An analysis of the records of 753 cooperating farmers in 1936 and 958 in 1937 indicates clearly that general-purpose tractor farms are considerably larger than standard tractor farms and that standard tractor farms are larger than horse farms.
The average net cost of keeping a horse on 53 Iowa horse-operated farms in 1936 and 49 farms in 1937 was $91.44 and $86.08, respectively. The horses worked an average of 814 hours in 1936 and 802 in 1937 at an average cost of 11.2 cents and 10.7 cents per hour. Feed costs constitute about 65 percent of the total cost of using horses.
Feed costs varied from $56 per horse on farms with about 75 acres in crops to $71 on farms with about 375 acres in crops. The pounds of grain per horse likewise varied from 2,050 to 4,518, respectively, on these farms. The average hours a horse worked per year, however, ranged from 680 on the small farms to 854 on the larger farms. Amounts of roughage fed per work horse did not differ with size of farm or hours of work. Expenses per horse varied with the number of hours they were worked. There was only a small difference in the cost per hour between horses working an average and those working a smaller number of hours. This was due to the heavier feeding cost, of the horses which worked most.
Goodsell, Wylie D.
"Cost and utilization of power and labor on Iowa farms,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 23
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol23/iss258/1