88 DRY FARMING 



when this soil was manured only 613 pounds were re- 

 quired, and (3) that when commercial fertilizers were 

 applied only 585 pounds of water were necessary to pro- 

 duce a pound of dry matter. Similarly he found that 

 *'on sandy loam, not cultivated, 603 pounds of water 

 were transpired to produce one pound of dry matter in 

 corn ; on the same soil, cultivated, only 252 pounds were 

 required. On a clay loam, not cultivated, 535 pounds 

 of water were transpired for each pound of dry matter, 

 whereas on the cultivated soil only 428 pounds were 

 necessary. On a clay soil, not cultivated, 753 pounds of 

 water were transpired for each pound of dry matter; 

 on cultivated soil, only 582 pounds/^ 



While our soils are new and rich an average rainfall 

 will generally produce a fair yield. As soon as they be- 

 come less "fertile" the same amount of rain is likely to 

 produce a smaller crop. The results of theses investi- 

 gations clearly show that the more fertile a soil is, the 

 greater yield it will produce from a given supply of 

 moisture. This is one reason why dry farmers should 

 strive to maintain the "fertility" of their soils. 



