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CEAP—Conservation Effects Assessment Project. APEX Modeled Estimates of Edge of Field Benefits to Nitrogen Loss Reduction in the Mississippi River Basin (MRB). DWM CEAP Analysis Approach. Conservative demonstration of potential benefits from DWM on eligible acres Two scenarios utilized:
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CEAP—Conservation Effects Assessment Project APEX Modeled Estimates of Edge of Field Benefits to Nitrogen Loss Reduction in the Mississippi River Basin (MRB)
DWM CEAP Analysis Approach • Conservative demonstration of potential benefits from DWM on eligible acres • Two scenarios utilized: • Addition of only DWM to existing suite of conservation practices • Addition of DWM and Enhanced Nutrient Management (ENM) – proper form, timing, rate and method – plus filter strips and/or riparian buffers as appropriate.
DWM CEAP Analysis Approach • Total acres estimated are from CEAP survey and NRI CEAP expansion factors using the following criteria: • Slopes less than 1% • Presence of existing subsurface tile drainage, open ditch surface drainage, or both • Inherent drainage class of : • Somewhat Poorly • Poorly • Very Poorly • Ponded
Edge of Field Total N Losses and Reduction in N Losses for Eligible Acres –Baseline, DWM and DWM/ENM
Summary of Findings • Drainage water management can be applied to over 14.2 million acres in the MRB. • Drainage water management should be used with sound nutrient management because: • When used alone during the winter it could reduce N loss from the edge of the field by over 74 million pounds. • By applying nutrients at the right rate, time, form and method along with drainage water management could reduce losses by a total of 224 million pounds. • Preliminary estimates indicate annual instream delivery of nitrogen to the Gulf may be reduced by 39 million pounds with DWM during the winter months and 120 million pounds when sound nutrient management is added.
Summary of Findings • In the majority of cases yields are maintained. • Under some circumstances nitrogen applications rates may need to be carefully increased to maintain yield when nutrient management and drainage water management are used together. • In colder climates, like the Upper Mississippi and Missouri Rivers, drainage water management practices should be used during the growing season since negligible results were found with winter application. • Furrow diking and edge of field practices like filter strips may be necessary to reduce increased runoff losses due to field saturation subsequent to drainage water management.
