How much phosphorus does it take to make Lake Erie green? Dr. Ivan O’Halloran, Associate Professor, University of Guelph, Ridgetown Campus

Jake Munroe, Soil Fertility Specialist, OMAFRA

2

3

Overview

• What causes an algal bloom?

• Why is Lake Erie particularly vulnerable?

• How the situation has changed from blooms of the past

• Phosphorus movement off agricultural land

• Ontario research: phosphorus and water quality

• Top tips for keeping phosphorus on your land and out of the water

4

What Causes an Algal Bloom?

• All living organisms require phosphorus (P)

• P is commonly the least abundant macronutrient and the first to limit biological productivity

• Excess P in lakes can stimulate excessive growth of algae

• Warm temperatures and lots of sunlight provide optimal conditions

5

Dissolved P and Lake Erie

6 • Total P entering Lake Erie has decreased since 1970s • Amount of dissolved P entering Lake Erie is much

higher than what it was in mid-1990s

Some Important Terms

• Dissolved Reactive Phosphorus (DRP)

• The portion of dissolved phosphorus that is bio-available

• Soil Test Phosphorus (STP)

• Soil test level for crop available phosphorus

• Point Source (PS) vs. Non-Point Source (NPS)

7

Lake Erie Isn’t Alone

8

Lake Winnipeg

Lake Winnipeg

9

10

Caspian Sea

11

12

Why is Lake Erie Vulnerable?

• Of the Great Lakes, Lake Erie is the:

• Smallest in volume

• Shallowest

• Warmest

• Watershed has a high population concentration

• Western basin is particularly shallow

13

14

Shallow Western Basin

15

Priority Watersheds

16

Lake Erie’s Phosphorus History

NPS

17

Current Target 11,000 tonnes

Why Have Blooms Returned?

Higher Percentage of

Dissolved P

• Reasons are not understood

Changing Land Use

• Increased P discharges from urban and agricultural landscapes

Residual P

Re-suspension of P from stream and lake

sediments

Aquatic Invasive Species

• Changes to water clarity and nutrient flows caused by Zebra and Quagga Mussels

Changing Climate

• Increased frequency of severe storms

• Increased temperatures

• Longer growing seasons

Algal Blooms

18

Ontario’s Contribution

•But this is

based only on contribution to Lake Erie directly

19

By Major Jurisdiction

Source: Ohio EPA, April 2010 (Ohio Lake Erie Phosphorus Task Force Final Report)

20

Rough Estimates of Ontario’s Contribution • Lake Huron ~1000 T/yr

• Assume 50% from Ontario 500 T/yr

• Lake St. Clair - Detroit River ~ 1,000 T/yr (?)

• Detroit ~500 T/yr

• Thames River ~350 T/yr

• Rest of watershed ~150 T/yr

• ~ 25% land area of watershed is in Ontario so assume we have 25% of the P ~28 T/yr

• The green numbers total to 878 T/yr ~9.8% of the load

• Ontario’s total P loading around 15-18%

21

How much does this mean from the field • Assume all Ontario P load comes from Lake Erie –

Lake St. Clair watershed 1,820,118 ha farmland • Ontario owns ~ 16% or 1600 T/yr of total P load

• NPS is ~ 60% of total 1188 T/yr

• What % of the NPS comes from farmland? • 10% 119 T/year 0.065 kg/ha

• 30% 356 T/year 0.196 kg/ha

• 50% 594 T/year 0.326 kg/ha

• 75% 891 T/year 0.490 kg/ha

• 100% 1188 T/year 0.653 kg/ha

22

0.06 -0.6 lbs/acre

350 T/yr

What these losses mean based on land area

23

CANADA TP lbs/acre

US TP lbs/acre

Thames 0.57 Maumee 1.0

Grand 0.41 Sandusky 1.26

Ontario 0.60 Honey Creek

1.15

Cuyahoga 1.52

Grand 0.69 Assuming all

P comes from crop

land

“The FLAW of Averages”

24

Why does P go from here

25

to here?

Requirements for P Movement

• Source of P

• Manures, fertilizers, NASM, crop residues, soil…………

• Driver

• Water movement (hydrology)

• Source x Driver =

• When P moves

• How much P moves

• What forms of P moves 26

1. Seasonal Distribution of Precipitation 2. Year-to-Year Variability of Precipitation/Seasonal Distribution

2012

2013

2014

Winter JFM Spring AMJ Summer JAS Fall OND

196

457

351

463

258

160

224

303

171

838 mm

1574 mm

869 mm

186

272 240

195

399

273

125 195

116

122

321

174 236

68

217

631 mm

1130 mm

680 mm

345 345

243 133

1066 mm

Year Maitland Thames Essex

Hydrology - Precipitation

27

Hydrology – Runoff (Surface & Tile)

Year Maitland Thames Essex

2012

2013

2014

Winter JFM Spring AMJ Summer JAS Fall OND

148

222 183

68 75

25

43 67

14 50

167 mm

596 mm

391 mm

80 35

276

18

70 6

56

155

126

154

59

57

42 40

34

94 mm

547 mm

186 mm 166 mm

28

Tile Drainage Effects on Runoff (Maitland Site Example)

(1574 mm precipitation)

(869 mm precipitation)

Surface Runoff by Season

2013 2014

Tile Runoff by Season

Annual Runoff (596 mm )

Surface Tile

(391 mm )

472

125

145

246

Tile Drainage Effects on Runoff (Thames Site Example)

(1130 mm

precipitation)

(680 mm precipitation)

Surface Runoff by Season

2013 2014

Tile Runoff by Season

Annual Runoff (547 mm )

Surface Tile

(186 mm )

486

60

16

170

RELATIVE CONTRIBUTION OF TILE AND SURFACE RUNOFF

TO ANNUAL P LOAD (MAITLAND SITE: MAY 2012 – APR 2013)

General Conclusions Surface – not dominant pathway for water movement (~22%) but accounts for: 81% DRP loss 50% total P loss

Surface Tile

Source: C. Van Esbroeck – Thesis

Total Runoff 375 mm

DRP 0.096 kg /ha

TP 0.371 kg/ha

294

81

.018

.078

.185 .186

Surface Tile

Total Runoff 276 mm

DRP 0.028 kg /ha

TP 0.267 kg /ha

239

37

.017

.011

.077

.19

RELATIVE CONTRIBUTION OF TILE AND SURFACE RUNOFF

TO ANNUAL P LOAD (THAMES SITE MAY 2012 – APR 2013)

Source: C. Van Esbroeck – Thesis

General Conclusions Surface – ~ 13% of water movement and accounts for: ~ 39% DRP loss ~ 28% total P loss Tile can also be a significant pathway but lower P concentration than runoff

P CONCENTRATIONS IN TILE AND SURFACE

RUNOFF

(a) DRP

(b) TP

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Maitland Thames Essex

mg

DR

P/L

0.00

0.05

0.10

0.15

0.20

Maitland Thames Essex

mg

TP/L

Tile Surface

Source: C. Van Esbroeck – Thesis

Surface Water Quality – 30 ppb or 0.03 mg/L total P

Sources – things you have some

control over

Soil test levels

Application of P

Placement and tillage

Timing

34

Agronomic Loss vs Environmental Impact

Assume -~ 2 ppm change in Soil Test P to change fertilizer P recommendation and this represents an agronomic significant amount

• Takes about 15-20 kg fertilizer P to increase soil test P by 1 ppm similar to decrease??

• so loss of 30-40 kg P/ha to maybe be a significant agronomic loss

• Assume - ~ 40 cm runoff/drainage water at 0.03 mg/L (Water Quality guidelines)

• 0.4 m x 10,000m2/ha x 1000 l/m3 x 0.03 mg/L = 0.12 kg /ha

Sources: Soil test P

Leaching DRP and

STP

Runoff DRP and

STP 36

P stratification in the soil crop residues & surface applications of P

Note: Soil test P differences would likely be greater if smaller depth increments used

Tillage and P Source

Placement (and timing)

Incorporated ↓ P at surface less

available for surface runoff

↑ erosion potential ?

through soil loss ??? likely depends upon degree of mixing and flow through soil

20 kg/ha P fall applied (~45 kg/ha or 41 lb/ac of P2O5)

Consequence of Fall Surface Applied P (by the numbers)

• Not Incorporated

– Most of P stays at surface

– Effective application rate is ????

• If stays in top 2.5 cm 6 x the rate

• Impact on soil test P

– maybe ↑ 6 – 30 ppm

20 kg/ha P fall applied (~45 kg/ha or 41 lb/ac of P2O5)

39

Leaching DRP and

STP

Runoff DRP and

STP (Wang 2010 thesis)

40

Applied P most available right

after application

Water movement: fall spring

periods

P transport: fall spring periods

41

Top Tips for P management

• 1) Apply P at the right time, in the right place

• 2) Promote good soil structure and improve water infiltration

• 3) Keep soil test in agronomic range

42

Apply P at the right time, in the right place

43

Apply P at the right time, in the right place

44

45

Promote soil structure and infiltration

Substantial surface runoff

Water infiltration No surface runoff

46

Promote soil structure and infiltration

Photo from T. Vollmershausen

47 0

20

40

60

80

100

120

0 10 20 30 40 50 60 70

ME

RP

(kg

P2O

5/h

a)

Soil Test P (ppm)

Band

Broadcast

Keep soil test in agronomic range

Putting It All Together

• Water quality issues in Lake Erie have a large economic impact

• Causes of algal blooms today are different than past

• Relatively small losses of P per field add up across the landscape

• Smart phosphorus management is win for both profitability and water quality

48

Thank You

Questions?

49

Jake Munroe jake.munroe@ontario.ca 519 271 9269 Stratford, Ontario

Dr. Ivan O’Halloran iohallor@uoguelph.ca

519 674 1500 ext. 63635 Ridgetown, Ontario