FLORIDA STATE HORTICULTURAL SOCIETY 
105 
as ammonia. On the other hand, if there 
is too great and sudden a formation of 
ammonia, owing to the conditions being 
unfavorable to its transformation into ni¬ 
trates, there is a possibility that ammonia 
may in some cases accumulate in the soil 
to such an extent as to be injurious to 
plants. In a word, the most important 
problems in connection with the feeding 
of plants are the selection of the proper 
plant foods and the compounding of the 
various materials in such proportions as 
will insure a proper and adequate supply 
of all necessary plant foods to meet the 
plant requirements from seeding time un¬ 
til full maturity is reached. 
Even if fertilizers are supplied in ade¬ 
quate quantities and of the right analysis, 
it is also important to have the right pro¬ 
portions of the different materials used in 
the mixtures. This may best be illus¬ 
trated by citing my own experiment with 
fertilizers in Aroostook County, Maine. I 
found it possible to produce 30-40 bush¬ 
els more of potatoes per acre with one 
fertilizer than with another, even when 
an analysis of both would show the same 
percentages of ammonia, available phos¬ 
phoric acid, and potash. The factors de¬ 
termining the difference in yields in these 
cases were the kinds of materials and 
their availability. Thus the difference in 
the value of the product from an acre of 
land produced by the two fertilizers hav¬ 
ing the same analysis was enough in most 
seasons to pay the entire cost of the fer¬ 
tilizer used. It is because of these impor¬ 
tant considerations that a careful study of 
soil and climatic conditions and of soil 
and plant requirements is necessary in or¬ 
der to manufacture fertilizers which will 
give the best possible results. 
FERTILIZERS 
Ammonia .—I notice that the previous 
speaker spoke of ammonia as that ingre¬ 
dient of the fertilizer which “produces 
plant growth.” I know it is a more or 
less common practice nowadays to speak 
of nitrogen,-or ammonia, as that which 
causes growth, of phosphoric acid as that 
which produces the seed, and of potash 
as the fertilizer ingredient which causes 
the production of starch, sugar, and cellu¬ 
lose. We must not forget, however, that 
there are at least ten different plant foods, 
all of which are important to the proper 
functioning of the plant; and if any one 
of these is entirely lacking, the plant will 
not thrive. Therefore, iron, magnesia, 
and lime are as necessary to growth as 
nitrogen is. We are led, however, to 
think of nitrogen as especially necessary 
to growth for the reason that when it is 
deficient in a soil, plants generally take 
on a light or yellow color and present an 
unthrifty appearance. And yet, I have 
seen Indian corn which looked as light- 
colored and unthrifty as a plant possibly 
could, when supplied with everything a 
plant requires excepting iron, but which, 
as soon as iron was supplied, recovered its 
normal green appearance and throve per¬ 
fectly. 
Another important consideration in 
connection with the use of fertilizers is 
their effect upon the soil. Nitrates, for 
example, are subject to ready loss by 
leaching on sandy soils if heavy rains oc¬ 
cur, and nitrate of soda in particular 
