Why are we here?
Developing strategies to utilize nitrogen more efficiently
improves profitability and reduces amount of nitrate that
would otherwise up in groundwater and surface waters
The effects of land-use on water quality are more obvious in places
like Spring Green because of the susceptible geologic conditions
Tangible costs associated low nitrogen use efficiency:
•
Costs of nitrogen itself
•
Cost of water treatment to remove agricultural chemicals that cause health effects.
•
Municipal Water Supplies
•
Private wells
•
Costs of disposing of locally produced nitrogen sources (i.e. manure, bio-solids,
industrial sludge) while importing industrially produced nitrogen from out of state.
Nitrogen Fertilizer Pricing
Form
Cost per ton
Cost per lb of nitrogen
Anhydrous Ammonia (82% N)
$783
$0.48
Nitrogen Solutions (30% N)
$373
$0.62
Urea (44-46% N)
$554
$0.62
Ammonium Nitrate (35% N)
$506
$0.73
Sulfate of Ammonium (21% N)
$451
$1.07
Source: Agricultural Prices for March 2012, National Agricultural Statistics Service, USDA.
As energy prices go, so
to do nitrogen fertilizer
costs.
Price ($ per lb of nitrogen)
1.2
1
Nitrogen Fertilizer Costs (1960-2012)
Anhydrous ammonia
Nitrogen solutions (30%)
0.8
0.6
Urea 44-46% nitrogen
As the price of
nitrogen fertilizers
increase, it becomes
increasingly important
to improve nitrogen
use efficiency to
maximize profitability
and reduce our
dependence on fossil
fuels.
Ammonium nitrate
Sulfate of ammonium
0.4
0.2
0
1950
1960
1970
1980
1990
2000
2010
2020
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
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 of a high input N crop
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
Factors affecting nitrogen loss to groundwater
• Amount of nitrogen applied
Within our
control
– As a function of crop type
– Nitrogen application rate relative to
economic optimum
• Percent of land base in production
Limited
control
• Nitrogen use efficiency
Out of our
control
• Geology
• Soil Type
• Precipitation / Climate
*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
No 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.
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/cnr-ap/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