measured removal of nitrogen from drainage through riparian buffers (per 100’) quality of buffer...
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Measured Removal of Nitrogen from Drainage Through Riparian Buffers (per 100’)
Quality of Buffer Nitrogen Removal
High 68-92%
Medium 45-68%
Low 15-45%
From: US Department of Agriculture
Nitrogen Removal or Accumulation Processes
• Storage in Vegetation
• Storage in Soils
• Biological Denitrification
• Chemical Denitrification
• Volatilization
• Nitrogen taken up by plants is used to build tissues and is stored as protein.
• Woody vegetation accumulates nitrogen on a scale of decades to centuries.
• The greatest accumulation occurs during the transition from one steady state to another (e.g. when farmland is converted to grassland and forest).
• Harvesting prolongs the accumulation period.
Storage in Vegetation
• Detritivores reduce dead organic material into (detritus) simpler compounds and relatively stable residual organic materials that are collectively referred to as soil organic matter. These are generally complex long-chained organic compounds.
• Soil organic matter reaches a steady state with additions from dead material and losses as ammonia and nitrate.
• The residence time of nitrogen in soils is on a scale of decades to centuries.
Storage in Soils
• This process occurs in oxygen-depleted environments typical of saturated soils and wetlands.
• Anaerobic organisms utilize the oxygen in nitrate and the carbon in organic matter for their metabolism. The net result is a release of elemental nitrogen (N2) nitrous oxide (N2O), and carbon dioxide (CO2) as gases to the atmosphere.
• Saturated soils and wetlands could in principle supply the biomass for denitrification indefinitely.
Biological Denitrification
• In oxygen-depleted environments there are chemical as well as biochemical pathways for denitrification. In soils and wetlands it is difficult to separate these biological from chemical processes.
• Chemical denitrification processes are much more important in deeper aquifers than in soils, wetlands, and shallow aquifers.
• Chemical denitrification processes primarily involve reduced iron and sulfur compounds. Nitrate is converted to nitrogen gas (N2) and iron and sulfur are oxidized.
• Depletion of iron and sulfur compounds in deeper aquifers will occur on a scale of decades to centuries or perhaps even millennia.
Chemical Denitrification
• Ammonia (NH3) volatilization and loss to the atmosphere can occur where organic materials are decomposing under anaerobic conditions.
• Ammonia loss from non-agricultural soils and wetlands is generally a minor pathway for nitrogen removal.
• Ammonia is very soluble in water and has a short residence time in the atmosphere.
• Almost all of this loss to the atmosphere returns to the soil with rainfall within a few days over a dispersed area.
Volatilization
Wells in Olmsted County that Exceeded the Nitrate Drinking Water Standard by Geologic Formation
(1960-1988)
• From: Olmsted County Well Index, Minnesota Geological Survey, 1989.
Bedrock Formation Percent of Wells
Upper Carbonate 27
St. Peter 5
Prairie du Chien 7
Jordan 1
Cropland draining to forested hillsides
FERTILIZER ON CORN
50
70
90
110
130
150
170
190
0 50 100 150 200
CORN YIELD BU/ACRE
N lb
s
N in Corn Grain
ExtensionRecommendation
TYPICAL TILE DRAINAGE AND LYSIMETER RESULTSCORN/SOYBEAN ROTATIONMG/L N= 14
INFILT= 6 inches= 170000 gal/acre
10 kg N= 20 lbs N/acre in infiltrate
31
7
6
18
30
19
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234 16 5
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234 16 5
31
7
6
18
30
19
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
16 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
1211107
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
31
7
6
18
30
19
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
3431 3332
30 29 28 27
35 36
2526
356 4
19
18
2120 22
1617 15
7 1098
12
2423
1314
11 12
19 20 21 23 2422
29
3231
30
33 34 35 36
2628 27 25
8
17
5
18
7
6
1416 15 13
119 10
4 3
12
2 1
31
262728
3635343332
30 29 25
31
262728
3635343332
30 29 25
31
262728
3635343332
30 29 25
Viola
Haverhill
CascadeKalmar
Eyota
Rochester Marion
Salem
OrionPleasant Grove
High Forest & TailRock Dell
CLUs in Soybean
Township Boundaries
CLUs in Soybeans
South Zumbro Watershed
Section Lines
Section Numbers2
Legend
Pr ep ar ed By: Roch es ter -O lms ted Pla nnin g Dep ar tm entGe og ra ph ic In for m atio n Sy ste ms Divisio n
No vem be r 200 1
1 0 1 2 Mile s
CLUs in Corn
N
LOCATION OF SOYBEANS AND CORNIN THE SOUTH ZUMBRO WATERSHED
2000
31
7
6
18
30
19
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234 16 5
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234 16 5
31
7
6
18
30
19
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
16 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
1211107
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
31
7
6
18
30
19
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
3431 3332
30 29 28 27
35 36
2526
356 4
19
18
2120 22
1617 15
7 1098
12
2423
1314
11 12
19 20 21 23 2422
29
3231
30
33 34 35 36
2628 27 25
8
17
5
18
7
6
1416 15 13
119 10
4 3
12
2 1
31
262728
3635343332
30 29 25
31
262728
3635343332
30 29 25
31
262728
3635343332
30 29 25
Viola
Haverhill
CascadeKalmar
Eyota
Rochester Marion
Salem
OrionPleasant Grove
High Forest & TailRock Dell
Township Boundaries
South Zumbro Watershed
Section Lines
Section Numbers2
Legend
Pr ep ar ed By: Roch es ter -O lms ted Pla nnin g Dep ar tm entGe og ra ph ic In for m atio n Sy ste ms Divisio n
No vem be r 200 1
1 0 1 2 Mile s
CLUs in Soybean
CLUs in Corn
N
LOCATION OF SOYBEANS AND CORNIN THE SOUTH ZUMBRO WATERSHED
2001
2001 2000CROP ACRES % ACRES
Corn 24974 33.1 24397 32.4
Soybeans 22631 30.0 20422 27.1Alfalfa 5612 7.4 5433 7.2CRP 5520 7.3 6763 9.0Sweet Corn 1700 2.3 1685 2.2Oats 1088 1.4 1572 2.1Peas 1079 1.4 1507 2.0
Excess N 460TONS
N
------Tons/Year------ Inputs: N P K
Fertilizer 7,078 884 3,161
Legumes 4,444 0 0
Precipitation* 1,100 1 5
Mineral 0 375 61
Total Input 12,622 1,260 3,227
Outputs:
Crop Exports 3,347 638 1,149
Milk & Slaughter 1,842 519 262
Total Exports 5,189 1,157 1,411
Inputs Minus Exports 7,433 102 1,816
Olmsted County Nutrient Balance For Agriculture (1990-1994 Average)
31
7
6 5
1718
8
32
30 29
2019
234
31
1
7
6 5
262728
22 24
131718
8 9
3635343332
30 29 25
23212019
16 15 14
121110
31 323231 33 34 35 36
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Salem
CLUs in Soybean
Township Boundaries
South Zumbro Watershed
Section Lines
Section Numbers2
Legend
Pr ep ar ed By: Roch es ter -O lms ted Pla nnin g Dep ar tm entGe og ra ph ic In for m atio n Sy ste ms Divisio n
No vem be r 200 1
CLUs in Corn
Septic Location#
400 0 400 800 120 0 Fe et
N
SEPTIC SYSTEM LOCATIONS ABOVETHE DECORAH IN SALEM TOWNSHIP
SUMMARY OF SEPTIC SYSTEMS S ZUMBRO WATERSHEDS ABOVE THE DECORAH SHALE
TOWNSHIP NO OF ISTSVIOLA 21NEW HAVEN 1KALMAR 22ROCHESTER 499ROCK DELL 177HIGH FOREST 118PLEASANT GROVE 31EYOTA 95MARION 389HAVERHILL 283FARMINGTON 3CASCADE 77SALEM 174
1890N/hse 22.4 lbs/hsetotal N 21 tons N