PRESS BULLETIN No. 85.
Florida Agrlcullural ExperimeMn Slalon.
FERTILIZER EXPERIMENTS WITH COTTON.
BY A. W. BLAIR.
During both seasons here referred to, the experiments were conducted
on second-quality high pine land, and Sea Island cotton seed was planted.
The experiment field was divided into tenth-acre plots, which were fertilized
with a variety of fertilizers in varying amounts. The following mixture
was taken as the standard for an acre:
200 pounds of acid phosphate (14 to 15 per cent.)
150 pounds of bright cottonseed meal.
50 pounds of muriate of potash (48 to 50 per cent.)
The quantities of these materials were increased -and decreased singly
and collectively within reasonable limits. Other materials were also tried;
but they did not give any better results, and in most cases were not so
good. If it is desired, kainit may be substituted in the above formula for
the muriate.of potash; in which case four times as much kainit as muriate
should be used to have the same amount of actual potash.
SOME RESULTS IN 1906.
(1) In 1906 plot 7, which received the standard, yielded an increase
over the plot that received no fertilizer of about 340 pounds of seed cotton
per acre. If we assume that this was worth 6c per pound, we have $20.40
as the gain, which was apparently due to the 400 pounds of fertilizer, for
the two plots in question were side by side. The cost of the 400 pounds
of fertilizer would probably not much exceed $5.50, thus leaving a net gain
of about $14.90 per acre.
(2) Plot 19, which received this mixture at the rate of 600 pounds
per acre, yielded at the rate of 150 pounds of seed cotton per acre more
than the standard plot, and this was the largest yield of any of the plots
in 1906. This increase, according to the price assumed, would be worth
$9.00, while the additional 200 pounds of fertilizing material would cost
about $2.75, leaving a net gain over the standard of $6.25 per acre; and a
net gain of $21.15 over the unfertilized plot.
(3) When, however, we put on 800 pounds per acre, that is, double the
standard (plot 20), the yield was not quite as good as with 600 pounds of
fertilizer. This would seem to indicate that there is no profit in applying
much, If any, more than 600 pounds per acre of a fertilizer of the grade
March 18, 1908.
(4) When only one-half the standard amount was applied, that i:,
200 pounds per acre, there was a falling off from the standard. The net
gain from plot 18, which was thus fertilized, was about $12.25 more than
the unfertilized plot, and $2.65 less than the standard.
SOME RESULTS IN 1907.
The results for the past year are not as conclusive as those for 1906,
owing to the injurious effects of the root-knot (for a description of this
disease see Farmers' Bulletin, No. 302, U. S. Dep. of Agr.); though here,
as in 1906, plot 19, which received 600 pounds per acre, gave the largest
yield of any (800 pounds of seed-cotton per acre); while plot 18, which
immediately adjoined -it, and received only 200 pounds of fertilizer (half
the standard) per acre, yielded nearly the same as in 1906 (350 pounds per
acre). It is especially significant that these two plots, lying side by
side, should give results which correspond so closely, plot for plot, for the
two years; since the experiment was conducted in Columbia county in 1906,
and in Alachua county in 1907.
The facts so far seem to indicate plainly that there is profit in applying
400 to 600 pounds per acre of a complete fertilizer on poor grade pine land,
but .that to go much beyond this amount is not profitable. That the prac-
tice, which is still quite prevalent, of putting on 100 to 200 pounds per
acre of a poorly balanced fertilizer (such as cottonseed meal or kainit), is
unprofitable, seems even more clearly indicated. There seem good reasons
for believing that the man who has been using 100 to 200 pounds of cotton-
seed meal or kainit per acre on cotton, may increase his yield to a profitable
extent by applying instead 200 to 400 pounds or more of a complete fertilizer.
State papers please copy.