The bee., 1913-11-07

re Raw Phosphate Rock Was Used.
that potash might not be a limiting fac
tor, but other experiments on the same
soil showed that its use was unneces
sary. Eight hundred pounds OF acld
phosphate and 1000 pounds rock phos
phate per acre equal money values)
are used once in a four-year rotation
The following yields will show how
poor the ground was, and will show
how clover will take hold of rock phos
plate and how the land improves as
organic matter and nitrogen are re
stored TO the soil. Manure was used
on these plots equivalent to the crops
removed. The materials were applied
July l, 1908. in growing a cowpea croI
which was turned under. then again
preceding corn in 1912:
Rock No Acid
phosphate treatment phosphate
Corn. 1909. 3.S blu. 40 blu. 11.3 bu
Oats. 1870. 9.3 blu. 80 blu. 1l.9 bu
Glover hay,
1911 -. .2.436 lbs. s-lbs. 2,16s lbs
Corn, 1912. 1923 Blu. 9.5 bu. 45.7 Blu
Gain in corn 29.1 bu. 30 bu. 1914 Blu
This experiment has not been con
Quoted long enough to get full com
parison, but it is valuable in that IL
gives some indications as to what may
be expected. The mo Treatment
plot and the Acid Phosphate" plo,
were both little more fertile in the
beginning than the Rock Phosphate
tAlnt MIA mi AxfA -.
the eye. The yield for the mo Treai
ment' plot bears out this statement
No doubt the acid phosphate plot was
at an advantage by having a better
cowpea crop plowed under. Another
factor to be taken into consideration
is that there is In the amount OF rock
phosphate applied, five times as much
phosphate as In the amount OF acid
phosphate, and that most of this
is in the soil for future use. The
phosphorus naturally in the soil Is
chiefly in the form of rock phosphate
which nature makes available when
organic matter is present. For a given
amount of money, four or five times
as much phosphorus can be added to
the soil in rock phosphate, as in acid
phosphate.
An experiment at London, Laurel
County, one year old, has given the
following results. Ground limestone
and sulfate of potash were used with
both the acid phosphate and rock phos-
plate. Acid No Rock
phosphate treatment phosphate
Cowpea hay,
1912 ALSO lbs. 1890 lbs. 5000 lbs.
Corn. 1912. 1878 blu. 24.s Blu. 400 bu.
Sweet clover,
1913 -. 2,S40 lbs. failure 1870 lbs.
From the results of these expert
ments, We are led to recommend the
use OF acid phosphate first on thin
soils, and from these and experiments
by other stations, We are led to recon-
mend the use of rock phosphate when
the soil has had sufficient organic mat
ter introduced into 1t.
When only a small amount OF phos-
plate is 10 be used merely for the
purpose of starting crop, without
reference 10 Increasing the content OF
PhoePhOiuS ia tue sVii' thSh We "ouiu
advise the use of acid phosphate. In
other words. in permanent process
Of increasing and maintaining fertility.
we would recommend the use OF raw
ground phosphate rock with the limita-
tons already noted.
At least so per cent Of raw phos-
phate rock should pass a screen Of
100 meshes to the linear inch or 10000
meshes 10 the square inch. In pur-
chasing this material, guaranty
should be required stating fineness and
the amount OF phosphorus.
Literature on soil fertility may DO
had by addressing the Kentucky Agri-
cultural Experiment Station. LeKing-
Tor. NY.