JAMAICA. 



BULLETIN 



OP THB 



BOTANICAL DEPARTMENT. 



New Series.l SEPTEMBER, 1898. ^ ' ' 



Part 9. 



AGRICULTURE OF THE SUGAR CANE.— III. 



Extracts from 'SSugar Cane, VoL I." by Dr. William Stubbs,, 

 Director of the Louisiana Sugar Experiment Station. 



Edited by Fbancis Watts, Government Chemist Jamaica. 



Manurial Requirements of Sugar Cane. 

 (coniinued) . 



phosphoric acid plat. 



Similar questions as to the requirements of this soil for phosphoric 

 acid, to those given under nitrogen, have been propounued to this plat, 

 I viz. : First — Does this soil need phosphoric acid to grow cane ? Second 



5 — If so, in what form can it best be prescribed ? and Third— In what 

 ^ quantities per acre ? The forms of phosphoric acid used were, " Die- 

 solved Bone Black." " Acid Phosphate," " Ground Bones," " Taomas 

 Slag," Charleston Floats," and Natural Phosphates or Guanos They 

 were used in such quantities as to lurnish thirty-six and seventy-two 

 7 pounds of phosphoric acid per acre. Larger quantities than seventy - 

 TWO pounds per acre have proven by experiments to be unprofiiabla 

 These forms were used alone, and combine! with excessive quantities of 

 nitrogen and potash. The most available and adaptable forms to cane 

 were used, viz. : — Sulphates of Ammonia and Potash. As in other 

 plats at regular irtetwals. there were the usual number of unfertilised 

 experiments, and experiments containing only Sulphates of Ammonia 

 and Potash. Like the nitrogen experiments, these have already ex- 

 tended over eight years, and will be continued indefinitely. The results 

 80 far indicate positively the value of phosphoric acid in manures for 

 sugar cane on these soils, but the demand for this ingredient is small in 

 comparison to that for nitrogen, the smaller quantity given above 

 (thirty-six pounds per acre), proving so far an ample quantity for maxi- 

 mum yields. Results further show that the soluble forms of phosphoric 

 acid are preferred, followed in order by slag meal, and finely ground 

 *' floats," etc. Therefore, quantities of phosphoric acid, from thirty to 

 forty pounds per acre, in a soluble form are to be recommended for 

 augar cane on our soils. Phosphoric Acid unlike nitrogen, can not be 



