted 

 as being tolerably accurate for the climate of the inter- 

 mountain region. 



YIELDS OP DRY MATTER IN POUNDS PER ACRE WITH VARYING 

 QUANTITIES OF WATER 



*45 inches. 



An examination of the above table will show that as 

 the quantity of irrigation water was increased throughout 

 the season, the yield of wheat increased without inter- 

 ruption; the corn increased up to 30 inches, but fell at 

 55 inches; the sugar beets and the potatoes increased 

 without interruption. This is in accordance with the law 

 above stated that, as water is increased the general ten- 

 dency of the yield of crops is to increase. The soil was deep 

 and porous, into which even very large quantities of water 

 sank to great depths. Thus, the soil was never over- 

 saturated, but with large irrigations the soil-water film 

 continued longer to be of maximum thickness than with 

 small irrigations. Even under these favorable conditions, 

 the yield of corn diminished after 30 inches of water had 



