Nitrate-Nitrogen Concentration
Greater than
10 mg/L
UNSAFE - for infants and
pregnant women; everyone
should avoid long term
consumption.
Greater than
2 mg/L
Impacted by local land use
activities but suitable for
drinking. May indicate other
contaminants.
Less than 2 mg/L
Close to “natural” or
background levels
Sources
• Agricultural fertilizer
• Lawn fertilizer
• Septic systems
• Animal wastes
• Decomposing wastes
Nitrate Nitrogen
WI DHS Drinking Water Recommendation:
 Methemoglobinemia (blue baby disease) (Knobeloch et. al. 2000)
 Range of other health effects such as thyroid
dysfunction (WI DHS, Ward, et. al. 2005)
Agricultural Benefits
 Nitrogen is an essential nutrient for plants
 Increases productivity of crops
 Farming in Spring Green likely not possible
without some nitrogen additions.
Environmental Effects
• Hypoxic zone in the Gulf of Mexico
• Increased eutrophication of surface waters
in nitrogen limited systems
http://www.uwsp.edu/cnr-ap/watershed/Pages/wellwaterviewer.aspx
Not just Wisconsin…
http://m.startribune.com/local/?id=184570171
http://www.hastingsstargazette.com/event/article/id/29317/
What can I do to reduce my
nitrate levels?

Long-term:


Reduce or eliminate nitrogen inputs
Short term (Lewandowski et. al. 2008)



Change well depth or relocate well
(not guaranteed) - $7,200
Bottled water - $190/person/year
Water treatment devices - $800 + 100/yr



Reverse osmosis
Distillation
Anion exchange
The Water Cycle: Where
does all the water go?
Town of Spring Green, Water Table Elevation
Water-table elevation map of Sauk County,
Wisconsin (Miscellaneous Map 55-DI)
2011
2010
2009
2008
31% of private well
samples above the
standard.
Plants are not 100% efficient at removing nutrients from the soil
Mixed Native Perennial
Corn
http://www.soilandhealth.org/01aglibr
ary/010137veg.roots/010137ch2.html
http://www.youtube.com/watch?v=iFCdAgeMGOA
http://soils.usda.gov/sqi/management/files/RSQIS6.pdf
http://www.bae.ncsu.edu/programs/extension/evans/ag452-1.html
How much nitrogen does it take to raise groundwater nitrate 1 ppm?
The actual amount will vary based on the amount of recharge. For Wisconsin this is likely
somewhere between 6 and 10 inches depending on where you live. For Spring Green we will
assume that nitrogen not taken up by the plant will mineralize and nitrify.
8 in.
1 kg 2.2 lbs
18.1 lbs N
1 ft. 28.32 liters 1 g
= per acre
12 in. 1 ft3
1000 mg 1000 g 1 kg
10 mg NO3-N 43,560 ft2
1 acre
liters
Nitrate-Nitrogen Concentration (mg/L)
1
2
3
4
Inches of
Recharge
N
1
2
3
4
5
6
7
8
9
10
5
10
15
20
30
40
3.4
6.8
10.2
13.6
17.0
20.4
23.7
27.1
30.5
33.9
4.5
9.0
13.6
18.1
22.6
27.1
31.7
36.2
40.7
45.2
6.8
13.6
20.4
27.1
33.9
40.7
47.5
54.3
61.1
67.8
9.0
18.1
27.1
36.2
45.2
54.3
63.3
72.4
81.4
90.5
lbs of Nitrogen per acre
0.2
0.5
0.7
0.9
1.1
1.4
1.6
1.8
2.0
2.3
0.5
0.9
1.4
1.8
2.3
2.7
3.2
3.6
4.1
4.5
0.7
1.4
2.0
2.7
3.4
4.1
4.7
5.4
6.1
6.8
0.9
1.8
2.7
3.6
4.5
5.4
6.3
7.2
8.1
9.0
1.1
2.3
3.4
4.5
5.7
6.8
7.9
9.0
10.2
11.3
2.3
4.5
6.8
9.0
11.3
13.6
15.8
18.1
20.4
22.6
Nitrate Concentration
Generalized Nitrate Leaching Potential
0
Economic Optimal Nitrogen Rates
Forest/
Prairie/
CRP
Alfalfa
Soybean
Corn Potato
CornSoybean
Masarik, UW-Extension
Nitrate Concentration
Generalized Nitrate Leaching Potential
0
Economic Optimal Nitrogen Rates
Forest/
Prairie/
CRP
Alfalfa
Soybean
Corn Potato
CornSoybean
Masarik, UW-Extension
Leaching Loss (lbs per acre per
year)
Even applying under the agronomic rate nitrate leaching will occur. The amount of
nitrate that leaches when you exceed the agronomic rate.
Economic optimum
250
200
150
100
50
0
0
50
100
150
200
250
Fertilization Rate (lbs per acre per year )
Flow-weighted NO3-N concentration
(mg L-1)
Based on Table 5 from C.J. Kucharik and K.R. Brye. Integrated BIosphere Simulator (IBIS) Yield
and Nitrate Loss Predictions for Wisconsin Maize Receiving Varied Amounts of Nitrogen
Fertilizer. J. Environ. Qual. 32:247–268 (2003).
30
a)
CP
NT
CP
NT
20
Y = 0.89 + 0.0046X + 0.00019X2
R2= 0.87
Y = 1.3 + 0.0068X + 0.00015X2
R2 = 0.88
10
0
0
100
200
300
N application rate (kg ha-1)
400
Masarik, 2003
Nitrate Concentration
GW NO3-N = f(Crop N Requirements, Excess N, Soils, Geology)
0
Economic Optimal Nitrogen Rates
Forest/
Prairie/
CRP
Alfalfa
Soybean
Corn Potato
CornSoybean
Masarik, UW-Extension
Poor
Good
UW Nitrogen Guidelines get us to
a baseline Level of nitrate
concentration in groundwater
Nitrate Concentration
Water Quality/
Nitrate
Concentration
0
Economic Optimal Nitrogen Rates
Forest/
Prairie/
CRP
Alfalfa
Soybean
Corn Potato
CornSoybean
Masarik, UW-Extension
Water quality as a function of crop N recommendations
Medium Inputs
No Inputs
Amount of nitrogen applied
Water Quality/
Nitrate
Concentration
Good
Poor
High Inputs
Water quality as a function of watershed area in
production
50%
Percent of land base in production
0%
Water Quality Nitrate
Concentration
Low
High
100%
Water quality as a function of Nitrogen Use Efficiency
Studies show efficiency typically about 30-50% (Cassman et. al. 2002)
Baseline or Reference
Condition
Less nitrogen than
economic optimal results in
the same or greater yield.
Research based
economic optimal
nitrogen application
Economic optimal nitrogen
application results in
greater yield.
Increased nitrogen
application results in
increased yield without an
increase in efficiency.
More
Less
Water Quality Nitrate
Concentration
Increased nitrogen
application results in
increased yield but
nitrogen use
efficiency decreases.
Amount of N loss
Less
More
*Strategies to Reduce Nitrate Leaching to Groundwater on Sandy Soils
Strategic
reduction
acreage
Create
groundwater
protection
zones around
municipal or
residential
wells
Convert
agricultural
acreage on
edges of fields
into
windbreaks or
grasses
Reduce
Nitrogen Input
Needs
Increase
acreage of
crops with
lower nitrogen
requirement
Modify
rotations so
that the
nitrogen mass
balance is able
to meet the
drinking water
standard for a
4 year period
Investigate ability of these
practices to increase nitrogen-use
efficiency
Reduce or
eliminate fall
application of
manure or
fertilizer
Cover crop
management
for nitrogen
efficiency
Slow release
fertilizer
(Polymer
coated urea)
Split
applications
*Assuming that all fields are already voluntarily following Nutrient Management plans,
applying nitrogen only at economic optimal rate, and crediting all nitrogen sources.
Poor
Good
Improve Nitrogen
Use Efficiency
Nitrate Concentration
Water Quality/
Nitrate
Concentration
0
Economic Optimal Nitrogen Rates
Forest/
Prairie/
CRP
Alfalfa
Soybean
Corn Potato
CornSoybean
Masarik, UW-Extension
Factors affecting nitrogen loss to groundwater
• Amount of nitrogen applied
Somewhat
Fixed
– As a function of crop type
– Nitrogen application rate relative to
economic optimum
• Percent of land base in production
Limited
ability to
adjust
• Nitrogen use efficiency
Out of our
control
• Geology
• Soil Type
• Precipitation / Climate
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)
36
0.04
16-20
Amount N lost to leaching (%)
20
0.4
80-90
1 Data from Masarik, Economic Optimum Rate on a silt-loam soil, 2003
2 Data from Tri-State Water Quality Council, 2005 and EPA 625/R-00/008
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
20 lbs
20 acres
20 acres
Comparing Land-use Impacts
20 lbs/septic system x 1 septic systems = 20 lbs
1/36th the impact on water quality
0.44 mg/L
Assuming 10 inches of recharge -
36 lbs/ac x 20 acres = 720 lbs
16 mg/L
Masarik, UW-Extension
Water table
Stream
Water table
Stream
36 lbs/ac x 20 acres = 720 lbs
20 lbs/septic system
Masarik, UW-Extension
Comparing Land-use Impacts
20 acres
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs
36 lbs/ac x 20 acres = 720 lbs
20 acres
36 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
20 lbs
20 lbs
20 lbs
20 lbs/septic system x 36 septic systems = 720 lbs
Using these numbers: 36 septic systems on 20 acres (0.55 acre lots) needed to achieve
same impact to water quality as 20 acres of corn
Masarik, UW-Extension
Pesticides in Drinking Water
• Insecticides, herbicides, fungicides and other
substances used to control pests.
• Health standards usually only account for
parent compound.
• Parent compounds breakdown over time.
• Little research into health effects from the
combination of chemicals..
•
Most frequently detected pesticides in WI:
– Alachlor* (Lasso) and its chemical breakdown products
(Alachlor ESA)
– Metolachlor (Dual) and its chemical breakdown products
(Metolachlor ESA)
– Atrazine** and its chemical breakdown products
– Metribuzin
– Cyanazine and its chemical breakdown products.
• * WI public health groundwater standard for breakdown component Alachlor ESA.
• ** WI public health groundwater standard is for the total chlorinated atrazine residue
DACT Screen
•
Sources of DACT: Triazine pesticides (mainly
atrazine but also simazine, propazine,
cyanazine, etc. used on corn crops)
•
Screen: Only measures the breakdown
component of triazine type pesticides known as
diaminochlorotriazine (DACT)
•
Specific to diaminochlorotriazine (DACT), does
not account for parent compound or other
breakdown components
•
Drinking water limit:
3 ppb of total atrazine
(atrazine + the 3 breakdown components)
•
If a level above 2 ppb is detected, the well is eligible for
follow up testing by DATCP. DATCP would perform a
test that looks for atrazine as well as other commonly
detected pesticides in water.
http://datcp.wi.gov/Environment/Water_Quality/Atrazine/Atrazine_Prohibition_Areas/index.aspx
Homeowners
$49
If you choose to perform all three the total is $110, a discount of $8 if performed individually.
Repeat well tests in Town of St. Joseph, St. Croix County
Additional References
•
Cassman, Kenneth G.; Dobermann, Achim R.; and Walters, Daniel T., "Agroecosystems, Nitrogen-use
Efficiency, and Nitrogen Management" (2002). Agronomy -- Faculty Publications. Paper 356.
http://digitalcommons.unl.edu/agronomyfacpub/356
•
•
Dinnes, Dana L.; Karlen, Douglas L.; Jaynes, Dan B.; Kaspar, Thomas C.; Hatfield, Jerry L.; Colvin,
Thomas S.; and Cambardella, Cynthia A., "Review and Interpretation: Nitrogen Management
Strategies to Reduce Nitrate Leaching in Tile-Drained Midwestern Soils" (2002). Publications from
USDA-ARS / UNL Faculty. Paper 263. http://digitalcommons.unl.edu/usdaarsfacpub/263
Nitrate Nitrogen in Surface Waters as Influenced by Climatic. Conditions and Agricultural Practices.
Gyles W. Randall* and David J. Mulla. 2001. J. Environ. Qual.
https://www.agronomy.org/publications/jeq/pdfs/30/2/337
•
•
Weed, D.A.J., and R.S. Kanwar. 1996. Nitrate and water present in and flowing from root-zone soil. J.
Environ. Qual. 25:709-719. https://www.agronomy.org/publications/jeq/abstracts/25/4/JEQ0250040709?access=0&view=pdf
WI Well Water Quality Viewer. Center for Watershed Science and Education. http://www.uwsp.edu/cnrap/watershed/Pages/wellwaterviewer.aspx
•
Brye, K.R. and J.M. Norman, L.G. Bundy, and S.T. Gower. 2001. Nitrogen and Carbon Leaching in
Agroecosystems and Their Role in Denitrification Potential. J. Environ. Qual. Vol. 30 No. 1, p. 58-70.
https://www.agronomy.org/publications/jeq/articles/30/1/58
•
Ward, M.H., T.M. deKok, P. Levallois, J. Brender, G. Gulis, B.T. Nolan, and J. VanDerslice. 2005. Workgroup Report:
Drinking-Water Nitrate and Health – Recent Finding and Research Need. Environmental Health Perspectives. Vol:
113 No. 11. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1310926/