Agricultural Edge‐of‐Field Phosphorus Losses in Ontario, Canada: Importance of the Nongrowing Season in Cold Regions

Abstract

Agricultural P losses are a global economic and water quality concern. Much of the current understanding of P dynamics in agricultural systems has been obtained from rainfall-driven runoff, and less is known about cold-season processes. An improved understanding of the magnitude, form, and transport flow paths of P losses from agricultural croplands year round, and the climatic drivers of these processes, is needed to prioritize and evaluate appropriate best management practices (BMPs) to protect soil-water quality in cold regions. This study examines multiyear, year-round, high-frequency edge-of-field P losses (soluble reactive P and total P [TP]) in overland flow and tile drainage from three croplands in southern Ontario, Canada. Annual and seasonal budgets for water, P, and estimates of field P budgets (including fertilizer inputs, crop uptake, and runoff ) were calculated for each site. Annual edge-of-field TP loads ranged from 0.18 to 1.93 kg ha −1 yr −1 (mean = 0.59 kg ha −1 yr −1 ) across the region, including years with fertilizer application. Tile drainage dominated runoff across sites, whereas the contribution of tiles and overland flow to P loss differed regionally, likely related to site-specific topography, soil type, and microclimate. The nongrowing season was the dominant period for runoff and P loss across sites, where TP loss during this period was often associated with overland flow during snowmelt. These results indicate that emphasis should be placed on BMPs that are effective during both the growing and nongrowing season in cold regions, but that the suitability of various BMPs may vary for different sites.• We conducted a multiyear, field-based study of edge-of-field runoff and P loss. • Tile drainage was the dominant pathway for runoff. • Contribution of tiles and overland flow to P loss differed regionally. • The nongrowing season was critical for edge-of-field runoff and P loss.

Evaluating Hydrologic Response in Tile‐Drained Landscapes: Implications for Phosphorus Transport

“…1) in Ontario, with subsequent determination of SRP at both laboratories. At the Ontario sites, samples were collected at 2‐ to 8‐h intervals throughout storm events to capture the entire event hydrograph, including baseflow at the beginning and end of the event as described in Plach et al (2019). At the Ohio sites, water samples were collected at 6‐h intervals, and the four samples collected in a 24‐h period were composited into a single sample for that 24‐h period.…”

“…Much of the evidence of enhanced P loss in tile drains has emerged from studies in fine-textured soils, where connectivity between surface soils and tile drains is increased by the presence of macropores (Stamm et al, 1998;Beauchemin et al, 1998). Research targeting clay-rich agricultural sites in Ohio, Indiana, and Ontario in North America has shown substantial P loss via tile drainage, with similar concentrations in surface and subsurface discharge King et al, 2018;Plach et al, 2019). In contrast, studies in coarser-textured soils in Sweden (Andersson et al, 2013) and across Quebec (Beauchemin et al, 1998) and Ontario (Plach et al, 2018a(Plach et al, , 2019Lam et al, 2016) in Canada have shown smaller P concentrations in tile drainage relative to surface runoff.…”

“…Research targeting clay-rich agricultural sites in Ohio, Indiana, and Ontario in North America has shown substantial P loss via tile drainage, with similar concentrations in surface and subsurface discharge King et al, 2018;Plach et al, 2019). In contrast, studies in coarser-textured soils in Sweden (Andersson et al, 2013) and across Quebec (Beauchemin et al, 1998) and Ontario (Plach et al, 2018a(Plach et al, , 2019Lam et al, 2016) in Canada have shown smaller P concentrations in tile drainage relative to surface runoff. It is unclear if these apparent differences are due to differences in soil texture and geochemistry (Plach et al, 2018a), climatological variables (Maccoux et al, 2016), management practices (Duncan et al, 2017;Jarvie et al, 2017), or a combination of these factors.…”

The Application of Geographic Information System (GIS) and Remote Sensing in Quantifying Snow Cover and Precipitation in Kabul Basin

“…Microclimate greatly influences snow characteristics in an area, so the is a need for differing planning to cope with too high rainfall (Plach et al, 2019). Meltsnow is the most influential source of irrigation in the area before the rainy season (Biemans., 2019).…”

The Latitudes, Attitudes, and Platitudes of Watershed Phosphorus Management in North America

“…Snowmelt and runoff over frozen or partially frozen soils are important, if not primary, processes for P transport in the northern watersheds, from the Chesapeake Bay to Lake Winnipeg. Indeed, runoff and P mobilization in the Lake Erie and Lake Winnipeg watersheds primarily occur throughout the nongrowing season (Macrae et al, 2007; Ford et al, 2018; King et al, 2018; Plach et al, 2019) and is most often dominated by spring snowmelt (Macrae et al, 2007), although large‐magnitude events can occur at other times of year, including the summer months (Macrae et al, 2010; Van Esbroeck et al, 2017). Mitigation strategies that are effective under rainfall‐dominated conditions during the growing season have not been successful during the winter period (Baulch et al, 2019; Kieta et al, 2018).…”