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SHOOTING A MOVING TARGET: A DISSOLVED PHOSPHORUS PROBLEM
PARADIGM
Rem Confesor Jr. Laura Johnson
Dave BakerKen Krieger
NCWQR, Heidelberg University310 E. Market St., Tiffin, [email protected]
Voice: 419-448-2204
Acknowledgment
GLRI-CSMI Grant
4R Research Project
USDA-NRCS-CIG Grant No. 69-3A75-13-216
2015 Seasonal HAB forecast
MOTIVATION
BMPs – Best Management Practices:
Necessary for nutrient export reduction from agricultural lands <= desired ecological responses.
Limited funding <= targeted implementation.Target: Critical source areas (CSAs)
CRITICAL SOURCE AREAs
Areas that are most vulnerable to nutrient and sediment loss.Identification traditionally based from risk indices, e.g., Phosphorus Index:
TransportPollutantSource
CSA
Critical Source Areas (CSAs) concept
A pollutant source (e.g., P, N, sediment) interacts with active hydrologic transport mechanisms.
CRITICAL SOURCE AREAs
Pollutant Source - depends on land use and management: tilled land -- sediment; elevated soil P, excessive P application -- P loss.
Transport potential - factors that affect hydrologic path/transport mechanism:
hydrologic soil group, drainage class.slope/terrain.land use/cover.hydrologic connectivity.
CRITICAL SOURCE AREAs
80% of the pollution comes from 20% problem area?
Acute vs. chronic sources?
Info to consider:In the Sandusky watershed , the median M3-P soil test at 0-1 in is ~60ppm.
NW Ohio Ag is highly-tiled system (as close as 20ft)
FURTHERMORE...The pollutant source and transport potential factors are taken into account in agricultural watershed models (e.g., SWAT, APEX, AGNPS, etc).
A word of caution:
"...all models are wrong...”
“… the only question of interest is: ‘Is the model illuminating and useful?’”
- George E.P. Box -
Terrain
Weather
Soil
Land use/crop cover Agricultural practices & mgt.:
tillage, fertilizer, etc.
Flow, sediment,nutrients (N & P),
etc.
Main SWAT Components
APPROACH
Implement a highly detailed Soil and Water Assessment Tool (SWAT) model setup
OBJECTIVES1.Identify CSAs.
2.Evaluate the characteristics of these CSAs.
Digital elevation model(slope/terrain)
Land use/ crop cover
Soil typeHydrologic Response Units (HRUs)
+
+
The hydrologic response unit (HRU)- SWAT’s basic spatial unit: unique combination of slope, landuse, & soil.
HRU CAVEAT
2008
2009
2010
2011Soybean
Soybean
corn
corn
4-Yr (2008 to 2011) crop rotation in a selected hru: CORN-SOYBEAN-CORN-SOYBEAN
Based from USDA Crop Data Layer
SWAT SETUP
Project Area/WatershedSandusky Watershed, northwest Ohio.Area: 1250 mi2 = 3236 km2 at USGS gage station in Fremont, OH
Sub-basin/HRU Delineation373 Sub-basins4350 (40/20/20 ha) HRUsArcSWAT2009; SWAT2009 rev 488
SWAT SETUP: Management practicesCorn
Fall Tillage Chisel Plow GE 23 ftFall Fertilizer 11-52-00 (115 kg/ha, 0.2 frt_sur)Late April-Early May Fertilizer Anh. NH4 (100 kg/ha, 0.05 frt_sur)Mid Apr-Mid May Plant Corn1 month after plant Fertilizer Anh. NH4 (120 kg/ha, 0.05 frt_sur)5 months after plant +/- 5 days Harvest and Kill
Corn doubled with soyFall Tillage Chisel PlowFall Fertilizer 11-52-00 (210 kg/ha, 0.2 frt_sur)Late April-Early May Fertilizer Anh. NH4 (100 kg/ha, 0.05 frt_sur)Mid Apr-Mid May Plant Corn1 month after plant Fertilizer Anh. NH4 (100 kg/ha, 0.05 frt_sur)5 months after plant +/- 5 days Harvest and KillLate Spring Plant SOY5 months after plant +/- 10 days Harvest and Kill
SWAT SETUP: Management practices
Soybeans
Winter wheat
Late Apr to Mid-May Plant SOYMid Apr Fertilizer 11-52-00 (95kg/ha, 1 frt_sur)5 months after plant +/- 10 days Harvest and Kill
Mid October Fertilizer 18-46-00 (130 kg/ha, 0.2 frt_sur)Mid/Late October Plant WWHEATLate March Fertilizer 46-00-00 (210 kg/ha, 0.2 frt_sur)Early-Late July Harvest and Kill
SOME RESULTS…
Water Year2008 2009 2010 2011
An
nu
al
wate
r yie
ld,
cm
0
25
50
75
Water Yield
Simulated annual dissolved P exports
2008 2009
Simulated annual dissolved P exports
2009 2010
Simulated annual dissolved P exports
2010 2011
Simulated annual dissolved P exports
2008 2009
2010 2011
Simulated annual dissolved P exports, kg/ha
2008 2009
2010 2011
Simulated annual sediment yield
2008 2009
2010 2011
Management practices
CPBCast CPInject MPInject No_Till NTBCast NTInject
Ch
ang
e in
SR
P e
xpo
rt, k
g/h
a-yr
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
Several Scenarios
Baseline reference
SUMMARY/TAKE HOME
Critical areas are changing with time and space.
Traditional concept of CSA may not be applicable to NW OH (Tile drain connectivity)
Targeting CSAs may not be enough to attain load reduction goals.
Watershed-wide implementation of “cultural” (e.g. 4R) BMPs rather than structural is needed.
NEXT STEPS/ONGOINGConvert to SWAT2012.
Update to include 2014 (2008-2014).
Include point sources.
Implement in the Maumee watershed.
More BMP scenarios.
Climate Change?
Rem Confesor Jr.National Center for Water Quality Research
Heidelberg University310 E. Market St., Tiffin, [email protected]
Voice: 419-448-2204
THANKS!!!
