COMMERCIAL FERTILIZERS FOR 
POTATOES. IIL* 
W. H. JorpDAN, 
SUMMARY. 
(1) Experiments in potato growing conducted for four years 
on four Long Island farms with fertilizers varying in quantity 
from 500 lbs. to 2,000 Ibs. per acre show that on the average the: 
largest profit was realized from the use of 1,000 Ibs. 
(2) The so-called Long Island formula, 4, 8 and 10, proved to 
be superior to a potato formula, 7,4 and 10. 
(3) Experiments with varying quantities of potash gave results 
which do not justify the use of such large quantities of this in- 
egredient as are now being applied in potato growing by many 
Long Island farmers whose conditions are similar to those under 
which these tests were made. 
(4) It is clearly evident that a large supply of available plant 
food does not necessarily insure a satisfactory crop. Other con- 
ditions which largely pertain to culture, such as texture, humus 
and water supply, exercise a controlling influence, and when these 
conditions are unfavorable their effect is not overcome by heavy 
applications of fertilizer. 
INTRODUCTION. 
Experiments in the use of commercial fertilizers in growing 
potatoes were begun on Long Island in 1895. The results pre- 
viously reached have been reported in four bulletins, Nos. 93, 
*Reprint of Bulletin No. 187. 
