Critical factors aff ecting field-scale losses of nitrogen and phosphorus in spring snowmelt runoff in the canadian prairies
Liu, K., Elliott, J.A., Lobb, D.A., Flaten, D.N., Yarotski, J. (2013). Critical factors aff ecting field-scale losses of nitrogen and phosphorus in spring snowmelt runoff in the canadian prairies, 42(2), 484-496. http://dx.doi.org/10.2134/jeq2012.0385
A long-term, fi eld-scale study in southern Manitoba, Canada, was used to identify the critical factors controlling yearly transport of nitrogen (N) and phosphorus (P) by snowmelt runoff Flow monitoring and water sampling for total and dissolved N and P were performed at the edge of fi eld. Th e fl ow-weighted mean concentrations and loads of N and P for the early (the fi rst half of yearly total volume of snowmelt runoff ), late (the second half of yearly total volume of snowmelt runoff ), and yearly snowmelt runoff were calculated as response variables. A data set of management practices, weather variables, and hydrologic variables was generated and used as predictor variables. Partial least squares regression analysis indicated that critical factors aff ecting the water chemistry of snowmelt runoff depended on the water quality variable and stage of runoff Management practices within each year, such as nitrogen application rate, number of tillage passes, and residue burial ratio, were critical factors for fl ow-weighted mean concentration of N, but not for P concentration or nutrient loads. However, the most important factors controlling nutrient concentrations and loads were those related to the volume of runoff , including snow water equivalent, fl ow rate, and runoff duration. Th e critical factors identifi ed for fi eld-scale yearly snowmelt losses provide the basis for modeling of nutrient losses in southern Manitoba and potentially throughout areas with similar climate in the northern Great Plains region, and will aid in the design of eff ective practices to reduce agricultural nonpoint nutrient pollution in downstream waters. © American Society of Agronomy, Crop Science Society of America,and Soil Science Society of America.