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Copyright 2005, Board of Trustees, University
Mimeographed Report No. 2 February, 1937
University of Florida
SUIB-TROPICAL Z7" ::.RIiE STATION
Homestead, Florida Subtropical Experiment Station
COMPARATIVE EFFECT ON YIELD OF BLISS TRIUMPH POTATOES Homestead
OF DIFFERENT SOURCES CF POTASH AND INORGANIC NITROGEN
W. M. Fifiel and H. S. Wolfe
Experiments were started in the fall of 1933 to determine the comparative values of nitrate
of soda or sulfate of ammonia as the inorganic source of nitrogen in a complete potato fertilizer.
Also sulfate of potash and muriate of potash were compared to determine which was the better source
of potash for complete fertilizers. The resultant yield of Bliss Triumph potatoes was taken as the
criterion of efficiency. These tests were made on the marl soil of the East Glade farm.
The results of these investigations for the first three years of the test are herein reported.
In each of these three years, a complete fertilizer analyzing 5 percent ammonia, 8 percent phosphoric
acid and 5 percent potash was used as a base. The first year it was applied at the rate of 2000
pounds per acre, and in the second and third years at the rate of 1500 pounds per acre.
The composition of the fertilizers was the same in each case except for the two materials be-
ing t;-sted. In the nitrogen tests, comparing the nitrate and ammonia forms, the potash was all de-
rived from the sulfate form. In the potash tests, comparing the muriate and sulfate forms, the in-
organic source of nitrogen was sulfate of ammonia. The rest of the mixture was composed of cotton-
seed meal, fish tankage, superphosphate, and manganese sulfate.
Each year the source of seed, the size and spacing of seed pieces, and all cultural practices
were uniform for each treatment.
Nitrate of Soda vs. Sulfate of Ammonia
The data obtained thus far in these investigations have been condensed for this report into
the form given in Table 1
Table 1. Average yields of potatoes, in bushels per acre, from treatments comparing
nitrate of soda and sulfate of ammonia as inorganic sources of nitrogen in
Inorganic source of N. No. 1 No. 2 No. 3 & 4 Culls Total
Nitrate of soda 135 29 7 7 179
Sulfate of ammonia 168 29 5 9 210
Nitrate of soda 166 25 7 5 203
Sulfate of ammonia 174 25 7 9 215
Nitrate of soda 256 28 11 5 300
Sulfate of ammonia 249 29 12 6 296
These data show that in both of the first two years of the test, the sulfate of ammonia plots
outyielded the nitrate of soda plots. In 1933-34, the yield was significantly larger, amounting to
33 bushels more of No. 1 tubers per acre. In 1934-35, the yields were more nearly equal, with only
8 bushels per acre more for the ammonia plots. In 1935-36, the yields were reversed, but still with
but little difference-;-7 bushels of No. 1 tubers-between the two.
The data of Table 1 are the averages of the yields of the various replications of each treat-
ment. To present a clearer picture of the actual plot performances, the replicate plot yields of
No. 1 tubers for each season are given in Table 2. It will be noted that in 1933-34 three replica-
tions, and in 1934-35 four replications of each treatment were planted, while in 1935-36, the num-
ber of replications was increased to ten. It is usually considered that increasing the number of
replications of a test increases also.the significance of the average differences in yield obtained.
Table 2. Replicate plot yields in bushels per acre of No. 1 tubers, comparing nitrate of soda and
sulfate of ammonia as inorganic sources of nitrogen in complete fertilizers.
Inorg. source of N. Rl R2 R3 R4 R5 R6 R7 R8 R9 R10 Average
Nitrate of soda 132 134 138 135
Sulfate of ammonia 165 174 166 168
Nitrate of soda 203 226 103 131 166
Sulfate of ammonia 199 174 176 145 174
Nitrate of soda 254 256 269 207 245 274 262 266 260 270 256
Sulfate of ammonia 255 219 240 226 257 239 273 264 264 253 249
The data of Table 2 bring out some interesting facts. In 1933-34, all of the ammonia plots
outyielded the nitrate plots significantly. In 1934-35, however, only two of the ammonia plots
yielded heavier than the corresponding nitrate plots, while in the other two replications the
nitrate plots yielded higher. In this year there was no significant difference in favor of either
source. In 1935-36, the nitrate plots definitely outyielded the ammonia ones in four of the ten
replications, while the ammonia plots yielded definitely higher in three replications, and in the
other three replications the yields were practically equal. The results for this year also were
not significantly favorable to either source.
From this study of replicate plot performance it can be inferred that the first year the
sulfate of ammonia proved to be the best source of inorganic nitrogen, while in the second and third
year, no significant differences in yield were obtained between the two treatments. Furthermore,
more significance can be attached to the results of the second and third years, since more replica-
tions were involved.
As far as the tests have progressed, than, it is apparent that very little significant dif-
ference in yield has been obtained between the two inorganic sources of nitrogen. If there be a
small difference, it is in favor of sulfate of ammonia.
Sulfate of Potash vs. Muriate of Potash
The data obtained thus far in these investigations have bean condensed into the form given
in Table 3.
Table 3. Averacg yields cf potatoes, in bushels per acre, from treatments comoarinr the
sulfate and muriate forms of potash as sources of potash in complete fertilizers.
Source of Potash No. 1 No. 2 Nc. 3 & 4 Culls Total
Sulfate of potash 198 24 5 9 236
Muriate of potash 188 21 5 12 226
Sulfate of potash 174 25 7 9 215
Muriate of potash 164 26 9 1 8 207
Sulfate of potash 249 29 12 6 296
Muriate of potash 251 30 11 5 297
The differences in yield obtained in these tests were 10 bushels of No. 1 tubers in 1933-34,
in favor of the sulfate form, 11 bushe.l of No. 1 in 1934-35, also in favor of the sulfate form, and
2 bushels of No. 1 in 1935-36, in favor of the muriate form. A difference of only 2 bushels per
acre certainly is not significant, and it is doubtful if 10 bushels constitute a difference of much
In order that the relative importance of these differences can be more easily determined, the
replicate plot yields of No. 1 tubers are given in Table 4 for each season. Four replications of
each treatment were planted in the first two years, and ten replications the third year.
Table 4 Replicate plot yields in bushels per acre of No. 1 tubers comparing the sulfate and
Muriate forms of potash as sources of potash in complete fertilizers.
Source of Potash R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 Average
Sulfate of potash 197 197 178 220 198
Muriate of potash 198 173 168 210 188
Sulfate of potash 199 174 176 145 174
Muriate of potash 198 195 158 104 164
Sulfate of potash 255 219 240 226 257 239 273 264 264 253 249
Muriate of potash 234 255 264 244 251 244 249 267 256 250 251
The replicate yields of 1933-34 show one replication of the sulfate form practically the
same as, and three replications 10 bushels or more higher than the muriate form. The yields of
1934-35 show one plot of sulfate about the same as, one plot lower and two plots higher than the
muriate form. The ten replications of 1935-36 are divided equally in half, five favoring the miuriate
and five the sulfate forms.
As in the nitrogen tests, the data are not clearcut in attributing a higher efficiency to
either of the potash forms, nor are they conclusive as to the similarity in yield between the two
forms. It can only be pointed out that the results indicate in general that either form could be
used without greatly affecting the yield, although there appears to be a slight advantage in favor
of sulfate of potash.
HSW 3-2-37 200