THE FERTILITY OF SOILS IN THE TROPICS 361 



in other respects are particularly favourable to biological 

 development, serve greatly to enhance the importance of 

 this factor; indeed, it may be suggested that under the 

 conditions in question relationships of this description 

 play a part the importance of which cannot be overstated. 



It is perhaps the natural outcome of the fact that up 

 to the present the work of tropical agricultural depart- 

 ments has been more especially concerned with questions 

 affecting the development of agricultural industries and 

 the investigation of problems cognate to them, that 

 the special aspects of soil fertility in the tropics 

 have not been more fully investigated. In many in- 

 stances, moreover, the lands which are being worked 

 have been but recently introduced into cultivation 

 and possess relatively large accumulations of fertility. 

 Under these circumstances the practical problem which 

 immediately presents itself for solution is the manner 

 in which these accumulations may be used up to the best 

 advantage. There are in some countries, it is true, con- 

 siderable tracts of land which have been under cultivation 

 for long periods of time, and under these conditions 

 intensive systems of agriculture have in many instances 

 become evolved. This is particularly the case when, as 

 in some of the West Indian islands, the total area of 

 cultivable land is limited; it is significant that under 

 these conditions the system of agriculture which has 

 evolved itself has for its basis the relatively frequent 

 application of organic manures, sometimes supplemented 

 by various artificial manures. 



A certain amount of preliminary investigation has been 

 carried out by the Agricultural Department in the Lee- 

 ward Islands during the years 1912 and 1913, in relation 

 to some of the more important conditions under which 

 soils in that colony exist. The detailed results of this 

 work have been published in the West Indian Bulletin, 

 vol. xiv (1914), pp. 146-152; in the present paper it will 

 suffice to indicate the general character of the results 

 obtained. 



The scope of the investigations has included measure- 

 ments of soil temperature and sodl moisture, measure- 

 ments of the rate of decay of soil organic matter as the 



