22 BULLETIN 997, U. S. DEPARTMENT OF AGRICULTURE. 
behind a disk, and 28 per cent independent of the disk. The size 
of the tractor had a direct bearing upon the combination used, for 
the 3-plow outfits were able to pull greater loads than the 2-plow 
machines. Only 61 per cent of the work done with 2-plow tractors 
was done with harrows, rollers, etc., behind disks, while 92 per cent 
of that done with 3-plow tractors was done behind disks. 
Farms where all work previous to planting was done with tractors. — 
While the larger part of the plowing and disking and a considerable 
portion of the lighter work of harrowing, planking, rolling, and 
packing on these farms was done with tractors, on only 39 of the 
286 — 14 per cent of the total — was all of the work of preparing the 
seed bed done with tractors. Even on farms whose operators 
considered their machines suitable for all this work, horses usually 
did part of it. 
Most of the farms where tractors were used exclusively were 
operated by one man alone. Where an extra man was available a 
part of this work was nearly always done with horses. 
The seed-bed preparation was done with tractors entirely on 21 
per cent of the farms with less than 160 crop acres, but horses were 
used for some seed bed preparation on all but 9 per cent of the farms 
with 160 or more crop acres. Thirty-four of these 39 men operated 
2-plow outfits and 5 of them 3-plow outfits. Thus 20 per cent of 
all the men who owned 2-plow machines and only 5 per cent of those 
who owned 3-plow machines did all of this work with tractors. 
Even though a larger percentage of the men on smaller farms owned 
2-plow machines, apparently the greater versatility of the smaller 
machines made them more satisfactory for all the kinds of work 
required in preparing the seed bed. 
Cutting grain. — Seven of the 286 men interviewed either raised 
no small grain or paid to have it cut by others. The kinds of power 
used by the remaining 279 were as follows : 
108 or 39 per cent used tractors only. 
22 or 8 per cent used tractors and horses. 
149 or 53 per cent used horses only. 
The 22 men who used both tractors and horses did not always use 
them simultaneously. More often the two sources of power were used 
at different times, one on oats and the other on wheat for example. 
The size of the farm apparently had little to do with the kind of 
power used in cutting grain. Forty per cent of the men who had 
less than 160 crop acres, 42 per cent of those with 160 to 239 crop 
acres, and 33 per cent of those with 240 or more crop acres cut all 
their grain with tractors. The size of the tractor however, did have 
some influence on its use for cutting grain. Fifty-four per cent of 
the grain was cut with tractors on the farms where 2-plow machines 
were owned and only 26 per cent on the farms where 3-plow machines 
