354 Report of Experiments on the GrowtJi of Barley, 
they did not ; yet, there was so little difference in the subse- 
quent produce of barley on the different mineral-manured plots, 
that only the average of all is given in each case in the Table, 
For comparison with the produce of barley after turnips, 
there is also given in the top line of each division of the Table 
XLVllI. (p. 355), that without manure in the same seasons 
(which were the second, third, and fourth of the 20), in the field 
in Avhich the crop has now been grown for so many years in 
succession. 
The figures show that, over the three years, there were ob- 
tained after the mineral-manured turnips, an average of only 20 
bushels of barley grain, and not quite 12 cwts. of straw, per 
acre per annum ; or not two-thirds as much as without manure 
after barley, clover, wheat, barley, and barley, in the same seasons, 
in the field in which the crop is now being grown continuously. 
■ If, as has been maintained on high authority, the increased 
produce of corn which is obtained in rotation, is due to the 
accumulation, or elaboration, during the growth of other crops, of 
the mineral constituents required for the corn, it might surely be 
expected that, after a series of mineral-manured turnip-crops, for 
which, on some of the plots, more of every mineral constituent 
was supplied in the manure than was taken off in the produce, 
we should have full crops of barley. But what are the facts? 
We have after the mineral-manured turnips three perfectly insig- 
nificant barley-crops, and much less than when barley was grown 
after three immediately preceding corn-crops. 
The question arises — in what constituent, or constituents, had 
the mineral-manured turnips so exhausted the soil as to bring 
it into a condition even far worse for the after growth of barley 
than Avhen (after clover) three white straw crops had been 
grown in succession — namely, wheat without manure, barley 
with sulphate of ammonia, and barley without manure ? 
It is seen that where, besides the mineral manures, ammonia- 
salts (experiment 2), rape-cake (experiment 3), and ammonia-salts 
and rape-cake together (experiment 4), were applied annually 
during the first 6 of the last 8 years of turnips, there was more 
produce of barley, both corn and straw, than where the mineral 
manures had been applied alone ; and there was more where 
rape-cake, or ammonia-salts and rape-cake together, were em- 
ployed, than where the ammonia-salts without rape-cake were 
used. The rape-cake not only supplied about twice as much 
nitrogen per acre as the ammonia-salts, but the nitrogen it con- 
tained would exist in a condition both less rapidly available and 
less liable to loss by drainage. The results obtained after the 
mineral-manured turnips (experiment 1) exclude the supposition 
that the increase of produce, where ammonia-salts had also been 
