SOME USEFUL PLANTS. 887 
largely used as a winter food for cattle under the name of 
ensilage. Much use is also made of dried corn stems, with 
the leaves, variously known as “corn fodder” and stover. 
The residues left after certain manufacturing processes 
are of great value as food for horses, cattle, sheep, or hogs. 
Among these are linseed meal and cotton-seed meal from 
which all the oil possible has been extracted by pressure. 
Brewers’ grains and distillery swill, the latter consisting 
of a sort of thin sour gruel of corn meal from which all 
the alcohol has been distilled, may be fed in moderate 
quantity to cattle and hogs without ill effects, and are 
used in the fresh condition and dried for shipment. The 
refuse from the manufacture of beet-sugar is also consider- 
ably utilized, both moist and after drying. 
(4) FERTILIZERS OF VEGETABLE ORIGIN 
413. Crops impoverish the soil by removing from it the 
raw materials for the manufacture of plant food. The 
most valuable of these are nitrates and potassium com- 
pounds. It is evident that the fertility of the soil can 
best be maintained by restoring to it all parts of the plant 
not to be sold at a profit. For instance, if beans are grown 
upon a piece of ground, the stems and leaves, after the 
crop has been gathered, should in some way be restored 
to the soil and plowed under, — not burned, since burn- 
ing would destroy much available nitrogen. Cotton-seed 
meal is much used as a fertilizer and restores to the soil 
most of the valuable material taken from it by the growth 
of the cotton crop. 
Wood-ashes is a useful fertilizer, from the amount of 
potassium salts which it contains. 
