Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).
Comparison of phosphorus export from controlled drainage and free drainage
Sonja Fransen, Ramanathan Sri Ranjan
University of Manitoba, Canada
Controlled drainage has been found to be a best management practice for decreasing drainage flows and thereby reduce the nutrient export from the field compared to free drainage. However, the ability of controlled drainage to reduce nutrient loading under different climate and soil conditions has not been thoroughly investigated. Year-round monitoring has also been a challenge, especially when trying to capture the significant contribution of the spring thaw event. The objective of this study was to conduct year-round measurements of nutrient loading and to compare the event-based nutrient export between controlled drainage and free drainage in a field site. Edge-of-field monitoring of the sites was done by measuring the flowrate at each of the control structures located at each drainage outlet for both field sites. The daily flow-weighted average of nutrient export was compared. Preliminary results show over 60% reduction of phosphorus exports in controlled drainage compared to free drainage.
2:10pm - 2:30pm
Modeling Non-point Source Phosphorus Export under southern Ontario Conditions in the Great Lakes Region
1School of Engineering (Water Resources Engineering), University of Guelph, Guelph, Ontario, N1G 2W1, Canada; 2Ontario Ministry of the Environment and Climate Change, Etobicoke, Ontario, M9P 3V6, Canada; 3School of Environmental Sciences, University of Guelph, Ontario, N1G 2W1, Canada
Non-point source (NPS) pollution such as phosphorus loss due to agricultural activities is a critical problem that has been threatening fresh water resources in southern Ontario. Hydrological and Water Quality (HWQ) models are important to help decision making processes to tackle the problem. However, modeling phosphorus generation and transport processes under southern Ontario conditions remain challenging. This is mainly due to the unique hydrological conditions in the region. In southern Ontario, phosphorus loss occurs under the dominance of saturation excess runoff generation and cold-climate conditions such as frequent freeze-thaw cycles. Such processes, however, are not yet fully incorporated into most HWQ models such as the Soil and Water Assessment Tools (SWAT) model. This work, therefore, aims at upgrading and applying the SWAT model for southern Ontario conditions. To achieve the objectives, the following work is being done: (1) variable source area concept will be incorporated into SWAT to simulate the dominant saturation excess runoff process; (2) the phosphorus module of SWAT model will be upgraded to consider cold-climate conditions; and (3) the modified model will be tested over the Gully Creek watershed, ON, Canada. The presentation will highlight the approach and results related to modeling phosphorus export in agricultural watershed under southern Ontario conditions
2:30pm - 2:50pm
Nitrogen and Phosphorus Uptake by Cattail during Wetland and Terrestrial Phytoremediation of End-of-Life Municipal Lagoons.
Nicholson Ngoni Jeke1, Francis Zvomuya1, Lisette Ross2
1University of Manitoba, Canada; 2Native Plant Solutions, Ducks Unlimited Canada
Phytoremediation offers great potential as a less expensive, sustainable alternative to landfilling and the spreading of biosolids on agricultural land during decommissioning of municipal lagoons. This study examined nitrogen (N) and phosphorus (P) uptake by cattail (Typha latifolia L.) from biosolids in a primary and a secondary cell of a municipal lagoon. A wetland was constructed in the primary cell while the secondary cell was managed as an upland (terrestrial) system. Plots (2 m × 2 m) were established in both cells and cattail was harvested either once or twice per season. Plant tissue and biosolids samples were collected and analyzed for N and P concentrations. Results from the first three seasons showed lower aboveground dry biomass yield and nutrient phytoextraction from two harvests per season relative to a single harvest, indicating no benefit from harvesting cattail twice per season. Dry biomass yield and nutrient uptake were lower in the terrestrial system compared with the wetland system, reflecting the lower nutrient content in the biosolids from the secondary cell relative to the primary cell. Uptake of N and P from a single cattail harvest in the wetland-based phytoremediation system (10.1 g m-2 and 1.2 gm -2) and the terrestrial-based system (6.0 g m-2 and 0.75 g m-2) suggests that in situ phytoremediation can effectively remove N and P from biosolids and therefore, may be a viable alternative to land spreading and landfilling of biosolids.
2:50pm - 3:10pm
Evaluation of subsurface drainage in promoting soil strength for field operations in southern Manitoba
Afua Mante, Ramanathan Sri Ranjan
University of Manitoba, Canada
The soil strength of drained and undrained fields in Southern Manitoba was compared to evaluate subsurface drainage in promoting soil strength for field operations in Southern Manitoba. The subsurface drain tile was installed at 0.9 m depth and at 15 m spacing. Consistency index, a measure of the resistance of the soil to deformation, was used to assess the strength of the top 0.5 m of the soil profile. Susceptibility and vulnerability assessments were used to assess the strength of the subsoil at 0.6 m depth of the soil profile. A consistency index of 0.75 was used as the criterion to assess the suitability of the soil to allow field operations. The consistency index analysis showed that irrespective of the watertable depth, the subsurface drained field did not lower the water content sufficient to promote soil strength suitable for field operations in the study area. This was attributed to an impeding layer, which prevented free drainage of water through the soil profile towards the drain. The impeding layer caused higher water content in the top 0.6 m of the soil profile making it highly susceptible and very vulnerable to compaction.