156 HOW CROPS FEED. 
vegetable matter in bogs and marshes. A soil is peaty or 
mucky when containing vegetable remains that have suf- 
fered partial decay under water. 
Vegetable Mold is a soil containing much organic mat- 
ter that has decayed without submergence in water, either 
resulting from the leaves, etc., of forest trees, from the 
roots of grasses, or from the frequent application of large 
doses of strawy manures. 
Ochery or Ferruginous Soils are those containing much 
oxide or silicates of iron; they have a yellow, red, or 
brown color. 
Other divisions are current among practical men, as, 
for example, surface and subsoil, active and inert soil, 
tilth, and hard pan. These terms mostly explain tlem- 
selves, When, at the depth of four inches to one foot or 
more, the soil assumes a different color and texture, these 
distinctions have meaning. 
The surface soil, active soil, or tilth, is the portion that 
is wrought by the instruments of tillage—that which is 
moistened by the rains, warmed by the sun, permeated by 
the atmosphere, in which the plant extends its roots, gath- 
ers its soil-food, and which, by the decay of the subter- 
ranean organs of vegetation, acquires a content of humus. 
Subsoil— Where the soil originally had the same char- 
acters to a great depth, it often becomes modified down 
to a certain point, by the agencies just enumerated, in 
such a manner that the eye at once makes the distinction 
into surface soil and subsoil. In many cases, however, 
such distinctions are entirely arbitrary, the earth changing 
its appearance gradually or even remaining uniform toa 
considerable depth. Again, the surface soil may have a 
greater downward extent than the active soil, or the tilth 
may extend into the subsoil. 
Hard pan is the appropriate name of a dense, almost 
impenetrable, crust or stratum of ochery clay or com- 
