250 SOILS: PROPSETISS AND MANAGEMENT 



economic use of water, as the plant, in order to supply 

 itself properly with food, must transpire excessive amounts 

 of water. As soil moisture may be controlled, this waste 

 may to a certain extent be eliminated. 



172. The influence of fertility on transpiration. — The 

 amount of available plant-food is also concerned in the 

 economic utilization of water. In general the data along 

 these lines show that the richer the soil, the lower is the 

 transpiration ratio. Therefore a farmer, in raising the 

 general fertihty of his soil by drainage, lime, good tillage, 

 green manures, barnyard manures, and fertilizers, provides 

 at the same time for a greater amount of plant production 

 for every unit of water utihzed. Again, quoting from 

 Hellriegel and Montgomery, the following figures are 

 available : — 



Effect op the Supply of Plan-t-pood Materials on the 

 Teanspiration Ratio op Barldy grown in Quartz Sand 

 with a Nutrient Solution; Calcium Nitrate being in 

 the Minimum. Hellriegel ^ 



Units 2 of Ca(N0s)2 

 Applied 



Dry Mattek Produced 

 PEE Pot (Grams) 



Tkanspieation Ratio 







4 



8 



12 



16 



20 



1,111 

 8,479 

 13,936 

 18,288 

 23,026 

 25,504 



724 

 399 

 347 

 345 

 302 

 292 



^ Hellriegel, H. Beitrage zu den Natiirwissenseliaftlielieii 

 Grundlage des Aekerbaus, p. 629. Brauiiseh-weig. 1883. 



2 A unit of Ca(N03)2 ectuals 1 mg.-ecLuivalent. A mg.- 

 equivalent of Ca(N08)2 equals 82.1 mg. 



