White Bluffs spokesman. [volume] (White Bluffs, Wash.) 1907-1938, 1930-10-03
WHAT PHOsPHATES
SHALL We use?

Because of the activity of sales
men within the territory pushing the
sale of tri-calciurn phosphate, sew
eral requests have come to the office
of the County Agent for information
upon the form of phosphate to be
used. We shall try to answer this
question BRIEFLY.
Phosphates, as mined from the
earth or found in bone are in the
form of tri-calcium phosphate, and in
this form are not soluble in either
water or the weak acids normally
found in the soil. Probably most of
the phosphate found in the soil is in
this form or one similar. In order to
make these forms of raw" phos-
pilates available it has been the prac
tlce to treat one ton of raw ground
rock with one ton Of sulphuric acid,
This changes part Of the phos-
plate to form which carries less
calcium but carries some acid. The
first form that would result would
be phosphate which will be at
least partially soluble in the weak
acids normally found in the soil. If
this action continued still further
then we would get form of plos-
plate which would be soluble in
water, ordinary acid phosphate or
superphosphate, j, e. the ton of raw
rock treated with the ton of acid,
will carry all three of the forms of
phosphate, and there is a part of it
which will be in a position to be
taken up by the plant. OF course. in
the addition of the acid no phos-
plate is added and hence a ton of
.superphosphate ,carries only one
half the percentage of the total phos
phate as does the original raw rock
or ground bone if treated with acid.
Keep in mind however, that the small
Ter amour of phosphate is much
more available to the plant than is
even the larger amount in the raw
form or the tri-calcium phosphate.
Still another form of phosphate is
ammophos. This fertilizer, however,
carries some nitrate as well as the
phosphate content. This has been
prepared through chemical means
and is all water soluble. Just how
long after this comes in contact
with the soil, it remains soluble one
cannot say as it would depend upon
the nature of the soil, but probably
would remain soluble until it would
be carried to greater depth in the
soil than probably any other form
If one were purchasing amnophos
for it's phosphate contents one would
want to purchase the fertilizer car
rying but the eleven percent of nit
rogen and 46 per cent of phosphate.
Ax,o1;c,%sD,, &c %l,se far%s1s1e~ 4
need to be only one-third as heavy
as the application of superphosphate.
We would question the use of raw
form Of phosphate, that is, any form
of tri-calcium- phosphate in this par
ticular section. In order to make this
phosphate available it must be re-
acted upon by acids and here where
our soils are generally more or less
alkaline it would seem reasonable
that there would be insufficient acids
present in the soil to break down as
raw a form as the tri-calcium- phos-
phate. If it were to be used it GER
tainly should be thoroughly mixed
with naanures if they are used or ap-
piled and thor roughly mixed with the
, green cover crop before it is worked
!. into the soil. The decay, of organic
t matter would form acids which
might possible be sufficient to make
available part of a reasonable ap-
. plication of the raw phosphate. The
question of the use of raw rock phos-
, phate in this section was taken up
, with Mr.. Hegnauer, Extension Crop
Specialist last winter and we were
advised that it was becoming a gen
1,,1,o 81,
raw rock phosphate had been used
in the past, to now use the acid OF
superphosphate. In view of this ad-
vice and the fact that our soils are
as rule at least slightly alkaline
here, the use of tri-calcium- phosphate
: or any form of raw phosphate fert.
ilizer would seem questionable.
!, E. c. DURDLE,
2 County Agent