Concentrating on Nutrient Loss Reduction: Analysis of the Manage Database Drainage Concentration Data.

Concentrating on nutrient loss reduction: Analysis of the MANAGE database drainage concentration data Allan Hertzberger1, Laura Christianson1, Daren Harmel2, 1 University of Illinois, Urbana-Champaign, IL 2 Center for Agricultural Resources Research, USDA-ARS, Fort Collins, CO The ability to satisfy growing demands for food production will increasingly rely on the use of agricultural intensification and crop specialization. It is now imperative to understand the negative environmental impacts of modern agricultural practices. The Measured Annual Nutrient loads from AGricultural Environments (MANAGE) water quality database is a series of tables which compile agricultural runoff loads and concentrations reported in peer-reviewed publications from across North America. In 2016, the MANAGE database was expanded to contain drainage nutrient concentration data to better understand factors contributing to fluxes of nitrogen (N) and phosphorus (P) in subsurface and surface drainage. An analysis performed on these recently compiled data provided insight into the controllable factors (e.g. tillage type, nutrient management, and crop selection) that influence N and P concentrations in agricultural drainage (primarily, subsurface “tile” drainage). Accounting for spatial and temporal variability in statistical models allowed for an accurate assessment of these controllable factors on drainage nutrient concentrations. Statistically significant differences existed between reported arithmetic versus flow-weighted mean nutrient concentrations, which highlights the importance of the need for transparent and consistent reporting of nutrient concentrations. This statistical approach will inform local, state, and federal agencies of the controllable factors promoting nutrient transport to surface water in an effort to improve the implementation of conservation practices.