IMPROVEMENT OF THE SUGAR CANE. 133 
It is of interest to ascertain the weights of canes which 
have been produced at different times in various places by 
the application of ten pounds of nitrogen per acre when 
accompanied by a sufficiency of the mineral constituents 
of plant food, either naturally present in the soil, or 
added by manures, and the following shows this :— 
Tons of canes per acre. 
LouISIANA. BARBADOS. BRITISH GUIANA. ANTIGUA., 
Audubon. f Colonial Botanic 
Kenner. Park. Dodd's. Company. Gardens. Skerret’s. 
1886-89, 1890-94, 1886-90, 1891-95, 1882-87, 1891-95, 1891-96. 
27 2°15 2°65 155 2'5 I°5 Nil, 
Average of nine crops. 
2°39 2°04 2°05. 
In tropical countries, except on such abnormal soils as the 
Antiguan ones appear tobe, we may fairly assume that over 
a series of years applications of sulphate of ammonia or 
of nitrate of soda, when applied in quantities not exceed- 
ing those which supply as much nitrogen as the sugar cane 
can make complete use of, will probably on the average 
result in a return of 2 tons of canes per acre for each 50 
lbs. of sulphate of ammonia or 65 lbs. of nitrate of soda 
applied, and that, under specially favourable soil and 
climatic conditions, the return may amount to over 2°5 
tons. Experience must with regard to each soil decide 
as to the amount of nitrogen which can be profitably 
employed. 
From consideration of the results which have been 
obtained at these experiment stations, the following, in 
my opinion, may be fairly regarded as proved in connec- 
tion with the manurial requirements of the sugar cane :— 
j, The yield of canes per acre is governed by the 
