688 GEOLOGY OF OHIO. 
Attention is called to one or two other points in connection with these 
analysis. | 
(a.) The marked disparity in the amounts of phosphoric acid which soil 
and subsoil respectively contain is doubtless due, in part at least, to the 
abstraction of this substance from the surface by the crops that have been 
raised here. Of all the constituents of the soil, this certainly is the one 
that according to theory should be most reduced by the prevalent system 
of tillage. There is still left in the soil a large aggregate of this sub- 
stance, it is true, but it is to be remembered that plants can not go on 
growing until all isremoved. To make agriculture profitable, these min- 
eral elements of plants must not only be present in the soil, but must be 
every where diffused, so that each rootlet of eaeh plant shall be able to 
secure its share. It is altogether probable that the change of one-tenth 
of one per cent. is enough to make the difference between sterility and 
generous harvests. 
(b.) The chief notable lack in these analyses is in the soluble forms of 
potash and soda, and in carbonate of lime. These are the very sub- 
stances that would be furnished by the application of ashes and lime- 
waste from the lime-kilns of the country. Ten thousand cords of wood 
are burned every year at Springfield in the manufacture of lime; but 
until within the last two or three years not one bushel in a thousand of 
the ashes produced has ever been restored to the land. At Yellow 
Springs and at Clifton—both of which are surrounded with clay soils of 
this general description, and where large quantities of lime are annually 
burned—the same thing is true, though lime and ashes may be had for 
the carting. i : 
Two other analyses are added, in this division, of soils of better grade 
than that already reported upon. No. 71s from the farm of John How- 
ell, Esq. (Mad River township, Clarke county), and No. 9 from the land of 
John Snyder, Hsq., of Springfield. Both of these analyses represent the 
average yellow clays of this region. No. 8 represents the composition of 
the subsoil of No. 7; but there is some reason to distrust the results 
shown in this analysis. In the comparatively large proportion of or- 
ganic matter it can hardly represent the average. 
4. One variety still remains to be described, viz., the soil of the 
black uplands of this region, including the upland prairies that are 
occasionally met. This soil might with a measure of propriety be dis- 
tributed among the two last named divisions, as it has differed in fortune 
from one or other of them in but a single particular. By the accidents 
of the later geological history of the country, these common deposits of 
bowlder clay and stratified sand and gravel have been left generally in 
