Hints on raising farm crops 57 
a grain crop might be raised on this field, 
such as oats, barley or wheat. Then a grass 
crop may he raised on the field the third year, 
such as clover, for example. By such a sys¬ 
tem, each of the three different types of plants 
can produce a much greater yield than when 
one crop is raised continually on this field. 
We will now inquire further into this matter, 
so that these reasons can be better explained. 
While it cannot be said that crop rotation 
increases fertility, it does prevent the fertility 
from being rapidly exhausted. One of the best 
things about a rotation is that it is a big 
help in keeping down weeds. If one is rais¬ 
ing a grass crop, or a grain crop, continuous¬ 
ly on the same field, weeds will soon enter 
, in and cause a great deal of difficulty. They 
►are especially troublesome when the crop is 
to be sold, because if there are any weeds in 
the farmer’s product, he is paid considerably 
less than the market price. By raising a cul¬ 
tivated crop once in every three or four years 
on this field, the farmer can get a good chance 
to eradicate these weeds. 
The physical condition of the soil is greatly 
improved by the rotation of crops. Some 
plants are very deep-rooted, such as clover 
and alfalfa. When the roots of these plants 
penetrate into the subsoil for several feet, 
they open up this soil, especially after the 
plants are cut, and the roots allowed to de¬ 
cay. This provides a good channel for mois¬ 
ture and air in the soil, as well as subduing 
the subsoil. When one of the crops in the 
rotation is plowed under, as is sometimes the 
