364 Report of Experiments on the Growth of Barley, 
corn-exhausted condition, was relatively richer in available 
mineral constituents than in available nitrogen. And the 
generally greater effect by nitrogenous and mineral manures 
together, than by farmyard manure — which contained not only 
very much more nitrogen, but a large amount of decomposing 
carbonaceous organic matter, and probably more of every mineral 
constituent than the crop — showed that the nitrogen of the farm- 
yard manure was in a far less rapidly available condition, and 
that its supply of carbon was at any rate unessential. 
It is hardly necessary to add, that the field results with barley, 
equally with those with wheat, are entirely inconsistent with the 
mineral theory so long in controversy, according to which — fer- 
tility was quite independent of the ammonia conveyed to the 
soil ; — if only the necessary mineral constituents were supplied in 
sufficient quantity and in available form, our cultivated plants, 
graminaceous as well as leguminous, would derive sufficient 
ammonia from the atmosphere ; — the presence of ammonia in our 
manures was immaterial ; and — the entire future prospects of 
agriculture depended upon our being able to dispense with 
ammonia in our manures, therefore with animal manures.* 
It is a very remarkable and very significant fact, that not only 
by farmyard manure, but also by artificial manures containing no 
carbon, an average of not far short of 50 bushels of barley-grain 
(or more if reckoned at only 52 lbs. per bushel), and nearly 
30 cwts. of straw, or much more than the average crop of the 
country under rotation, should have been obtained by the growth 
of the crop year after year on the same land for twenty years in 
succession. Not only was such an average obtained over the 
twenty years, but there was even rather more corn, higher quality, 
only little less straw, and nearly identical total produce (corn 
and straw together), over the second compared with the first ten 
years, showing that, hitherto at least, there is practically no ex- 
haustion by the continuous growth of such large crops under 
such conditions of soil and manuring. 
It was with farmyard manure, however, the annual use of 
which has resulted in a very great accumulation within the soil, 
of nitrogen, of carbon, and probably of every mineral constituent 
also, that there has been the greatest increase of produce, and 
especially of corn, over the second as compared with the first ten 
years. On the other hand, without manure, with mineral manure 
alone, and with ammonia-salts alone — that is, with defective soil 
conditions — there was a considerable deficiency of both corn and 
straw over the second half of the period ; the greater deficiency 
the more defective the manuring, and the greater the relative 
* For further remarks on the present position of the mineral theory controversy, 
see pp. 90-91 and 98-100. 
