THE FREE AVATER OF* THE SOIL. 



21.1 



The waterings were made simultaneously at tbemonient 

 when all the Avater previously given to No. 1 was Ab- 

 sorbed by the soil. During the 67 days of the experi- 

 ment the plants were watered 17 times. The subjoined 

 table gives the results : 



The experiment demonstrates that the quantity of 

 Water supplied to a plant has a decided effect upon the 

 yield. Pot No. 2 was most favorably situated in this re- 

 spect. No. 1 had a sni-plus of Avater and the other pots 

 received too little. The experiment does not teach what 

 proportion of water in the soil was most advantageous, 

 for neither the weight of tlie soil nor the size of the pot 

 is mentioned. 



Hellriegel {Chem. Acker smann, 1868, p. 15) experiment- 

 ed with wheat, rye, and oats, in a pure sand mixed with a 

 sufficiency of plant-food. The sand when saturated with 

 water contained 25° l„ of the liquid. The following table 

 gives further particulars of his experiments and the re- 

 sults. The weights are grams. 



In each case the proportion of water in the soil was 

 preserved Avithin the limits given in the first column of 

 the table, throughout the entire period of growth. It is 

 seen that in this sandy soil 10-15 per cent of water ena- 



