38 BULLETIN 57, HAWAII EXPERIMENT STATION 
Table 16 shows that the top growth of canna requires considerably 
more fertilizer elements than do the rootstocks. The former require 
10 times as much lime as the latter, about double the quantities of 
nitrogen and potash, and nearly equal quantities of phosphoric acid. 
Stated in terms of commercial forms of fertilizer, the tops require 680 
pounds of nitrate of soda, 250 pounds of limestone, 495 pounds of 
superphosphate (acid phosphate), and 616 pounds of sulphate of 
potash, representing a total of 2,041 pounds of fertilizer returned to 
the soil when the tops are plowed under. The rootstocks remove 
from the soil approximately 385 pounds of nitrate of soda, 26 pounds 
of limestone, 441 pounds of acid phosphate, and 376 pounds of 
sulphate of potash, or a total of 1,228 pounds. The pulp contains 
69 pounds of nitrate of soda, 17 pounds of limestone, 111 pounds of 
acid phosphate, and 56 pounds of sulphate of potash, totaling 253 
pounds. If the pulp and tops are returned to the soil the crop will 
remove the equivalent of 975 pounds of fertilizer. 
The immature tops of edible canna are very palatable and make a 
nutritious green feed. Nearly all the leaves of the mature (dormant) 
tops have shriveled, and the fibrous stems, although not very palat- 
able, if finely cut might be used as feed because of their sugar content. 
If the whole top growth of the hill could be cut so as to avoid hand 
selection and fed fresh or as silage, quantities of the tops might be 
used on the near-by ranches for green roughage. The top growth is 
worth more than a dollar per ton when left on the land for its fer- 
tilizer elements. 
Field methods of successfully handling the tops as green manure 
have not yet been developed. If the field is cross disked immediately 
after harvesting with a heavily weighted disk, the tops can probably 
be cut into short lengths and plowed under. They will soon rot if 
kept moist. Decomposition may also be effected by placing the 
tops in piles or windrows across the field. The repeated incorpora- 
tion in the soil of such heavy applications of succulent green matter 
may eventually have a deleterious effect. Allowing a partial drying 
out of the tissue after disking and before plowing under would be 
advantageous from this standpoint. 
The apparent palatability of the waste pulp from the starch fac- 
tories suggests its use as a carbohydrate feed. It is comparatively 
low in protein, but high in carbohydrates, and not excessively high 
in fiber content. Locally used pulp can be taken from the factory 
direct to the animals. The pulp is dried in the same manner as 
starch for shipping. The dried pulp is a mixture of long, coarse 
fibers and fine tissue. Grinding and sifting facilitate separation of 
the long fibers from the pulp proper, which then has the consistency 
of bran. To the pulp can be added the brown sludge which is sepa- 
rated from the starch during purification. 
MANUFACTURE OF STARCH 
After the tops have been cut, the rootstocks are dug by means of 
a tractor-drawn middle burster having a high beam. They are 
then carried to the mill for starch-making. (Fig. 19.) The washing 
machine consists of a horizontal, cylindrical iron drum 3J^ by 12 feet 
with iron slats for sides. The slats are 2 inches wide and are separated 
by intervals of an inch. The drum has attached to its perimeter a 
worm running the entire length. Wooden cleats running parallel to 
