Nov. 29, 1915 



Ash Composition of Upland Rice 



36] 



but it was impossible to wash them white. The analyses show that the 

 material which could not be washed off was probably finely divided ferric 

 oxid. The percentages of iron found in the ash of the roots ranged from 

 5.36 to 8.48. This was obviously due to iron contamination from the soil. 

 It was evident, however, that this was a selective contamination chiefly 

 of iron particles, as the ratio of FcjOg to AI2O3 to SiOg in the soil was about 

 I to 1.5 to 6.^ Thus, a contamination of the soil as such which would 

 have increased the iron content 6 per cent would have raised the silica 

 36 per cent and the alumina content 9 per cent. As the high iron content 

 of the root ash is thought to be due to selective contamination from the 

 soil, the results for iron are not reported. The percentages of the other 

 constituents, except possibly silica, could not have been materially 

 affected by soil contamination. 



Table III. — Ash composition of the roots and of the whole rice plant aboveground 



The percentages of iron in the ash of the whole plant aboveground 

 showed but little variation after the sharp drop from the 18- to the 26- 

 day-old sample. 



Leaving out of consideration the 123-day-old sample, the composition 

 of which was probably influenced appreciably by the leaching of rain, it 

 can be seen that during the growth of the plant the percentages of lime 

 and magnesia in the ash tended to remain constant, the silica increased, 

 the phosphoric acid and sulphuric acid decreased, the potash, somewhat 

 irregular, tended to decrease, and the soda was irregular. The variations 

 in the percentages of soda are somewhat peculiar, the increase from the 

 18- to 26-day-old sample being out of all proportion to changes in other 

 constituents. Soda in the ash of the roots, however, increased to an 



' Iron is much higher in the finer soil separates than in the coarser. (Failyer, G. H., Smith, J. G., and 

 Wade, H. R. The mineral composition of soil particles. U. S. Dept. Agr. Bur. Soils Bui. 54, 36 p. 1908.) 



