167 
Joseph Harris, in his Prize Essay in the Transactions of the New York 
Agricultural Society, given also in the Patent Office Report for 1852-3, 
gives the results of some experiments, one of which we quote :—“ It is 
seen that in 1844 with mineral manures and no ammonia (of course by 
this he means no azotized manure as plants do unquestionably assimilate 
ammonia in a limited degree from rain water) the increase of grain over 
the unmanured plot is less than one bushel and no increase of straw, 
while for the next five consecutive years when ammonia was supplied and 
no minerals, there is an average increase of ten bushels per acre and 
about as much again straw.” * * Can any one after carefully study¬ 
ing the above results avoid concluding that ammonia is ‘the one thing 
needful’ for the growth of wheat in agricultural quantity ?” 
John Bennet Lawes, in an Essay published by the Royal Agricul¬ 
tural Society of England, (see Patent Office Report, 1847, p. 221,) 
written in opposition to the well known views of Liebig, says, in regard 
to this question :—“ It affects the whole economy of cultivation, and the 
final solution of it must very materially influence the action of all prac¬ 
tical agriculturists. With regard to the most important crop (wheat) 
my own experiments are so decisive, and through the whole series the 
results are so uniform, that it is hardly possible to have two opinions on 
the subject, and what is still more, they are in accordance with the dic¬ 
tates of reason and the practical experience of agriculture. The absolute 
necessity of supplying nitrogen to enable the soil to produce more wheat 
than it could do in a natural state, is so apparent throughout this series 
of experiments, that it is difficult to entertain the slightest doubt upon 
this subject.” He then adds the following paragraph, showing precisely 
what is the proper action of mineral manures :—“ The various contra¬ 
dictory results obtained by the application of mineral manures to wheat 
are completely accounted for, when it is known that they only increase 
the produce in proportion to the available azotized matter existing in the 
soil.” 
Hence taking this principle for granted, which can be done quite safely 
we think, from the above evidence, we have an easy test of the value of 
> * 
manures, and a sure guide in our investigations. 
[Note.— There is also another point which it may be well to notice in th ; s 
connection—the nitrification of soils. Baron Liebig maintains that it io*duo to 
