26 BULLETIN 648, U. S. DEPARTMENT OF AGRICULTURE. 
Acres of crop land per mule. — In Table X the farms are grouped 
according to the amount of crop land worked per mule. The farms 
that have the fewest acres per mule, or an average of 16, secured only 
67 days productive work from each animal, but as the number of 
acres increased, the number of days per mule increased regularly to 
an average of 139 on the group that operated the largest area per 
animal. This increased employment' of the work stock resulted in a 
corresponding decrease in the cost per day of productive labor from 
$1.50 to $0.90. Such an economy in so important an item of cost 
must necessarily result in lower costs of production and greater 
profits. The cost of producing cotton decreased from 9J cents per 
pound on the first-mentioned group of farms to 8.3 cents on the 
farms that operated 30 or 35 acres per mule, but it increased to 9 
cents on the farms that had more than 35 acres per animal. This 
result was corroborated by the index of earnings, which increases 
markedly up to the point of 30 to 35 acres per mule. Beyond this 
the profits are less. 
An apparent irregularity appears in that the index earnings were 
greater for the first than for the second group of farms shown in 
Table X. The explanation is that two or three farms with good 
crop yields and a low investment secured a high percentage of re- 
turns in spite of inadequate utilization of work stock. The number 
of farms in the group was insufficient fully to neutralize the influence 
of these few abnormal farms. 
It will be noted that the farms which cultivated the fewest acres 
per mule average smaller in size than those which operated a larger 
area per animal. Undoubtedly the larger farms possess advantages 
which facilitate their organization upon a basis providing for the 
more efficient employment of work stock labor. 
It may further be stated that the cultivation of an increased number 
of acres per work animal was not at the expense of crop yields. In 
fact, the lowest yields were found in the group that worked the 
smallest area per animal. 
It is not probable that all the differences in costs and profits shown 
can be attributed to the differences in relative employment of work 
stock, for the men who keep their work stock efficiently employed are 
likely to be also more efficient in other respects. But the method of 
grouping used eliminates the effect of other factors as far as pos- 
sible, and it is believed that the influence of area per mule has not 
been greatly overemphasized. 
Farmers are often advised to reduce the number of acres per mule 
in order to cultivate the remaining acres more intensively, but the 
preceding table would seem to show that it is much more important 
to cultivate a sufficient number of acres per work animal to keep that 
