Gums, Resins, 



394 



[NOVEMBHR, 1910. 



lake. Occasionally an Island of coffee 

 colored water appeared boiling and 

 swirling on the inky surface of the Rio 

 Negro; but of blending there seemed to 

 be none. 



MANIHOT RUBBER TREES. 



(Prom the Agricultural Bulletin of the 

 Straits and F.M.S., Vol. IX., 

 No. 8, June, 1910.) 



The Effect of Nitrate of Soda Upon 

 the Flow of Ceara Latex. 

 Prom the time that plantation rubber 

 first came to the front we have been 

 steadily advocating the necessity of 

 adequately feeding the trees by means of 

 fertilisers, first of all to replace that 

 which you take away in the milk, and 

 secondly to try and increase not only 

 the yield of the milk, but the percentage 

 of the rubber contained therein. To 

 show how correct we were in our ideas, 

 we produce the following from Bulletin 

 No. 19 of the Hawaii Experimental Sta- 

 tion. The author of this brochure, which 

 is entitled " Experiments in tapping 

 Ceara Rubber Trees," is Mr. E, W. Wil- 

 cox, Special Agent in charge of the 

 Experimental Station. The experiments 

 were arranged by Mr. Wilcox in consul- 

 tation with Mr. Hosmer, then Territorial 

 Porester, and the actual tapping was 

 done by Mr. Q. Q. Bradford, Assistant in 

 Rubber Investigations, and the labourers 

 under his direction. In his report Mr, 

 Wilcoxacknowledgesthe active co-opera- 

 tion of the directors of the four rubber 

 plantations on Maui in allowing their 

 trees to be experimented on, and in fur- 

 nishing the labourers and accommoda- 

 tions for Mr. Bradford when carrying 

 out the experiments : — 



"While fertilisers have been used in 

 rabbet' plantations for increasing the 

 growth and vigour of rubber trees, we 

 have found no record of experiments to 

 determine the possibility of increasing 

 the flow of latex temporarily during the 

 tapping period. It is apparent that if 

 the flow can be onsiderably increased 

 by the application of a quick-acting fer- 

 tiliser, economy will be secured in the 

 operations of tapping and collecting 

 latex. The first experiment with nitrate 

 of soda was carried out at Keanse, Maui, 

 on Ceara rubber trees averaging 14 in. 

 in circumference. A uniform series of 

 trees was found and divided into three 

 groups which received \ lb., | lb., and no 

 nitrate of soda respectively. Before 

 applying the nitrate of soda, the yield of 

 the whole group of trees was tested by 



means of uniform tapping. The weight 

 of dry rubber from three trees which 

 received £ lb of nitrate of soda eack was 

 2-3 oz.; from three trees which received 

 i lb. of nitrate of soda 1-3 oz.; and from 

 the three unfertilised 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 raining 

 during the experiment, which exteuded 

 over a period of about two weeks, and 

 the nitrate of soda was therefore rapidly 

 dissolved and utilised 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 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 indicat- 

 ed 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 fertiliser had been 

 applied. The flow of latex was, how- 

 ever, in all cases somewhat more vig- 

 orous from trees which had received 

 nitrate of soda, and coagulation of rub- 

 ber 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 \ lb. nitrate of soda per tree. In 

 this case the soil was moist at the time 

 of the application of the fertiliser, and 

 no irrigation was applied duriner 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 wa9 con- 

 sidered sufficiently important to be put 

 to further test on rubber trees neai the 

 station offices. These trees were about 

 11 in. in circumference. Prom one group 

 of five trees 0-9 oz, of dry rubber was 

 obtained in three days, before applying 

 the nitrate of soda, and 1-3 oz. from the 

 same trees, in three days following the 

 application of the fertiliser. 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 the 



