1. Water Quality

2. Hypoxia – What is it?
An area of low dissolved oxygen
concentrations that cannot support marine
life. Typically O2 < 2 ppm

3. Hypoxia – Why does it occur?
 Algae bloom in freshwater
 Algae settle to bottom
 Algae decomposition consumes O2

4. Hypoxia – How large an area?
x
http://www.epa.gov/gmpo/pdf/2007-hypoxia-pred-web-5.pdf
Turner and Rabalais, 2007
X – size in 2008

5. Hypoxia – Is nutrient flux constant?
co.water.usgs.gov

6. Hypoxia – Nitrogen Source?
20 – 25 lb/A
www.umces.edu/President/hypoxia.htm

7. Hypoxia – Source of Phosphorus?

8. Look to the Future
Planted area: Corn, wheat, and soybeans
Million acres
100
90 Corn
80
Soybeans
70
60
Wheat
50
40
1980 1985 1990 1995 2000 2005 2010 2015
Source: USDA Agricultural Projections to Projections to
USDA Agricultural 2016, February 2007. 2016
Economic Research Service, USDA.
D. R. Keeney

9. Corn/Soybean and Perennial
Nitrate-N Concentrations in Tile
Drain
25
 Tile drainage system
20
 U of MN - Lamberton
Gyles Randall, 2003
15
mg/L
Midpoint
10 of range
5
0
Corn/Bean Perennials
D. R. Keeney

10. Tom Kaspar

11. Rye after corn silage
Tom Kaspar

12. Cumulative annual nitrate-N load of drainage
water for 2002-2005
90
81.1
80
Control
70
Annual nitrate-N load (kg/ha)
Rye Cover Crop
60
50.8
50 47.2
40.4
40
33.9 34.4
30
23.0 19.8
20
11.2 11.1
10
0
2002 2003 2004 2005 Avg.
Kaspar et al., JEQ 36:1503-1511

13. Cropping System Impacts on Drainage
Water Quality and Quantity
Dr. Matt Helmers, Dr. Xiaobo Zhou, and
Carl Pederson

14. ISU South Reynoldson Farm
Boone County, IA
Comparison of Biofuel Systems
(COBS)
Each of the 24 plots is 90 ft x 200 ft
Photo by T. Schultz
August 2009

15. Tile Drainage Flow 2010

16. Tile Drainage Flow 2011

17. NO3-N Concentration 2010

18. NO3-N Concentration 2011

19. NO3-N Loss 2010

20. NO3-N Loss 2011

21. Iowa Daily Erosion Project
 Estimates daily soil erosion, runoff and
soil moisture for the state of Iowa
 Daily estimations since 2002
 Published in Jan/Feb 2006 Journal of the
Soil and Water Conservation Society
 Served on the web at
http://wepp.mesonet.agron.iastate.edu
 Parameterizes WEPP erosion model with
radar rainfall, climate stations, and NRI

22. Simulated crops
 Eight scenarios based on ISU research
Residue Cover
Rotation Tillage Abbreviation
Removal Crop
NRI NRI No No NRI
Corn/Soy Min-till No No CS-MT
Cont. Corn Min-till Yes No CC-MTRR
Corn/Soy No-till No No CS-NT
Cont. Corn No-till No No CC-NT
Cont. Corn No-till Yes No CC-NTRR
Cont. Corn No-till Yes Yes CC-NTRRCC
Switchgrass No-till Yes No Sw-NTRR

23. NEXRAD – Aug 22, 2007
Statewide mean precipitation: 1.56 in.

24. Switchgrass – NT, RR
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

25. Cont. Corn – NT
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

26. Corn/Soybean – NT
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

27. Cont. Corn – NT, RR
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

28. Cont. Corn – NT, RR, CC
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

29. NRI Projected Rotation
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

30. Corn/Soy - MT
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

31. Cont. Corn - MTRR
Sw-NTRR
CC-NT
CS-NT
CC-NTRR
CC-NTRRCC
NRI
CS-MT
CC-MTRR

32. Event Summary
8/22/2007 Mean Loss 8/22/2007 Mean
Management
(tons/acre) Runoff (in)
Sw-NTRR 0.044 0.657
CC-NT 0.113 0.662
CS-NT 0.184 0.651
CC-NTRR 0.230 0.649
CC-NTRRCC 0.232 0.650
NRI 0.320 0.640
CS-MT 0.406 0.647
CC-MTRR 0.458 0.646

33. Cumulative
sediment export (lb acre-1)
Cumulative
surface runoff (in acre-1)
4/ 4/
0
5000
10000
15000
20000
0
1
2
3
4
5
6
10 10
/2 /2
0 08 00
8
4/ 4/
17 17
/2 /2
0 08 00
8
4/ 4/
18 18
/2 /2
0 08 00
8
4/ 4/
25 25
/2 /2
0 08 00
8
5/ 5/
25 25
/2 /2
0 08 00
8
100% Row-crop
100% Row-crop
5/ 5/
30 30
/2 /2
0 08 00
8
6/ 6/
3/ 3/
20 20
Date
08 08
10% Perennial Cover at Toe Slope
10% Perennial Cover at Toe Slope
6/ 6/
5/ 5/
20 20
20% Perennial Cover in Contour Strips
10% Perennial Cover in Contour Strips
20% Perennial Cover in Contour Strips
10% Perennial Cover in Contour Strips
08 08
6/ 6/
6/ 6/
20 20
08 08
6/ 6/
8/ 8/
20 20
08 08
6/ 6/
12 12
/2 /2
0 08 00
8
6/ 6/
26 26
/2 /2
0 08 00
8

34. Thoughts to Ponder
 Corn grain ethanol
 N applications likely unchanged
 P applications likely unchanged
 Water quality impacts likely unchanged
 Cover crop management good for system

35. Thoughts to Ponder (II)
 Cellulosic - conversion of corn stalks
 Likely greater water quality challenges than
current ag systems
 Opportunities with cover crops to improve WQ
 Sediment/Phosphorus issues increase
 Cellulosic – conversion of perennials
 Favorable WQ opportunities
• Surface
• Subsurface