FLORIDA STATE HORTICULTURAL SOCIETY 
107 
or the destruction of nitrates within the 
soil. It has been proved by the most 
painstaking experiments that if a soil be¬ 
comes water-logged up to a certain limit, 
nitrates instead of being formed or con¬ 
served in the soil, begin to undergo de¬ 
composition, especially if the soil con¬ 
tains considerable amounts of fresh ma¬ 
nures and certain other kinds of organic 
matter in the early stages of decomposi¬ 
tion. This change may go only so far 
that ammonia is formed; or it may even 
progress to such an extent that the major 
part of the nitrogen existing in nitrates 
already in the soil or applied to it in fer¬ 
tilizers, may be changed into gaseous 
form and thrown off into the air. The 
nitrogen would then be in the same form 
as the nitrogen in the air which we are 
breathing in this room at the present mo¬ 
ment, and it would be of no more use to 
plants than the naturally-existing free ni¬ 
trogen already in the air. A very small 
part of the nitrogen under these condi¬ 
tions is transformed into organic material 
consisting of the micro-organisms which 
bring about this change. Thus it is im¬ 
portant that soils be properly drained. If 
they are not, organic material which has 
considerably decomposed or which has 
been well composted is far safer than or¬ 
ganic material in a less advanced stage of 
decomposition, since the latter is capable 
of supplying a greater amount of nutri¬ 
ment to the denitrifying organisms. 
Phosphoric Acid .—In regard to phos¬ 
phoric acid, it is a well-known fact that 
in Europe in the early days no such thing 
as superphosphate, or acid phosphate, was 
known. Due, however, to the work of 
Von Liebig during the latter part of the 
first half of the preceding century, it was 
shown that the crop-producing efficiency 
of ground bone was very greatly in¬ 
creased by treating it with sulphuric acid 
(oil of vitriol). Still later phosphate 
rock which is a far less effective source 
of phosphoric acid than bone when both 
are untreated, was also subjected to the 
same treatment, whereupon it was found 
that the available phosphoric acid, thus 
produced, was as efficient a source of 
plant food as if it had been produced by 
treatment of bone with sulphuric acid. 
Ordinary bone and phosphate rock con¬ 
sist chiefly of tricalcium phosphate, some¬ 
times called a “three-lime” phosphate. 
In the manufacture of superphosphate 
(acid phosphate) either from phosphate 
rock or from bone, it is customary to add 
enough sulphuric acid to combine with 
two of the three atoms of lime, so that 
only one atom of lime remains in com¬ 
bination with phosphoric acid. This re¬ 
maining compound containing only one 
atom of lime is soluble in water, supply¬ 
ing what is known as “soluble phosphoric 
acid.” The other two-thirds of the lime 
in the bone or in the phosphate rock are 
changed into land plaster, or gypsum, 
which remains in the mixture. This, 
therefore, the farmer secures without 
cost, since the charge for the superphos¬ 
phate is based merely upon the percent¬ 
age of available phosphoric acid. 
It has been found in some of the states 
on the Pacific Coast and elsewhere that 
sulphur, even in such combinations as 
land plaster, or gypsum, is very helpful to 
the growth of certain plants; and it is 
not at all impossible that the sulphur con¬ 
tained in the land plaster, associated with 
