56 HINTS ON SOILS AND FERTILIZERS 
BENEFITS FROM SOIL ORGANISMS 
Soil organisms, and the benefits derived from 
these minute organisms, form a subject with 
which few farmers are familiar. Of these vari¬ 
ous soil organisms, bacteria are without doubt 
the most numerous, and also the most impor¬ 
tant. We do not ordinarily appreciate the great 
quantity of these bacteria that are present in 
the soil, neither do we begin to realize the im¬ 
mense number found in just a thimble-full of 
ordinary soil. It is no mis-statement of facts 
when we say that an ordinary thimble-full of 
soil contains about one billion of these micro¬ 
organisms. (A “micro-organism” is an organ¬ 
ism which is too small to be seen by the naked 
eye, becoming visible under a powerful micro¬ 
scope.) This will serve to give us some idea 
of their number as well as their importance. 
There are three kinds of bacteria that we will 
especially emphasize, namely, those that cause 
decomposition, those which convert nitrogen 
from the air, and those which convert nitrogen 
from material already in the soil. 
If we stop to ponder for a moment, we will 
have to admit that there is some agency al¬ 
ways at work decomposing material things in 
this world. For instance, if we leave rubbish 
exposed to the weather for any length of time, 
and note the condition of the rubbish at some 
later date, we find that it is not in the same 
physical condition as it was when we first de¬ 
posited it. It has undergone some decomposi¬ 
tion. In fact, this decaying process is always 
