6 T BIN ID AD AND TOBAGO BULLETIN. [XVIIL 1. 



CACAO. 



NITROGEN CONTENTS OF CACAO SOILS PLANTED 

 "WITH & WITHOUT BOIS IMMORTEL SHADE. 



By Joseph de Verteuil, F.I.C, F.C.S., 



Superintendent of Field Experiments. 



At a meeting of the Cacao Committee of the Board of Agriculture, 

 held in December, 1917, Mr. W. C. Jardine asked that the nitrogen 

 contents of the soil be determined, in the Full and No Shade plots 

 of Field 5, River Estate, at the end of March, June, September, and 

 December respectively. The object of these analyses is to ascertain 

 whether there is a larger amount of nitrogen and nitrates in the soil 

 where the cacao trees are shaded with bois immortel {Erythrina spp.) 

 than where there is no immortel shade, and therefore whether the 

 immortel trees are beneficial to the cacao trees in producing a larger 

 supply of nitrogen in the soil. 



Samples of soil were accordingly taken during 1918 and analysed. 



These soils laiay be described as sandy loams, and their mechanical 

 composition was very similar. The samples contained an average of 

 91 and 93 per cent, of fine soil and 9 and 7 per cent, of coarse sand for 

 the Full and No Shade plots respectively. 



The composition of the air-dried fine soil for each quarter respectively: 

 was as follows : — 



March, 1918. 



Moisture 



Volatile matter and combined water 



Mineral matter ... 



June, 1918. 



Moisture 



Volatile matter and combined water 



Mineral matter ... 



September, 1918. 



Moisture 



Volatile matter and combined water 



Minera 1 matter ... 



December, lOlS. 



Moisture 



Volatile matter and combined water 



Mineral matter... 



