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hills, as is very frequently the case with the more important beds, 

 they are apt to drain too easily and become too dry in times of 

 drought, while the soil is so light and friable that it washes away 

 readily during the rainy season. In some estates considerable areas 

 have been planted on sandstones and the cacao trees have grown very 

 well at first, but the soil will become exhausted in a few years if 

 manuring is not resorted to. 



Almost any manure will enrich a light sandy soil, but lime and 

 basic slag will probably prove the most effective. 



East of Sangre Grande much of the cacao grown on the higher 

 ground is in soil rather too light to give the best results without 

 manuring. 



All the main sandstone beds have been mapped in those parts of 

 the island that have been surveyed geologically. 



(6.) The Tertiary limestones form the best cacao land in Trinidad. 

 The advantages they possess may be summed up as follows : they 

 form fairly porous soils, but with sufficient bases for all the require- 

 ments of the trees, the percentage of lime is, of course, high, they 

 occur in well marked and often steep ridges which drain well and 

 easily and yield good supplies of water, and the rock disintegrates 

 irregularly leaving blocks and masses amid a lighter friable soil, thus 

 preserving the surface from being washed away and producing an 

 ideal mechanical environment for the roots to spread in. Admixture 

 with argillaceous or arenaceous material is usually appreciable, and by 

 the solution of the lime carbonate this material becomes gradually 

 concentrated on the surface, so the actual soil does not contain an 

 excess of lime to the exclusion of other material of importance to the 

 growth of cacao. 



Manuring with lime is, of course, unnecessary, and forking 

 round the trees should- not be required, but basic slag and farmyard 

 manure might be used with effect on many estates. 



The best instances of cacao estates on the Tertiary limestones are 

 in the Montserrat Hills, which are due to a great outcrop of the 

 coralline and shelly limestone. Brigand Hill and Tamana are of the 

 same material. Smaller and more compact limestones, occupying a 

 higher horizon, have been mapped among the clays between the 

 Cunapo and Sangre Grande rivers and in the Manzanilla district : 

 they form sharp ridges covered with a somewhat argillaceous soil, and 

 the cacao planted on them appears to flourish. 



The carbonaceous rocks of the Tertiary Series do not cover suffi- 

 cient areas to make their outcrops important as soil-forming recks, 

 but the presence of carbonaceous matter in bands of clay and sand- 

 stone must help in some cases to lighten the soil. 



Outcrops of porcellanite, i.e., clay burnt by the spontaneous 

 combustion of underlying or intercalated bituminous or lignitic bands, 

 have proved in some cases excellent places for gi owing cacao. The 

 rock disintegrates into a rich heavy soil containing all the basic con- 

 stituents of the unburnt clay, mingled with hard fragments of 

 unaffected porcellanite, which keep the soil rubbly and prevent it from 

 becoming too stiff and impervious. As the outcrops always form well 

 marked ridges or hills, they drain freely. East of Sangre Grande 

 there is a good instance of such an outcrop planted with cacao. 



