150 COCOA 



CHAP. 



manure, either cattle- or sheep-dung, great quantities 

 being applied at the beginning of the rainy season. 



We see, therefore, that close planting and careful 

 tillage and manuring are considered necessary where 

 cocoa is grown without shade ; while in countries where 

 shade trees are used, the planting is generally wider and 

 the tillage and manuring often neglected when once the 

 trees are established. These facts indicate that in these 

 countries the shade trees must do what is done by man 

 in Grenada. 



We have already referred to the remarkable fact 

 that in every country one or two kinds of trees are 

 regarded as being the most suitable as shade trees. 

 Another fact is not less important : the Erythrinas of 

 Surinam and the Antilles, Venezuela and Java, the 

 Ingas of Venezuela, Central America and Ecuador, the 

 Gliricidias of Central America, the "saman" of Venezuela, 

 the Albizzias of Java and Ceylon, all belong to one 

 order of plants, the so-called leguminous plants (Legu- 

 minosae). Plants of this order have long been recognised 

 as soil improvers on account of their power to increase 

 the amount of nitrogen. 



In view, then, of the facts (l) that the growing of cocoa 

 without shade trees is, generally speaking, unsuccessful 

 when the soil is not tilled and manured thoroughly, and 

 (2) that tilling and manuring are omitted in most 

 countries where shade trees are used, we may conclude 

 that the use of the shade trees is in the first place the 

 improvement, or at any rate the conservation, of the 

 good qualities of the soil. As they belong to the 

 leguminous order of plants, the shade trees enrich the 

 soil with nitrogen and make it friable with their 

 extensive root -system, while they afford humus by 

 means of the fallen leaves and flowers, and preserve the 

 humus and the texture of the soil by the shade which 

 they afford. 



It is a well-known fact that in tropical countries an 

 unshaded soil, exposed to the direct influence of the rays 

 of the sun, rapidly deteriorates. For instance, places 



