414 
Report of Experiments with different Manures 
representing as they do the percentage mineral composition of 
the produce of three very different seasons — the characters of 
which differed so widely in several other respects — is somewhat 
remarkable. The differences are indeed too slight to justify the 
deduction from them of any very defined conclusions. Still, it 
may be observed, that the tendency of the variations is to show a 
scarcely maintained, and in some cases an even diminished pro- 
portion, of those constituents which may be considered the most 
characteristic of the hay crop, when it is suj)plied liberally with 
all the necessary mineral constituents. Thus, the proportion of 
phosphoric acid is about equal in the three seasons, whilst that 
of the lime, the potash, and the silica, show a tendency to de- 
crease from year to year. The carbonic acid too, which is cha- 
racteristic of the ash of the non-graminaceous part of the herbage, 
also diminishes somewhat from the first to the third year. On 
the other hand, the soda and the chlorine — constituents the most 
of all characteristic of crude and succulent growth — increase 
very obviously in their proportion in the ash from year to year. 
Upon the Avhole then, these results, comparatively slight as 
the differences are, still indicate, as did those which have gone 
before, that there was a probable relative deficiency of lime, 
potash, and silica ; — especially of the latter two. 
With regard to the results given in the fourth column atten- 
tion may be called to the fact, that the figures represent the 
mean composition of the ash of specimens of hay grown under 
sixteen different manuring conditions, in each of the three widely 
differing seasons. The results may therefore be taken as show- 
ing the average mineral composition of the mixed herbage grown 
under a great variety of circumstances. 
Nitrogen. 
For the information of the chemical reader it may be mentioned, 
that the nitrogen in the hay, as given in the Table, was deter- 
mined by burning with soda-lime, and estimating by the volu- 
metric method. Duplicate determinations were always made. 
The individual results are given for reference in Tables V., VI., 
and VII., in the Appendix. The mean results only, are given in 
Table XV. on the next page ; and these will be in sufficient 
detail for the purpose of our illustrations. The nitroffen was 
thus determined, in the hay from every one of the experimental 
plots, in each of the three years of the experiments. The figures 
in the first set of four colunuis (Table XV.) represent the per- 
centages of Nitrogen in the J'resJt hay — that is, in the condition 
in wliich it was carted from the land. Tlie figures in the second 
Division represent tlie percentages in the Dry substance of 
the hay. 
