Technological change in United States agriculture: The case of substitution of gasoline tractor power for horse power.

摘要

I model the substitution from horse farming to tractor farming in the Corn Belt, specifically Iowa, from 1920 to 1940. I find the data on the proportion of tractors on Iowa farms to be very well replicated when I use an LP model maximizing new income. I use an alternate wage value in the objective function to value the labor hours released from field crop tasks when the tractor is substituted for horse teams. Previous models have attempted to explain the tractor-horse substitution by looking at differential per acre costs. I show that the incentive for adoption of a new technology rests on the effect on a farmer's total income—not on a per acre cost comparison.