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The weight of dry rubber from three trees which received ^ lb. of 

 nitrate of soda each was 2-3 oz.; from three trees which received 

 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 54 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 O-Qoz. 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 ^ 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 

 they will favour us with the results of their experiments. TROPICAL 

 LIFE, March, 1910, (P. 53). 



