204 COCOA 



shown the following increases in 1912-13 as compared 

 with 1910-11 : 



A increased 10 per cent. 

 G 31 



U ii 



In order, therefore, to carry out experiments in cacao 

 cultivation, the natural yield of the plot appears to possess 

 many advantages as a basis for a working standard of 

 comparison. This yield will vary to some extent from 

 year to year owing to variations in the amount of rain- 

 fall, to the increasing age of the trees, and to other 

 causes. But this variation is considerably less than that 

 obtained from adjacent plots of the same area. 



On all well organized estates the owners keep a record 

 of the annual yield from the different fields, and make 

 field comparisons from year to year. A whole field is 

 usually too large an area for experiments, but there is 

 this advantage that the yield is already on record. At an 

 early stage in the experiments at River Estate a whole 

 field was placed under experiment. The trees were 30 

 years old and healthy in appearance, the soil was poor, 

 and the yield was abnormally low. The yield before and 

 after the experiments were made was as follows : 



YEAR RAINFALL YIELD 



Inches Bags 



1910 ... 74'86 ... 5-58 (natural yield) 



IQII ... 62*04 IQ'60 / , 



x (under 



\l\l ::: %% ::: TSf 



The normal rainfall in the district is about 80 in. 



One section in this field was kept as a control, and has 

 shown a rapidly diminishing yield, part of which is no 

 doubt due to insufficient rainfall. But it will be noticed 

 that a diminution in the rainfall has not affected the yield 

 in the manured plots to the same extent, and not at all 

 in the plot to which pen manure had been applied. This 

 beneficial influence of pen manure and mulch has been 

 shown in the experiments made in other parts of the 

 Colony. The yield from each plot in this field is shown 

 in Table H (p. 212). 



Attention may here be drawn to the marked increase 



