<P> The Haber - Bosch method for synthesizing ammonium nitrate represented a major breakthrough and allowed crop yields to overcome previous constraints . It was first patented by German chemist Fritz Haber . In 1910 Carl Bosch, while working for German chemical company BASF, successfully commercialized the process and secured further patents . In the years after World War II, the use of synthetic fertilizer increased rapidly, in sync with the increasing world population . </P> <P> In the past century agriculture has been characterized by increased productivity, the substitution of synthetic fertilizers and pesticides for labor, water pollution, and farm subsidies . Other applications of scientific research since 1950 in agriculture include gene manipulation, hydroponics, and the development of economically viable biofuels such as ethanol . </P> <P> In recent years there has been a backlash against the external environmental effects of conventional agriculture, resulting in the organic movement . Famines continued to sweep the globe through the 20th century . Through the effects of climactic events, government policy, war and crop failure, millions of people died in each of at least ten famines between the 1920s and the 1990s . </P> <P> The historical processes that have allowed agricultural crops to be cultivated and eaten well beyond their centers of origin continues in the present through globalization . On average, 68.7% of a nation's food supplies and 69.3% of its agricultural production are of crops with foreign origins . </P>

Farming was very difficult for the early farmers of the plains because of