and Magazine of the Ceylon Agricultural Society. 



271 



careful experiment ; and the next few years 

 should produce an instrument which will be a 

 marked improvement on the present weapons. 

 Excellent work With regular shavings, as thin 

 even as '20-25 to the inch, have been done with 

 the gouge, the Farrier's knife, and with more 

 modern specially adapted tapping knives. It is 

 important to make certain of the periods which 

 should be allowed to elapse between tappings 

 in order to get maximum yields. After having 

 collected figures of yields on a large number of 

 estates it is difficult to lay down an absolute 

 rule as to the procedure which experience shows 

 to be the best. Carefully kept data on some 

 estates show that after a period of some three 

 months alternate days' tapping the amount of 

 latex per tree decreases to an amount which is of 

 less value than the cost of tapping, but after a 

 rest of two months the trees again on the fourth 

 or fifth tapping yield the maximum, which after 

 some 40 tappings begins to rapidly decrease. 

 The reverse of these observations is to be found 

 on other estates where accurate figures of 

 yields show that after continuous tapping for 

 some two or three years, the amount obtained 

 varies only slightly, never steadily decreasing. 

 The variation is caused by climatic conditions, 

 short periods of little or no rainfall reducing 

 the yield and periods of excessive rainfall pro- 

 ducing somewhat the same result. This is 



DUE TO THE RELATIVELY LESS ACTIVE FUNCTIONING 

 OF THE ROOTS 



owing to drought or excess of water. 

 Many planters believe in stopping tapping when 

 the trees are leafless, a period of some three 

 weeks each year. The experiments which have 

 been continuously carried on for some 18 months 

 by this department on 17-year old trees at Krian 

 show a slight decrease of yield during the 

 leafless period. The notion is also prevalent 

 that tapping should be discontinued during the 

 fruit-bearing period. The figures obtained at 

 Krian show a decrease during the time the 

 trees were in fruit, but no sufficient decrease to 

 seriously increase the cost of tapping. The 

 figures relating to these tapping experiments 

 will be published in the " Agricultural Bulle- 

 tin." Careful records have been kept of the 

 weight and bulk of latex each day from each 

 tree, and the ensuing weight of dry rubber. 

 The question of 



HOW FAR IT IS ADVISABLE TO REFRAIN FROM 

 TAPPING RUBBER TREES AFTER A PERIOD 



of tapping is one upon which planting 

 opinion differs very greatly. On some estates, 

 after a period of some weeks or months of tap- 

 ping, a period of about equal length is allowed 

 to elapse withaut tapping. On others and the 

 majority of places tapping is continued without 

 cessation, in some cases trees having without 

 any reduction of yield been tapped for 3.V to 4 

 years every other day without cessation. On 

 the question of daily or alternate days' tapping- 

 planters are also divided, and experience of 

 yields points somewhat to the advantage of the 

 latter practice. There is no physiological reason 

 why the tapping should cease during the loaf- 

 less or fruit-bearing period ; the cutting of the 

 small portions of the bark which tapping implies 

 being in the case of a tree of 20" or more in girth 



so slight an injury as to be negligible. The 

 best and simplest criterion for deciding how 

 long to continue tapping is found in keeping 

 a record of the amount of latex from each tree 

 from 1,000 trees or from a field. If these figures 

 show no serious and continuous decline, there 

 is no reason to stop tapping. On the other 

 hand when, after a series of tappings, say 40 

 or 50, the amount of latex obtained decreases in 

 a marked manner and this decrease is con- 

 stant, the yield being less and less, than it is 

 advisable to stop for a period of a month at least, 

 and not to begin again until by an experimental 

 tapping it is found that the flow is again large. 

 On one estate the tapping for a number of cuts 

 was habitually stopped when the yield had 

 attained the maximum, and after some weeks 

 tapping again produced less yield which in- 

 creased till the arbitary time of ceasing. This 

 method, which is adopted to a great extent from 

 fear of using too much bark, is most unprofitable 

 as it leads to stopping before the best yields 

 have been obtained. It is naturally wise to so 

 arrange tapping operations that it will not be 

 necessary to retap renewed bark for some con- 

 siderable period, but we do not yet know by 

 experiment in the Malay States what length of 

 ime is necessary for a healthy tree, carefully 

 tapped, to produce new bark containing a large 

 number of well-filled latex vessels. The time of 

 four years has been arbitarily fixed by some plan- 

 ters and their tapping schemes are arranged 

 in relation to that period. That four years, 

 three years, or two years are necessary for the 

 formation of bark suitable for tapping cannot 

 yet be definitely stated, but it is highly pro- 

 bable from isolated cases where such experi- 

 ments have been made that four years is 

 unnecessarily long. Experimental work and 

 observations on tapping and yield of rubber 

 made in Ceylon are unfortunately of little value 

 tor Malaya. The climate of Ceylon rubber dis- 

 tricts, with its periods of dry weather, is not 

 comparable with the conditions in Malaya, 

 where rubber trees are in active growth of root, 

 leaf and other tissues practically every day of 

 the year, and where, even when they are leafless, 

 the growth of trees is not entirely stopped. On 

 one estate in Perak the yield of dry rubber per 

 acre was 800 lb., a little less than 4 lb. per tree, 

 even though the trees were crowded together 

 220 to the acre ; this rubber was sold at an 

 average price of some 4s per lb. , thus realising 

 about £160 gross profit per acre, of which more 

 than 50 per cent, must have been net profit. 



Preparation of Rubber for the Market. 



There is still no agreement as to the best 

 form in which to prepare rubber for the home 

 market; block, crepe, sheet and biscuit are made 

 by different planters for different reasons. 

 One reason which makes it difficult for the pro- 

 ducer to make up his mind as to the best form 

 in which to make his rubber is that it is not 

 easy to find what the broker and the manufac- 

 turer like best. A big price for a break of crepe 

 gives the impression that this form is desired 

 and will fetch a better price than block or sheet. 

 Shortly after a purchase of block rubber at a 

 prico higher than the rest on the market seems 

 to imply that this kind of rubber is wished for. 

 The leading brokers, buyers and manufacturers 



