Phosphorus Transport in Agricultural Drain Tiles
in the Saginaw Bay Watershed
David S. Karpovich
H. H. Dow Endowed Chair of Chemistry
Director, Saginaw Bay ESI
Saginaw Valley State University
Summer 2015
Research team
Justin Martin - Bullock Creek High School, graduated
Alicia Ball - Garber High School, senior
Evan Craig – Cass City High School, senior
Craig Coopersmith II - White Pine Middle School, teacher
Kathlyn Underwood - SVSU, Biology sophomore
Sampling locations
•
•
•
•
•
•
Arenac County
Pine and Rifle River Watersheds
Flat farmland, row crops
Tiled fields, vegetative buffers
Organic & conventional fertilizer
Landowner permission
Measurements & Data
• Soil (>5 samples/field)
•
•
•
•
Porosity
Soil type
Sand, silt, clay
Phosphorus
• Tile and ditch water
•
SRP and TP
• Rain events
Rifle River
Sample sites
Pine River
Standish
Saginaw Bay
Soil erosion
•
•
•
Vegetative buffer strips
•
•
Considered effective in
reducing suspended solid and
phosphorus run-off
Long-time assumption that
phosphorus only moves with
surface erosion (~0.0005 lbs
P/ton soil)
Run-off puts suspended solids
in stream water
Insoluble phosphorus
accompanies suspended solids
Considered a major source of P
to Saginaw Bay
Our sampling targets
Field tiles at a glance
2 to 4 ft deep
Field Soil Characteristics
Soil type
Filter
strip
Tillage
method
Fertilizer
method
P
%Porosity
% sand
% silt
% clay
(mg/kg)
1
Allen Dale
Loamy Sand
No
No-till
conventional
48
33
27
40
75
2
Selkirk Silty
Clay Loam
No
conventional
organic
50
33
20
47
46
3
Sims Loam
No
conventional
organic
23
20
10
70
75
4
Sims Loam
No
conventional
organic
52
50
13
37
5
Selkirk Loam
Yes
conventional
organic
6
Allen Dale
Loamy Sand
Yes
conventional
organic
7
Sims Loam
No
conventional conventional
8
Selkirk Fine
Sandy Loam
Yes
conventional conventional
75
38
83
10
7
44
33
20
47
Samples taken
• Field tile effluent and receiving ditch water
• Four dates (two rain events, two dry)
• Measured for SRP and TP
37
75
Phosphorus (mg/L)
Phosphorus in ditch water
0.25
0.20
0.15
0.10
TP
0.05
SRP
0.00
1
2
3
4
5
6
7
8
Site
Phosphorus in Tile water
Phosphorus (mg/L)
0.25
0.20
0.15
0.10
TP
0.05
SRP
0.00
1
2
3
4
5
Site
6
7
8
Summary of Results
• SRP Tile/Ditch = 1.79 + 1.11
• Subsurface water does transport SRP
• TP Tile/Ditch = 0.63 + 0.24
• Subsurface water also transports TP
• Tile SRP/TP = 0.90 + 0.16
• Higher than “typical” for watershed streams
• Greater mobility of SRP in water compared to TP on particles
• Ditch SRP/TP = 0.39 + 0.21
• Lower than typical for streams, grassy ditches may be a sink for SRP
• Possible correlations to note (preliminary)
• Tile phosphorus and porosity (weak, positive, 0.4)
• Tile/ditch phosphorus and soil P (strong, negative, -0.8)
• Phosphorus is transported in subsurface water,
not just by surface soil erosion.
• Need to determine volume and loading
Acknowledgements
• Dow Chemical Company Foundation for the funding of the
Dow Science and Sustainability Education Center
– For funding of Alicia Ball, Evan Craig, Kathlyn Underwood, Jeremy
Schultz, and Craig Coopersmith)
•
American Chemical Society Project SEED
– For funding Justin Martin
• Saginaw Bay Environmental Science Institute at SVSU
– Hosted Dow SSEC internship program
– Facilitated and directed research
• Professor Martin Arford (Geography) and Jeremy Schultz
(biology senior) for soil data