THE CULTIVATION OF COCOA 161 



the effect of tillage, but it may be remembered that 

 the surface parts of the soil are always more or less 

 pressed together and are more exposed to the air 

 than the underlying parts, and that in this way the 

 different layers of the soil have a different composition. 

 Tillage makes the soil more uniform. Moreover, the 

 bacterial life in the soil is beneficially influenced by 

 aeration, and the number of bacteria increases. This is, 

 generally speaking, beneficial to the plants, because the 

 bacteria play an important role in decomposing the soil 

 and in making plant-food available. It is still more im- 

 portant that a special kind of bacteria should multiply 

 by the free access of air viz. the so-called " nitrifying " 

 bacteria, which oxidise the nitrogen of the nitrogenous 

 plant-food. In many cases also tillage certainly improves 

 the structure of the soil, but too great a value is often 

 attached to this effect. Tillage is frequently not 

 useful at all in this respect, and sometimes the effect is 

 even bad, as the structure of the untilled soil is better 

 that is to say, tillage sometimes pulverises the particles 

 of the soil too much, so that after a few showers it 

 becomes more compact than before. In the case of 

 heavy clay soils, however, this is not so much to be 

 feared when the soil is left divided in large lumps ; and 

 tillage, thus performed, may be very useful in improving 

 the structure of soils of this kind. 



In cocoa plantations the operation of tillage is 

 generally done in such a way as to leave Unforked a 

 space 3 to 4 feet in radius round each tree, while the 

 large roots of the tree are cut at this distance by means 

 of a sharp knife so as to obtain a clean wound. 



The best time for forking is, of course, the dry 

 season. When the rains begin to lessen, the time 

 has come for the planter to examine the soil carefully 

 to see whether its condition allows of forking. It must 

 not be too wet, for then the labourers are unable to 

 perform the work, and also the effect is not so good ; but, 

 on the other hand, the planter must be careful not to 

 wait too long, and not to allow the soil to get too dry, 



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