362 



Journal of Agricultural Research 



Vol. V. No. 9 



equally great extent from the 1 8- to 26-day-old sample. Variations in the 

 percentages of potash in the ash of the plant aboveground were for the 

 most part accompanied by similar variations in the ash of the roots. The 

 percentages of soda in the ash seem, as a rule, to fluctuate inversely as 

 the percentages of potash. This is in accord with results showing that 

 soda can to a small extent replace or exercise part of the functions of 

 potash.^ 



In the ash of the roots lime, magnesia, phosphoric acid, and chlorin all 

 decreased fairly regularly with the age of the sample. 



In Table IV are given the percentages of the ash constituents present 

 in the dry matter of the roots and of the whole plant aboveground. 



Table IV. — Ash constitiients in dry substance of the roots and the whole rice plant above- 

 ground 



In the first four samples the percentages of ash in the dry matter of 

 the plant aboveground varied inversely as the percentages of dry matter 

 in the green plant, and, as noted above, the percentages of dry matter 

 seemed to be lower during the periods of greater precipitation. Thus, 

 with dry weather preceding the sample, the percentage of dry matter in 

 the green plant was high and the percentage of ash low.^ An average 

 of several crops of rice growTi at different times to eliminate the effect of 

 temporary weather conditions would doubtless show gradually increasing 

 percentages of dry matter in the green plant and gradually decreasing 

 percentages of total ash in the dry matter. 



I.Theil: Die Stickstoffdiingung 

 . Agr. Exp. 



1 Wagner, Paul. Forschungen auf dem Gebiete der Pflanzenernahrung. 

 der Landwirthschaftlichen Kulturpflanzen. p. 231, Berlin, 1892. 



Hartwell, B. L., and Pember, F. R. Sodium as a partial substitute for potassium. In R. 

 Sta. 2ist Ann. Rpt., 1907-1908, p. 243-247. 1908. 



2 This is probably owing to the fact that during wet weather the growth of new leaves and tissues is 

 especially active, while in dry weather organic matter is formed more rapidly than mineral matter is 

 absorbed. 



