Every soil scientist knows that soils vary enormously from one site to another. Soils differ in texture, structure, density, color, organic matter content, water holding capacity, acidity, and more; all of these characteristics shape and are shaped by the human and non-human activities that take place within and around the soil. In this sense, soil is a social being, existing and changing in intimate relationship with a multitude of biotic and abiotic processes.

In California’s Salinas Valley, an industrialized agricultural region of international economic importance, soil connects people amidst massive socio-environmental inequality. While the fertility of the soil is exploited for the benefit of predominantly white land- and agribusiness-owners, leaching of fertilizers into regional groundwater supplies has poisoned the drinking water of rural, working-class communities of color who labor in the surrounding fields. And although soil scientists have important tools that can support improved nutrient management on farms, activists caution that soil science knowledge must be accessible and useful to the people who are most in need of socio-environmental change. In this context, my dissertation explores the kinds of expertise that differently positioned people bring to the problem of regional soil management and groundwater contamination, with a focus on three types of actors: academic researchers, agricultural extensionists, and small-scale farmers. Findings highlight the social dimensions of both soil management soil science, and contribute to scholarship on environmental politics in agricultural landscapes.