36 QUINCE CULTURE. 
CHAPTER V. 
MANURES FOR THE QUINCE. 
WHATEVER can be used to increase the fertility of the 
soil by supplying plant food isa manure. The chemical 
analysis of any plant will show its constituents, and give 
the relative proportion of each, and so serve as a guide 
in supplying what that plant needs. About nine-tenths 
are water and air; the rest is made up of earths and 
metals, as lime, clay, iron, magnesia, silex, potash, and 
soda, with gases and combustibles, as oxygen, hydrogen, 
nitrogen, chlorine, carbon, sulphur, and phosphorus. 
In the process of growth the plant selects such of these 
as its nature demands; and when it dies and decays it 
restores to the earth these elements of fertility. 
Artificial fertilizers are made by mechanically com- 
bining in desired proportions the elements of plant food, 
to supply any deficiency of the soil under cultivation. 
The action of any manure depends on its soluble salts. 
‘The salts contain the sulphur, phosphorus, and carbon, 
as sulphuric acid, phosphoric acid, and carbonic acid, 
and the chlorine as muriatic acid.” 
All animal and vegetable matters in the process of 
decomposition form ammonia. It is estimated that the 
annual rainfall on an acre brings to the soil enough 
ammonia and nitric acid from the air to equal one hun- 
dred pounds of guano. The soil, to get the full benefit 
of this atmospheric manure, must be kept porous to 
receive it, and well drained that it may not run off on its 
surface. When fire consumes vegetation, its gases return 
to the air, leaving as ashes the earthy matters drawn from 
the soil. In the process of decomposition the result is 
the same, only the combustion is slower. 
Wood ashes contain all the elements of plant food ex- 
cept nitrogen. Two and a half tons of seasoned hard 
