6 BULLETIN 1167, V. S. DEPARTMENT OF AGRICULTURE. 
The crowns of the underground tubers should generally be reserved 
for planting. Because of a hard texture and often some discolora- 
tion of the flesh this part of the tuber is likely to be scarcely edible, 
and furthermore the crowns ordinarily sprout a little sooner than 
cuttings from other parts. Any part of the yam tuber may be used 
satisfactorily for propagation, however, and under similar conditions 
little difference in yield is to be expected between plants propagated 
from different parts of the tuber. Tubers may be cut into pieces 
weighing from a few ounces to a pound each, depending upon the 
size of the tuber. 
It is advisable to dry the freshly cut surfaces in the sun for a few 
hours before planting. Some growers and handlers favor dusting 
the cut surfaces with air-slaked lime or even with fine wood ashes 
before drying. At the Porto Rico Agricultural Experiment Sta- 
tion 8 the application of Bordeaux mixture to the freshly cut surfaces 
gave better results than any other treatment. Experiments made at 
the Plant Introduction Garden, Brooksville, Fla., have shown the 
simple sun drying to be satisfactory there. 
Depending upon the variety and also upon the size and character 
of the tuber or piece of tuber planted, one to several yams are pro- 
duced in a hill. A piece weighing half a pound or more unless it 
already has a well-developed single sprout will often sprout at two 
or more points (PL V, Fig. 1) and each of the resulting plants will 
produce a tuber. A much smaller piece usually develops but one 
sprout and one tuber. Great size of individual tubers does not re- 
sult when there are more than one in a hill. The size to which yam 
tubers grow is further influenced by the distance apart of the plants 
and the fertility of the soil, as well as by length of season and 
weather conditions. 
WHERE AND HOW TO PLANT. 
Most varieties of the greater yam do better in a deep, mellow, 
somewhat sandy loam than in heavy clay soils : some have also done 
well in properly drained muck. The tubers are planted 2 to 3 inches 
deep. To obtain the best results trenches (PL VI) or holes 18 inches 
deep and 18 inches or more in width filled with loose soil and de- 
caying vegetable matter or well-rotted manure should be prepared, 
or ridges composed in part of such material may be thrown up. The 
width of holes or trenches is generally made about half the distance 
between the rows. For hole planting, 3 by 3 feet apart is good 
spacing, but this may be varied somewhat and the holes made ob- 
long instead of round if desired. In trench planting, 3i-foot rows 
with the plants 15 to 18 inches apart in the row are recommended. 9 
Greater distances apart in rich soil may give larger tubers but 
smaller acre yields. 
If undecayed vegetable matter is used it should be mixed with 
the soil several weeks before planting time. The idea is to provide 
a bed of loose, rich soil in which the rather large tubers may develop 
freely. A compact soil tends to produce misshapen tubers. 
8 Kinman, C. F. Yam culture in Porto Rico. Porto Rico Agr. Exp. Sta. Bui. 27, p. 7. 
1921. 
9 The best distances for planting vams will varv slightly according to the variety and 
the soil conditions, but the distances specified will be found generally satisfactory. In 
the West Indies the distances recommended are approximately the same as those above. 
(See Rpt Agr. Dept Grenada, 1920, p. 4. 1921.) 
