22 MISC. PUBLICATION 650, U. S. DEPT. OF AGRICULTURE 
If a tractor is used, a 16-inch-deep furrow can be turned and the 
roots removed by hand as the clods are forked over by harvesters 
stationed at intervals along the field. If oxen are used, two 8-inch 
furrows must be plowed, one below the other, so as to break open the 
eround to a depth of 16 inches for the harvesters. The roots need 
only to be separated from clods of earth and any attached pieces of 
vine before they may be dried and packed in bales for shipment. 
Derris roots, being much smaller in diameter than those of loncho- 
carpus, dry out in a week or two if left outside in clear weather or 
within 3 weeks if dried under well-ventilated shelters. In Puerto 
Rico experimental plots, 25 to 27 months old, yielded from 885 to 1,738 
pounds of air-dry roots per acre when the tr ‘ailing system of culture 
was used and 3,040 pounds when the plants were trellised. 
DESIGN OF A MECHANICAL HARVESTER 
Since the expenses of harvesting derris by present hand methods may 
easily exceed the total of all other production costs when a trailing 
Figure 14.—Whirlwind terracer being used in derris harvest trials for digging 
roots after tops were removed with other equipment. Tractor was operated in 
low gear and terracer in low speed. 
crop 1s grown on heavy soils under climatic conditions promoting deep 
rooting, the development of mechanized methods has seemed desirable. 
Workers at the Estacién Experimental Agricola del Ecuador ° at 
© Nutt, Grorce B. REPORT ON DERRIS HARVESTING INVESTIGATIONS CON- 
DUCTED AT PICHILINGUE, ECUADOR. 11 pp., illus. August 1945. [Unpublished 
manuscript fledjin CB Or sliae seme 
