62 
common salt is ineffectual on poor land ; nitrate of 
soda is suited to clay lands in wet seasons, and also to 
chalk, if applied in humid weather; rape dust is to be 
put on clays and moist lands, but is serviceable on all ; 
and it is also probable, from hence, that particular soils 
produce peculiar modifications in manures applied to 
them, eitheir during the stage of their decomposition, or 
in their mode of chemical union with them, and for this 
reason there is an adaptation of particular soils to grow 
particular plants. For it is certain that plants which 
flourish in wet clayey soils do not choose this habitat on 
account of the clay, for they do not contain more alumina 
than those growing in other regions, neither is it on 
account of the moisture, for if that were the case all bog 
^ plants would be succulent and juicy, which is not the 
case. There are, evidently, then, various effects produced 
uponulmic acid by the native soil of different plants. 
It is also true that certain manures are adapted to 
particular crops, and ought to be applied accordingly^ 
This Grisenthwaite proved ten years ago. The inquiry^ 
therefore, of the Agricultural Society should have been 
to obtain a list of manures applied to particular crops, and 
upon what soils? The other question, viz.. What manures 
will supply the deficiencies in each soil 1 is plainly im- 
possible to be answered ; for if chemistry is unable to 
ascertain of what earth a soil is deficient, and also the 
modifications which are effected upon ulmic acid by 
different soils, it seems very improbable that any effec- 
tual knowledge can be gained respecting the deficiencies 
of manures in soils, particularly without a consideration 
of the crop intended to be produced by its application. 
Now, in order to explain the operation of different 
manures, I have introduced a table,^ principally from 
Madden and Sir H. Davy, and it will appear from this 
• See the Table, No. 2. 
