Terrestrial Field Degradation Based on Soil, Climatic, and Geographic Factors

Field degradation data of pesticides and their metabolites from North America, Europe, and the Tropics have been reviewed, assessed, and compared. The study focused on field residue trial data with degradation as the only or predominant dissipation process and included kinetic evaluations with and without normalization to reference conditions for soil temperature and moisture to study the effect of climate and soil separately. The Koppen-Trewartha classification has been used to group North American and European trial data into similar climate groups before comparison. Generally, non-normalized field degradation followed a temperature gradient and was slower in temperate regions compared to the subtropics and tropics. Within North America degradation in Canada was slower compared to the U.S. and within the U.S. pesticide degradation on temperate sites was slower than on subtropical ones. Between Northern and Southern Europe and between Europe and North America non-normalized and normalized degradation was generally not different. Upon normalization the latitudinal trend across North America disappeared and soil properties became evident as drivers for degradation. Only normalized field degradation on cold and dry sites low in organic matter in the Pacific Northwest as well as on intensely weathered sites with acidic soils in the Southeast was slower compared to other regions in the U.S.