SOIL CONDITIONS AFFECTING PLANT GRO WTH 49 



Similar results have been obtained by Wilfarth (Table XL), 

 (309a) with sugar beets grown in pots of soil containing known 

 but varying amounts of nitrate. 



Table XI. 



-Effect of Varying Food Supply on the Water Require- 

 ments OF Sugar Beet. Wilfarth. 



10 



50 



40 



20 

 Water applied. 



Fig. 8. — Effect of water supply on the effectiveness of farmyard manure. 

 Yield of maize (stover and grain) in tons per acre for o to 40 inches irrigation 

 water. (Harris and Butt, Utah, 123.) 



Two deductions may be drawn: (l) water is economised 

 by increasing the food supply ; (2) the total amount of water 

 required during the growing season may be greater than is 

 supplied by the rain, in which case the balance must be 

 otherwise provided, or the food cannot be utilised. 



4 



