Phosphorus losses from agricultural fields in Ontario, Canada: Implications for land management efficacy in cold regions
Abstract
Agricultural phosphorus (P) losses are a growing global economic and water-quality concern in cold weather regions. An improved understanding of the magnitude, form and transport flow paths of P losses from agricultural croplands, and, the climatic drivers of these processes is needed to apply and evaluate appropriate beneficial soil management practices (BMPs) to protect soil-water quality in cold regions. This study examines multi-year (2012-2017) high-frequency edge-of-field P losses (dissolved reactive P (SRP) and total P (TP)) in surface runoff and tile drainage from 3 croplands in Ontario, Canada across four seasons, including winter. Annual and seasonal budgets for water, SRP and TP, as well as estimates of annual field budgets for P (i.e., based on fertilizer inputs, crop uptake, runoff and soil storage), were calculated for each site. Distinct runoff and P loadings, and the relative contribution of tile drainage and surface runoff to annual and seasonal P budgets were evident among years in contrasting landscapes and soil types. The non-growing season (October-April) was important to runoff and P loss from sites with loam-textured soils in the hummocky landscape of mid-western Ontario, whereby the majority of SRP and TP loss occurred by overland flow during a few peak rainfall and snowmelt-driven runoff events. In contrast, runoff, and SRP and TP losses were more eventually distributed year-round at the clay-textured site in the flat landscape of southwestern Ontario. Although tile drainage was the dominant pathway for runoff across the region, a greater portion of annual SRP and TP was lost through the tile drains at the clay site relative to the loam sites. These results, including estimates of annual field budgets for P, and implications for BMP efficacy in cold weather regions based on slope and soil-texture will be presented.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B33M2853P
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCESDE: 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCESDE: 1863 Snow and ice;
- HYDROLOGY