Report of Experiments on the Growth of Wlieat. 139 
was not so great as in some other seasons. Thus, though in no 
preceding year had the produce obtained by the mixed mineral 
manure and the excessive amount of 800 lbs. of ammonia-salts 
exceeded 50 bushels of dressed corn per acre, that obtained in 
1863 by the mixed mineral manure and only 400 lbs. of ammonia- 
salts was about 53;| bushels, of lbs. weight per bushel ; whilst 
the mixed mineral manure with 600 lbs. of ammonia-salts, gave 
scarcely 55^ bushels, and with 800 lbs. scarcely 56 bushels. 
Extraordinary as are these amounts of produce, even for good 
wheat-land cultivated and manured in the ordinary way, they are 
still more remarkable for the 20th crop of wheat in succession 
on land of only average wheat-producing quality, which has not 
been manured with farmyard manure for j ust a quarter of a cen- 
tury. Nevertheless, there can be no doubt that if the heavier 
crops had not been so much laid they would have yielded even 
considerably more. That they did not do so, in a season upon 
the whole so favourable for the effect of liberal nitrogenous 
manuring, shows that the higher amounts of ammonia-salts em- 
ployed were not only excessive for average, but even for un- 
usually favourable seasons. 
In conclusion, in regard to these results, it should be observed 
that whilst the mixed mineral manure and ammonia-salts yielded 
as much as 55.2 bushels of dressed corn, and 6866 lbs. of straw, 
the same mixed mineral-manure, when used alone, gave scarcely 
19f bushels of dressed corn, and only 1728 lbs. of straw. There 
was an increase, therefore, due to the action of ammonia-salts, 
of 36 bushels of dressed corn, and 5138 lbs. of straw. In this 
fact there is surely striking confirmation of the utter inade- 
quacy of mineral-manures alone to enable the wheat-plant to 
obtain from the atmosphere a sufficiency of nitrogen for the pro- 
duction of full crops. 
No idea is more fixed and prevalent in the farmer's mind than 
that, after all his labour and money have been expended, he is 
still at the mercy of the seasons for his reward. The fore- 
going short abstracts of the results obtained in different seasons, 
with the few comments made upon them, supply very interesting 
evidence relating to this point ; and Tables XXII. — XXVI., in- 
clusive, in the Appendix, afford the means of studying the subject 
in much more detail. But the extent of this dependence upon 
season will be made more strikingly manifest, by placing side 
by side, at one view, the results obtained by one and the same 
description and amount of manure in the least favourable, and 
in the most favourable of the last twelve seasons, during Avhich 
