28 
Different varieties of pineapples may vary somewhat in their 
sensitiveness to lime, but, as the Cabezona variety has been found 
showing chlorosis in asoil containing 3.30 per cent of calcium carbonate, 
this variety can not be considered more resistant than the Red Spanish. 
In only one case were the native varieties Caraquefia and Pan de 
Azucar found growing in a calcareous soil. This soil contained 21.77 
per cent of calctum carbonate and the plants were strongly chlorotic. 
At present the Cabezona and Red Spanish are the only varieties of 
pineapples grown commercially in Porto Rico. It is possible that 
the Smooth Cayenne and some other varieties which have poorer 
shipping qualities might prove more resistant. 
From the foregoing it appears that pineapples are almost as sensi- 
tive to calcium carbonate as lupines, which will not grow in a soil 
containing 2 per cent of calcium carbonate. 
Since calcareous soils containing a large amount of humus do not 
produce chlorotic plants, it might be thought that by raising the humus 
content of these soils they could be made to grow pineapples. In 
fact, applications of barnyard manure were found to produce some 
improvement in the plants. For most of these calcareous soils, 
however, it is impracticable to raise the humus content sufficiently 
high to render them suitable for pineapples. Probably heavy appli- 
cations of barnyard manure or other organic matter to soils contain- 
ing but 2 per cent of calcium carbonate would much improve the 
condition of the plants. 
In the following pages is described another means of overcoming 
the disturbances in the plant associated with the chlorosis, and of 
restoring the normal green (chlorophyll) to the leaves. Nevertheless, 
it is improbable that this treatment will be commercially successful. 
In the present condition of the pineapple industry in Porto Rico, 
where there are still large unplanted areas suitable for pineapples, it is 
not advisable to plant on soils which require extra, and fairly expen- 
sive, treatment to produce acrop. It is better to abandon the plant- 
ings of pineapples on these calcareous soils and put in crops which 
are adapted to this type of soil. 
The calcareous sands near the sea are well adapted to coconuts. 
On the sandy soils which do not contain an excessive amount of car- 
bonate of lime, gandules and citrus trees are found growing well. 
Tobacco does well on the calcareous soils which are not too near the 
sea. Itis advisable to plant these calcareous soils to one of the above 
crops rather than to pineapples which will require extra treatment 
to yield a crop. 
[Bull. 11] 
