SORGHUM EXPERIMENTS OX THE GREAT PLAINS. 71 
The graph also indicates a difference in the relative growth rate 
of the varieties. The rates are much alike in Freed sorghum and 
feterita. Dwarf milo, a variety which has practically the same 
length of growing season as feterita, is more like Blackhull kafir and 
Sumac sorgo in its rate of growth. Dwarf milo is therefore early 
because of its low stature and not on account of the rapidity of its 
growth. Freed sorghum and feterita, on the other hand, mature 
quickly, because they grow rapidly when climatic and soil conditions 
are favorable. 
The Blackhull kafir used in these experiments was a dwarf strain 
(F. C. I. No. 5894) which matured small quantities of seed on nearly 
all the plats. Sumac sorgo, however, did not mature normally. 
The manner in which all the Sumac date curves flattened out long 
before the crop matured shows the effect of a drought in slowing 
down the growth and lengthening the growing season. The grow- 
ing season of the varieties which had the slowest rate of growth was 
naturally lengthened most by the drought. This explains very 
largely the superiority shown by feterita in years of severe drought. 
SUMMARY OF IXFORMATIOX ON DATE OF SEEDIXG. 
While it would be difficult to summarize further in tabular form 
the experimental data obtained at the eight stations on the best date 
for seeding sorghum, it is possible to state a number of general prin- 
ciples that are applicable to the entire sorghum belt. 
The principal factors which must be considered in determining the 
best date to seed the sorghums are: (1) Soil conditions, especially as 
to moisture, temperature, clanger of blowing, and freedom from weeds; 
(2) the available growing season — the normal and extreme limits of 
the frost-free period; (3) the characteristics of the chosen variety, 
especially its earliness ; and (4) the purpose for which the sorghum is 
being grown, whether for fodder, silage, or grain. 
The results clearly indicate that ordinarily nothing is gained by 
seeding before the soil is warm, moist, and clean and danger of soil 
blowing is past. The available time for seeding extends roughly 
from the average date of the last killing frost in spring to within 90 
or 100 days of the average date of the first killing frost in the fall. 
There is, therefore, in northern Kansas a maximum period of 60 
days, from May 1 to July 1, in which seeding can be done. To the 
southward this period gradually lengthens, until at the most southern 
stations it lasts irom April 1 to August 1, or about 120 days. Seeding 
sorghum near either limit of the period indicated above is rarely 
profitable in any part of the sorghum belt. The time limits for seed- 
ing the most desirable varieties in order that the grower may avail 
himself of the best chances of getting a maximum crop are very 
much reduced. 
Irrespective of locality the maximum yields of forage are obtained 
from sorghum varieties that utilize most fully the entire available 
growing season. This means that Sumac sorgo will be grown as far 
north as it can be depended upon to mature, and north of that the 
Orange and Red Amber or similar varieties will be grown up to and 
even beyond their limits of maturity. This tendency to use a variety 
that requires a rather long growing season restricts very much the 
optimum period for seeding. In the South, where Sumac is grown. 
