IMPROVEMENT OF THE SUGAR CANE. 135 
quantities of from 60 to 160 Ibs. of sulphate of potash 
per acre results in greatly increasing the effe€tiveness of 
the nitrogenous manurings ; while on many others, these 
applications have but little effe€t. Soils containing less 
than ‘or % of potash, soluble in cold 1 % citric acid 
solution, will, as a rule, respond favourably when planted 
in sugar cane to manurings with potash salts. Soils 
having from ‘o1 to ‘oz % of potash thus soluble may or 
may not be favourably affected by potassic manurings, 
while on soils containing more than the latter amount, 
the yield of sugar canes will usually not be increased by 
manurings with potash. In this colony the alluvial clay 
soils are, as a rule, so rich in potash that no marked in- 
crease in yield of canes can be expected from the use of 
potash salts. It is, however, worthy of notice that while 
the pegass soils of the colony generally contain fairly 
high proportions of potash soluble in hydrochloric acid, 
they frequently contain but traces soluble in citric acid 
solution, and upon them the use of potassic manures may, 
perhaps, be accompanied with benefit. 
It is, perhaps, worthy of mention that the volcanic soils 
of the West Indian Islands differ from the extremely 
tertile soils of Hawai principally by their low contents 
of available potash, the soils of Hawai being even richer 
in this constituent than the alluvial soils of this colony, 
