MANGANESE CHLOROSIS OF PINEAPPLE. 
11 
an alkaline reaction and a pH value approximately 8.2-8.4 (that of 
carbonate of lime in water). 
AMOUNT AND FORM OF LIME IN THE MANGANIFEROUS SOILS. 
The amount of lime that is contained in manganiferous soils is of 
interest in connection with the reaction of these soils. Kelley 
reported manganiferous soils containing as low as 0.19 and 0.24 per 
cent of lime, and his iigures average about 0.05 per cent of lime. 
(See Table 1.) Soils analyzed by the writer .averaged about 0.4 
per cent of lime. (See Table 2.) 
An attempt was made to determine the presence of carbonate- in 
the manganiferous soils by the methods of Maclntire and Willis 
(34, 35) of treating the soils with 1-15 H 3 P0 4 , and by their later 
method with 1-15 HC1. Table 5 gives the results. 
Table 5. — Carbon dioxid content of the manganiferous soils by the method of 
• Maclntire and Willis. 
Laboratory soil number. 
Carbon Carbon 
, dioxid (1/15 dioxid (1/15 
H3PO4). HC1). 
Laborat 
ory 
soil 
number. 
Carbon 
dioxid (1 ,15 
EUPO4). 
Carbon 
dioxid (1 15 
HC1). 
635. 
636 
Per cent. 
0.03 
.04 
.02 
.03 
Per cent. 
0.04 
.07 
.06 
.06 
639 
640 
641 
Percent. 
0.04 
.03 
• . 03 
Per cent. 
0.03 
.05 
637 
638 
.06 
The quantity of carbon dioxid found in these soils was negligible 
and indicated the practical absence of carbonates, as soils that are 
known to be free from carbon dioxid produce considerable amounts 
of CO, owing to the action of acids on the soil organic matter. The 
values which were found for the hydrogen-ion concentrations of these 
soils proved the absence from them of calcium carbonate. The 
small quantity of lime in the soils is, therefore, probably present in 
the form of silicate and not as carbonate. Some of it may be present 
as a mangariite, as James (23) suggests. It will be shown later that 
the injurious effects of the manganiferous soils are due to deficiencies 
of iron in the plant and not to toxic effects of calcium manganite, as 
James further suggests. 
EFFECTS OF MANGANESE ON RICE. 
It has already been explained that the toxic effects of manganif- 
erous soils on pineapple plants are characterized by yellowing of the 
leaves, cracking open and decaying of immature fruit, which is 
stunted and red or pink instead of normal size and green, and by a 
general unhealthy appearance of the plants. The injurious effects 
of manganese are verv completelv described by Wilcox and Kellev 
(46) and by Kelley {28, 29, 30. 31, 3.2). 
6 Constituents other than lime do not appear of significance since they show little variation from the 
normal. 
