THE FERTILITY OF SOILS IN THE TROPICS 425 



Bernegan [6] states that the cultivation of bananas 

 made enormous progress in Teneriffe, due to irrigation. 

 The Cavendish variety is principally grown, planted 10 ft. 

 apart, and heavily manured with dung (stable compost) 

 and guano. 



Artificial fertilizers, more particularly potash manures, 

 give good results in the banana culture in India [7]. 



The most important crop cultivated by the natives of 

 the Lake Victoria Nyanza districts is the banana, which 

 receives the greatest care and the largest amounts of 

 dung [8]. 



Lime is of very great importance to bananas, and 

 experiments in Panama have proved the great benefits 

 derived by the liming of soil in the cultivation of bananas 

 [i]; this is also proved by our own manurial experi- 

 ments. 



Phosphoric acid is of value, but potash must be sup- 

 plied particularly in liberal amounts. A number of fer- 

 tilizer experiments reported by J. M. Hattrick [9], as 

 carried out in Queensland and in Fiji, fully bear this out, 

 and the author quoted states that for every is. spent on 

 potash the planter received 6s. in return. 



With regard to the conservation of humus in banana 

 soils, it must be stated that a good deal is returned to 

 the soil by tne leaves and stalks of the plant after the 

 bunch has been cut. The method practised in Jamaica, 

 to cut the stalk into small pieces, is undoubtedly to be 

 preferred to the method generally practised in Queens- 

 land of chopping the stalk down, and allowing it to rot 

 near the stool of growing bananas. It is stated [5] that 

 one man can chop 100 stalks into small pieces in a day. 



The growing of green manure crops, like velvet beans, 

 Mauritius beans, etc., is practised in some localities, and 

 can be strongly recommended, as long as the cover-crop 

 is not allowed to grow too near the stools, so as to 

 prevent robbing the bananas of the necessary moisture. 



The only evidence of replanting old banana lands I 

 could find refers to Costa Rica, where periodical inunda- 

 tions keep up the fertility of the soil [10]. In that 

 country, as a rule, banana lands are replanted every six 

 to seven years, but in some cases, with flooded lands, 



