The Brookings register. [volume] (Brookings, Brookings County, S.D.) 1903-1971, 1915-01-07

manure ldssiSHluS Ho Fdlue 10 the
manure which is common in the sec.
ton, although it has an average value
of about 1925 per TOM the total cost
of treatment was 1896.
Figuring the farm value of corn as
SOC per bushel (the average value for
South Dakota on November LIST, 1914.
as reported by the Department of Ag-
riculture)the increased yield, 1869
bushels has a value of $3.50. The
profit on the investment, if benefit was
only realized the first year, would be
at the rate of 86%. 1t is needless to
add that the large residue, 59.2 pounds
of the element phosphorus left in the
soil over and above that removed by
the first crop was obtained almost
without cost. 1t should be said also
in justice to rock phosphate that 1t al
most invariably gives larger yields
after the first year, until such time as
it needs replenishing by further appli-
cation. 1t is reasonable to believe,
then. that this acre will show as
large, if not a larger, increase for the
next FIVE years, at least, without fur
the investment.
The fourth plot receiving
and acid phosphate gave the largest
yield I'VE the no treatment plot; 400
bushels or an increase of Ala per cent.
The phosphate applied to this acre
had been previously treated with sui
phuric acid, which rendered the phos-
phorus readily available to the plants.
The 200 pounds of acid phosphate ap-
piled cost, On a basis of car load lots
on track at Brookings, $1.57 or $3.50
per ton. The 200 pounds contained
15.7 pounds of the element phosphorus
or enough for more than two Al bushel
crop as obtained on this acre.
The cost of treatment on the same
basis as above, was $5.07. The value
of the added yield was $3.50 and the
profit on the investment was at the
rate of 1856 per cent. 1t is readily
seen that phosphorus in this form,
although more available is more ex-
p~ensivethan in the form of rock phos-
phorus when one considers that the
residue left in the soil on Plot 4 (acid
phosphateplot) was much smaller,
only So pounds Of phosphorus as com
paredwith 59.2 pounds for Plot 3 crock
phosphate).
The fifth plot receiving 200 pounds
of acid phosphorus only, gave an add
ed yield over the no treatment plot of
11.11bushels or an increase of 1878 per
cent. This treatment was applied at a
cost of $2.07. The added yield was
worth 1922 and the profits on the in.
ve~stmentwas at the rate of 1904 per
cent. The amount of the element phos-
phorus added to plot 5, was 1877
pounds, enough for more than two Al
bushel crops as obtained on this acre.
The residue of phosphorus remaining
on this acre was $40 pounds.
Plot 5 only further strengthens the
argument that Brookings county soils
respond wonderfully to the application
of phosphorus. This large increase in
yield and profit on investment was OBJ
tanned without the application of or
ganic matter; only phosphorus in an
available form. Citizens should take
warning, however, from the appalling
decrease in humus content of South
Dakota soils, and realize that they are
nearing the limit beyond which
profitable returns can no longer be OBJ
tanned without first looking to the sup
ply of organic matter and should care
fully save and return all manure and
crop residues to the land.
A summary of the above may be
in the following table: