8 
SOIL SURVEY OF WAUPACA COUNTY. 
suggestions for their management, based upon the work of the 
Soil Survey within the area, covered in the report, and upon 
the results of field tests made by the Experiment Station. 
Soil fertility depends upon two factors: first, upon the physi¬ 
cal characteristics of the soil, such as water holding capacity, 
workability, etc., and second, upon the chemical composition 
of the material composing the soil. The chemical composition 
depends upon the mode of origin of the soil, and the source of 
material from which the soil is derived. 
Water holding capacity and other physical properties of soil 
all depend chiefly upon texture, which refers to the size of the 
individual soil grains, or particles. A coarse sandy soil, for ex¬ 
ample, will not retain moisture so long as a loam soil, or clay 
loam, because the finer the soil grains, the greater will be the 
total soil-grain surface area to -which moisture may adhere. 
Texture is determined in the field by rubbing the soil between 
the thumb and fingers, and with experience one soon becomes 
expert at judging the size of soil grains. This field judgment 
is verified in the laboratory by a mechanical analysis, which 
is made by a simple method of separating soil grains into dif¬ 
ferent groups, of which there are seven. These are known as 
clay, silt, very fine sand, fine sand, medium sand, coarse sand, 
and fine gravel. 
A chemical analysis is also made of the soil to determine the 
amounts of various essential plant-food elements which are 
present. A chemical analysis shows whether the soil contains 
a large store of plant food, or only a small quantity, and it in¬ 
dicates which kinds of plant food will probably be needed first. 
The amount of organic matter in the soil is also determined, and 
tests are made to show conditions relative to soil acidity. 
SOIL CLASSIFICATION 
Soils are grouped according to texture into soil classes, a soil 
class being made up of soils having the same texture, though 
differing in other respects. A fine sand, for example, may be 
light colored and of alluvial origin, while another fine sand may 
be dark in color and of residual origin, while a third fine sand 
may have been blown into sand dunes by the wind, yet all of 
these soils would belong to the same class, because the greater 
