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The weight of dry rubber from three trees which received y 2 lb of 
nitrate of soda each was 2-3 oz.; from three trees which received' U 
lb. of nitrate of soda 1-3 oz.; and from the three unfertilized trees 1-2 
oz. The nitrate of soda was placed in the soil at a depth of 3 or 4 in 
and at some distance from the trunk, around each tree, where it 
would most quickly become available to the roots. The weather was 
rainy during the experiment, which 'extended over a period of about 
two weeks, and the nitrate of soda was therefore rapidly dissolved 
and utilized by the tree, or washed away in the drainage water. The 
effect of the nitrate of soda upon the flow of latex was manifested 
within forty-eight hours. 
A similar experiment was made on rubber trees growing on 
Tantulas, averaging about 12 in. in circumference. The soil about 
these trees was very loose and porous, and at the time when the 
nitrate of soda was applied, was unusually dry. After applying the 
- nitrate of soda the soil was thoroughly irrigated. The results from 
tapping these trees indicated that the nitrate of soda was almost 
entirely washed away by the heavy irrigation, so that little effect was 
noted in the amount of rubber obtained from trees to which the 
fertilizer had been applied. The flow of latex was, however, in all 
cases, somewhat more vigorous from trees which had received nitrate 
of soda, and coagulation of the rubber from the latex took place more 
promptly. In a subsequent test, in the same locality, upon other 
trees, the yield of rubber was doubled by the application of l / 2 lb. 
nitrate of soda per tree. In this case the soil was moist at the time 
of the application of the fertilizer, and no irrigation was applied 
during the experiment. Under ordinary conditions, on the windward 
side of the islands, the soil is sufficiently moist at all times to render 
the nitrate of soda promptly available. 
The matter of the influence of nitrate of soda upon the flow of 
latex was considered sufficiently important to be put to a further 
test on rubber trees near the station offices. These trees were about 
II in. in circumference. From one group of five trees 0-90Z, of dry 
rubber was obtained in three days, before applying the nitrate of 
soda, and 1.3 oz. from the same trees, in the three days following the 
application of the fertilizer. In this case each tree received l / 2 lb. 
nitrate of soda. On another group of five trees the yield of rubber 
during the three days the nitrate of soda was applied was 0.9, and 
during the three days following its application 1.2 oz. It appears 
from these experiments, that the flow of latex may be temporarily 
stimulated by applying nitrate of soda. It now remains for the 
planters to determine the exact economy of the method by applying 
it on a large scale as soon as rubber trees become mature.” 
Such results should, and probably will, encourage planters of all 
varieties of rubber, Hevea, Castilloa, Funtumia, etc., to try the effects 
of nitrate of soda on their yields. When they do so, we trust that 
' ' the y w iH favour us with the results of their experiments. TROPICAL 
- y LIFE, March, 1910, (P.53). 
