The Size Distribution of Farms and International Productivity Differences

Using internationally comparable data from the World Agricultural Census, we document a factor of 36 difference in average farm size between rich and poor countries. Small farms of less than 2 hectares represent more than 70% of farms in poor countries but only 15% in rich countries, whereas large farms of more than 20 hectares represent none of the farms in poor countries and almost 40% in rich countries. Two questions emerge. First, what explains the striking differences in farm size across countries? Second, are farm-size differences important in understanding agricultural and aggregate productivity gaps across countries? We develop a two sector model with agriculture and non-agriculture that features a non-degenerate size distribution of farms. The theory embeds a Lucas (1978) span-of-control model of farm size into a standard sectoral model with non-homothetic preferences. In the model calibrated to the United States, a reduction in economy-wide productivity from 1 to 1/4 produces an increase in the share of employment in agriculture from 2.5% to 53%, a 21-fold reduction in average farm size, and a 25-fold reduction in agricultural labor productivity. These results are broadly consistent with data on the sectoral allocation of labor and the size distribution of farms across countries.