IMPROVEMENT OF THE SUGAR CANE. 131 
of six experiments with plant canes, making in each nine 
comparisons with and without nitrogen, the manures 
containing nitrogen yielded in round numbers 22 cwts. 
fess sugar per acre than did manures consisting only 
of phosphates and potash. Similarly on this curious soil 
the addition of phosphates, whether soluble as in super- 
phosphate, available but not soluble in pure water as in 
slag phosphate, or insoluble and pra€tically inert as in 
mineral phosphates, has reduced the yield of sugar; 
manures with phosphates having given in round number 
4 cwts /ess sugar per acre than manurings with nitrogen 
and potash gave. Asan example of these results, the 
average returns obtained in 1896 may be quoted :— 
Nitrogen experiments. 
Tons of canes per acre. 
Not manured a or se 21°1 
Mixed minerals a= das des 20°! 
” 39 and nitrogen as sulphate of 
ammonia ee 245 
Hs 5 »» as nitrate of soda... 24° 
Phosphoric acid experiments. 
Not manured yi se wae 23'9 
Nitrogen and potash ... ose on 28'8 
Nitrogen, potash and superphosphates re 24°2 
ra o mineral phosphates _... 29'2 
55 =! slag phosphates es 27.4 
But with ratoons in Mr. WATT’S experiments both 
nitrogenous and phosphatic manures appear to aét, in 
what, I think, we are entitled to consider more normal 
ways. His average results in 1896 were as follows :— 
Nitrogen experiments. 
Not manured I1‘9 tons of canes per acre, 
Mixed minerals 12°7 - “ 
* » and nitrogen in sulph. of ammonia 10°7 £ nk 
i, » and nitrogen in nitrate of soda = 1137 & 
R2 
