Report of Experiments on the Growth of Wheat. 481 
Average Annual Produce on Plots 15a, \bb, and li). 
Several incidental points were sought to be determined by this 
series. 
During the whole 12 years, and for several years previously, 
each plot received, respectively, the same manure year after year. 
All had the same amount of bone-ash as in the so-called mixed 
mineral manure, but acted upon by hydrochloric instead of sul- 
phuric acid. Plots 15a, and 15i, had also the same amounts 
of sulphates of potass, soda, and magnesia as in the mixed 
mineral manure, but plot 19 had none of these. Further, 15a 
had also annually 400 lbs. of sulphate of ammonia, and plots \bb 
and X% 300 lbs. sulphate of ammonia and 500 lbs. rapecake. 
The object of substituting 400 lbs. of sulphate of ammonia, as 
on plot 15a, by 300 lbs. of sulphate of ammonia and 500 lbs. of 
rapecake on 15& and 19, was to supply nearly the same amount 
of nitrogen in the three cases, with in the two latter a certain 
amount of organic matter in addition, yielding by decomposition 
carbon in an available form to the plant. The amount of rape- 
cake used would, in fact, contain rather more nitrogen than the 
sulphate of ammonia it substituted ; but, owing to the compara- 
tively slow action of the rapecake, there would probably be not 
more annually available until after some years of accumulation. 
The rapecake would, of course, also supply a certain amount of 
mineral constituents. Upon the whole, then, it might be ex- 
pected that, independently of its superiority or otherwise as 
supplying carbon-yielding matter, the 500 lbs. of rapecake used 
year after year would be somewhat more effective than the 
100 lbs. sulphate of ammonia which it substituted. 
The effects of these several combinations will be best tested by 
comparing the results with those of plots 7. The only material 
difference between the manuring of the latter and that of 15a 
was, that in the manure of 15a the bone-ash was acted upon by 
hydrochloric acid instead of sulphuric acid, and there was about 
8 per cent, or about one-twelfth less ammonia. The result was 
an average of rather more than 3 bushels of dressed corn, and of 
417 lbs. = about 3f cwts. of straw, less than on plots 7. About 
one-half of this deficiency may be attributed to the less amount 
of ammonia supplied, the remainder only being due to the less 
effective condition of the bone-ash acted upon by hydrochloric 
instead of sulphuric acid. 
Plot 15&, manured exactly as 15a, excepting that 100 lbs. of 
the sulphate of ammonia was replaced by 500 lbs. of rapecake, 
gave more nearly the amount of produce of plots 7, yielding 
If bushel of dressed corn, and rather more than 2 cwts. of straw, 
more than 15a, though still 1\ bushel of corn and 184 lbs. of 
