Wisconsin State Agricultural Society . 115 
unless it is finely pulverized. The object of making it fine is two¬ 
fold. 
First, to allow the roots to readily penetrate it in search of that 
food which is present in so small quantities that it must be sought 
through a wide range of soil, and secondly, to put the soil in that 
mechanical condition best suited to changing the insoluble mineral 
food to a soluble form, in which state alone it can be utilized by the 
plant. 
As before stated, the required change is produced by the air, by 
heat and frost, and by the action of natural waters which are charged 
with carbonic acid, and which have a much higher solvent power 
than pure water. 
The processes of tilling are to put the soil in that condition in 
which these natural agents may most readily act upon it. This 
action takes place entirely upon the surface of the rocky particles, 
and consequently will be in proportion to the amount of surface 
exposed. 
Now the extent of surface exposed to the action of a solvent is 
increased by increasing the fineness of the particles. Thus Magnus 
found that barley would grow and ripen seed in powdered feldspar, 
and Professor Storer matured buckwheat in quarry sand and freshly 
burned coal ashes. Had the material used in either of these experi¬ 
ments been coarse, instead of fine as they were, plants would not 
have grown in them. It is not enough that a soil shall contain all 
the elements required for plant growth, to make it fertile. The food 
must be dissolved, and the rapidity of its solution depends, other 
things being the same, upon the fineness of its particles. Hence 
the farmer breaks up his soil,Fringing it into the finest possible con¬ 
dition, that the decomposing action of air and water may be rapid, 
and that the roots of the growing plants may be enabled to extend 
themselves through the soil to absorb any food there in readiness 
for them. Fineness of itself, however, is not enough. If it were, 
the heaviest clay soil would be more fertile than the lightest loam. 
The clay is too fine, so fine that the particles fit into the interstices, 
rendering the whole compact, thus excluding the air and prevent¬ 
ing that rapidity of action which it is the object of cultivation to 
attain. But the highest degree of fineness consistent with light¬ 
ness and porosity is always to be desired. 
Cultivation of soils then, is, in one sense, analogous to the masti- 
