COST AND UTILIZATION OF POWER ON FARMS. 
19 
As the size of farm, and consequently the amount of plowing, 
increased, the percentage of those who did it all with tractors de- 
creased. Sixty-seven per cent of the men with less than 160 crop 
acres, 52 per cent of those with 160 to 239 crop acres, and only 35 
per cent of those with 240 or more crop acres did all their spring 
plowing with their tractors. 
The number of acres plowed with horses on the smaller farms, as 
shown in Table 14, indicates that on many of these farms the horses 
were used only for finishing or for plowing small and irregular fields. 
On many of the larger farms, however, the amount of spring plowing 
to be done was so great that the tractors could not do it all in the 
time available, and horses were worked regularly at plowing during 
the plowing season. This condition existed on nearly all of the 22 
farms with 320 or more crop acres, where an average of 63 acres of 
spring plowing was done with horses. 
Fall plowing.— Table 16 shows the number of men on farms of 
different sizes who did all their fall plowing with tractors, those who 
used both tractors and horses, and those who used horses only. 
Table 16.— Kind of power used for fall plowing on farms of different sizes. 
Size of farms (crop acres). 
Number 
of 
farmers. 
Farmers 
using 
tractors 
only. 
Farmers 
using 
tractors 
and 
horses. 
Farmers 
using 
horses 
only. 
Less than 80 
2 
20 
62 
42 
38 
29 
16 
16 
2 
16 
55 
35 
34 
23 
15 
10 
80 to 119 
4 
6 
5 
3 
5 
1 
3 
120 to 159 
1 
160 to 199 
2 
200 to 239 
1 
240 to 279 
1 
280 to 319 
3 
Total 
225 
100 
190 
84 
27 
12 
3 
Per cent 
4 
A much larger percentage used tractors exclusively for fall plowing 
than for spring plowing, and no marked tendency was shown on the 
large farms to supplement the tractors with horses. Except where 
land is being plowed for winter wheat, the season for fall plowing is 
long, compared with the season for spring plowing. Furthermore, 
the hot weather which usually occurs during the fall plowing season 
and the harder plowing give the tractor a somewhat greater advan- 
tage over horses than it has in spring plowing. 
Disking. — Though the tractors were used more for plowing than 
for any other operation on these farms, 73 per cent of the total disk- 
ing was done with them. On the farms where winter wheat followed 
corn and occupied an important place in the rotation, the seed bed 
was prepared almost entirely with the tractor and disk. The method 
usually emplo~ed was first to cut and shock the corn and then disk 
