ELEMENTS OF AGRICULTURE. 
CHAPTER III. 
Manures . 
LESSON XI. 
FORMATION, COMPOSITION, AND ACTION OF MANURES. 
74. All substances, both liquid and solid, of vegetable 
or animal origin, that by their decomposition fertilize the 
earth by serving as food for plants, are called manures. 
Thus, a crop of clover turned in by the plough, as it de¬ 
composes, furnishes a supply of manure of vegetable 
origin. The remains of dead animals, on the other hand, 
furnish manure of animal origin. 
75. Manures may be divided into several classes: 1. 
Ordinary manure, a mixture of animal and vegetable sub¬ 
stances. 2. Animal manure, strictly of animal origin. 3 
Vegetable manures, as green crops turned under, straw, etc. 
76. The value of manures depends upon their nature. 
Those of animal origin are usually exceedingly active, and 
of little duration. Among vegetable substances, those* 
most valuable as food are also most valuable as manure. 
77. The continual application of purely vegetable ma¬ 
nures will not bring land up to the highest degree of fer¬ 
tility. They must be aided by animal manures, which, 
by means of the azote which they contain, exercise upon 
the soil a peculiar influence. 
78. Though in general the development of plants is 
greatly favored by the application of manures, yet there 
are cases in which they will do more harm ihan good, if 
great attention is not paid to their condition and mode of 
