Nitrate in Wisconsin’s
Groundwater
What, Why, and Where?
WN@tL – January 20, 2016
Kevin Masarik
Center for Watershed Science and Education
Through the University of Wisconsin-Extension, all Wisconsin people can access
University resources and engage in lifelong learning, wherever they live and work.
Outline of Tonight’s Talk
 Basics
of groundwater
 Nitrate
in Wisconsin’s
groundwater






What is nitrate?
Why do people care?
How does nitrate get into
groundwater?
Where in Wisconsin do we find
nitrate?
Is it getting better or worse?
What are ways to reduce nitrate?
http://wisconsinwatch.org
Groundwater 101
Source: Unknown
Watershed – the land area where water originates for
lakes, rivers or streams. Water flows from high
elevation to low elevation.
Runoff
Impermeable bedrock
Groundwater flow
Impermeable bedrock
Central Wisconsin
January 18, 2016
-10 °F
January 18, 2016
Wisconsin has 3 major basins
Lake Superior Basin
Basins of Wisconsin
Sub-continental Divide
Mississippi River
Basin
Lake Michigan
Basin
The basins can be divided into regional watersheds….
….regional watersheds can be further defined to show just
how local groundwater quality really is.
http://pubs.usgs.gov/circ/circ1186/pdf/circ1186.pdf
Groundwater:
Wisconsin’s Buried Treasure
• 95% of Wisconsin
Communities
• 850,000 private residential
wells
• Supplies almost all water for
agriculture – livestock,
irrigation, dairy operations
• 1/3 of industrial water use
• 1/2 of commercial water use
• Supplies the majority of the
water for Wisconsin’s lakes
and streams
75% of Wisconsin
residents
Nitrogen Cycle
Nitrogen is neither created nor destroyed
Nitrogen
in harvest
Sources of Nitrogen
Atmosphere
Septic
system
effluent
Soil organic matter
Mineralization
Vadose
Zone
Groundwater
NO2-
NO3- = Nitrate
NH4+ = Ammonium
NO2- = Nitrite
NO3Modified from: https://nevegetable.org
Nitrogen contributes to Gulf Hypoxia
http://water.usgs.gov/nawqa/sparrow/gulf_findings/delivery.html
•
Excessive nutrients contribute to growth
of large amounts of algae that decay
and consume oxygen – hypoxia.
•
Negatively affects the economic and
ecological health of one of the nation’s
most productive fisheries.
Nitrate and Human Health
Infants and pregnant women
•
•
Methemoglobinemia or “blue-baby syndrome”
Possible correlation to central nervous system malformations
Adults
Possible correlations to:
• Non-Hodgkin’s lymphoma
• Various cancers (ex. gastric, bladder)
• Thyroid function
• Diabetes in children
*Many are statistical studies that provide correlation between nitrate and health problems
*Studies don’t always agree, but cannot say with certainty that nitrate poses no health risk.
Nitrate often indicator of other possible contaminants
(ex. other agricultural contaminants, septic effluent, etc.)
Wisconsin Groundwater Coordinating Council, 2015; Weyer, 1999
Nitrate in drinking water
• Greater than 10 mg/L
Impacted at a level that exceeds
Nitrate Nitrogen
state and federal limits for
drinking water
10
•
DO NOT give water to
infants
•
DO NOT consume if you
are a woman who is
pregnant or trying to
conceive
•
RECOMMEND everyone
avoid long-term
consumption
• Between 1 and 10 mg/L
Evidence of land-use impacts
1
0
• Less than 1 mg/L
Natural or background levels in
WI groundwater
Considered suitable
for drinking water
Public vs. Private Water Supplies
Public Water Supplies
• Regularly tested and regulated
by drinking water standards.
Private Wells
• Not required to be regularly
tested.
• Not required to take corrective
action
• Owners must take special
precautions to ensure safe
drinking water.
http://www.wisconsinwatch.org/2013/05/22/20-years-after-fatal-outbreak-milwaukeeleads-on-water-testing/
Nitrogen is vital to
agriculture
 Ancient civilizations farmed fertile
flood plains
 Animal manures
 Crop rotations w/legumes
 Prairies and other organic rich soils
 Industrial fixation of N leads to
commercial fertilizer and dramatic
increase in N applications
 Manure management challenging
7
N
14.01
Nitrogen
N, P, K
More
Less
Nitrogen Fertilizer Added (lb/acre)
Maximum Yield
Slope = Added Yield
Increasing
Yield or Biomass Accumulation (kg/ha)
Yield response to nitrogen
Economic Optimum
• variable from year to year
depending on energy costs, fertilizer
costs, price of commodities
0
Increasing
Fertilizer Added (kg/ha)
Fertilizer Unit
Historical Nitrogen Use
U.S. Consumption of Nitrogen Fertilizer (1960-2011)
Nitrogen (1,000 nutrient short tons)
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
1960
1970
1980
1990
2000
2010
Year
USDA Fertilizer Use and Price, 2013
http://www.ers.usda.gov/data-products/fertilizer-use-and-price.aspx
Nitrogen fertilizer recommendations for
common crops
* Legumes have symbiotic relationship with N fixing bacteria
Alternative Field Crops Manual, 1989. University of Minnesota and University of Wisconsin -Madison
Nutrient application guidelines for field, vegetable and fruit crops in Wisconsin. A2809. 2012. University of Wisconsin-Madison
Miscanthus and switchgrass recommendations: Anderson et al., 2013; McIsaac et al., 2010; Vogel et al., 2002; Arundale et al, 2014
Efficiency of plants at utilizing nitrogen –
the corn example
http://www.bae.ncsu.edu/programs/
extension/evans/ag452-1.html
http://www.youtube.com/watch?v=iFCdAgeMGOA
http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch2.html
Comparing Annual to Perennial
Ecosystems
http://www.soilandhealth.org/01aglibrary/010137veg.r
oots/010137ch2.html
Nitrogen fertilizer use
efficiency for Midwestern
corn systems
37%
(Cassman et. al. 2002)
Mixed Native Perennial
http://soils.usda.gov/sqi/management/files/RSQIS6.pdf
Long-term Nitrate Leaching Study of
Corn Agroecosystems and a Prairie
UW-Madison Arlington Research Farm
Optimal
(1996-2003)
No Fertilizer
Optimal
Goose Pond Sanctuary:
26 year old restored prairie
Brye et al., 2001, Brye et al., 2000, Brye et al., 2003, Masarik et al., 2014
Annual Nitrate
Leaching losses
Eight-year summary at Arlington, WI
Chiselplow
No-tillage
Prairie
Total precipitation (cm)
618
618
618
Total drainage (cm)
319
227
98
Precipitation lost to drainage (%)
52
37
16
Total NO3--N leaching loss (kg ha-1)
303
277
0.43
Amount N lost to leaching (%)
18
19
0.5
Flow weighted mean NO3-N Conc.
(mg L-1)
9.5
12.2
0.04
Equates to approximately 32 lbs per acre per year on average
that leaches past the root zone of corn agroecosystems
Effect of cropping systems on nitrate leaching loss
in the Midwest
Cropping
systems
Corn-Corn
Annual
Corn-Soybean
Mixed
Perennial
C-S-O/A-A
Alfalfa
CRP
Switchgrass
Miscanthus
Prairie
Pasture
N Inputs
Nitrate-N
Leaching
Water
Drainage
kg N ha-1 yr-1
kg N ha-1 yr-1
mm yr-1
138
180
151-221
202
202
136-0
168-0
168-0
171-0
171-0-57-0
0
0
0
112
0
112
0
0
55
37
17-32
63
43
51
34-46
34
10-35
8-18
2
1
<1-4
2-11
2-7
<1-1
<1
1-10
193
399
63-187
590
280
226
ND
470
ND
ND
104
160
ND
52-156
ND
52-147
122
ND
Data Source
Randall et al., 1997 (1)
Masarik et al., 2014 (2)
Thomas et al., 2014 (3)
Weed and Kanwar, 1996 (4)
Randall and Iragavarapu, 1995 (5)
Randall et al., 1997 (1)
McIsaac et al., 2010 (6)
Weed and Kanwar, 1996 (4)
Cambardella et al., 2015 (7)
Cambardella et al., 2015 (7)
Randall et al., 1997 (1)
Randall et al., 1997 (1)
McIsaac et al., 2010 (6)
Thomas et al., 2014 (3)
McIsaac et al., 2010 (6)
Thomas et al., 2014 (3)
Masarik, et al., 2014 (2)
Cambardella et al., 2015 (7)
*16 -37X greater nitrate loss below continual corn cropping systems compared to perennial systems
Nitrate concentration below
root zone
Nitrate Leaching Potential
0
Economic Optimal Nitrogen Rates
Forest/
Alfalfa
Soybean Corn Potato
Prairie/
CornCRP
Soybean
Masarik, UW-Extension
Groundwater Susceptibility
The GCSM was developed by the DNR, the US
Geological Survey (USGS), the Wisconsin
Geological & Natural History Survey (WGNHS),
and the University of Wisconsin – Madison in
the mid-1980s.
Nitrate concentration below
root zone
Nitrate Leaching Potential
0
Economic Optimal Nitrogen Rates
Forest/
Alfalfa
Soybean Corn Potato
Prairie/
CornCRP
Soybean
Masarik, UW-Extension
Nitrate Leaching Potential
Nitrate Leaching Potential
Water Quality/
Nitrate
Concentration
Less
0
Greater
Economic Optimal Nitrogen Rates
Forest/
Prairie/
CRP
Alfalfa
Corn
Soybean
CornSoybean
Potato
Masarik, UW-Extension
Septic systems and nitrate
Robertson and Harman 1999
• Designed to dispose of human waste in a manner that prevents
bacteriological contamination of groundwater supplies.
• Do not effectively remove all contaminants from wastewater:
Nitrate, chloride, viruses?, pharmaceuticals?, hormones?
Comparing Land-use Impacts
Corn1
(per acre)
Prairie1
(per acre)
Septic 2
System
Total Nitrogen Inputs (lb)
169
9
20-25
Nitrogen Leaching Loss (lb)
32
0.04
16-20
Amount N lost to leaching (%)
19
0.4
80-90
1 Data from Masarik, 2014
2 Data from Tri-State Water Quality Council, 2005 and EPA 625/R-00/008
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
20 lbs
20 acres
20 acres
Comparing Land-use Impacts
20 lbs/septic system x 1 septic systems = 20 lbs
1/32nd the impact on water quality
0.44 mg/L
Assuming 10 inches of recharge
32 lbs/ac x 20 acres = 640 lbs
14 mg/L
Water table
Stream
Water table
Stream
32 lbs/ac x 20 acres = 640 lbs
20 lbs/septic system
Comparing Land-use Impacts
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs
32 lbs/ac x 20 acres = 640 lbs
20 acres
20 acres
32 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs
20 lbs/septic system x 32 septic systems = 640 lbs
Using these numbers: 32 septic systems on 20 acres (0.6 acre lots) needed to achieve
same impact to water quality as 20 acres of corn
What do we know about
nitrate in groundwater?
Well water studies


9% of private wells exceed the
drinking water standard
21% of wells in agricultural areas
Private Well Water Testing



>30 years of data
125,000 samples
Groundwater Retrieval Network,
County Health Departments, UWExtension
Public Water Systems

Groundwater Retrieval Network
DATCP, 2008
Private Well
Nitrate
Concentrations
Average Nitrate-Nitrogen
Concentration by County
WI Well Water Viewer, 2015
Average Nitrate-Nitrogen
Concentration by Township
WI Well Water Viewer, 2015
Percent of well samples above the
10 mg/L nitrate-nitrogen standard
WI Well Water Viewer, 2015
WI Well Water Viewer
http://www.uwsp.edu/cnr-ap/watershed/Pages/WellWaterViewer.aspx
How to explain the variability
of nitrate across WI?

Coarse textured
surficial deposits

Shallow carbonate
rock aquifers

Watershed land use
portfolio
Siim Sepp
Bill Hafs
Coarse textured surficial deposits
Map created using: Groundwater Contamination Susceptibility Model (GCSM); Surficial Deposits ("sdppw95c")
The GCSM was developed by the DNR, the US Geological Survey (USGS), the Wisconsin Geological & Natural History Survey
(WGNHS), and the University of Wisconsin – Madison in the mid-1980s.
Shallow carbonate
rock aquifers
Photo credits: Ken Bradbury, WGNHS
Watershed land use portfolio
Low
High
Nitrate concentration in groundwater
Agricultural Lands of Wisconsin
Annual Row Crops
Forage Crops/
Pasture/
CRP
Maps produced using WISCLAND
Data Coverage. 2002. WiDNR/EDM
Agricultural Lands of Wisconsin
Row Cropping Systems
Forage Crops/Pasture/CRP
Maps produced using WISCLAND Data Coverage. 2002. WiDNR/EDM
Nitrate Trends
Masarik et al., 2014
Examples of TNC
wells with
decreasing trend
Examples of TNC
wells with an
increasing trend
Examples of TNC wells w/no trend
Location and
result for TNC
wells
Counties that
have seen more
TNC wells
increase (red)
or
decrease (blue)
Masarik et al., 2014
Slide courtesy of Jim Vanden Brook, DATCP 2012
Slide courtesy of Jim Vanden Brook, DATCP 2012
Study of
nitrate in
Dane County
McDonald et al., 2015
Modeling and historical data shows
relationship to fertilizer use over time
Dane
County
Study
McDonald et al., 2015
Other Studies:
Mechenich et al., 1997; Kraft et al., 2004; Kraft et al., 2004; Masarik et al., 2007;
Reason for nitrate trends

Shallow groundwater


Change in land use
Deeper groundwater/
rivers and streams

Lag time between land
use and groundwater
http://www.youtube.com/watch?v=BKrN2HdvGp4
What can be done to reduce nitrate levels?

Short term

Municipal Wells (GCC, 2015)

47 systems have spent >$32 million as of 2012




Water Treatment
New wells
Blending
Private Wells (Lewandowski et. al. 2008)
New well (not guaranteed, deeper adds to expense) - $7,200
 Bottled water - $190/person/year
 Water treatment devices $800 + 100/yr




Reverse osmosis
Distillation
Anion exchange
Long-term nitrogen reduction strategies
Practice
Timing
Nitrification Inhibitor
Cover Crops
Perennial
Extended Rotations
Details
% Nitrate-N
Reduction
Fall to Spring Pre-plant
6 (25)
Spring pre-plant/sidedress 40-60 split compared to fall
applied
5 (28)
Sidedress – Soil test based compared to pre-plant
7 (37)
Nitrapyrin – Fall – Compared to applied w/out nitrapyrin
9 (19)
Rye
31 (29)
Oat
28 (2)
Biofuel Crops (ex. switchgrass, miscanthus)
72 (23)
Conservation Reserve Program
85 (9)
At least 2 years of alfalfa or other perennial crops in a 4
or 5 year rotation
42 (12)
Iowa Nutrient Reduction Strategy, 2014
Improve delivery and efficiency of nitrogen
Conclusions
• (+) Some success in bringing down excessively
high concentrations
• (-) Nitrate loss to groundwater inevitable even under
current best management practices.
• (+) In areas where land use is consistent expect
groundwater nitrate concentrations to stabilize
• (-/+) Where land use changes - expect
concentrations to either increase or decrease
depending on change
Kevin Masarik, Center for Watershed Science and Education
kmasarik@uwsp.edu
http://www.uwsp.edu/cnr-ap/watershed