Atlanta semi-weekly journal. (Atlanta, Ga.) 1898-1920, 1909-10-29
QUESTIONS g ANSWERS

FERTILIZER FOR SWEET OR IRISH
POTATOES.
c. II. c., Atlanta, Ca. writes: 1 would
like a fertilizer formula suitable for
growing sweet and Irish potatoes. Which
do YOU think is best to use on potatoes
muriate or sulphate OF potash?
A suitable fertilizer for Irish potatoes
should ordinarily contain from to per
cent of nitrogen, from to per cent of
phOsphoric acid and from 6 to 9 per cent
Of potash. The higher amounts of plant
food should be used on sandy sails. For
loamy lands and those containing
a considerable amount Of vegeta-
BILE matter or TO which liberal quantities
OF farmyard manure can be applied the
smaller amounts Of plant food will an
swer. and in fact the nitrogen may some
times be reduced to as low as per
cent As a rule, SO much nitrogen Is
not needed for sweet potatoes. as their
nature and character of growth is diff
ferent from the Irish potato. The Irish
potato must be forced along rapidly and,
mature early in the season in order to
bring the grower profitable price. The
sweet potato occupies a much longer
period OF growth, relatively speaking.
and Is less affected by viscissitudes of
weather. Two TO three per cent OF nitro
gen is. as a rule, sufficient for sweet po-
tatoes. while from to per cent OF
phosphoric acid and to 6 Pc cent Of
potash win, as a rule answer for this
crop. Here again larger amounts should
be used on sandy soils, and OF course. as
the sweet potato does best on this type
OF soil. the heavier fertilization is prob
ably advisable In your case.
Many tests have haen rnada IN datar-
mine the relative influence of sulphate
and muriate OF potash on Irish potatoes
II was thought for a long time that the
muriate produced a potato which did not
cook quite as well. being somewhat slick
and more retentive of water apparently
than those produced where sulphate was
used in liberal amounts. or late this
statement has been challenged, and IL Is
doubtful under actual field conditions II
there Is enough difference in the cook
ing qualities evidenced to justify the use
OF sulphate over muriate, provided the
muriate can be purchased cheaper than
the sulphate. Where the sulphate can be
bought just as cheap as the muriate, we
would be inclined to use II.
A good formula to use in preparing a
fertilizer for Irish potatoes would be as
follows: 600 pounds OF tankage contain
ing at least 5 per cent OF nitrogen, and II
per cent Of phosphoric acid; 500 pounds of
high-grade acid phosphate. 400 pounds Of
high-grade sulphate OF potash, and 200
pounds Of rich loan. There should be us
ed as a top dressing on potatoes 200
pounds OF nitrate OF soda containing IS
per cent OF nitrogen. This will give you
a formula containing approximately per
cent Of nitrogen. 7s per cent OF phosphOric
acid and "a per cent OF potash.
For SWEET potatoes a satisfactory fertil-
izer may be prepared by mixing together
500 pounds Of is per cent acid phosphate.
500 pounds OF cotton seed meal containing
per cent OF nitrogen, and 500 pounds OF
sulphate OF potash. This fertilizer will
contain about 2.S per cent OF nitrogen. s
per cent Of phosphoric acid and per cent
OF potash. Since IL would be difficult to
contain as high grade OF cotton-seed
meal as suggested, the formula would
probably run a little lower I'm actual prac-