U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Document Type


Date of this Version



Journal of Soil and Water Conservation. 51:137-139


U.S. government work


At the turn of the century, with the exception of trains and water transportation, the transportation and agriculture industries of the U.S. were powered largely by herbaceous biomass. The herbaceous biomass was converted to usable energy by draft animals, primarily horses and mules. After 1900, automobiles, trucks, and tractors began to be used in transportation and agriculture. However, in 1920 there were still 25 million horses and mules on farms and ranches and 2 million draft animals in the cities of the United States (Ensminger 1955; (census of Agriculture 1920). The energy requirements of these animals were considerable. In the midwest, the feed requirements for a work horse during the six month crop growing season were 5,200 Ibs of roughage (hay or herbaceous biomass), 3,200 lbs of concentrate, usually oats, and pasture (Williams and Speelman 1934). Horses were an important source of power during and immediately after World War II. By 1954, U.S. agriculture and industry was largely powered by gasoline, diesel, or electrical motors and there were only 5 million horses and mules in the U.S (Census of Agriculture 1954). The decrease in the numbers of draft animals released approximately 80 million acres of land for other purposes (Census of Agriculture 1954).