24 
BULLETIN 648, U. S. DEPARTMENT OF AGRICULTURE. 
even." But if he increases this yield to half a carload he can sell for 
$50 without loss, and if he further increases the production to two- 
thirds of a car per acre, $40 per load will cover all costs. 
All the yields of sweet potatoes found show a wide margin of 
profit. Average yields of 70 bushels per acre cost 36 cents per 
bushel; increasing the yield to 100 bushels reduced the cost to 28 
cents, while a further increase to 162 bushels further reduced the cost 
to 22 cents. The records for this crop are few in number and repre- 
sent small scale production. But the costs and margins shown would 
indicate that the crop offers commercial possibilities for the grower. 
The manner in which the costs per crop unit decrease with increas- 
ing yields is shown for the six important crops by the curves in 
figure 11. 
There is, of course, for each crop under any set of conditions a 
point beyond which any further increase in yield can be secured only 
at a cost per unit higher than the returns. On some individual farms 
in Brooks County this point of " diminishing returns " has no doubt 
been reached or exceeded : but these tabulations show that in no case 
have any of the groups of farms studied brought the crop yields to 
that point. Evidently one of the surest means of increasing the 
profitableness of these farms is the increasing of the crop yields. 
UTILIZATION OF WORK-STOCK LABOR. 
The largest item of cost, next to that of man labor, is the cost of 
work stock. In this study it was found to amount to $509 per farm, 
which is approximately equal to half of the cost of all man labor, 
or 19.2 per cent of the cost of producing all farm crops. Figured 
on the basis of the cost per day of productive labor, the work stock 
cost $1.07, as compared with $1.20 for man labor. Manifestly, the 
utilization of work stock so as to keep down this large element of cost 
is one of the chief factors in determining profits on these farms. 
Table IX. — Relation of number of productive days mule labor per mule to 
farm returns, acres per mule, and cost of mule labor per day (Brooks 
County, Ga.). 
Productive days mule labor per mule. 
Number 
of farms. 
Average 
number 
of mule 
days 
per mule. 
Cost of 
mule 
hbor 
per day. 
12 
26 
33 
02 
88 
112 
11.70 
76 to 100 
123 
101 to 12.5 . 
1.00 
126 to 150 
21 137 
14 172 
.84 
.72 
1.07 
