Experiments with different Top-dressings upon Wheat. 387 
experience of practical men affords certain useful indications to 
the scientific observer, but nothing more. In the absence of 
clear, unmistakeable, and sufficiently extensive practical evidence, 
no definite answer can be given to the question so frequently 
addressed to the agricultural chemist, Shall I apply nitrate of 
soda or guano upon my wheat? 
We do not know, even in a general way, the comparative 
efficacy of nitrates and of ammoniacal manures : how is it 
possible, I would ask, to answer such a question in a particular 
instance ? The importance of this question will be admitted by 
every one, especially at a time when the price of corn is low, and 
that of Peruvian guano high. Extensive deposits of nitrates of 
potash and soda are more likely to be discovered when diligent 
search is made after them than new and extensive deposits of 
guano equal to, or approaching in efficacy, Peruvian. Apart 
from the theoretical aspect, the question as to the relative merits 
of nitrogen in the shape of nitric acid or ammonia is of great 
practical interest. Fully impressed with the importance of 
this subject, I have undertaken, at the request of the Council of 
the Royal Agricultural Society, a series of field experiments 
with top-dressings upon wheat, and have now the pleasure of 
laying before the members of the Society the results of a series 
of experiments made last season (1859). Similar experiments I 
hope to continue from year to year ; for the longer I am engaged 
in carrying out experimental trials in the field, the more I am 
convinced that the experience derived from one, two, or three 
years' experimenting in the field is alike inadequate to further 
the progress of scientific agriculture, and to supply the farmer 
with information from which he can derive practical advantage. 
The time has arrived when an extension of field experiments 
is imperatively demanded. Practical experiments should be 
instituted in all parts of the countr}-, and tried on every descrip- 
tion of soil, and under the most varied conditions. They should 
be conceived in a philosophical spirit, and carried out with that 
accuracy and love of truth which ought, and generally does, cha- 
racterize the labours of the student of natural science. Mere 
random trials, made without plan or definite object in view, are 
only calculated to lead astray, and thus do more harm than good. 
Unfortunately, success in a field experiment cannot be always 
secured : the disturbing influences which spoil the result are 
numerous and frequently uncontrollable ; and, as the labour, 
anxiety, and expense which attend field experiments are very 
great, it can hardly be expected that many agriculturists will 
engage in this work. After having gone to the trouble of pre- 
paring and measuring out the land, selecting the seed, procuring 
and weighing out the various fertilizers intended for trial, after 
having them analysed and taken notes from day to day of the 
2 c 2 
