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

Abstract

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 best management practices and improving model accuracy in cold weather agricultural systems.Abbreviations: BMP, best management practice; DRP, dissolved reactive phosphorus; TP, total phosphorus; TSS, total suspended sediment.

Agricultural Water Quality in Cold Climates: Processes, Drivers, Management Options, and Research Needs

“…The contribution of snowmelt to annual runoff and nutrient losses presents regional differences. In regions with relatively mild winters such as southwest Wisconsin, USA, Hoffman et al (2019) find that P runoff loss is dominated by snowmelt or rain on snow events in approximately half of 12 monitoring years and by summer rain events in the other half. In contrast, in regions with harsher winters such as the northern Great Plains, snowmelt plays a more dominant role in annual runoff and total P loss.…”

“…A diagram showing key agronomic, biogeochemical, and hydrological characteristics influencing nutrient losses in cold agricultural regions. The papers in this special section investigate different aspects of these characteristics, including the importance of the nongrowing season (Good et al, 2019; Plach et al, 2019; Ulén et al, 2019) and snowmelt (Hoffman et al, 2019; Kokulan et al, 2019; Wilson et al, 2019a) in annual flow and nutrient transport, the impacts of vegetative nutrient release (Cober et al, 2019; Costa et al, 2019; Liu et al, 2019b; Schneider et al, 2019; Vanrobaeys et al, 2019), the impacts of winter and fall nutrient applications (He et al, 2019; Sadhukhan et al, 2019; Smith et al, 2019; Stock et al, 2019; Vadas et al, 2019; Vetsch et al, 2019; Zopp et al, 2019), the influence of soil on nutrient loss (Dharmakeerthi et al, 2019; Liu et al, 2019a; Satchithanantham et al, 2019; Wilson et al, 2019b), and the patterns of nutrient concentrations in streams (Casson et al, 2019). …”

“…Climate change will have important impacts on cold region hydrology and already appears to be increasing the importance of rain on frozen soils and rain on snow events, and overall rainfall runoff in some regions, such as the northern Great Plains (Wilson et al, 2019a). Jointly, these factors have contributed to a high degree of spatial and temporal variability in nutrient transport in cold agricultural regions (Hoffman et al, 2019; Wilson et al, 2019a).…”

Influence of Soil and Manure Management Practices on Surface Runoff Phosphorus and Nitrogen Loss in a Corn Silage Production System: A Paired Watershed Approach

“…Much of the annual runoff in cold climate regions is from snowmelt [11,13,34,35,39,68,69]. An average of 53% of annual runoff (averaged across watersheds and control/treatment periods) was derived from snowmelt.…”

Soil Tillage and Crop Growth Effects on Surface and Subsurface Runoff, Loss of Soil, Phosphorus and Nitrogen in a Cold Climate

“…Severe erosion and loss of total phosphorus occur during events with rain on frozen or snowcovered soil [11]. Hoffman et al [31] showed that late winter snowmelt and mixed snowmelt and rain events increased total phosphorus losses and the DRP/TP ratios with a need to focus management actions on this period.…”