Long‐term Variation in Agricultural Edge‐of‐Field Phosphorus Transport during Snowmelt, Rain, and Mixed Runoff Events

作者：Adam Hoffman, Austin Polebitski, Michael R. Penn, Dennis Busch · 发表于：Journal of Environmental Quality · 年份：2019 · DOI：10.2134/jeq2018.11.0420 · 被引用次数：31 · 研究领域：Soil and Water Nutrient Dynamics、Hydrology and Watershed Management Studies、Soil erosion and sediment transport

Runoff of nutrients and erosion of soil from agricultural lands affect soil fertility and are important nonpoint contributors of P and N to surface and ground waters, yet studies of edge‐of‐field nutrient transport from snowmelt or rainfall runoff on frozen ground are limited. The objective of this study was to quantify the temporal and spatial variation in edge‐of‐field snowmelt, rain, and mixed (rain on snow) runoff events for sediment and P loadings in five agricultural subwatersheds over a 12‐yr period. Edge‐of‐field runoff events from five subwatersheds at Pioneer Farm near Platteville, WI, ranging in size from approximately 4 to 30 ha were sampled using automated samplers from 2002 through 2014 to determine sediment and P yields (mass loads). Mean dissolved reactive P (DRP) runoff concentrations for each event type (rain = 1.24 mg L −1 , snow = 1.90 mg L −1 , mix = 2.23 mg L −1 ) were above total P (TP) water quality guidelines for surface waters. The percentages of TP that was DRP for snow, mixed, and rain events were 74, 84, and 39%, respectively. Although variation in total annual P yield in edge‐of‐field runoff was noted between years and among sites within a given year, when aggregated over the study period, the subwatersheds showed similar transport characteristics with respect to DRP and TP yield. This study highlights the importance of examining long‐term datasets in quantifying annual yields and understanding the timing of DRP and TP transport for developing be...