Assessing Phosphorus Export in Tile Drainage from Farms with different Tillage Practices across Ontario: Challenges

Transcription

1 Assessing Phosphorus Export in Tile Drainage from Farms with different Tillage Practices across Ontario: Challenges Macrae 1, M.L., Brunke 2, R., English 3, M.C., Lam 1, V., McKague 4, K., O Halloran 5, I., Opolko 3, G., Van Esbroeck 1, C. and Wang 5, Y. 1 Department of Geography and Environmental Management, University of Waterloo, Waterloo ON Canada N2L. 2 Nutrient Management, Ontario Ministry of Agriculture, Food and Rural Affairs, London, Ontario, N6E 1L3. Phone: (519) Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo ON Canada N2L 3C5. 4 Water Quality, Ontario Ministry of Agriculture, Food and Rural Affairs, London, Ontario, N4T 1W2. 5 Ridgetown Campus, University of Guelph, Ridgetown, Ontario, N0P 2C0 June

2 Agricultural lands identified as source of phosphorus (P) to surface water bodies Many areas of uncertainty surrounding how/where/when/why the loading of P occurs Examples of uncertainty surrounding tile drains include: How much P is lost from agricultural fields via tile drains? (spatial variability) How does P in drainage tiles compare to overland flow? If (and how) management practices such as tillage type affect the partitioning of runoff and P export via these pathways Ontario? Is seasonality (i.e. winter and melt) important?

3 Objectives: 1) Quantify P movement from agricultural fields in tile drains (field scale plot scale) 2) Contribution of winter period (in particular spring snowmelt) to annual runoff and P loads 3) Tile runoff Vs Surface runoff for P quantity and speciation? (Watershed-within-field scale) 4) Effects of tillage practices on P movement (plot scale) [no-till, min till, disk till] in Ontario

4 On-farm research 6 (now 8) farms 3 plot scale; 5 field scale Year-round data collection, hifrequency during storms Landowners participate in data collection and research process Collaboration researchers, government, farmers

5 Tile line intercepted for flow and chemistry monitoring. Meteorological variables, soil moisture/temperature and water table position also monitored (remote access). Tile line access and ISCO in shed to prevent freezing.

6 Water Quality Sampling Approach What are we trying to capture in our sampling? P Concentration Tile Flow How do we define events? How do we select events to sample? ISCO water samplers at all sites triggered during some periods but not all (will discuss reasons for this later) Mass of P Exported Cooperators involved in sampling at some sites but not all Time

7 Drought Low Snow Year Weather Conditions Over Study Period, Innisfil Site Mild Dry! Typical or atypical of the norm? Jan/11 Jan/12 Jan/13

8 m 3 /d Ilderton Londesborough St. Mary s Innisfil I Innisfil II Bainsville

9 Upslope Plot (B) MNT Downslope Plot (C) MNT CT MNT Tile Runoff and Dissolved P Concentrations, Median Max Innisfil Dissolved I Site, P Dissolved P Site (mg/l) (mg/l) Innisfil 1 < Innisfil 2 < St. Mary's Bainsville Londesborough Ilderton * *Ilderton Both DP site and experienced TP Concentrations high DP following varied in manure time (TP application not shown but here) tile P concentrations SRP/TP ranged were from similar ~1-75% to other SRP sites higher otherwise fraction of TP in winter

10 C/MNT B/MNT C/MNT B/CT C/MNT B/MNT C/MNT B/CT Tillage increased infiltration and runoff at Innisfil sites but decreased infiltration and runoff at St. Mary s site SRP concentrations increased at Innisfil site following tillage

11 Dissolved P concentrations in tile effluent are lower than those in overland flow Site Tile Dissolved P (mg/l) Overland Flow Dissolved P (mg/l) Ilderton (2 Events) (< ) ( ) Londesborough (4 Events) (< *) (< ) Bainsville (2 events) (< ) ( ) Table: Median (Min-Max) dissolved P concentrations in overland flow and tile effluent *the high concentration at Londesborough site occurred immediately following P application

12 Relative Contributions of Tile Drains and Overland Flow to Field-scale Losses at Londesborough Site, Feb 2012 Feb 2013 % Annual Runoff % Annual TP Mass % Annual SRP Mass Tile Overland Flow SRP ranged from 1-23% of TP (in tiles) and 35-65% of TP in Overland Flow at this site

13 Gaps, Limitations and Challenges Gaps: Paucity of long-term data Winter sampling Mass Vs Concentrations; Tiles Vs Overland Flow Challenge: Equipment Function Weirs Vs Flow-monitoring equipment Winter performance of equipment? Reliance on technicians and co-operators Vs smart sensors /triggers

14 Gaps, Limitations and Challenges 65mm Gaps: Paucity of + snowmelt longterm data 40mm 14mm rain Winter sampling 18mm rain + snowmelt Mass Vs Concentrations; Tiles Vs Overland Flow Challenge: Equipment Function Weirs Vs Flow-monitoring equipment Figure: Depth of water in tile at Ilderton site Tile diameter 20 cm Reliance on technicians and co-operators Vs smart sensors /triggers

15 Gaps, Limitations and Challenges Limitations and Challenges: On-farm research Vs controlled conditions Importance of 2-way communication between co-operators and researchers How to deal with unexpected farm activities or weird weather Site-specific challenges (e.g. drainage capacity of tile network; issues with placement of equipment; theft/vandalism; runoff from adjacent land or residential inputs)

16 Gaps, Limitations and Challenges Challenge: Natural variability within a site Topography Importance of baseline data Challenges: Differences in land management practices What is no-till in Ontario? How to meaningfully compare across multiple sites with different crops, fertilizer input rates (and methods)?

17 Next Steps and Recommendations Long term data set >10 years? Comparisons across sites over multiple years Explain why we are seeing differences in effects of tillage can we determine situations where till or no-till is BMP? Link temporal variability in P losses and runoff to flow paths (preferential/matrix flow into tile drains) mechanistic studies Validate and refine models especially for winter and spring freshet Pairing field studies and lab experiments Continued dialogue between researchers, managers and stakeholders through individual meetings and meetings with groups

18 Funding: Ontario Ministry of Agriculture, Food and Rural Affairs Best Management Practices Verification and Demonstration Program, Lake Simcoe Program Environment Canada - Lake Simcoe Clean Up Fund Growing Forward (Agricultural Adaptation Council Farm Innovation Plan [FIP]) Logistical & Technical Support: ANSWERS group: D. Lobb, K. Eisses, B. McIntosh, K. Nixon, S. McRae, L. Taylor); Innovative Farmers of Ontario (IFAO); Land Improvement Contractors of Ontario (LICO), A. MacLean, E. Thuss, I. Martin, J. English, J. Owens, C. Duke