A FORTNIGHTLY REVIEW 



OF THE 



IMPERIAL DEPARTMENT OF AGRICULTURE FOR THE WEST INDIES. 



Vol. XVI. No. 405. 



BARBADOS, NOVEMBER 3, 1917. 



Price Id. 



CONTENTS. 



Page. 



Page. 



Aimatti) Dye .S51 



Bats as Guardians of 



Cotton 344 



Bougainvillaea Sports and 



Hybridr, 341 



Coco-nut Butter, How to 

 Keep Firm 345 



Correction 344 



Cotton and Wool Spun 

 from Glass 345 



Cuban Sugar Factory, A 

 Modern 339 



Departmental Reports ... 343 

 Fruit and Vegetables, 



Home Drying of 342 



Gleanings 348 



India, Agricultural Devel- 

 opment in 347 



Infertility under Trees .. .337 

 Insect Notes: — 

 The Pink Boll Worm... 34t) 



Insect Notes {Continwii.) 

 Tlie Black Weevil Borer 



of Bananas 

 The Sweet Potato Root 

 Weevil 



Items of Local Interest ... 



Limestone on Crop Yield, 

 Influence of 



Market Reports 



Mote. r Tractors ... 33;t. 



Notes and Comments ... 



Plant Diseases 



Plants Piiisonous to Live 

 Stock 



Rubber in Germany, Pro- 

 duction from Indigenous 

 Weeds 



Rul)l)er, Quality of Plant- 

 ation 



Salads and Spinach 



Sea Island Cotton Market 



Tomatoes 



347 



347 

 341 



345 

 352 

 351 

 344 

 350 



345 



344 



340 

 349 

 342 

 349 



Infertility under Trees. 



.ANY trees in the tropics, notably the tam- 

 |afind and the West Indian evergreen {Ficus 

 • nitida), are well known to cause infertil- 

 ity around them. It is quite impossible to grow 

 hardy grasses around a tamarind even at some 

 distance away from the spread of its branches. 

 Bamboos also are almost as bad in this particular. 

 Anyone will notice that a bamboo clump stands with 

 bare ground for some distance around it. 



One reason given for thi.s is that it is on account 

 of the shade. This does not seem valid, (1 ) 1 ( c; i s 



the infertility spreads further away from the tree 

 than its permanent shade, and (2) because many trees 

 giving just as dense a shade do not seem to affect the 

 soil in the same waj'. Another point to be considered 

 is that even after such trees, as a tamarind for instance, 

 have been uprooted and removed, the soil of the spot 

 still requires much care before its fertility under 

 ordinary crop is restored. Shade therefore, that is 

 the undue interception of the rays of the sun on the 

 soil, is not a sufficient explanation of the problem. 



The question as to what are the real causes of 

 this infertility produced by certain trees has been the 

 subject of investigation by the Agricultural Research 

 Institute, Pusa, India, the results of which have been 

 set forth in a paper by Mr. Jatindra Nath Sen in the 

 Agricultural Journal of India, for July 1917. 



A sample of soil one foot deep was taken from 

 under a tamarind tree. The soil of the upper six 

 inches and that of the lower six inches was placed 

 separately in cultivation jars, after all parts of the tam- 

 arind roots had been removed. A sample of soil from 

 a grass plot at a distance was similarly treated as 

 a control. Seeds of maize were then sown in all the jars. 

 In order to test whether fallen leaves or parts of the 

 tree were responsible for the infertility, tamarind 

 leaves and portions of roots were added to the soil in 

 .some jars of each set. 



The moisture of the soil in the jars was kept at 

 20 per cent, in every case. 



At the end of two months it was apparent that 

 all the plants in 'tamarind soil' were very sickly, while 

 those in 'grass soil' were vigorous. The addition of 



