Nov. 29, 191S 



Ash Composition of Upland Rice 



363 



On account of the fluctuations in the amount of total ash, it is thought 

 that the percentages of the various ash constituents in the dry matter 

 are less significant than the composition of the ash, which would be un- 

 affected by temporary weather conditions. 



The plants were not analyzed at frequent interv^als while ripening; 

 nevertheless, the preceding work throws some light on the question of 

 loss of mineral elements at this time. In Table V are given the absolute 

 weights of the ash constituents in one plant at 103 and at 123 days. 



Table V. — Gain or loss of ash constituents by the rice plant aboveground during last 

 20 days of growth 



It is evident that the aboveground part of the plant lost considerable 

 soda between the last two periods. The roots also must have lost con- 

 siderable soda, as the percentage of soda in the dry matter of the roots 

 dropped from 0.36 per cent at 103 days to 0.07 per cent at 123 days, 

 while the absolute weight of roots could have increased but little during 

 this interval. The results do not show whether there was any loss of the 

 remaining ash constituents. It is only apparent that, as compared with 

 103 days, the plant aboveground contained at 123 days the same or a 

 slightly greater quantity of all ash constituents except soda. It is, of 

 course, possible that between 103 and 123 days there might have been an 

 increase followed by a loss of the other ash constituents. The marked loss 

 of soda was more than compensated for by a gain in potash. The in- 

 creases in the other elements were relatively slight, and the apparent losses 

 of lime and phosphoric acid are without significance when the probable 

 errors of the weights of the plant at the two periods are considered. 



DISCUSSION OF RESULTS 



It is unnecessary to detail all the changes in ash composition that 

 occurred during the growth of the plant, as these are evident in the tables. 

 In common with similar studies of many other plants the percentages 

 of potash, phosphoric acid, and sulphur in the ash and of nitrogen in the 

 dry matter decreased with the age of the plant, while the silica increased. 



The results show that while the iron content of the ash of the whole 

 plant varied but little with the age of the plant, the percentage of iron in 



