136 The Philippine Journal of Science i9i8 



obtained by carefully controlled tests and trials. To fill this 

 deficiency and to develop a system of fertilization trials that 

 could be followed elsewhere in the Islands, I undertook the 

 present experiments. 



METHOD AND TIME OF APPLICATION OF FERTILIZERS 



Deerr,* speaking of the proper application of various artificial 

 manures, says that readily soluble forms of fertilizers such as 

 nitrate of soda and ammonium salts should be applied as top 

 dressings. Organic forms of nitrogen requiring the action of 

 soil organisms must be buried 5 or 6 centimeters in the soil. 

 Superphosphates are applied either as top dressings or are 

 buried at a slight depth. Basic slag and mineral phosphates 

 must be incorporated in the soil. Potash salts should be also 

 incorporated. 



Most investigators agree that the best time for application is 

 during the early growth of the cane. They differ as to the 

 advisability of a second application. Watt's ^ experiments in the 

 Leeward Islands led him to conclude that the one-application 

 system is better. In Hawaii, however, the application of nitrate 

 of soda at the second growing season is found beneficial. The 

 two-time application is practiced in Barbados. 



THE AMOUNT OF FERTILIZERS TO BE APPLIED 



For the stiff clay of Demerara, Harrison " recommended the 

 application of 50 pounds (54.24 kilograms per hectare) of 

 nitrogen in the form of sulphate of ammonia, with 500 to 600 

 pounds of ground phosphate slag per acre (543.12 to 654.48 

 kilograms per hectare). In Barbados the planters use from 40 

 to 80 pounds of nitrogen in the form of nitrate of soda and 

 ammonium sulphate, combined (43.44 to 86.88 kilograms per 

 hectare), and 80 to 100 pounds (87 to 109 kilograms per hec- 

 tare) of sulphate of potash per acre. In Louisiana the amount 

 of fertilizer used is from 400 to 700 pounds per acre (436.32 

 to 872.64 kilograms per hectare) . In Hawaii as much as 2,400 

 kilograms of fertilizers are applied per hectare.^ The amount 

 of fertilizers to be applied is a question that should be determined 

 for each locality. 



" Deerr, Noel, Cane Sugar (1911). 



" Ibid. 



' Sugar Cane. Published by German Kali Works. 



'Deerr, Noel, Cane Sugar (1911). 



