41 
the soil may be plowed and cultivated as long as the plan- 
tation exists and leguminous cover crops may be grown 
to some extent. In such plantations it is good practice to 
plant legumes, such as sword beans or cow peas, at the 
beginning of the rainy season, plow these crops in before the 
dry season begins and after that keep the soil pulverized and 
loose on the top by frequent stirring with cultivators, such 
as Planet Juniors or a small disk harrow, until the rainy 
season starts again. 
FERTILIZING OR MANURING 
A fertilizer is any material supplying plant food, but 
in discussing it in its narrower sense, only the three ele- 
ments, nitrogen, potasium and phosphorus, are included. 
These are the only elements of plant food in which ordinary 
soils are deficient. The analysis of a soil is not a sure guide to 
its. productivity, nor is the analysis of a crop more than an 
indication of what fertilizers should be used. Herbert 
Wright in his book on Cacao gives figures from analysis 
made by Boname showing that each ton of marketable 
cacao takes from the soil 112 kilograms of mineral matter 
of which 57 kilograms are potash, 9 kilograms phosphoric 
acid and 20 kilograms nitrogen. With a crop of 450 pounds 
per acre this would be about 25 pounds potash, +!4 pounds 
phosphoric acid and 10 pounds nitrogen. Hart * quotes Har- 
rison from Demerara, \Marcana from Venezuela and Boname 
from Guadeloupe giving four analyses to show the unavoi/l- 
able loss of plant foods, that is those actually removed in the 
marketable products. The average from the four are as 
follows: 8.4 pounds nitrogen, +.2 pounds phosphoric acid 
and 4.4 pounds potash. From the same authority we quote 
* West Indian Committee Cireular Vol. 25 No. 298. 
