Atlanta semi-weekly journal. (Atlanta, Ga.) 1898-1920, 1917-03-13
USING GROUND PHOSPHATE
ROCK IN THE SOUTH

decided lise i'm the price of this mate
rial. This has tended 10 make the acid
phosphate of commerce which has been
- extensively used for fertilizing pur-
poses i'm the south much higher in price
shan n mas been Tor number of years
past. ON this account a decided effort
Eas been made in the last year or two
to place on the market considerable
Quantities of sroUnd phosphate rock
=, hich has not been treated with sui
phuriC acid. Farmers using this mate
vial seem TO lie under the impression
shat II contains from % TO 50 per cent
Of available phosphoric acid; also that
y will Sive them Immediate results. AS
a matter Of fact. but little of the phos-
phoriC acid i'm floats will become avail
,bie during the first year after its APP
plication. and even then. the amount
available will be determined by the sup
lly Of organic matter in the land. AS
our soils are low ~ this material ii
has not seemed wise or proper to ad-
wise the use OF the ground rock under
existing conditions. and certainly ii
should not be used by the farmer unless
he fully understands its composition,
Is merits and the relative availability
OF the plant food it contains.
To this end short summary of a
pamphlet ON the use of ground phos-
Dhate rock by Prof. W. \. Worsham.
Jr.. professor Of agricultural chemistry
I'm the Georgia state College of Agri-
culture. has been prepared for the in
formation and advice OF our readers.
These suggestions should be carefully
kept in mind as they are of vital impor-
lance TO our readers.
Practically all the phosphate rock
sold in this state comes from the states
of South Carolina. Tennessee and Flori-
da. The material from these different
sources vary somewhat in physical ap-
pearance and in the percentage of phos-
phoric acid. but the chemical coTcbina-
tiOn of the phosphoric acid is the same
i'm all cases. il being combined with
lime. iron and alumina. In some cases
it occurs mixed with clay and other
worthless material. This contamination
causes the variation in phosphoric acid
content. the more impurities the lower
the percentage of phosphoric acid. These
impurities may be washed out in many
cases, and a very high grade phosphate
rock obtained. The rock that contains
a high, per cent OF iron and alumina is
less valuable than that with a low per
cent Of these constituents The phos-
phoric acid combined with iron and
alumina is far less soluble and will take
a much longer time to become availa BILE,
if It ever becomes available, than that
combined with lime.
: The phosphate rock from South Caro-
lima is found in river beds and deposits
on land. 1t is washed free from impu-
rites, has a low per cent of iron and
slumina and is quite uniform in COM
position, containing from 26 to 2s per
cent of phOsphoric acid. The phosphate
rock from Tennessee is obtained fairly
free of impurities with only a small
per cent of iron and alumina and con-
tains from 80 to 30 per cent of phos-
phoric acid.
The percentage of phosphoric acid is
more variable i'm Florida material, since
81 occurs in different physical forms.
Ii appears as pebbles i'm river beds sas
powders large and small, and as soft
rock which resembles clay, and is large
~ contaminated with it. 1t varies in
percentage composition from is to 80
per cent of phOsphorc acid. Having
more clay mixed with ii. makes it natu-
rally poorer in phosphOric acid. The
percentage of iron and alumina is also
somewhat higher in this grade OF rock.
Some of the ground phosphate rock
may contain a small quantity of lime
stone or carbonate of lime, but il is so
small that il is of no practical value
used. and should not be considered I'm
liking the price of phosphate rock. The
claim is sometimes made that the phos-
phate rock contains lime and phospnorlc
acid i'm combination, and that its appli-
cations serve the double purpose of sup
plying both lime and phosphoric acid,
which most soils need. The lime COM
bined with phosphoric acid i'm rick phos-
phate is no more available than the
the purposes of improving the. physical
condition of the soil and correcting
acidity, as limestone, burnt lime or
slaked lime does.
Therefore, in determining the reia-
tive values of the different phosphate
rocks offered for sale under the names
floats" ''phoslime" and other trade
names and arriving at the price to b
paid for same, bear in mind the follow
ing facts: 1. That in all cases unavail-
able phosphoric acid is being purchased.
.. That the phosphoric acid in the raw
rock, regardless of its source, is I'm the
same chemical combination being COM
bined with lime. iron and alumina, and
the less iron and alumina the better
3. That the fineness to which II is
ground determines the rate at which il
becomes available when mixed with the
soil. If the fineness is the same and
the percent OF iron and alumina is low.
then the per cent of total phosphoriC
acid alone should determine the price.
In some cases ground phosphate rock
is being offered for sale at prices con-
siderably too high claims being made
that il possesses some peculiar property
OF chemical combination which makes
the phosphoric acid more valuable. Oft
en- this material is of low grade and can
not be sold for the manufacture of acid
phosphate. Therefore. il is put on the
market in the raw state with claims that
can not be substantiated and in order
TO give weight to these claims the high
price is asked. Most of the ground rock
put on the market contains from IS to -
per cent of total phosphoric acid and
is ground so that 80 per cent will pass
through 100 mesh screen.
At the present time phosphate rocl
finely ground with A, guarantee of % g.
per cent of phosphoric acid. is quoted
laid down in Athens from sources II
Tennessee at $3.50 per ton in bulk in
paper-lined cars.
From another source a finely GROUND
rock containing - per cent total phos.
phOric acid is offered al S4.25 {. o. D
at plant in bulk in paper-lined carr
There are no conditions due to the pres
ent war which should affect the price
or the raw phosphate rock. and thesS
r~f~pe chor11d he faf eta