The roots of industrial agricu lture are embedded in the hist oric publication of Justus von Liebig's Chemistry in the Application to Agriculture and Physiology (1840). Von Liebig argued that we could sustain the productivity of agriculture without continuing mixed farming practices and the laborious task of manuring soils. Substituting synthetic fertilizers for such nutrient cycling practices substantially simplified farming practices, and the ability to substitute synthetic fer tilizers for nutrient cycling led farmers to specialize in the production of a few high-value crops and abandon the mixed farming practices which incorporated green manures and livestock into farming systems.