Experiments on the Growth of Wheat. 
21& 
It is seen in the Tables that the experiments have already 
extended over four seasons, namely, 1851-2-3-4. And althoujjh, 
owing to the variable effects of climatic ajrencies according to the 
nature of the manurial matters in the soil, and the stage or ten- 
dency of growth of the plant depending on it, and to the little 
that has yet been accomplished towards reducing the results of 
these complex influences within the rule and measure of calcula- 
tion, it is highly important that such experiments should be con- 
ducted through a considerable series of years, so as to get a fair 
average, and thus to exclude the influence both of recent accu- 
mulati(ms in the soil, and of the climate of individual seasons — 
nevertheless, the results of these first four seasons are of very 
considerable interest. And they can hardly fail to afford further 
proof to the practical farmer as to what are the constituents which, 
in the general course of agriculture with rotation and home ma- 
nuring, and especially with a liberal growth of corn, are likely 
to be most exhausted, and which therefore it is most important to 
supply by artificial manures if he would increase his breadth 
and produce of corn. 
The first point to call attention to in the Tables is the last 
column of Table II., where we have given for each plot the num- 
ber of bushels of corn obtained in the first season of 1851, over 
and above the average of the three succeeding; seasons. It is seen 
that there is in every case a larger produce, by 14 to 20 bushels, 
or even more, obtained by the same manure in the first year than 
in the average of the following years. This result speaks well 
for the previous " condition" of the land ; and it is also very 
instructive as showing how useless, for the purposes of any general 
conclusions, are experiments with manures conducted over a single 
season only. It is in fact not until some of the elements of 
fertility, the due proportion of which to the others is compre- 
hended in the term " condition," have been removed from the 
soil by the crop, that any safe deductions can be formed from the 
results of experiments with manures. Although it is possible 
that the field was not quite uniform as regards the accumulation 
from previous manures, it is at the same time not surprising that 
we should find the excess of produce in the first year greater on 
some of the plots than on the others, when it is remembered how 
very variable were the conditions of growth provided by the 
experimental manures, and also how different would be the pro- 
gress or tendency of growth, and consequently the influence of 
the varying season, dependent on the varying supply of the ele- 
ments of growth by manure. It is however very unfortunate that 
the quantity of straw as well as corn was not ascertained in the 
first year ; for it is exceedingly probable that had it been so, 
there would have been found to be a much greater uniformity in 
the excess of the gross or total jn'oduce of the first year over that 
