94 AMERICAN WHEAT AND CORN. 



10. With higher percentages of potash in the grain ashes over the 

 second period, there are also higher percentages of lime, and there is a 

 tendency to higher percentages of magnesia ; but there is in every case, 

 excepting without manure, a lower percentage of phosphoric acid, and 

 with this, in every case but one, a higher percentage of sulphuric acid 

 over the second period. 



11. Per 1,000 dry substance of the grain there is generally a lower 

 amount of each ash constituent (excepting lime and sulphuric acid) 

 over the later and better seed-forming and maturing period ; there is- 

 also a lower amount of nitrogen, and, therefore, a higher proportion of 

 non-nitrogenous constituents. Comparing plot with plot, the amounts of 

 potash per 1,000 dry substance of the grain are fairly uniform, but even 

 in the grain, and in the straw in a much more marked degree, it is low- 

 est where it is the most exhausted. Comparing plots 126, 136, 146, and 

 76, the amounts per 1,000 dry substance of the grain are over the first 

 period 6.46, 6.43, 6.41, and 6.53, and over the second period 6.14, 6.22, 

 6.16, and 6.33; but in the straw they are over the first period 10.54 r 

 12.90, 11.65, and 12.84, and over the second period, with the increasing 

 exhaustion on the first and third plots, 9.14, 13.29, 9.55, and 12.58. 



12. The amounts of phosphoric acid per 1,000 dry substance of the 

 grain varied more according to supply than did that of the potash; but 

 it was, with every condition of manuring, lower over the second and 

 more favorable period. Over the first period it ranged from 8.70 to 10.87 r 

 and over the second period from 7.89 to 10.35. On Plots 126, 136, 146, and 

 76 it was, over the first period, 10.05, 10.05, 10.15, and 10.12, and over 

 the second period 9.21, 9.31, 9.38, and 9.49, or much lower over The sec- 

 ond period, but within each period almost uniform on the four plots. 

 Taking the whole series of plots, it was the lowest on 10a and 106, where 

 it was most exhausted; but it was also low on 116, where it was annually 

 supplied, though without potash, and with defective development ac- 

 cordingly. 



13. The results of the third series of analyses agree with those of the 

 first and second in showing, upon the whole, marked uniformity in the 

 mineral composition of the ripened grain, even when there is wide vari- 

 ation in that of the straw dependent on supply or exhaustion. They 

 also show distinct influence of season, and that the differences in the 

 mineral composition of the grain due to season are associated with dif- 

 ferences in the organic composition. With less variation in the condi- 

 tions of season, and of influence therefrom, but with a wider range of 

 mineral supply or exhaustion than in the other series, there is a wider 

 range in the mineral composition of the grain, according to supply or 

 exhaustion ; it is, however, comparatively little influenced by excess of 

 supply, but more by deficiency. The three series show that, under 

 otherwise comparable conditions, there is, in the better matured grain, 

 that is, in the grain of higher quality, a lower percentage of total min- 

 eral matter (ash) ; in the ash, a higher percentage of potash, but lower 



