Edible Products. 



250 



[March, 1909. 



ations are not of direct benefit, but 

 only indirectly, inasmuch as heat is 

 thereby produced which supports the 

 action of a body (enzyme) furnished by 

 the bacteria, which dissolves the adhesive 

 substance between parchment envelope 

 and slimy layer. — Philippine Agricul- 

 tural Review, Vol. I., No. 9, September, 

 1908. 



MANIOC OR CASSAVA. 



By Edwin B. Copeland. 



{Concluded from page Sfy.~) 

 The best time at which to harvest 

 the roots for starch manufacture ought 

 to be very carefully determined locally 

 wherever the manufacture of starch 

 is an industry. In the Straits Settle- 

 ments the Chinese are said to wait until 

 the roots are eighteen months old, while 

 the European planters harvest their crop 

 in about ten months. In determining 

 the most popular age, various factors 

 must be considered — the weight of roots, 

 their starch contents, and the rental of 

 the land, or its productivity if replanted, 

 being the most important. The weight 

 and the content of starch depend upon 

 the variety grown, the climate and 

 season, and the cultivation. The de- 

 pendence upon variety and season is 

 well shown in the following table repre- 

 senting the yield of five native Jamaica 

 varieties. The 1907 crop had an excep- 

 tionally wet season. 



Bulletin, Department of Agriculture, 

 Jamaica, 5 (1907) 78, Cassava Trials in 

 1907. H. H. Cousins. Of twenty-two 

 varieties, only the five which gave the 

 largest yield of starch in 1907 are 

 copied here : — 



Starch per acre. 



1907. 



Tubers 



(tons). % lb. 



Luana Sweet ... 13-3 33'61 10,015 



Duff House ... 114 35'69 9,114 



Black Bunch of Keys 114 34 85 8,899 



Brown Stick ... 1P4 34'37 8,777 



Blue Top ... 11-3 34-62 8,763 

 1906. 



12 18 



mos. mos. 



(lb.). (lb.). 



Luana Sweet ... 5,322 7,102 



Duff House ... 4,107 12,632 



Black Bunch of Keys 2,388 8,894 



Brown Stick ... 2,384 8,927 



Blue Top ... 5,636 15,818 

 There were five other varieties in the 



1906 crop whose yield of starch when 



eighteen months old was over five tons 

 per acre. As between twelve and 

 eighteen months, the general result is 

 that tor the sake of greater yield it is 

 decidedly better to leave the plants a 

 year and a half. Conditions in the 

 Phillippines are the same. While the 

 percentage of starch, a scant ten in the 

 roots of 5-month-old plants, reaches 

 its maximum at about ten months, the 

 most rapid growth of the roots is then 

 only well under way. The percentage 

 of starch begins to decrease, at least 

 sometimes, before the plants are twelve 

 months old, but the total amount con- 

 tinues to increase rapidly, and the slight- 

 ly increased woodiness does not seriously 

 interfere with its extraction. 



When manioc is raised for food, the 

 roots are dug like potatoes for use as 

 wanted. When it is grown on a large 

 scale, the plants are sometimes pulled 

 by hand from very light soil, but the 

 work is done much more easily by the 

 use of a lifter. The simplest lifter is a 

 straight wooden stick, 2 or 3 meters 

 long, strong enough so that it will not 

 break, which is used as a lever. The 

 fulcrum end rests on the ground, and 

 is provided on the underside with an 

 old spade blade or some other flat body 

 to prevent its sinking in. Near the ful- 

 crum end is fastened a hook or other 

 grappling device. By lifting the long 

 arm of the lever and shaking the plant 

 is pulled out of the ground reasonably 

 free from adhering soil. If some roots 

 break off they are dug individually. 

 When the field is in sufficiently good cul- 

 tivation to permit ploughing, a furrow 

 is run alongside of each row, making 

 the roots pull up more easily and with 

 less breaking. 



The yield of manioc has been the 

 subject of day dreams. Semler, not too 

 positively, cites a New Caledonia plan- 

 tation whose yield in two years ranged 

 from 25 to 250 metric tons of roots per 

 hectare. Reports in German East Africa 

 sent to the Experiment Station at 

 Amani range from 2*5 to 225 tons. Such 

 reports as these larger ones must be 

 due to mistake or misunderstanding, or 

 to computing the yield per hectare 

 from that of a few exceptional plants. 

 Single plants indubitably have produced 

 twenty-five kilograms of roots, and 

 10,000 such plants on a hectare would 

 yield 250 tons. But such yields do not 

 occur. The yield of some notably good 

 Jamaica varieties has already been 

 given. Twenty-five Colombian varieties, 

 grown in Jamaica in 1907 pioduced3'l to 

 13-3 English tons per acre. From Florida 

 there have been reports of 30 or 40 tons 



