Vol. IX. No. 211. 



THE AGRICULTURAL NEWS. 



165 



the physical qualities of the soil luu.st be maintained by the 

 frequent use of manure, or by turning under a cover crop of 

 weed.s. As in California, some of the growers have an 

 impression tiiat stable manure makes the fruit coarse in 

 texture and of poorer keeping quality. The manure is applied 

 generally in the spring, but sometimes in the autumn. It is 

 dug into the irrigating basin around the tree or into the bottom 

 of the irrigating furrows. In .some groves, the manure 

 is applied in the basin round the tree every other year, 

 and in the years between, further away from the tree 

 in the bottom of deep furrows, in order to reach the 

 fine, distant, feeding roots. It is not practicable to discuss 

 the manuring que.stion further, as there is an endless variation 

 in the methods of application, and in the quantities of natural 

 and artificial manure in use. The variation in the quantity 

 of manure per tree will run from 40 ft), to 150 ft)., and in 

 chemical manure from 2 ft), to 10 ft)., depending on the nature 

 of the manure, the condition of the trees, and the general 

 practice of the grower. 



THE TONKIN RUBBER TREE. 



Information regarding the Tonkin rubber tree, or 

 teonon (BleekroJea tonkinensis), was given in the 

 Agricaltural News, Vol. VIII, p. 377. The additional 

 particulars which are presented below regarding this 

 plant are taken from I'Ayriculiurc Pratique des Pays 

 Cltauds for January and February, 1910: — 



The flowering of this plant takes place at two periods of 

 the year — ifarch to April and August to September; but 

 these dates vary to a .small extent with the latitude. The 

 fruits appear as small berries, which are green at first, and 

 become yellow-orange when ripe. At this stage, the fruit 

 opens in order to free the seed. The plant is reiiroduced 

 easily by means of these seeds, but it must be mentioned that 

 the fruits are much sought after by birds, so that the dissem- 

 ination of the plant by natural means is diminished to 

 a great extent. A certain number of seeds aie,, however, saved 

 by the fact that the fruits, while still on the branches, open 

 and drop the seed. An additional method of rejiroduction is 

 by means of numerous root bud."*. It is easily reproduced b}' 

 cuttings containing these. 



Up to the time of the discovery of this plant, the genus 

 BleeA-rodea included two species: B. insi'jnis. a native of 

 Borneo, and Ji. /iiadaf^asciriensis, a native of Madagascar. 

 Owing to various circumstances, and in consideration of the 

 close relationship of teonon to these, it was not thought worth 

 while to create a new genus. 



It was purely by chance that the natives gained an idea 

 of the value of the latex of jS. tonl-itiensis; thfir recognition of 

 this arose from a demand by several firms in Tonkin for rubber. 

 This caused the latex to be collected in ways which would 

 produce as much of it as possible with the least trouble. One 

 of the methods is to make cuts in the lower part of the trunk 

 and in the bigger brani'hes, to a height of about 10 feet. 

 A large number of these is made, on account of the idea 

 that the greater the number of the cuts, the greater 

 \nll be the yield of latex. As a matter of fact, the 

 quantity is lessened by this treatment, because the late.x- 

 bearing ves.sels are divided to such an extent as to 

 interfere with its natural flow. Another method, which is 

 also employed for rubber-yielding lianes, is to strip off large 

 portions of the bark. Finally, a means which is rougher 

 than either of these is to cut the plant into, pieces, and to 

 extract the rubber by holding one end of the portion so 



obtained over a slow fire; this causes the latex to become 

 mixed with the ordinary juice of the plant. 



In whatever way it may be obtained, the latex is collect- 

 ed in small ve.ssels, each made of an internode of the bamboo, 

 cut to a point at one end in order that the liquid may flow into 

 them more easily. The pieces of bamboo, with their contents, 

 are carried to the village, where they are boiled in water. In 

 this way, pudding-shaped pieces of rubber are obtained, 

 which, owing to the method by which they are prepared, 

 contain all the impurities at the middle. 



The latex is usually collected before the beginning, and 

 after the end, of the rainy season. The natives are inclined 

 to limit their labours to the second period, because they 

 consider that the yield is greater at this time. There may be 

 some reason for this opinion, on account of the fact that, at 

 the end of the rainy season circulation takes place more 

 rapidly in the plant by reason of its greater water content. 

 At any rate, it is certain that the plant is extremely sensitive 

 to seasonal changes, and gives yields which vary greatly 

 according to the latitude in which it grows. It is certain, too, 

 that the circumstances of temperature have a well-marked 

 action on the flow of latex from this tree. Trials appear 

 to have shown that the most abundant flow is obtained when 

 the shade temperature is between 24 and 28° C. 



The composition of the raw rubber is as follows : — 



Per cent. 

 Water 2832 



Ash 0-62 



Rubber GO-76 



Resin 3-67 



Foreign matters (by difference) 6-63 



In this anal^-sis, the amount of true rubber appears 

 small, but this is due to the large proportion of water in the 

 specimen examined, on aceoimt of the fact that this had only 

 been made three days before the analysis was undertaken. 



USES OF WEEDS. 



An article in the Tropical Agriadturist for February, 

 1910, contains a summary of the uses to which weeds may be 

 put. These are pre.sented as follows :-- 



Plants which are weeds under certain circumstances, may 

 under other circumstances have the following recognized 

 uses: — 



(1) The use as nitrogen plants grown for the purpose of 

 enriching the soil in this most important element. 



(2) As cover plants grown to .shade the soil and to 

 enrich it with added humus, but not necessarily with nitrogen. 



(3) Plants grown on .steep slopes in order to check wash. 



(4) Shade plants and wind-breaks. 



(5) Sand-binding plants, which prevent the spread of 

 shifting sands. 



(6) Climbing plants grown for the purpose of smother- 

 ing particular weeds. 



It must not be forgotten that weeds are also indirectly 

 of use to the agriculturist in that they often .serve to give an 

 indication of the type and (|uality of the .soil on which they 

 grow, and what is more important, their tendency to appear 

 after a crop has been jilanted often ensures that adeijuate 

 tillage will be practised for the latter, on account of the 

 disturbance of the soil that is entailed in removing them. 



Weeds are interesting, too, from an historical point of 

 view, for all plants that are now cultivated are derived from 

 wild forms that would, in an ordinary way, be regarded as 

 weeds. Closely connected with this is the fact that many of 

 them yield useful drugs, and some are even used as food. 



