DIRECTIONS FOR BLUEBERRY CULTURE. 
15 
temporary stimulation of vegetative growth, is likely to cause serious 
injury later. For those desiring to experiment with fertilizers the 
following acid mixture is recommended, applied at the rate of 1,000 
pounds per acre, or one-fifth of a pound per square yard : 
Pounds. 
Acid phosphate (high grade, about 16 per cent available phos- 
phoric acid) 600 
Sulphate of potash (50 per cent potash) 200 
Sulphate of ammonia (20 per cent nitrogen) 200 
(Muriate of potash may be substituted for sulphate of 
potash. ) 
This and similar acid mixtures have been used with success on 
blueberr}^ plants in both pot and field experiments, with no evidence 
thus far of cumulative injurious effects. However, as no fertilizer 
is required to make the swamp blueberry fruit abundantly and con- 
tinuously in suitable peat and sand soils properly handled, the use 
of fertilizers in commercial plantations is not at present advocated. 
The swamp blueberry does not require a yearly pruning. When 
one of the stems of a bush becomes unproductive from injury or old 
age it should, of course, be cut out. If a large part of a bush needs 
removal it is better to cut all the stems to the ground and let the 
plant send up new shoots, all of the same age, to form a wholly new 
and symmetrical top. 
YIELD AND PROFITS. 
By proper manipulation in the greenhouse, seedling blueberry 
plants can often be made to ripen a few berries in less than a year, 
but they do not come into commercial bearing in field plantations 
until they are 3 to 4 years old (Pis. XIV, XV, XVI), when the 
plants are 1 to 3 feet high. They then increase slowly to full size 
and full bearing. Wild bushes of the swamp blueberry live to great 
age, often 50 to 100 years, still bearing heavily, and they often 
attain a height of 6 to 8 feet when growing in full sunlight; still 
more when shaded. Individual stems may remain productive for 
10 to 25 years. When dead they are replaced by new and vigorous 
shoots from the root. 
The field plantings resulting from the recent experiments in blue- 
berry culture are too young to show the mature yield. Fortunately 
however, there is, near Elkhart, Ind., a small blueberry planting of 
mature age. The returns from this plantation set forward our 
knowledge of yields by at least a decade. The plantation is about 
2J acres in extent. It was started in 1889 in a natural blueberry 
bog, which was first drained and then set with unselected wild-blue- 
berry bushes. The plantation was profitable from the first, but 
exact records of yield and receipts are available only for the years 
1910 to 1915, when the plantation was 21 to 26 years old. The data 
^re shown in Table I. 
