This data set brings together and categorizes many of the chemicals, solids, and microorganisms that are used in agriculture or produced as by-products of agriculture in the United States (as of 2009). Each entry in the data set includes the name, Chemical Abstracts Service Registry Number, purpose(s) in agriculture, and a reference. For pesticides and their degradates, the pesticidal use, parent pesticide, and the United States Environmental Protection Agency Pesticide Chemical Code are included. The data were compiled as part of a U.S. Geological Survey study to improve the understanding of field-scale and watershed-scale hydrology and the environmental behavior of individual chemicals. The goals of the study were to provide a foundation of understanding for making optimal management decisions and to help set the expectations of water quality improvements which can result from changes in agricultural management and policy decisions.