April, 1909.] 



341 



Edible Products. 



basic slag and sulphate of ammonia is 

 followed by profitable increases in crops, 

 but that the best results may be expect- 

 ed when pen manure or other suitable 

 organic manures are used in addition to 

 artificials. 



In 1906, all these cacao plots were 

 relinquished, for it was thought that 

 they had served their purpose, and a new 

 series was undertaken on similar lines 

 as those established in Dominica and 

 Grenada. Under the new arrangement, 

 all working expenses and cost of manures 

 are borne by the plot proprietors, 

 scientific advice being given as to treat- 

 ment by the officers of the Department. 

 Each plot is divided in five equal 

 sections (generally J-acre sections) and 

 is treated as follows :— 



Section. Mammal treatment, Cultural treatment: 



A. Control, no manure ... Annual forking. 



B. Stable manure, 5 tons ... do 



C. Mulching with grass or 



leaves, 10 tons ... No forking. 



D. Basic Slag, 4 cwt., Sulphate 



of ammonia, 1 cwt. ... Annual forking. 



E. Sulphate of potash, £ cwt., 



Sulphate of ammonia 3 



cwt. lime, 10 cwt. ... do 



It is too early yet to say much of the 

 results that have been obtained, but 

 accurate returns are being kept and 

 will be reported later. In section C. it 

 has been found that a mulch of 10 tons 

 per acre was hardly sufficient to cover 

 the ground thoroughly, and planters 

 who contemplate giving this system a 

 trial are recommended to increase the 

 quantity. The cost of cutting and 

 applying grass and bush from adjoin- 

 ing vacant lands is about 2s. 6d. to 

 3s. per ton. 



Plots of cacao have been established 

 at the Experiment Station attached to 

 the Agricultural School. The general 

 condition in 1906-7 of one of these plots 

 was much improved by two appli- 

 cations of grass in the form of a mulch. 

 At each mulch, about 100 bundles of 

 rough grass, of approximately 100 lb. 

 weight each, were used, and it was 

 calculated that the cost of cutting, 

 heading, and spreading this grass work- 

 ed out at 2ki. per bundle, or about 4s. 

 0d- per ton. 



Since mulching has been adopted, 

 there has been a very noticeable im- 

 provement in the vigour of the trees, 

 and they are less affected in the dry 

 season. The soil also appears to have 

 benefitted by this treatment, and 

 fungus diseases have been less pre- 

 valent 



CACAO EXPERIMENTS IN BRITISH 

 GUIANA. 



By Professor J. B. Harrison, c.m.g., 



M.A., F.I.C, P.C.S., F.G.S., 



Director of Science and Agriculture, 

 British Guiana. 



When the Government acquired On- 

 derneemiug many years ago some acres 

 of it were occupied by a recently 

 started cultivation of cacao. This was 

 gradually extended, and about 16 acres 

 are now occupied by this crop. Not 

 much attention seems to have been 

 given to the cacao plants, and when 

 in 1899 I was placed in advisory con- 

 trol of the Onderneeming School Farm, 

 the cacao plantation was in very bad 

 order and its yields were very low. 

 When first started, Oronoque trees 

 (Erythrina glauca) were planted closely 

 together through the cultivation to 

 supply shade. They had been allowed 

 to grow almost without restraint, and 

 the result was a more or less forest- 

 like growth, in the gloom of which the 

 cacao trees struggled for existence. But 

 although drawn up and more or less 

 dwarfed in their general development, 

 the cacao trees were singularly free 

 from disease. 



I commenced operations on the cacao 

 field in the year 1900 by cautiously and 

 gradually thinning out the Oronoque 

 trees, so that in the course of twelve 

 to eighteen months I had reduced their 

 number by three-fourths, the greater 

 part of those left standing being in 

 positions where they form a windbreak 

 or shelter-belt to the fields, whilst those 

 remaining sparsely scattered through 

 the cultivation had been severely prun- 

 ed. This resulted in letting in light 

 and air to the cacao, but in so gradual 

 a manner that the trees were not 

 injured by unaccustomed exposure. 

 During the four years preceding the 

 reduction of the shade the mean annual 

 yield was 1,064 lb. of cured cacao, whilst 

 during the succeeding six years the 

 annual crop has been at the mean rate 

 of 1,850 lb. 



After the cacao trees had become 

 accustomed to the altered conditions 

 under which they were growing, a 

 series of trials with artificial manure 

 was commenced. 



I realized that experiments of this 

 sort with fruit-bearing trees, such as 

 cacao, offered a far more difficult 

 problem for solving than do experi- 

 ments with sugar-cane. The individu- 

 ality of the trees appeared to me to be 

 a disturbing factor, and one that would 

 be exceedingly difficult to overcome, 



