CHAPTER FL 
MANURES. 
The Food of the Plant—Special Manures—Infiuence of Manures 
rich in Nitrogen at the various Stages of the development of 
Cane—Analysis of the Ash—Function of the Mineral Food or 
Ash-ingredients—The Elements of Sugar, whence derived—Pre- 
cautions necessary to be observed—By what Means Exhaustion 
of the Soil by Successive Crops of Cane may be prevented, with- 
out practicing a System of Rotation of Crops. 
Ir has been fully proved by experiment that the perfec- 
tion of saccharine richness in the cane can be attained 
and preserved only by care in providing for the plant suit- 
able food. The fact that certain kinds of soil, differing 
from each other only in the relative proportion of some 
few chemical constituents, influencing very differently the 
plant as to both the quantity and the quality of its saccha- 
rine secretions, indicates the propriety of ascertaining def- 
initely the nature of the influence exerted by these ingre- 
dients of the soil under various conditions, and of apply- 
ing to it as fertilizers those substances which, not injurious 
in other respects, stimulate the formation of sugar in the 
juice. On the other hand, those special manures should be 
withheld, which, however beneficial in other respects they 
may seem to be, at that period, directly hinder the plant in 
the performance of its peculiar function. 
The specific action of certain agents upon the constitu- 
tion of the juice is also variously modified accordingly as 
they are applied at different stages of growth and devel- 
(46 ) 
