10 
BULLETIN 814, U. S. DEPARTMENT OF AGRICULTURE. 
An average day's work in going once over well-packed land (with- 
out any lap) for 7, 8, and 9 foot disks, drawn by 4 horses, and 10- 
foot disks drawn by 6 horses, is given in Table VII. The average 
performance of the same units in going once over freshly plowed 
land (without any lap) is given in Table VIII. 
Table VIII. — Disk harroiv on freshly-ploived land. 
Width. 
Number of 
horses. 
Number of 
reports. 
Acres per day. 
Average. 
Acreage most 
often reported. 
Feet. 
7 
8 
9 
10 
4 
4 
4 
6 
60 
368 
23 
14.3 
15.5 
, 16. 9 
22.7 
15 (25 reports). 
15 (111 reports). 
Scattering. 
(20 (7 reports). 
\25 (7 reports). 
Many farmers report that there is practically no difference be- 
tween the rate of doing, work on well-packed land and freshly- 
plowed land, as the disks must ordinarily be set at a somewhat 
greater angle in disking corn stubble or fall plowing, thus making 
the draft of the implement greater and overcoming the advantage 
of firmer footing for the horses. On an average, however, a day's 
work on well-packed land is from 1 to 2 acres greater than on 
freshly plowed land. 
The 9-foot disk, drawn by 4 horses seems to be the most efficient 
unit so far as horse labor is concerned, this unit covering about 4.7 
acres per horse per day on well-packed land, and 4.2 acres on freshly- 
plowed land. However, the fact that so many men are using 8-foot 
disks indicates that the 9-foot size is perhaps a slight overload for 
4 horses. 
A 10-foot disk makes the same load per horse for 5 horses as the 
8-foot implement does for 4 horses, but most of these farmers who 
use 10- foot disks hitch 6 horses to them. While such an outfit per- 
mits one man to cover more ground per day than does any of the 
other units shown in the tables, the efficiency of the horse labor 
is less .than when 4 horses are used with the 8-foot disk. 
THE SPIKE-TOOTH HARROW. 
Spike-tooth harrows ranging from 12 to over 25 feet in width 
were reported, and 95 per cent of the farmers stated that they 
hitch 4 horses to this implement. Fewer than 20 farmers using 
3-section harrows, each section being from 4 to 5 feet wide, reported 
the use of 3 horses, and about the same number reported 5 and 6 
horses for harrows 16 feet or more in width. (See Table IX.) 
Eighty per cent of these men use 4-section harrows, and about 50 
