The Contributions of Muscle and Machine Work to Land and Labor Productivity in World Agriculture Since 1800

Since 1800, there have been enormous changes in mechanical technologies farmers use and in the relative contributions of human and animal muscles and machines to farm work. We develop a database from 1800 to 2012 of on-farm physical work in world agriculture from muscles and machines. We do so to analyze how on-farm physical work has contributed to changes in land and human labor productivities. We find two distinct periods. First, from 1800 to around 1950, land productivity (measured as kcal food supply per hectare of cropland) was relatively stagnant at about 1.7 million kcal/ha, in part due to a scarcity of on-farm physical work. During this period, physical work was scarce because most of on-farm physical work (approximately 80% in 1950) was being powered by low power, low energy efficiency muscle work provided by humans and draft animals. From 1950 to 2012, land productivity nearly tripled as more machine-based work inputs became available. The additional machine-based work inputs have contributed to the growth in land and labor productivities, as they have enabled farmers to control more physical work enabling more irrigation and agrochemical applications. However, the tripling of land productivity has required a near 4.5-fold increase in physical work per hectare, suggesting diminishing returns. Farmers accomplished this extra work with less final energy because they transitioned from low-efficiency muscle work to high-efficiency machines which drove farm-wide energy conversion efficiency up fourfold from 1950 to 2012. By 1990, machine conversion efficiencies started to plateau. Given diminishing returns and plateauing efficiencies, we predict that fuel and electricity usage on farms will increase to continue raising land productivity.