This is an intellectual history that traces the influence of ecological thought on the theory, practice, and policy of agriculture in the United States since the 1930s. Ecology served as both a scientific and ethical guide for two broad social movements analyzed in this dissertation. The "permanent agriculture" movement of the 1930s through the 1950s emerged from concerns over the destruction of the soil, and the desire to harmonize human technological endeavors with the interconnected biological and social universes in which humans functioned. Champions of permanent agriculture effectively promoted an ideology devoted to long-term land use planning, comprehensive soil conservation and restoration, organic-type farming, and a societal commitment to ecologically inspired harmony, prosperity, and permanence;In an overall period of crisis in American society, the message of peace, abundance, and health offered by permanent agriculture allowed for the "new farming" movement to reach a national audience in the 1940s and early 1950s, despite resistance from agricultural scientists and researchers, the agricultural policy camp, and other components of the "agricultural establishment." As the cult of interdependence devolved in the 1950s however, the goal of creating a permanent ecological agriculture subsided. Still, as Rachel Carson's Silent Spring (1962) dramatically indicated, ecological concerns reemerged in the 1960s, accompanied by a new sense of societal holism and a desire for "appropriate" or "soft" technology. By the late 1970s, another ecological farming movement arose devoted to the idea of sustainability. Sustainable ecological agriculture derived from older ideas such as organic farming, and new concerns about misguided human technology and culture, particularly the environmental, energy, and economic crises in agriculture and society in the 1970s and 1980s. Proponents of the more recent strain of the "new farming" successfully promoted farming systems devoted to ecological and technological sensibility, planned permanence, and to the perpetuation of smaller-scale farms and a return to rural-urban balance. Like the permanent agriculture movement, sustainable agriculture first faced resistance from the agricultural research-policy-agribusiness nexus, only to face eventual co-option and "taming" by that very establishment;The rise of ecological agriculture since the 1930s highlights two interesting social movements and the contemporary cultures they represented. Ecological agriculture also illustrates the centrality of agricultural issues in the rise of an environmental ethic in the United States, and offers some suggestions on how an abundant food supply might be ensured in the future.