Mechanization of agriculture in the twentieth century helped to dramatically increase global production of food and fiber to feed and clothe a burgeoning world population. Among the significant developments in agricultural mechanization in the twentieth century were the introduction of the tractor, various mechanical harvesters and pickers, and labor-saving technologies associated with internal combustion engines, electric motors, and hydraulics. While mechanization increased output and relieved some of the drudgery and hard work of rural life, it also created unintended consequences for rural societies and the natural environment.
By decreasing the need for labor, mechanization helped accelerate the population migration from rural to urban areas. For example, in 1790, 90 percent of Americans worked in agriculture, yet by 2000 only about 3 percent of the American workforce was rural. Blessed with great expanses of land and limited labor, technologically inclined Americans dominated the mechanization of agriculture during the twentieth century. Due to mechanization, irrigation, and science, the average American farmer in 1940 fed an estimated ten people, and by 2000 the number was over 100 people. Yet even as mechanization increased the speed of planting and harvesting, reduced labor costs, and increased profits, mechanization also created widespread technological unemployment in the countryside and resulted in huge losses in the rural population.
After Nicholas Otto patented the internal combustion engine in 1876, the days of horse and steam power in agriculture were eventually eclipsed on the farm by gasoline and diesel engine power. Early steam tractors weighed as much as 5 tons or more and required substantial labor to operate and fuel. The operators were continually at risk from possible explosion of the boiler that powered these iron-wheeled beasts. A number of American manufacturers, such as the Hart-Parr Company, the John Deere Plow Company, and International Harvester, were engaged in building gasolinepowered tractors at the beginning of the twentieth century.
As tractors became more powerful, practical, and affordable, their presence increased on the farmstead. With a tricycle design for enhanced maneuverability, a PTO (power take-off) to run equipment, hydraulic lifts, a three point hitch, and pneumatic tires, tractors could pull a plow, mow and bale hay, disk weeds, or dig furrows among other tasks. In 1907 some 600 gasoline-fueled tractors were in operation in the U.S.; by 1950 nearly 3.5 million tractors were in use in the U.S. alone.
Tractors, unlike horses and mules, did not require five acres to feed every year, and they did not need rest. Henry Ford’s all-purpose Fordson in 1917, and the International Harvester Farmall in 1924 enjoyed high sales in the 1920s. Other tractor improvements included roll bars, improved seating, variable hydrostatic transmission for increased speeds, and Harry Ferguson’s hydromechanical servo, which allowed the tractor operator to control the depth of implements in the soil by keeping a constant load on the tractor. The first diesel designed to power movable machinery in the U.S. was built in 1930, and by the mid-1930s the first diesel tractor was sold.
From the World War I campaign to increase wheat production in the U.S. to the Soviet Union’s ‘‘virgin lands’’ projects of the 1950s and 1960s, tractors have increased the amount of land under cultivation throughout the globe. While yields increased, so did potential environmental catastrophes, such as the American Dust Bowl in the 1930s, and the failure of much of Soviet’s virgin lands program. By the end of the twentieth century the U.S. had only two major tractor manufacturers, and India led the world in tractor production, building nearly 300,000 units per year. In Africa most of the farm labor continued to be done by people or animals. Along with the gasoline-powered tractor came other devices to increase efficiency and profits by reducing labor and expanding the scope of production. In the large wheat area of the American West, the first combine harvesters appeared in the 1890s. After Cyrus McCormick’s famous reaper appeared in the 1830s, inventors tried to find ways to combine the harvesting and threshing process. Hiram Moore and others made several attempts at manufacturing combines in the mid-nineteenth century, but it took until around 1900 for largescale farmers on the American West Coast to employ the first commercially and mechanically viable combines.
Tractors pulled the first combines, and they used a rotary header to gather the plant, a cutting bar, and an internal thresher, but by the 1940s the machines were self-propelled. Gasoline powered engines or the PTO of a tractor operated the cutter, and the various mechanical fingers and pulleys that drew the crop into the thresher and shook the grain loose from the plant, with the grain being augured into a grain tank, and the crop residue sprayed back onto the field. Early combines required a four-man crew and could cut up to a 16-foot (5- meter) swath. Over the years combines became larger, with rubber tires, self-enclosed air conditioned cabs, headlights to allow night harvesting, and wider swathes.
Combines represented a tremendous capital investment for farmers, and they contributed to the growth in the size of individual farms and the population decline in rural communities. But whether a farmer purchased a combine, or hired a custom crew, combines were less expensive and more dependable than hiring a crew of laborers to harvest large fields. While the first combines primarily harvested wheat, mechanical engineers would later build machines to combine harvest rice, oats, soybeans, and corn by mid-century. Early models of these machines often left up to 50 percent of the grain in the field and were prone to problems when operated in muddy fields as well as mechanical difficulties. Yet even with these difficulties, combine harvesters became increasingly efficient, and they remain a symbol of the mechanization of agriculture in the twentieth century.
Inventors, corporations, mechanical engineers, and professors perfected machines to harvest grains, but cotton remained primarily a handpicked crop until the 1950s. Cotton bolls ripened at different times, and developing a machine that could pick trash-free fiber without damaging the cotton took over 100 years. In the 1920s and 1930s, early versions of the cotton picker often used vacuum pumps and blowers to either suction or blow the cotton into large bags. Engineers John and Mack Rust experimented with combines that used smooth wet spindles to pick the crop and barbed and serrated spindles to twist the lint from the boll. In the mid-1930s the Rust machine could pick almost 180 kilograms of cotton per hour. In 1948 the International Harvester Corporation was the first company to successfully market a mechanical cotton picker. It used rotating metal drums with wetted spindles that pulled the lint from the bolls, rubber doffers to remove the fibers from the spindles, and an air conveyor to blow the cotton into a container.
Cotton harvesters became more efficient, less expensive, and more economically viable for farmers, especially those with larger holdings. Additional improvements reduced the amount of plant material, or trash, in the cotton, and by the late 1960s most of the cotton crop in the U.S. was machine picked. An early two-row cotton picker displaced 80 workers, and in the U.S. alone millions of workers were technologically unemployed by the mechanization of the cotton harvest. Like cotton, sugar beet harvesting was difficult to mechanize. Sugar beets have deep roots and heavy foliage. Growers relied on a large number of laborers to grow, harvest, and transport the crop. Beets had to be pulled from the ground, topped with a knife, and then loaded onto trucks or wagons. In the 1930s it took about 30 hours of labor to harvest an acre of sugar beets. A successful harvesting device would require the machine to top the beets and to remove the excess dirt and clods from the crop. Early machines topped the beets at ground level and lifted the roots with a spiked wheel onto a conveyor belt and into a truck. By the 1970s sugar beet harvesters had been enhanced to the point where they could harvest 24 acres in a ten-hour day.
Mechanization of agriculture most often occurred in developed nations willing to invest in labor-saving technology. In the U.S., farmers in the Central Valley of California have been at the forefront of agricultural mechanization. The early combines and cotton pickers were first utilized in California, where growers were often dependent upon migratory labor. Tomatoes were another major California crop that required vast supplies of labor. Creating a mechanical tomato picker involved a number of obstacles. Tomatoes on the plant ripened at different times, the vines snarled machines, and the fruit itself was easily bruised and not suited to machines. Consequently, to develop the machine-harvested tomato required the cooperation of engineers and crop scientists. New varieties of tomatoes that ripened simultaneously and were tough skinned emerged from university and corporate laboratories and test plots, such as The tomato picker developed by the 1960s worked by lifting and cutting the vines and shaking the plant on a shaking bed, where the harvested tomatoes would then fall onto a conveyor belt which transported the fruit to a bin while the vines fell to the ground. Though the early pickers had many technical problems and often malfunctioned, they could harvest 10 tons, or one third of an acre of tomatoes, per hour. Most of the tomatoes harvested mechanically ended up as catsup, juice,
or tomato paste, and the process of mechanically harvesting market-fresh tomatoes remained problematic in the 1990s. Tens of thousands of farm laborers in California alone lost their jobs with the advent of tomato harvesters. The mechanical tomato harvester also allowed for a sweeping increase in tomato production worldwide. When contemplating the mechanization of agriculture, we associate large and complicated machines roaring through a field as the symbol of
technological change in the countryside. But mechanization of the farm had many smaller, less extravagant elements, such as the influence of electrification. Many rural communities in the developing world still lack electricity. In the U.S. in the early 1930s, the federal Rural Electrification Administration helped bring electricity to the farms of America. Electricity powered milking machines, cream separators, and irrigation pumps. Electric power also allowed for environmentally controlled barns and greenhouses, cold storage units, and grain dryers that facilitated the mechanization of the grain harvest. Small electric motors could make a number of tasks on the farm easier, whether it be an auger to move grain, or a grinder or arc welder in the workshop. Many other devices helped to mechanize agriculture in the twentieth century. Automobiles, trucks, and other transportation improvements transformed rural society and reated new market opportunities and new competitors for farmers. Giant feed lots confined thousands of animals for meat or dairy production using highly mechanized facilities for feeding the animals and removing the waste.
Citrus growers used wheeled machines with revolving blades to trim the trees in their orchards; in almond orchards, machines grab and shake the fruit from the tree and another machine sweeps the crop from the ground. Pesticide sprayers with tall wheels and giant booms glide over rows of vegetables. On grape vineyards plastic-fingered pickers shake grapes from the vines on their way to be pressed into wine; and elaborate systems for drip irrigation allow for the precise application of water, fertilizers, and other chemicals. Every year brings new changes, technological improvements and mechanical innovations, but with each new step toward mechanization there is a corresponding increase in capital costs, technological unemployment, and environmental disruption. Clearly the move from human- and horsepowered agriculture reduces the number of people required to grow food and fiber, and by the last half of the twentieth century developing countries were embracing the mechanization of their indigenous agriculture on the Western model.