In a paper recently published by the American Economic Review, Rodolfo Manuelli and Ananth Seshardi write on the slow adoption of the tractor in American agriculture:
Many new technologies display long adoption lags, and this is often interpreted as evidence of frictions inconsistent with the standard neoclassical model. We study the diffusion of the tractor in American agriculture between 1910 and 1960-a well-known case of slow diffusion-and show that the speed of adoption was consistent with the predictions of a simple neoclassical growth model. The reason for the slow rate of diffusion was that tractor quality kept improving over this period and, more importantly, that only when wages increased did it become relatively unprofitable to operate the alternative, labor-intensive, horse technology.
A couple thoughts. It is amazing that, what today seems ubiquitous on the farm, took almost 50 years to reach near full adoption. The decline in use of horses and mules is quite dramatic. It is also interesting to see how changes in relative prices (in this case, wages, and the quality-adjusted tractor price) have big impacts on technology adoption. From a broader perspective, this historical look is a good reminder that the benefits of technologies developed today often take a long-time to fully be realized, and that adoption rates are influenced by a whole host of factors that may, at first blush, seem to have little to do with the technology. It also reminds us of the risk of rejecting food and farm technologies today. When we get 50 years down the road, we can't suddenly decide we wish things were different. It takes time.