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shown in the trend of the yield — curves of controls. The facts 

 have to be investigated. Results of utility could be possibly 

 procured after a number of years but on the lengths of the. period it 

 is difficult to hazard a guess. 



Some of the facts are being investigated on Tumbuk Estate 

 (Mr. F. H. Dale) and will, it is hoped, be communicated fi-om time to 

 time but the difficulties of any manager in executing work of this kind 

 are vei"y great. 



The case uf old coconuts presents a simpler issue. After a 

 period of years of bearing the palms reach a stationary maximum- 

 production-period which we may assume is a fairly long span ere 

 the loss of fruit due to oncoming senility supervenes. In the 

 absence of i"ecords, it would perhaps be safe to assume, that after 

 10 to 15 years, all the palms in any field of an estate would have 

 reached this stage or have so nearly approached it as to cause little 

 fluctuation, and now the disturbing factor so bafflingly difficult in 

 the young palm is excluded. Thus it becomes possible to procure 

 more comparable data of the yields of blocks of palms over a period 

 of time, the collection of which data constitutes the preliminary work 

 mentioned above as a basis on which to calculate the size of 

 expei-iments for the attainment of results of accuracy. 



Without going into the long explanation as to the particular 

 method it may be stated that this has actually been done on Gapis 

 Estate where by taking preliminary records of yield over a period of 

 six months, it was possible to initiate experiments on eight blocks 

 of 100 trees each, using two as controls, and one pair each for 

 the trial of three manures, in the detection of differences over 

 15 per cent. 



In Ceylon experiments have for some years been conducted on a 

 basis — not of absolute yield — but of proportionate increase in plot- ■ 

 yields from period to period, that is, that each plot used has been 

 used largely as its own control. There is little doubt that this 

 method provides information of great utility. Manurial treatment 

 to permanent crops is a cumulative business and records over a 

 period of years on blocks of palms irrespective of control plots gives 

 very useful information. In the Chilaw experiments I'ecently 

 published the yields from January to February in two consecutive 

 years were compared, the result of treatment being displayed in 

 proportionate increase in yield from January to February of one year 

 to January to February of the next year. The method given as in 

 vogue there is not without its utility in the detection of differences 

 of considerable magnitude, but there its utility (and in this 

 particular instance it is well illustrated) seems to end, for the yields 

 of the plots untreated show tremendous variation and the causes of 

 these are quite unexplained. It seems impossible to put any general 

 intei'pretation to the results obtained. ^^ 



