The document discusses the impact of agricultural phosphorus on eutrophication in Western Lake Erie, highlighting sources of phosphorus and the resulting harmful algal blooms. It emphasizes the importance of managing phosphorus sources and transport mechanisms through various conservation strategies to mitigate nutrient loss. The findings suggest that improving soil health can enhance nutrient retention and reduce the need for fertilizers.

1. Agricultural Phosphorus in Western
Lake Erie – Opportunities,
Uncertainty and Competing Interests
KEVIN
KING
USDA‐ARS
DOUG
SMITH
USDA‐ARS
PETE
KLEINMAN
USDA‐ARS
ANDREW
SHARPLEY
U. ARKANSAS
LAURA
JOHNSON
HEIDELBERG U.

2. Lake Erie Eutrophication
Historical Success
Source: Baker and Richards,
Heidelberg University
Google

3. Lake Erie Eutrophication
Today’s harmful algal blooms
Source: NOAA
2011 algal bloom

4. 0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
DissolvedReactivePhosphorusFWMC(mg/L)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
1975 1980 1985 1990 1995 2000 2005 2010
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
Maumee
Sandusky
Cuyahoga
River % Agric. % Urban % Forest
Maumee 73 11 7
Sandusky 78 8 9
Cuyahoga 9 40 34
Source: Johnson,
Heidelberg University
Reversal of fortune
dissolved phosphorus

5. DRP
(kg P/ha)
TP
(kg P/ha)
Maumee 0.293 1.32
Sandusky 0.415 1.81
Honey Cr. 0.577 1.89
Rock Cr. 0.335 1.98
Low phosphorus loads
< 2 kg/ha
Source: Johnson,
Heidelberg U.

6. 7.5
5.0
2.5
0
ParticulateP(kgha-1)
Penrichmentratio
1
6
4
2
8
10
Particulate P
P enrichment ratio
Erosion (tonnes ha-1)
10 10010.10.010.001
Phosphorus enrichment ratio
The lower the erosion, the greater the
P concentration of the sediment
Source: Sharpley,
University of Arkansas

7. In‐channel phosphorus
Sedimentation
Mark Tomer, ARS
Mark Tomer, ARS
Joe Magner,
Univ. Minn.
Entrained wetlands
Constructed wetlands
Two‐stage ditch
Stream
restoration/reconnecti
on

8. Field management of phosphorus
Controlling source and transport
Phosphorus
Source
Transport
Mechanism
Critical Critical
source
area
Hydrologic connectivityFlat, internal drainage

9. Field management of phosphorus
Controlling source and transport
Phosphorus
Source
Transport
Mechanism
Transport
Mechanism
Critical source
area
Hydrologic connectivityFlat, internal drainage

10. P Loss (kg/ha)
10
20
3
0
0 421 mg/kg
447 mg/kg
2001
2002
2003
2004
2005
Kleinman et al., 2007 (J. Soil and Water Conserv.)
1500
500
0
1000
Precip(mm)
In hydrologically connected systems
Loads driven by precipitation

11. Lake Erie Eutrophication
Harmful algal blooms
Satellite Images: NOAA/NASA
2012 algal bloom
St. Joe’s Watershed 2011 2012
Annual 45” 25”
March‐June 19” 7” Source: Smith,
USDA‐ARS
2011 algal bloom

12. In hydrologically connected systems
Loads driven by runoff/drainage
Conservation Technology
Innovation Center (Purdue)

13. Drainage and subsurface P loss
Many parallels with surface runoff
Dissolved P in tile drainage (mg/L)
Soil test P, upper 2 inches (mg/kg)Source: King,
USDA‐ARS

14. Tile drainage phosphorus loss
Surface runoff through pipes
Source: M. Shipitalo, USDA‐ARS
Mar Apr May
Flowdepth(ft)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
DRPconc.(mg/L)
0.0
0.2
0.4
0.6
0.8
1.0
flow depth
concentration
Source: King, USDA‐ARS
Source: Shipitalo, USDA‐ARS

15. Concentration of P along flow pathways
Incidental transfers of applied P
.
Dates custom applicators were in fields
Source: Johnson, Heidelberg U.

16. 0
1
2
3
4
Before Broadcast Tilled‐in
Concentration of P along flow pathways
4R strategy – placement of applied P
Dairy slurry
P loss in leachate (kg/ha)
Kleinman et al., 2009
Tillage to incorporate
manure and disrupt
macropores

17. Concentration of P along flow pathways
4R strategy – rate/timing of applied P
0
2
4
6
8
10
12
0 50 100 150 200 250 300 350
Days since Manure Application
100 T/ha
35 T/ha
200 T/ha
Dissolved P in tile drainage (mg/L)
Klausner et al., 1976; Brookes et al., 2000
Days after manure was applied

18. Source: Johnson, Heidelberg U.
0
12
8
6
4
2
10
36
28
55 60
49
34
26
Vertical stratification of soil P
Supports tillage where high P is a concern
Sampling depth (inches)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
Dissolved P (mg/L)
Maumee
Sandusky
20101980 20001990
No‐till
expands
Mostly rotational no‐till
Rota onal no ll →59%
Con nuous no ll → 8%

19. Kleinman et al., 2010 (Canadian J. Soil Science)
0
100
200
300
400
500
600
2000 2002 2005 2007 2009
Mehlich‐3 soil P (mg/kg)
Lime
0
1
2
3
Dissolved P in ditch flow (mg/L)
Legacy P
No change after one decade

20. • In stream/channel
• Edge‐of‐field
• In field
All of the above, and more
Traditional conservation strategies
don’t solve dissolved nutrient losses
In‐ditch filters
Edge‐of‐field
filters
Source: Bryant, USDA‐ARS

21. Unnecessary
conflict

22. Once the soil is healthy and has good water infiltration and
water holding capacity it may be possible to surface apply
fertilizer knowing that there will be little or no water runoff
and that the nutrients will infiltrate and percolate through
the soil via matrix flow.
This will allow the nutrients to interact and bond with the
soil. In addition, fertility requirements will likely be lower in
a healthy soil due to better nutrient retention and recycling.
The overall retention of nutrients and improved soil biota
can affect nutrient cycling, may increase efficiency and
reduce fertilizer needs.
p. 38
No tillCover crops