20 SOIL REQUIREMENTS OF THE COCOA TREE 



starved, its productive powers are decreased, and death 

 follows, either through lack of nutrition or disease, for 

 if an epidemic be present a tree in a bad state of health 

 is more likely to be seriously affected than a healthy 

 one. 



Characteristic Root-system of a Cocoa Tree. Plate 3 

 well illustrates the characteristic root-system of a cocoa 

 tree. Although only seven years of age the " tap " 

 root was 8 ft. long, and many of the extremities of the 

 so-called surface-feeding roots were 12 ft. distant from 

 the trunk. The cocoa tree develops an unusually long 

 "tap" root as compared with that of many other 

 species of trees of similar size. This amply demon- 

 strates how very necessary it is for the cocoa planter to 

 investigate the character of the sub-soil before deciding 

 upon a site for his plantation. A water-logged sub- 

 soil is quite as detrimental to the tree's development as 

 a hard, stony one ; stagnant water destroys the hygienic 

 conditions which are so essential for healthy root growth. 

 Roots in such areas are more subject to fungoid attacks, 

 as will be shown in the chapter devoted to pests. 



Biological Condition of Soil. The quantity of plant- 

 food available in a soluble form is largely affected by 

 the number of nitrifying and other bacteria present. 

 Under favourable conditions these micro-organisms act 

 upon the nitrogenous compounds of organic matter 

 which are present in most soils, changing them into 

 ammonia and ultimately to nitrates, in which state they 

 form a soluble plant-food. For the life and multiplica- 

 tion of soil-bacteria, air, moisture, and heat are essential. 

 Water-logged land is invariably sour and inadequately 

 aerated, conditions which are inimical to the life of 

 soil-bacteria . Drainage operations would probably render 

 such lands fertile, but this operation should of course 

 depend upon the necessary expenditure. It will in most 

 instances be found more economical to choose a better 

 site. 



Soil Moisture. Stagnant water must not be confused 

 with soil moisture, for a humid soil is a most valuable 

 auxiliary to successful cocoa cultivation. The soil's 

 power of retaining moisture is largely dependent upon 

 the amount of organic matter which it contains. Light, 

 sandy soils are invariably lacking in this respect, and 



