30 TOBACCO CULTURE IN THE WEST INDIES 
PHOSPHORIC ACID 
The phosphoric acid content of the tobacco plant is so 
small, that this, although a most necessary plant foo'l. is 
seldom considered in tobacco culture. Nevertheless it has 
been found by experiments in Cuba, and indicated by ex- 
periments in Porto Rico, that phosphate fertilizers have 
more influence on the growth of tobacco than those contain- 
ing nitrogen or potash, or both. The reason for this has 
not been thoroughly explained; it may be that the phos- 
phorie acid in the soils in these two islands is so insoluble 
that the tobacco plant cannot supply its needs even though 
a chemical analysis shows large phosphoric acid content 
but undoubtedly its action is largely indirect. 
Unfortunately the experiments conducted in Cuba and 
Porto Rico cover a short period of time only and there is 
yet no published data to show the influence of phosphoric 
acid on the quality of tobacco. From the writer’s observa- 
tion and from statements of intelligent planters it appears 
that tobacco fertilized with large amounts of phosphoric 
acid or phosphate of lime burns extremely badly and pro- 
duces a dark colored, flaky ash. In view of this we would 
recomended planters to consider carefully whether they 
ean afford to sacrifice quality for gain in weight. It is 
clear that phosphoric acid must be applied but it is equally 
clear, from experiments conducted in nearly all civilized 
countries for the last forty years, that no more phos- 
phoriec acid should be applied than is necessary to actually 
supply the plant’s need, which for cigar tobacco is less 
than one half of one percent of the weight of the dried 
plant. 
