112 
FLORIDA STATE HORTICULTURAL SOCIETY 
and by so doing to ascertain if it were 
possible to reduce the cost of the Irish 
potato fertilizer now on the market, 
without diminishing their crop produc¬ 
ing power, I used the following ma¬ 
terials : 500 pounds of acid phosphate; 
200 pounds of sulphate of potash; 500 
pounds cotton seed meal, for the “nor¬ 
mal” mixtures mentioned. I used mul¬ 
tiples of that, namely, one and a half 
times, and twice that application to de¬ 
termine exactly how large an application 
was possible with economical results, 
and then from different plots I omitted 
consecutively one-half of each of these 
ingredients to reduce the cost of the fer¬ 
tilizer without interfering with the crop. 
The first important consideration is 
that this so-called application varies 
very materially from the usual potato 
fertilizers. It contains approximately 
four per cent, of phosphoric acid, three 
per cent, of nitrogen and eight per cent, 
of potash. The result of the application 
of this mixture gave me the following 
yields of crop: 
The normal application produced 
per acre 3576 pounds of market 
potatoes. The one and a half normal ap¬ 
plication produced 3390 pounds of mar¬ 
ket potatoes. The double normal appli¬ 
cation produced 3240 pounds of pota¬ 
toes. The one-half normal phosphoric 
acid produced 2718 pounds. Reducing 
the nitrogen one-half gave 2160, and re¬ 
ducing the potash one-half, 2076. The 
facts, therefore, that seem to be demon¬ 
strated are: First, that the normal appli¬ 
cation contains as large a quantity of 
the different fertilizers as can be profit¬ 
ably used, and that neither by increasing 
or diminishing the application do we in¬ 
crease the crop. As a matter of fact, the 
bdst yield was that obtained from the 
normal application, and by increasing 
one-half we obtained really a smaller 
crop, showing that the crop-producing 
power of that soil cannot be increased 
by increasing the fertilizer. Neither 
one of the three constitutents could be 
diminished to any considerable degree 
in this mixture without very materially 
decreasing the crop. By dropping out 
one-half of the cheapest ingredient the 
crop fell off, and dropping one-half of the 
potash application the crop fell from 
3576 to 2076, or fifteen hundred pounds 
exactly, by reducing the amount of pot¬ 
ash one-half. 
There was one other interesting point 
considered in connection with this same 
crop. Two check plots were planted, 
one of them without any fertilizer what¬ 
ever, the land being new land, and the 
result of this test showed the extreme 
variability of the soil itself, and there¬ 
fore, the uncertainty of results. One of 
the check plots yielded 1218 pounds of 
potatoes, and another plot, only a few 
yards away and apparently of the same 
soil, produced only 455 pounds, or a dif¬ 
ference of seventy per cent, with no ap¬ 
parent difference of soil, the result show¬ 
ing an extreme difference for which 
there is no explanation. The average 
yield of potatoes on the different plots 
was approximately 108 bushels per acre, 
showing a fair yield. 
It seems to me that these points are 
worthy of consideration, particularly in 
view of the fact that they differ in many 
respects from the actual practice to-day 
of most of the large potato growers, par¬ 
ticularly those in the Marion county and 
St. Johns county sections. But the soil 
on which the tests were made were of 
the better class of mixed pine lands, and 
although the results could not apply to 
