<P> During World War I prices shot up and farmers borrowed heavily to buy out their neighbors and expand their holdings . This gave them very high debts that made them vulnerable to the downturn in farm prices in 1920 . Throughout the 1920s and down to 1934 low prices and high debt were major problems for farmers in all regions . </P> <P> Beginning with the 1917 US National War Garden Commission, the government encouraged Victory gardens, agricultural plantings in private yards and public parks for personal use and for the war effort . Production from these gardens exceeded $1.2 billion by the end of World War I. Victory gardens were encouraged during World War II When rationing made for food shortages . </P> <P> A popular Tin Pan Alley song of 1919 asked, concerning the United States troops returning from World War I, "How Ya Gonna Keep' em Down on the Farm (After They've Seen Paree)?". In fact, many did not remain "down on the farm"; there was a great migration of youth from farms to nearby towns and smaller cities . The average distance moved was only 10 miles (16 km). Few went to the cities over 100,000 . However, agriculture became increasingly mechanized with widespread use of the tractor, other heavy equipment, and superior techniques disseminated through County Agents, who were employed by state agricultural colleges and funded by the Federal government . The early 1920s saw a rapid expansion in the American agricultural economy largely due to new technologies and especially mechanization . Competition from Europe and Russia had disappeared due to the war and American agricultural goods were being shipped around the world . </P> <P> The new technologies, such as the combine harvester, meant that the most efficient farms were larger in size and, gradually, the small family farm that had long been the model were replaced by larger and more business - oriented firms . Despite this increase in farm size and capital intensity, the great majority of agricultural production continued to be undertaken by family - owned enterprises . </P>

Major agricultural invention from the mid to late 1800s or early 1900s