Scientific Agriculture. 



430 



[May, 1912, 



agree with the variations in the Ceylon 

 crop generally. Thus there was an in- 

 crease in 1908-09, and a falling off in 

 1909-10, which continued ia 1910-11. 



On group C the heavy shade once 

 planted was never cleared. The most 

 notable difference between curve C and 

 curves A and B is the failure of the 

 cacao on group C to respond with the 

 increased crop to the good seasonal con- 

 ditions which evidently prevailed in 

 1908-09. It is clearly impossible to attri- 

 bute the decreased crop produced during 

 the last-named season to the want of 

 manure, because the unmanured group 

 B. showed just as great an increase in 

 crop in 1908-09 as did the manured 

 group A. The falling off can only be 

 attributed to excessive shade. The 

 effect of this shade appears later in 

 the case of group C than in that of 

 the other two groups, partly because 

 the dadaps were planted later, and partly 

 because they grew more slowly, doubt- 

 less owing to the fact that much of the 

 available space was already occupied by 

 coconuts. It will be seen that the last 

 state of these plots was even worse than 

 .the first. 



To sum up. We have a steady in- 

 crease in crop from 1903 to 1906 on all 

 three groups of plots, associated with 

 the clearance of excessive shade in 1902 

 and the planting up of dadaps in 1904-95. 

 The increase is more marked on the 

 manured than on the unmanured plots. 

 Associated with excessive density of 

 shade we have a marked falling off in 

 crop in groups A and B in 1906-07. This 

 was followed by an increase in 1907-08 

 after the excessive shade had been 

 cleared. During this period the crop 

 on group C remained nearly constant, 

 a circumstance which may be associated 

 with the later planting and slower 

 growth of the shade trees. By 1908 the 

 shade on these plots too became ex- 

 cessive, and the crop fell off accordingly, 

 until at the end of the period of experi- 

 ment the condition and crop of these 

 plots was as bad as at the beginning. 

 Finally from 1908 to 1911 normal con- 

 ditions of shade prevailed on groups A 



and B, and during this period the vari- 

 ations in the crop from these plots agreed 

 with those of the crop on Ceylon Es- 

 tates generally. I do not think that 

 any experiment could have been devised 

 which would have demonstrated the 

 effect of shade on the crop of cacao more 

 conclusively. Considering the crops on 

 the Experiment Station by themselves, 

 the only result which could possibly 

 be thought discrepant is the increase 

 in crop which occurred during the 

 season 1907-08, and immediately fol- 

 lowed the clearing of excessive shade, 

 is itself followed by a still greater 

 increase in 1908-09. But if we take 

 into account the exports of cacao 

 from Ceylon as a whole, it appears 

 that the season 1908-09 was a better 

 one for cacao than the season 1907-08, 

 a fact which sufficiently explains the 

 further increase of crop. 



Explanation of Diagram. 



The double line shows the average 

 annual crop per acre from the group of 

 manured plots A. The crop seasons are 

 marked at the bottom of the diagram, 

 and the actual number of good pods 

 obtained per acre is shown in the column , 

 at the left. 



The two unbroken lines shows simil- 

 arly the average annual crop from the 

 two groups of unmanured plots B and C. 



The broken line shows the export of 

 cured cacao from Ceylon. The export 

 is in each case that for the second year of 

 the two recorded at the foot of the 

 diagram. The amount in cwts. is to be 

 found by multiplying the figures in the 

 column at the left by 10. Thus the ex- 

 port for 1907 was 92,500 cwts. This 

 amount probably represents approxim- 

 ately the crop for the season 1906-07. 



The crop figures for the Experiment 

 Station from 1905 onwards are given for 

 the season July to June. Figures for 

 the seasonal crop are not available 

 before 1905. For 1903 and 1904 therefore 

 the crop shown is that from January 

 to December as given in the Controller's 

 Reports :— 



