|LABARGE, GREGORY - The Ohio State University|
|REUTTER, JEFFRY - The Ohio State University|
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2017
Publication Date: 1/18/2018
Citation: King, K.W., Williams, M.R., Smith, D.R., LaBarge, G.A., Reutter, J., Duncan, E.W., Pease, L.A. 2018. Addressing agricultural phosphorus loss in artificially drained landscapes with 4R nutrient management practices. Journal of Soil and Water Conservation. 73:35-47.
Interpretive Summary: Losses of phosphorus fertilizer from agricultural crop production have been linked to harmful and nuisance algal blooms (HNABs) plaguing Lake Erie and other inland waters. The 4R nutrient stewardship and certification program was established to promote the right source, right rate, right time, and right placement of fertilizer management. The 4R approach was demonstrated to reduce P losses across multiple fields in the Lake Erie basin. Implementation of the 4R principles proved to be a viable management strategy for reducing P in surface runoff and subsurface tile drainage, ultimately reducing the frequency and extent of harmful algal blooms.
Technical Abstract: Agricultural phosphorus (P) loss has been linked to the eutrophication of surface water bodies throughout the world and minimizing offsite P transport continues to be a priority in many watersheds. In the U.S. Midwest and other tile-drained regions, there is a critical need to identify nutrient management practices that decrease P loss in both surface and subsurface flow paths. An edge-of-field (EOF) network monitoring 40 agricultural fields was established in northwest Ohio, USA to quantify the impacts of prevailing and novel best management practices on surface and subsurface P concentrations and loads. In this study, we evaluate nutrient management practices across these fields with varying characteristics in order to identify a suite of management practices within the 4R nutrient management framework (‘right source’, ‘right rate’, ‘right time’, ‘right place’) that reduce agricultural P loss in artificially drained landscapes. EOF monitoring data indicate that applying organic fertilizers at P-based rates, considering the solubility of the fertilizer source, soil testing and following recommended application rates, avoiding fertilizer application during wet periods of the year (e.g., winter, early spring) and prior to large precipitation events, and placing fertilizer in the subsurface are all practices that result in decreased P loss. Findings also highlight the importance of field hydrology on surface and subsurface P transport and suggest that water management practices may also be effective at decreasing P loss. While the effectiveness of the nutrient management practices evaluated in this study will likely vary across fields with different characteristics, implementation of these practices should be considered a directionally correct (i.e. will reduce nutrient loss) approach for addressing excess P loss from artificially drained landscapes.