DRYLAND FARMING. 345 



The amount of water required by tiie plants was lessened 

 as the plant food deficiency was rectified. 



Montgomery, experimenting on Nebraska soils in 1911, 

 obtained the following results with wheat : — 



Transportation ratio. 

 Yielding Capacity. Manured. Unmaimred. 



Poor (15 bushels) 350 549 



Medium (30 bushels) 341 479 



Fertile (50 bushels) 346 392 



The yield on the manured ground was nearly double that 

 obtained on the unmanured soil. Pagnoul, in France, found 

 the transpiration ratio on fescue grass on fertile soil to be 555 

 as against 1,190 on an infertile soil. 



Widstoe, in Utah, obtained the following results with 

 wheat : — 



Transportation ratio. 

 Soil. Not cultivated. Cultivated. 



Fertile sandy loam ... 603 252 



Fertile clayey loam ... 595 528 



Infertile clay 753 582 



Cultivation increases the availability of plant food, and 

 in so doing lessens the transpiration ratio. 



All these experiments indicate that the more fertile the 

 soil the less is the water requirement of crops. They show 

 indirectly the importance of ascertaining soil deficiencies in 

 parts where moisture is limited, since deficiency of one of the 

 essential plant foods will sometimes double the amount of 

 water transpired. 



The economy in the use of moisture effected by the recti- 

 fication of a soil deficiency may in practice be responsible for 

 the difference between good crops and cror> failures. 



Weeds. — Briggs and Shantz obtained the following trans- 

 piration ratios for the various weeds mentioned : — 



Amaranth (A. retrofiexus) ... 

 Pursland (P. oleracea) 

 Gum Weed (Grindelia squ<irrosa) 

 Lamb's Quarters (C. album) 

 Ragweed (A . art emesii folia) 



287 

 292 

 608 

 801 

 948 



