Overview – Nutrient Fate and Transport Mark B. David University of Illinois at Urbana-Champaign Presented at Building Science Assessments for State-Level.

Overview – Nutrient Fate and Transport

Mark B. David

University of Illinois at Urbana-Champaign

Presented at Building Science Assessments for State-Level Nutrient

Reduction Strategies

Nov. 13, 2012

What I will cover

• what the problem is

• N and P sources, balances, and river exports in the Mississippi River Basin (MRB)– Illinois as example

– what is going to the Gulf

• importance of modified hydrology (tile drainage)

• timing of flow and nutrients; fate

• myths; the challenge ahead

What is the problem?• both local and

downstream water quality problems from nitrate and total P

– local: algal production due to P; drinking water for N

– downstream: hypoxia in the Gulf of Mexico

• USEPA requiring nutrient criteria in flowing waters

Hypoxic zone, 2012

What was new (in 2007, now old)

• reaffirmed previous assessment

• importance of spring (April, May, June) nitrate

• now phosphorus recognized as having role in Gulf

• no one answer to fix problem– both agriculture and people (sewage effluent)

• recommended 45% reduction in N and P going down Mississippi River

Mississippi River Basin

Nitrogen

Water F

lux (m

illion m

3)

0

200000

400000

600000

800000

1000000

1200000

Riverin

e N F

lux

(million

metric ton

s N yr

-1)

0.0

0.5

1.0

1.5

2.0

2.5

19551960

19651970

19751980

19851990

19952000

20052010

2015

0.0

0.5

1.0

1.5

2.0

2.5

Nitrate-N

Ammonium

Total N

Particulate/organic N

Mississippi River Basin Phosphorus

Water F

lux (m

illion m

3)

0

200000

400000

600000

800000

1000000

1200000

19551960

19651970

19751980

19851990

19952000

20052010

2015

Riverin

e P F

lux

(million

metric ton

s yr-1

)

0.00

0.05

0.10

0.15

0.20

0.25

Total P

Soluble reactive P

Major Mississippi Subbasins

Major Mississippi Subbasins

Nutrient loads for 2001 to

2010

0

10

20

30

40

50

Subbasin

Miss-Clinton

Miss-Grafton

Missouri-Om

aha

Missouri-Herm

ann

Miss-Thebes

Ohio-Cannelton

Ohio-Grand Chain

Arkansas-Little Rock

Red River-Alexandra

Lower Miss

Nutrient load (1,000 m

etric tons N or P

yr-1

)0

50

100

150

200

250

300

350

2001-20052006-2010

Total P

Nitrate-N

Nutrient yields for 2001 to

2010

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Subbasin

Miss-Clinton

Miss-Grafton

Missouri-Om

aha

Missouri-Herm

ann

Miss-Thebes

Ohio-Cannelton

Ohio-Grand Chain

Arkansas-Little Rock

Red River-Alexandra

Lower Miss

Nutrient yield (kg N

or P ha

-1 yr

-1)

0

2

4

6

8

10

12

14

16

2001-20052006-2010

Total P

Nitrate-N

Spring nitrate, upper Miss and Ohio

Water F

lux (cm

)

0

5

10

15

20

25

30

1975 1980 1985 1990 1995 2000 2005 2010 20150

5

10

15

20

25

30

Mississippi River at Grafton

Ohio River at Grand Chain, IL

Riverin

e Nitrate-N

Flu

x (m

illion m

etric tons N

)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

1975 1980 1985 1990 1995 2000 2005 2010 20150.00

0.05

0.10

0.15

0.20

0.25

0.30

Mississippi River at Grafton

Ohio River at Grand Chain, IL

1975 1980 1985 1990 1995 2000 2005 2010 2015

Sp

ring

Nitra

te (to

ns N

yr-1

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7MRB Grafton and Ohio

Source of spring nitrate

County Level Analysis of Mississippi River Basin

• counties in MRB (all 1768)

• 1997 to 2006 annual data on fertilizer, crops, animals, people, deposition

• predictive model from watersheds applied to all MRB counties

• both N and P

From David et al. (2010)

Nutrient Balances

inputs

-

+

-

+

- outputs

Annual N Fertilizer Applications

Fertilizer (kg N ha-1)0.0 - 11.2

11.3 - 27.2

27.3 - 45.4

45.5 - 65.9

66.0 - 107.1 From David et al. (2010)

Drain

0.0 - 5.1

5.2 - 16.3

16.4 - 31.7

31.8 - 51.4

51.5 - 81.8

Tile drainage is concentrated in the corn belt

Fraction of county

From David et al. (2010)

nni

-5 - 20

20 - 40

40 - 60

60 - 200

Net N Inputs (NNI)

kg N ha-1

Some counties negative, N from soil mineralization

Illinois N budgetthrough

2012

0

20

40

60

80

100

Nitrogen (kg N

ha-1

)

0

20

40

60

80

100

120

Fertilizer

1950 1960 1970 1980 1990 2000 20100

10

20

30

40

50 Net Nitrogen Inputs

ManureHuman consumption

Grain harvest

NOy deposition

Legume N

Linking N balances to N Export

• hydrology overwhelming factor

– channelization, tile drainage

• can look at watershed N export as a fraction of net N inputs

– most studies, about 25%

– however in MRB we know it is larger in critical areas

– can be > 100% in heavily tile drained watersheds

Drainage by tiles and ditches

Patterned tile systems

Embarras River - Camargo

Embarras River

19931994

19951996

19971998

19992000

20012002

20032004

20052006

20072008

20092010

20112012

NIT

RA

TE

(mg N

L-1

)

0

5

10

15

20

Embarras River

Water Year

19951996

19971998

19992000

20012002

20032004

20052006

20072008

20092010

20112012

Nitrate E

xport (kg

N h

a-1

yr-1

)

0

10

20

30

40

50

60

Predicted N Yield (kg N/ha)

0.00 - 3.00

3.01 - 7.50

7.51 - 10.00

10.01 - 15.00

15.01 - 25.00

Modeled January to June Nitrate Export

Best model includes fertilizer, sewage effluent,and tile drainage

Components of P Mass Balances

• net P inputs

= inputs – outputs

inputs (fertilizer)

outputs (grain harvest - human and animal consumption)

• net indicates additions or removals from soil

• little P (relative to N) is lost to streams, but it is biologically important

• surface runoff and tile leaching

• manure

From Jacobson et al. (2011)

Fertilizer P Row Crop %

Manure P Net P Inputs

Modeled January to June Total P

From Jacobson et al. (2011)

Illinois P budgetthrough

2012

0

5

10

15

20

Phosphorus (kg P

ha-1

)

0

5

10

15

20

Fertilizer

1950 1960 1970 1980 1990 2000 2010-10

-5

0

5

10

15

20

Balance

ManureHuman consumption

Grain harvest

P from fields to rivers –

Embarras River

From Gentry et al. (2007)

Particulate P from

fields to rivers

From Gentry et al. (2007)

Importance of a Few Storm Events

From Royer et al. (2006)

Fate of N

• limited in-stream losses of nitrate during high flow periods

– Lake Shelbyville

– Saylorville Reservoir

• retention times too short

• spring nitrate, headed to Gulf

Depth/Time of Travel (m yr-1)

0.1 1 10 100 1000 10000

N R

em

ove

d (%

)

0

20

40

60

80

100Lake Shelbyville, IllinoisGarnier et al. (1999)Royer et al. (2004)Saylorville Reservoir, Iowa

Crumpton equation

Fate of P

• some sediment removal

• problem of sediment already in streams/rivers

– stream bank, bed erosion

• algal biomass can move downstream

• no way to easily get out of system (like nitrate)

Source: Clay Soil and Water Conservation District, Minnesota

What we know about nutrient sources

• Upper Mississippi and Ohio subbasins are the major source of nitrate and total P– even more so in critical

spring period

• the tile drained cornbelt is clearly identified

• mass balance of P has greatly decreased, but not N

What can we do in agriculture?

• given, – it is not typically over fertilization

based on current rates and yields

– may be zero or negative N & P balances in some areas of the tile drained Midwest

• three types of conservation practices could help– nutrient-use efficiency

– in-field management

– off-site measures

Potential Efficiencies -SAB report

Jan08

Jul08

Jan09

Jul09

Jan10

Jul10

Jan11

Jul11

Jan12

Nitra

te-N

Co

nce

ntra

tion

(mg

N L

-1)

0

5

10

15

20

25

30Corn-Corn-Soy MiscanthusSwitchgrass Prairie

Perennial biofuels quickly reduce nitrate loss

From Smith et al. (2013)

Point sources in MRB?

• sewage effluent and industrial (22% of annual N and 34% of P)

• however, only 14% (N) and 20% (P) of spring load

• not going to solve problem, but could help for P

A few myths

• no-till solves all problems

• a few (bad) actors are the problem

• over application of N (or P) is most of the problem

• just targeting a few fields will solve most of the problem

• edge of field denitrification can solve the problem

• the response will take a long time (decades?)

What’s making it difficult

• more corn (and fertilizer)

• more intensive tile drainage

• warmer winters

• more intense winter/spring precipitation

• fall N in Illinois, Indiana, Ohio

• the intensity of agriculture across the cornbelt

• many (most?) practices to reduce nutrient loss don’t increase yield

Conclusions

• N and P balances don’t relate well to nitrate and P loss across the MRB (but could increase losses in a drought year)

• counties with high fertilizer inputs have high crop fractions (& corn acres) and tile drainage– all lead to nitrate loss

– corn & soybeans on tile drained land much more important than manure, deposition, or sewage effluent

• P from both surface runoff and tiles– sewage effluent also important

• high winter/spring flow and nutrient losses are a challenge, and seem to be getting worse

Job ahead for us

• 45% reductions in N and P will be quite difficult in upper MRB

• we haven’t really started

– not in any meaningful way

• variety of methods and costs

– many or most unrelated to yields

• scale of problem is impressive

• but, we do know how to do it!