MINERAL MANURES, 53 
which are appropriated most largely are not more indis- 
pensable than others which appear in comparatively minute 
proportions. These ingredients are present in almost every 
soil in sufficient abundance, when they have not been re- 
moved by an improvident system of cropping. As sugar 
is composed of elements derived entirely from the air, it is 
evident that as in the case of the Louisiana cane, there 
would be no necessity for rotation if all that has been 
taken from the soil is returned in the trash. A soil which 
possessed these ingredients at first would not, by successive 
crops of cane, become exhausted at all, if the sugar only 
were taken away. Practically, however, this cannot be 
effectually accomplished. The uncrystallizable portion 
of the juice contains salts which are annually removed with 
the molasses that is marketed, These are chiefly the 
phosphates of lime and potash and the carbonate of lime. 
The leaves are used for fodder, and much is usually wasted 
before their conversion into manure. ‘The seed, also, if 
not returned to the soil upon which it grew, abstracts in 
large quantity the same and other ingredients. Hence, 
while it may be asserted in general terms that the begasse 
or trash is a most valuable manure when applied to the 
cane, it will be necessary to return from other sources the 
equivalent of this annual waste. 
6 
e 
5* 
