284 Report of Experiments on the Growth of Barley, 
ment will show in what degree the accumulated residue from 
the previous manuring is effective for succeeding crops ; and the 
effects of the different artificial manures now to be considered, 
will show to what constituents of the dung the increase of pro- 
duce it has yielded has most probably been mainly due. 
Average Annual Produce by purely Mineral Manure. 
Under this head attention will chiefly be directed to the results 
obtained on the plots, and by the manures, as under : — 
Plot 2 O — Superphosphate of Lime. 
Plots O — "Mixed Alkali-salts" — a mixture of sulphates of 
Potass, Soda, and Magnesia. 
Plot 4 O — " Mixed Mineral Manure " — a mixture of the " Su- 
perphosphate of Lime," and the " mixed Alkali-salts." 
Table XXIX. shows the average annual produce and increase 
by these manures. (See next page.) 
The first point to remark is that, as without manure and with 
farmyard manure, so with these purely mineral manures, the 
weight per bushel of dressed corn is, in each case, considerably 
higher over the second than over the first 10 years. The propor- 
tion of corn to straw is also higher over the later years. This 
result is doubtless in great measure due to season. Still it is 
clear that in these points of quality there is no deterioration in 
the crop. 
In point of quantity, however, the result is very different. 
There is, with each of the manures, a very considerable falling 
off in the average annual amount of corn, of straw, and of total 
produce, over the second as compared with the first 10 years ; 
and rather more where the salts of potass, soda, and magnesia, are 
used, whether alone or in admixture with superphosphate, than 
where the superphosphate is used alone. Where the superphos- 
phate and mixed alkali-salts are used together, the greater falling 
off in the later as compared with the earlier years would seem to 
be connected with a higher produce by that manure than by the 
superphosphate alone in the earlier years ; whilst, in the later 
years, the produce by the two manures approximates more closely. 
Lastly on this point, the average annual increase over the unma- 
nured produce is not, by either manure, widely different over the 
two periods ; but where the superphosphate and the mixed alkali- 
salts are each used separately, the increase is rather greater, and 
where they are used together rather less, over the second 10 
years — indicating a slightly less rate of decline than without 
manure with the two former, and a slightly greater decline with 
the more complete manure — accounted for by its proportionally 
greater increase over the earlier years. 
