THE FERTILITY OF SOILS IN THE TROPICS 



Chemical Analyses. 

 SERIES I. GOOD SOILS. 



SERIES II. BAD SOILS. 



The first three soils of Series II are probably deficient 

 in all the plant food constituents, nitrogen, potash, and 

 phosphate. On No. i are old trees yielding only a few 

 nuts a year. No. 4 is well supplied with phosphate and 

 potash but lacking in nitrogen; it has yielded during the 

 past three years an average of only twenty-four nuts per 

 tree. The average for No. 5 for the same period is forty 

 nuts; this soil contains very little available phosphate, 

 as also does No. 6, the average for which is thirty nuts 

 per tree. 



The soils in Series I are all excellent yielders, the 

 trees giving seventy to eighty nuts a year. No. 3, in 

 fact, which is manured reg'ularly with cow-dung, is stated 

 to yield 100 nuts per tree. This soil is from a small 

 native holding. None of these soils contains much nitro- 

 gen, the percentage being about the same as seemed 

 sufficient in the case of rubber. Potash and phosphate 

 are present in all in good amounts. Soil No. 7, how- 

 ever, in which the available quantity of the latter sub- 

 stance is less than in the others, has for several years 

 been showing a constantly diminishing yield, which has 

 dropped from eighty nuts to fifty. 



