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Reducing Nutrients Through Conservation: A Paired Watershed Study
Ashleigh Hammac
Master of Research in Soil Science Defense
07/31/2014
North Carolina State University
Soil Science Department
Outline Introduction Objective Methods & Materials Results Conclusions Acknowledgements Questions
IntroductionImportance of Study
Increase in Eutrophicationo Eutrophication: a natural process of water bodies
becoming more enriched and productive through an increase in nutrient supply (Smith et al, 1998)
o Algal Blooms • CyanoHABs
Smith et al, 1998
Why is it important to reduce nutrients? Eutrophic Conditions for Water
ResourcesFreshwater lakes 0.065-0.12 mg TN L-1
0.003 mg TP L-1
Streams >0.03 mg TN L-1
0.075 mg TP L-1
Marine >0.04 mg TN L-1
Teaching Great Lake Science Australian dinoflagellates Red Tide
Algal Blooms and CyanoHABs
IntroductionImportance of Study
Increase in Eutrophicationo Algal Blooms
• CyanoHABs Human Health
o Nitrate-Nitrogen(NO3-N) concentrations• >10mg NO3-N L-1 drinking water EPA limitations• Methameblogmeia (blue baby syndrome)
What degrades water quality???
IntroductionImportance of Study: North Carolina
North Carolina Division of Water Quality determined that non-point sources of pollution such as agriculture to be the single largest contributor of nutrients to the Neuse River and Cape Fear River Basins (NCDWQ 1996)
http://www.learnnc.org/lp/editions/nchist-recent/6202
IntroductionImportance of Study: North Carolina
Point and Non-point Source Pollution
o Point Source: delivered directly from discrete conveyance such as waste water treatment plants, industrial facilities or direct dumping of waste into streams. Point source pollutants are federally regulated.
o Non-point Source: diffuse sources that do not have a discernable direct source and are normally moved through the system by runoff
• Includes oils, sediments, animal wastes, fertilizers, herbicides, insecticides (EPA, 1998a)• Less regulated.
IntroductionImportance of Study: Jordan
Lake The Jordan Lake Watershed has
pressures to decrease the amount of sediment and nutrients in it’s bodies of watero Environmental Management
Commission: 1983 it placed Jordan Lake Reservoir on a Nutrient Sensitive Water
• Ordered limits on phosphorus wastewater discharge
• Saw no response to controls Additional regulations imposed in
January 2008 that affected point and non-point (urban and ag) sources of nutrients.
Greensboro
Chapel Hill
Durham
Burlington
Jordan Lake
Reidsville
Map Produced: R. Austin, D.Osmond
²
Jordan Lake Watershed
0 10 205 Miles
Cape Fear River Basin
North Caro lina State UniversityDepartment of Soil Science
North Carolina Stateplane, Zone 4901, NAD83 meters
Introduction Nutrient Load Reductions
required by the state of North Carolina from the 1997-2001 baseline periodo Haw Sub Basin:
• 8% Nitrogen and 5% Phosphoruso Upper New Hope Sub Basin:
• 35% Nitrogen and 5% Phosphorus
o Lower New Hope Sub Basin: • 0% Nitrogen and 0%
Phosphorus
Slide credit: Dr. Osmond, NCSU
Objective
To quantify the effectiveness of agricultural conservation practices, such as livestock exclusion and nutrient management, on surface water quality in the Jordan Lake watershed of North Carolina
Materials and MethodsOverview
Water Quality Monitoring:o Automated runoff samplerso Precipitation data
Land Use Monitoringo Farmer surveys
Paired Watershed Design
Materials and Methods: Water Quality Monitoring
Monitoring Stations:o Automated Sampler
• ISCO 6700 and 6720• Integrated flow meter
o Permanent staff gauge• Stage-discharge relationships measured and adjusted
periodically.o Tipping bucket rain gauge
• 15 minute basis
Control CroplandCredit: Wesley Childres
Treatment PastureCredit: Wesley Childres
Control PastureCredit: Wesley Childres
Treatment PastureCredit: Wesley Childres
Methods and Materials: Water Quality Monitoring
Storm Event Samples Continuous Rainfall Grab Samples*
Chemical AnalysisKjeldahl Nitrogen (TKN)
Ammonium Nitrogen (NH4-N)
Nitrate + Nitrite Nitrogen (NOx-N)
Total Phosphorus (TP)
Dissolved Phosphorus (DP)*
Bacteria (E. coli)*
Total Suspended Solids (TSS)
Materials and Methods: Sampling Procedures
Storm Event Sampling: bi-weekly (2 week intervals)o 125-150mL sample for TKN, NH4-N, NOx-N, and TP
• Acidifiedo 250-500mL sample for TSS
• Non acidified
Grab Samples: seasonalStorm samples are acquired within 12 hours of a storm eventBase flow sampleso Analyze for:
• Bacteria (e-Coli)• Dissolved Phosphorus• Analyzed within 6-8 hours
Materials and MethodsOverview
Water Quality Monitoring:o Automated runoff samplerso Precipitation data
Land Use Monitoringo Farmer surveys
Paired Watershed Design
Materials and Methods: Additional Monitoring
Land use monitoring:o Collected annually through farmer surveys
• Crop(s)• Planting and harvest dates
• Fertilizer application(s)• Method• Type• Amount• Placement
• Animal stocking density• Diet additives
o Bi-weekly field survey• Record visible land uses, animal stocking densities at time
of sampling.
Materials and MethodsOverview
Water Quality Monitoring:o Automated runoff samplerso Precipitation data
Land Use Monitoringo Farmer surveys
Paired Watershed Design
Materials and Methods: Paired Watershed Design
DefinitionComparisons of adjacent sub watersheds with similar land uses in two temporal periods:
o Pre-BMP: Before conservation practices• No changes made to the land use practices• 2-3 years of monitoring• All watersheds monitored simultaneously
o Post-BMP: After conservation practices• 2-5 years of monitoring• 1 out of at least 2 watersheds have BMPs implemented
Materials and Methods: Paired Watershed Design
Why use paired watershed design?o Addresses the dynamic system interactions
o Non-biased; aka no “assumptions” of how the system interacts
o Variability of weather isn’t optimal but occurs.• Consistent data for “typical” weather is acquired
over a long pre and post-BMP period
Materials and Methods: Control vs. Treatment
The determination of which sub-watersheds are the Control vs. Treatment is mostly up to farmer
cooperation
Pasture (L)
Pasture (M)
Control and Treatment for Pastures
Crop (V)
Crop (R)
Control and Treatment Croplands
Pasture “Pair”
Crop“Pair”
Methods and Materials: Paired Watershed Design
The Jordan Lake Paired Watershed Study
Stages of Water Quality Monitoring:
o Pre-BMP • Crop and Pasture: Start of 2008
o Post-BMP• Pasture: Spring 2011 (Fertilization) and Fall 2011 (Exclusion
Fencing)• Crop: Fall 2012
Began work at NCSU (Fall 2012)
Materials and Methods: Control Pasture (L)
• 193 ac, 40% beef and dairy pasture
• Aquic Hapludult (<6% slope)• Soil Test M3P 166 mg kg-1
Multiple Land Uses
Materials & Methods: Control Pasture (L)
Cropland and Hayland Pre-Treatment (2008-2010)
o Cropland: • Corn 22.1 acres (11.5%)
• 2010• 17-17-17, 336 kg ha-1
• (300 lb ac-1)
• 85 lb N ac-1 sidedress• Harvest mid August• Ripped/disked in 2010• Fallow 2008-2009
o Hayland:• Hay 16.2 ac (8.4%)• 2.5 tons ac-1, 2-3 times per year• Fertilized with Pullet Manure
• 3 tons ac-1
Post-Treatment (2011-2013)
o Cropland:• Soybean 22.1 acres (11.5%)
• 2013• 17-17-17, 336 kg ha-1
• (300 lb ac-1)
• 85 lb N ac-1 sidedress• Harvest mid November.• Fallow 2011-2012
o Hayland:• Hay 16.2 ac (8.4%)• 2.5 tons ac-1, 2-3 times per year• Fertilized with Pullet Manure
• 3 tons ac-1
Materials & Methods: Control Pasture (L)Pastures and Forest
Pre-Treatment (2008-2010)
Pasture72.7 ac (37.7%)
o Dairy and Beef Cow• Near 100 cows total • Even mix of dairy and beef
cows.o Fed with Additives
• Fed with hay in winter: 12% protein additive and High Mag block.
Forest 61.3 ac (31.8%)
Post-Treatment (2011-2013)
Pasture72.7 ac (37.7%)
o Beef Cow• Near 80 cows total• Mostly beef cows.
o Fed with Additives• Fed with hay in winter: 12% protein
additive and High Mag block.
Forest 61.3 ac (31.8%)
• ≈ 5 ac cut in 2013.
Pasture Control (L)
Crop
Pasture
Station
Hay
M: Treatment Pasture (M)
• 134 ac, 90% beef pasture• Aquic Hapludult (3-6%)• Soil test M3P 118-1060 mg kg-1
Materials and Methods: Treatment Pasture (M)
Pre-Treatment Land Use:2008-2010
Fertilizer: o 15-15-15 at 336 kg ha-1
• (300 lb ac-1) o Biosolids applied in April 2010
Crop: fescue for cattle
Uses additives.
Rotates cows in fields.
Post-Treatment Land Use:2011-2013
Nutrient Management in 2011, 2012, and 2013. o STP very high (range)o Nitrogen fertilizer
• Under applied at 78 kg ha-1 • (70 lb N ac-1)
Livestock Exclusion by fencingo Installed in 2011.
Continued field rotations.
Livestock average:
26 adult cow26 calves
Station
Pasture
Pasture Treatment(M)
Results Data interpretations in preliminary stage!
o 1st - 3rd years of Post Treatment installation monitoring• Pastures only
o End: March 2014 • (data collection not finished)
Analysis done only for Pasture Pairo Pre and Post Treatment data for pastures only
Pasture Paired Watershed: Hydrology Comparison
Paired Watershed studies rely on a significant hydrologic relationship.
Statistical comparison of chemical constituents is reasonable.
0 1,000,000 2,000,000 3,000,000 4,000,000 5,000,000 6,000,0000
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
f(x) = 0.952024273476317 x + 10524.8510678421R² = 0.737398906871159
f(x) = 1.04559498241859 x + 95322.1462332817R² = 0.871061792838042
Pre & Post-BMP Period Hydrology 12/20/08-6/2/13
pre
Pasture-Control (gal)
Past
ure-
BMP
(gal
)
Pasture Paired Watershed:Total Suspended Solids
ComparisonTotal Suspended Solid Loads for only comparable storm events.
0 1,000,000 2,000,000 3,000,000 4,000,000 5,000,000 6,000,0000
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
3,500,000
4,000,000
4,500,000
5,000,000
f(x) = 0.288491324502112 x + 41602.9338896438R² = 0.515666086793298
f(x) = 0.785433104331726 x + 166651.722302231R² = 0.749528541885421
Pasture Pre-BMP & Post-BMP TSS Load 12/20/08-06/02/13
pre
Pasture-Control (kg)
Pas
ture
-BM
P (k
g)
Decrease in TSS for the treatment watershed from pre to post treatment periods
Pasture Paired Watershed:Total Phosphorus Comparison
0 5000 10000 15000 20000 25000 300000
5,000
10,000
15,000
20,000
25,000
f(x) = 0.666073261997441 x + 352.831164211523R² = 0.633064371914685
f(x) = 1.34445613904203 x + 456.131860821905R² = 0.853388714291037
Pasture Pre-BMP & Post-BMP TP Load 12/20/08-06/02/13
Pre
Pasture-Control (g)
Pas
ture
-BM
P (g
)
Pasture Paired Watershed:Total Kjeldahl Nitrogen Comparison
0 5000 10000 15000 20000 25000 30000 35000 40000 450000
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
f(x) = 0.984810799625441 x − 88.8272084315981R² = 0.821506976559331
f(x) = 1.20699415659013 x + 1046.87349918206R² = 0.763485651201399
Pasture Pre-BMP & Post-BMP TKN Load12/20/08-06/02/13
pre
Pasture-Control (g)
Pas
ture
-BM
P (g
)
Pasture Paired Watershed:Nitrate-Nitrogen Comparison
0 2000 4000 6000 8000 10000 120000
5000
10000
15000
20000
25000
30000
f(x) = 0.445337094437797 x + 356.452157882746R² = 0.231688811492995
f(x) = 0.894270351105529 x + 128.188493153112R² = 0.458096491228025
Pasture Pre-BMP & Post-BMP NOx-N Load12/20/08- 06/02/13
pre
Pasture-Control (g)
Pas
ture
-BM
P (g
)
Low R2 indicates an increase in Nitrate-Nitrite Nitrogen in the Treatment.
Low R2 indicates that the relationship is not significant plotted this way.
Mean Concentrations Pastures: Pre & Post Treatment
(12/07- 09/11) to (10/2011-06/2013)Constituent Treatment
(M) BeforeTreatment (M) After
Control (L) Before
Control (L) After
TKN (mg/L) 5.53 3.29 2.99 2.89NOx-N (mg/L) 0.79 0.74 1.05 0.53
NH4-N(mg/L) 2.33 0.54 0.68 0.47
TN (mg/L) 5 3 2 2TP (mg/L) 2.56 1.74 1.79 1.57
TSS (mg/L) 356 151 224 114E. Coli*
(mpn/100ml)1087 268 1755 601
*geomean
Load Changes from Pasture Outlets
(12/07- 09/11) to (10/2011-06/2013)Constituent Pasture Control
(L) Reduction (%)Pasture Treatment (M) Reduction (%)
TKN (kg/ha/yr) -25.4 4.7
NOx-N (kg/ha/yr) 39.8 -12.1
NH4-N (kg/ha/yr) 19.1 52.3
TN (kg/ha/yr) -5.6 2.1
TP (kg/ha/yr) -2.0 28.3
TSS (kg/ha/yr) 45.4 59.1
Conclusions:Difference in Treatment and
Control ReductionsConstituent Difference in Pasture Treatment
& Control Reductions (%)TKN (kg/ha/yr) 30.11
NOx-N (kg/ha/yr)* -51.87*
NH4-N (kg/ha/yr) 33.19
TN (kg/ha/yr) 2.1
TP (kg/ha/yr) 30.28
TSS (kg/ha/yr) 13.69
*Did not improve by comparison after BMP installation.
ConclusionsPasture Control (L)
Increasedo TKNo TNo TP
Decreasedo NOx-No NH4-No TSS
Pasture Treatment (M)
Increasedo NOx-N
Decreasedo TKNo NH4-No TNo TPo TSS
AcknowledgementsThank you!
Dr. Deanna Osmond Dr. Garry Grabow Dr. Matt Polizzotto Daniel Line Wesley Childres
Fundingo USDA NIFAo NC DENR, USEPA 319 pass-through funds
