92 AMERICAN WHEAT AND CORN. 



it, but the lowest is on plot 10#, where it is the most exhausted. The 

 straic ashes also show a higher percentage of potash in the two better 

 seasons. 



17. With decline in the percentage of phosphoric acid in the ashes 

 there is increase in sulphuric acid, and in the straw ashes increase of 

 chlorine in a greater degree. It is a question how far the small amounts 

 of sulphuric acid and chlorine in the grain ashes are due to the pres- 

 ence of so much acid phosphate, and how far the much larger amounts 

 in the straw ashes are due to their, excess of base to acid other than 

 silica, although of this there is so much. 



18. Calculated per 1,000 dry substance of the grain, there is, with every 

 condition as to manuring, a higher amount of potash in 1858, and almost 

 without exception in 1863, than in the two unfavorable seasons. On 

 the other hand, the proportion of phosphoric acid is in 1858 almost 

 without exception, and in 1863 without exception, lower than in the 

 unfavorable seasons. 



19. The second series of analyses, as did the first, consistently show 

 considerable variation in the mineral composition of wheat grain, ac- 

 cording to season, but little according to manuring (excepting in cases 

 of abnormal exhaustion), provided the seed be properly matured. In 

 fact, variations in the mineral composition are associated with differ- 

 ences in the organic composition. 



THIRD SERIES OF ANALYSES. 



1. This series was more especially arranged to trace the influence of 

 supply or exhaustion. The ashes represent the produce obtained under 

 ten different conditions as to manuring, each over ten years, 1852-1861 r 

 and ten years, 1862-1871. Nine of the plots are substantially dupli- 

 cates of those to which series two relates j and the tenth, 106, is a dupli- 

 cate of 10a, with ammonium-salts alone, excepting that twice prior to 

 the period now under consideration it received mineral manure, includ- 

 ing potash and phosphoric acid, when 10a did not. 



2. The average results per acre, of the ten plots, for each of the twa 

 periods, show that the first ten years were on the average the more 

 favorable for luxuriance, that is, for total accumulation by the plant r 

 and the second ten the more favorable for seed formation and matura- 

 tion. Accordingly, with less mineral matter in the total produce per 

 acre over the second ten years, there was as much or more of almost 

 every individual ash constituent accumulated in the grain. 



3. With each condition of manuring where the nitrogen supply was 

 not deficient, there was more grain, and of better quality, over the sec- 

 ond ten years. Comparing plot with plot, there was over both periods, 

 with equal nitrogen supply, considerable increase by the addition of 

 superphosphate and potash. Comparing the second period with the 

 first, the influence of supply or exhaustion, especially of potash, is very 

 marked (100, 106, 116, 126, 146, 136, and 76). 



