164 
FLORIDA STATE HORTICULTURAL SOCIETY 
kinds, and are usually sold under special 
brands. These are also known as arti¬ 
ficial, prepared or manufactured fertiliz¬ 
ers or manures. When they consist only 
of inorganic materials, they are usually 
termed chemical fertilizers or manures. 
While commercial fertilizers contain 
numerous constituent elements, their chief 
value depends on the presence of only 
three forms of plant food, and these are 
compounds of nitrogen , phosphorus and 
potassium. 
Nitrogen is generally conceded to be 
the agent most actively concerned in the 
vegetative functions of vigorous growth, 
especially of the stems and leaves; but if 
present in excess gives rise to a weak and 
sappy growth which in the nature of 
things is soft and vulnerable to attack by 
insects and disease. (Certain forms of 
nitrogenous fertilizers under certain con¬ 
ditions, are also connected intimately with 
what might be termed derangements of 
the digestive system of citrus trees.) The 
action of this element tends to prolong 
growth and to. delay fruition and matur¬ 
ity, and generally to develop the vegeta¬ 
tive functions at the expense of those con¬ 
cerned in fruit development or reproduc¬ 
tion. 
Phosphoric acid is intimately con¬ 
cerned in the most vital functions of cell 
life and reproduction. In the early life 
of the young plant it greatly stimulates 
root production. If present in excess it 
tends to force maturity and the reproduct¬ 
ive functions of the tree or premature 
fruit bearing. It is supposed to be con¬ 
cerned also in the proper balancing of the 
flavor of the fruit. 
Potash is in some way connected with 
the elaboration of starch, sugar and cellu¬ 
lose, to the efficient production of which 
by the plant cells its presence is vital. Yet 
according to recent experimental results 
on cane sugar, it does not seem possible 
by this means to increase the percentage 
of sugar in the cane juice. It is also- prob¬ 
ably responsible! (for the production of 
certain organic acids concerned in the 
flavor of fruits and vegetables. It tends 
to stiffen the straw of grains, and to 
harden the vegetative part generally of 
other plants and trees; produces better 
carrying qualities in marketable products, 
and it increases the ability of the plant or 
tree to resist disease. It possesses a regu¬ 
latory action on the blooming and fruit¬ 
setting of fruit trees, and influences the 
color of blossoms. Like nitrogen, it tends 
to prolong growth and delay maturity. 
Commercial fertilizers, in the commonly 
accepted sense of the term, are essentially 
a product of our modern agricultural sys¬ 
tem. He who refuses to avail himself of 
the power thus placed in his hands, intel¬ 
ligently utilizing the same to restore, 
maintain, or increase the productive power 
of the soil; and thereby raise larger, bet¬ 
ter and more profitable crops, is equally 
standing in his own light with the man 
who' refuses to profit by the work of the 
plant-breeding specialist, or the ingenious 
development of modern agricultural ma¬ 
chinery. In this connection, it may be in¬ 
teresting as well as surprising to you to 
learn that Florida alone, in the year 1914, 
consumed 240,812 tons of fertilizers and 
fertilizer materials, valued approximately 
at six and a quarter million dollars, and 
