quantifying the effects of tillage

Quantifying the effects of tillage practices on annual runoff and

phosphorus export through drainage tiles and surface runoff in

southern Ontario, Canada

Merrin L. Macrae1, R. Brunke2, M. English3, G. Ferguson2; V. Lam1; K. McKague2; I. O’Halloran4, G. Opolko3, C. Van

Esbroeck1; and Y. Wang4

1 University of Waterloo,, Ontario, Canada mmacrae@uwaterloo.ca2 Ontario Ministry of Agriculture and Food, Ontario, Canada

3 Wilfrid Laurier University, Ontario, Canada4 University of Guelph, Ontario, Canada

Water quality issues related to algal growth are a priority issue in North America

Lake Simcoe, Photo Credit M. King

• Despite significant efforts over decades, and implementation of BMPs, P levels in Lakes still a problem

• Reduced or no-till (RT,NT) have been encouraged to reduce losses of particulate P (PP) in overland flow, but may increase dissolved P (DRP) loss in tile drains is NT a BMP?.

Photo Credit NOAA

• Most of our knowledge around P transport, tiles, tillage largely done during green season or regions without significant frost

• Spring is critical period for runoff in many regions – poorly understood

• Need to understand year-round processes to evaluate effectiveness of BMPs and role of tile drains

Sediment entering Lakes Erie & St. Clair, March

• To provide estimates of annual runoff and dissolved and particulate phosphorus (P) export rates in drainage tiles from sites in southern Ontario, Canada (north sides of Lakes Erie and Ontario).

• To determine the effects of tillage practices on P export in tile drainage.

• To determine relative contributions of surface runoff and tile drainage to field scale P losses.

Objectives for Today:

• 6 sites in Ontario Southern Ontario have been instrumented with runoffmonitoring equipment, automated water samplers and meteorologicalstations to collect high-frequency data year-round. Both tile drainageand surface runoff monitored at field scale. Tillage tested at plot scale.

Methods:

Seasonality in Precipitation and

Air Temperature, S. Ontario, Canada

• Approx. 900-1100 mm/yrPrecipitation - fairly evenly distributed throughout seasons but can be highly variable from day to day, month to month and season to season

• 30-40% falls as snow significant input to system during melt

Runoff and P Concentrations in Tile Drainage, Ontario, Canada, 2011-2013

• DRP dominates TP in winter; TP in summer (rainfall?)• Most annual P loss occurs Nov-March – driven by runoff gen.

• Minimal flow during summer growing season

• Most runoff occurs between November and March

V. Lam MSc. UW

Annual Losses of Phosphorus in Tile Drain Effluent

• DRP loss (2011-2012) 0.006 – 0.019 kg/ha/yr

• TP loss (2011 – 2012) 0.095 – 0.211 kg/ha/yr

• DRP represented 6-9% of TP annually

• Sites use multiple BMPs: • Soil P levels managed carefully ~12-25 mg/kg STP

(Olsen) at the surface (0-1” depth)• Shallow vertical tillage 1 in 3 years (minimum till).• Fertilizer applied in bands.

V. Lam, C. van Esbroeck, MSc. UW

Are There Differences in P Export with Tillage? Example from St. Mary’s, ON

1:1 Line is shown in figure in blackDRP (mg/l) TDP (mg/L) TP (mg/l)

G. Opolko, MSc. WLU

How Do Runoff Losses in Tiles Compare to Overland Flow?

• Most runoff leaves fields via tiles (~85%)

• Runoff = 36% of PPT

• Most overland flow occurs in winter (thaws) although large events during other periods can produce surface runoff

Monthly runoff, Oct. 2011 - Apr. 2013Londesborough, ON

Annual runoff May 2012-Apr. 2013, Londesborough, ON

C. van Esbroeck, MSc. UW

Median (Min-Max) P concentrations in tile effluent and overland flow during events

• Overland flow [P] > tile drain [P]

• High concentrations at tile drainage at both sites occurred immediately following P application

(a) DRP

(b) TP

TileOF

C. van Esbroeck, MSc. UW

Annual Loss & Speciation of P: Tiles versus Overland Flow May 2012-Apr 2013

• Most runoff leaves fields via tiles (~85%)

Runoff DRP

• More DRP leaves in surface runoff (esp. Site 3)• Tiles and surface runoff contribute equal amounts of

particulate P surface runoff would likely have more TP if sites were tilled

TP

C. van Esbroeck, MSc. UW

Summary• Most runoff and P loss happens in “pulses” seasonality

IS very important, especially spring freshet tiles and overland flow largely inactive during growing season.

• Tillage practices do not appear to impacting DRP or TP concentrations in tile drain effluent at our sites.

• Overland flow was the dominant pathway for DRP, and an equal pathway for TP at both sites, despite the fact that it was a small runoff contributor on an annual basis.

This im

Acknowledgements• 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]) and CAAP Programs– Grain Farmers of Ontario

• Logistical & Technical Support: ANSWERS farmers (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