92 Report of Experiments on the Growth of Barleij, 
condition for the after-growth of grain, and would, in the course 
of ordinary practice, be re-manured before growing another crop. 
It was, therefore, in a suitable state for testing the effects of 
different manures upon the crop, and for showing, by the results, in 
what constituents, or class o-f constituents, the soil had, by the 
previous cropping, become practically the most deficient. 
The area of 4^ acres was divided into 24 nearly square plots ; 
most of which were exactly one-fifth of an acre each, but the 
remainder somewhat less. Two plots were left unmanured ; one 
was manured every year with farmyard-manure ; and others with 
different manures, which, respectively, supplied certain con- 
stituents of farmyard-manure, separately or in combination. 
We here repeat, in answer to objections recently reiterated 
(this time in Germany), that we believe comparative results 
obtained by growing crops year after year on the same land, 
without manure, and with different manurial constituents, singly 
and in admixture, are far better calculated to indicate in what 
constituent or constituents the soil is relatively deficient, so far as 
the available supply for the crop to be grown is concerned, than 
' what is generally understood as an analysis of the soil. On this 
point it may be well to quote a paragraph from our paper on the 
growth of Wheat for twenty years in succession on the same land : — 
" Our conclusion, as indicated in former papers, and frequently 
expressed in answer to the objections of chemical friends who had 
not paid special attention to the applications of chemistry to agri- 
culture, was, that far more had yet to be done in determining 
the chemical and physical qualities of soils in relation to the 
atmosphere, and to manurial substances exposed to their action, 
as well as in perfecting methods of analysis, before comparative 
analyses could aid us much in deciding upon the relative produc- 
tiveness of different soils, to say nothing of the still more difficult 
problem of estimating, by such means, the condition of fertility 
or exhaustion of one and the same soil at different times. Of 
late years very much has been done in these departments of 
investigation ; still, as recent discussions abundantly show, far 
too little is even yet known of what a soil either is or ought to be, 
in a chemical point of view, to render the results of the analysis 
of soils directly applicable to the solution of questions such as 
those we had in view in our inquiry. But if our knowledge of 
the chemistry of soils should progress as rapidly as it has during 
the last twenty years, the analysis of a soil will ere long become 
much more significant than it is at present." (' Journal of the 
Royal Agricultural Society,' vol. xxv. p. 98.) 
In accordance with the views here indicated, we have from 
time to time, from 1846 up to 1870, taken samples of the soils 
and subsoils of our different experimental plots, until the collec- 
