April 1, 1913.] 



THE INDIA RUBBER WORLD 



363 



TESTING OF GERMAN EAST AFRICAN RUBBER 

 SOILS AND PRODUCTS. 



r^URING his visit in 1911 to German East Africa, Dr. Eduard 

 ■*-^ Marckwald, of Berlin, in addition to investigating actual 

 conditions on many points (as reported in The India Rubber 

 World, .March, 1912, p. 269) laid the foundation of researches, 

 which have since been more or less completely carried out, par- 

 ticularly as to fertilizing agents. 



These tests, made in East Africa, are fully described in the 

 latest quarterly report of the Colonial Rubber Section of the 

 Henriques Laboratory, Berlin. In making them three samples 

 of chemical compounds, weighing 145, 185 and 145 pounds, were 

 prepared, with various proportions of sulphate of potash, super- 

 phosphate, bone meal and sulphate of ammonia. In a fourth 

 sample the first of the agents named was omitted ; the sample 

 weighing 100 poiuids. These samples were incorporated with 

 the soil by a thorough mixing, one field being left unfertilized, 

 for comparison with the three others. For convenience of hand- 

 ling, these samples were each divided into three. 



According to the report of the Henriques Laboratory, the re- 

 sults obtained are by no means uniform or conclusive as to the 

 effects of artificial fertilization. This fact, it is added, should 

 cause no surprise, as experience with salts and other fertilizers 

 has often shown them in virgin soil, to be directly prejudicial, 

 or to have no effect. The above-named tests were unofficial, 

 but official tests have led to similar conclusions. 



Apart from the question of the effects produced by artificial 

 fertilization, the report urges that results obtained show German 

 East African plantations to be in a position to deliver first class 

 rubber, adapted for all technical requirements. The German 

 Potash Syndicate contributed financially to the carrying out of 

 the above-named experiments. 



SOILS FOR RUBBER. 



The experiments made in Germany by Dr. Wohltmann, of 

 Halle, and Dr. Marshall, dealing with the properties of South 

 American soils, indicate that the demands of rubber plantations 

 for nutriment from the soil are not very exacting; the samples 

 of South American soils showing only an extremely small pro- 

 portion of nutritive substance. The results of experiments have 

 been reprinted from the "Tropenpflanzer." 



Other experiments indicate the importance of fineness and 

 deepness in soils intended for rubber cultivation. Heavy soils, 

 of the nature originally preferred, have given relatively unfavor- 

 able results. Soils in West Africa, Ceylon and Sumatra, which 

 had at first been condemned on account of their low proportion of 

 nutriment, have now been approved for rubber. 



SAMPLES EXAMINED. 



Samples of rubber received from East Africa included two 

 of Manihot rubber, which, after being treated, proved to be a 

 first-class product. 



.\n interesting group of five samples was received from Mr. 

 R. Fyffe, director of the Botanic Gardens. Uganda. One sample 

 was of Clitandra Orientalis and showed good working qualities, 

 while a sample of Hei'ea rubber was very pure and proved in 

 working equal to wild Para soft cure. A third sample of 

 Kickxia, coagulated with tannic acid, was very clean ; producing 

 a good rubber after normal working. Another sample of Mani- 

 hot, tapped according to Mr. Fyffe's process and coagulated 

 with water, proved well vulcanized even after an hour's heating. 

 It would not dissolve (a fault common to Manihot rubber) ; the 

 quality only proving a better class of second grade. The fifth 

 sample was of Landolphia Davei, which likewise was perfectly 

 clean, and was coagulated with acetic acid, but could only be 

 designated as second grade. Its working qualities corresponded 

 with what might be expected from its origin. A sample from 

 Togo was good and fully equal in value to the best East African 

 grades. From Kamerun a large number of samples was re- 



ceived, produced by various methods of coagulation. In addi- 

 tion a sample of Kickxia came to hand from the Gold Coast 

 Botanic Station. 



Jn all, 63 crude rubber samples were examined. The work of 

 the Laboratory was, however, not confined to rubber; castor 

 seeds from New Guinea, and other tropical products having also 

 been dealt with. 



Other subjects handled included the determination of albumen 

 in rubber, on which the work of the laboratory is complete, and 

 the results of which will soon be published. 



RUBBER CULTURE IN SOUTHERN ASIA. 



IN a recent discussion of the above question in the "Tropen- 

 * pflanzer," Herr Emil Helfferich, of Hamburg, supplemented 

 his former investigations in that direction. Continuing its earlier 

 review of Herr Helfferich's work, the "Annales de ITnstitut 

 Colonial" of Bordeaux remarks that plantation rubber has now 

 taken possession of the market; everything pointing to its soon 

 occupying the leading place. The first yields had aroused con- 

 siderable enthusiasm, the most fantastic calculations having been 

 made as to the future of the plantations. The results achieved 

 and the analysis of the reports published by some companies, 

 today allow of a more just appreciation of the value of these 

 enterprises, and of formulating some rules as to the organization 

 of rubber plantations. It is no longer a question of the varieties 

 to cultivate, Hevca more and more replacing all others ; vines 

 and Manitoba being almost abandoned on the African continent, 

 in the same way as Caslilloa and Ficus are in Southern Asia. 



Hevca plantations, it is remarked, should only be established in 

 well drained soil, freed from the roots of old trees, or ligneous 

 debris, which might afford a home to that dreaded parasite, the 

 fames scmistolus, which attacks the roots. Some of the best 

 known estates, such as Batu Caves, Glenshiel, Highlands and 

 Lowlands, Federated Malay and Vallambrosa, have had to make 

 considerable sacrifices in combating this pest. 



GENERAL PLANTATION REQUIREMENTS. 



In the choice of seeds, it is necessary to select those from 

 healthy trees, in regions free from disease, at an altitude and 

 under a climate as near as possible to those of the plantation 

 contemplated. 



As to distance, opinions are divided as to whether it is best 

 to give the trees enough space for them to attain their full devel- 

 opment, or to place them close together, in order to better utilize 

 the soil, and thus facilitate the work of the plantation. An 

 average distance of 26 feet is recommended by Herr Helfferich, 

 making about ISO trees to the acre. This number of trees would 

 be subject to reduction where there is risk of disease being 

 propagated or of yield diminished. 



As to interplanting, Java and Sumatra, it is added, have advan- 

 tages over Malaya in "Robusta" coffee, but this does not grow 

 uniformly well. It needs a deep soil rich in humus, and ought 

 to be planted at same time as the Hevea. 



English planters, it is remarked, favor clean weeding as a pre- 

 ventive of parasitical diseases, but it is calculated to do harm 

 to the soil in plantations on sloping ground. Dutch planters, on 

 the other hand, seek to avoid this result by covering the soil with 

 vegetation, which impedes the growth of weeds and increases 

 the quantity of azote which would be utilized by the Hevea. 

 This system, however, renders it more difficult to combat diseases 

 attacking the roots ; the managers of the Kuala Lumpur and 

 Glenshiel estates having pulled up the Passiffora and other plants 

 which covered the soil of their plantations. 



Excessive pruning favors the growth of the trunk and the 

 widening of the top of the tree, but it exposes the tree to the 

 action of the wind, and cutting should therefore be practised 

 with caution. It should, however, be recalled that the yield in 



