56 
FLORIDA STATE HORTICULTURAL SOCIETY 
soil were deficient in this base, what 
would become of the phosphoric acid ? It 
is not likely that much would leach out of 
the soil, but most of it would become com¬ 
bined with iron and aluminum compounds 
in the soil, and in this form would be quite 
insoluble and unavailable. It is seen, then, 
that lime prevents leaching of the phos¬ 
phoric acid and by combining with it pre¬ 
vents the (formation of insoluble com¬ 
pounds, thus increasing its final availabil¬ 
ity. Van Slyke, in this connection, writes: 
“We do not know of any experimental ev¬ 
idence showing that pure soluble or acid 
calcium phosphate tends by itself to make 
a soil acid. The acid portion of the com¬ 
pound is sooner or later removed from the 
soil by growing plants. Where acid phos¬ 
phate is used in considerable amounts the 
complaint is often heard that it burns out 
or exhausts the soil, as is apparently evi¬ 
denced by decreased crop yield. This may 
be due to one or both of two causes : (i) 
to soil acidity, or (2) to an insufficient 
amount of organic matter—conditions 
easily corrected not by discontinuing the 
use of acid phosphate, but by the applica¬ 
tion of calcium carbonate or organic mat¬ 
ter, or both. It is well known that on dis¬ 
tinctly acid soils the amount of available 
phosphoric acid is small, while the propor¬ 
tion of insoluble iron and aluminum phos¬ 
phate is unusually high.” 
Prof. Cavanaugh, agricultural chemist 
of New York College, wrote me concern¬ 
ing the behavior of fertilizer on sandy soils 
as follows: 
k T think you are entirely on the right 
track. I am convinced that the phosphate 
fertilizers will give far better results if 
the soil is first treated with applications of 
lime. I have seen some samples of the 
Florida soils and know something of their 
character. I suggest your recommending 
the application of hydrated lime, or if one 
must use ground limestone, to get it in a 
rather fine condition. When this has been 
thoroughly incorporated or worked into 
the soil, the acid phosphate will revert 
after it has been applied and moistened 
and will furnish probably a much better 
source for the growth of plants than the 
basic slag.” 
Also a letter from H. O. Buckman, soil 
expert of the Department of Soil Tech¬ 
nology in New York State College of Ag¬ 
riculture, reads in part as follows: 
”1 think that you are right in consid¬ 
ering that acid phosphate plus lime would 
give you better results that basic slag plus 
lime on a sandy soil poor in organic mat¬ 
ter. The reasons which you give are the 
ones which I would consider to be the 
correct ones. The presence of an excess 
of lime, as you state, is to be sure that the 
reversion is to the form of the dicalcium 
phosphate.” 
Another chemical effect is the reaction 
which takes place betewen sulphate of 
ammonia and carbonate of lime to form 
carbonate of ammonia and sulphate of 
lime. The latter is leached out of the soil, 
while the carbonate of ammonia combines 
with humus, forming compounds which 
do not leach, and is gradually converted by 
bacteria in the soil to nitric acid which, 
combining with more lime in the soil, be¬ 
comes nitrate of lime—a readily available 
plant food. 
It also assists chemically in the trans- 
