8 TEINIDAD AND TOBAGO BULLETIN. [XVIIL 1. 



not been utilised by the cacao plants or washed out of the soil by the 

 rains. It is so to speak the reserve of nitrates in the soil. This amount 

 although small in appearance represents 10^ lb. ot nitrate nitrogen 

 per acre and as a good average cacao crop for the Colony viz. 4 bags 

 per acre, removes from the soil in one year only 14 to 15 lb. of 

 nitrogen, it would appear to be ample for the crop produced, since 

 the formation of nitrates is continuous under favourable tropical 

 conditions such as exist in the field in question. It must not be 

 forgotten however, that a larger amount of nitrogen is required for the 

 production of new wood, leaves and the husks of the cacao pods. 

 This has been estimated by Marcano d) at 130 lb. per acre per annum. But 

 as the trimmings, leaves and cacao husks are allowed to remain on the 

 soil and decompose they are . sooner or later converted into nitrates 

 for the plants' use. 



During this process of decomposition there is a small loss of 

 nitrogen which may be estimated at 25 per cent, on 32 lb. per acre, 

 and although there is at present no indication of a shortage of nitrates in 

 the No Shade plot, this may occur later. But before this question can 

 be definitely answered it will be necessary to carry out similar manurial 

 experiments with different quantities of nitrogenous manures on Full 

 and No Shade plots of known bearing capacity i.e. on which a record of 

 the natural yield has been ascertained. 



(1.) Essais D' Agronomic Tropicale V, Marcano. 



