Building Science Assessments for
State-Level Nutrient Reduction Stategies
Effects of Conservation Tillage Systems on Dissolved Phosphorus
Dr. David Baker
Heidelberg University
Tiffin, Ohio 44883
November 15, 2012
Davenport, IA
This talk -Lessons learned from agricultural phosphorus
control programs in the Lake Erie Basin
The teacher has been:
1. Detailed, long-term monitoring data for
several major watersheds draining into Lake
Erie.
2. Information on changing crop production
practices in those watersheds.
This research was supported by state and federal agencies, foundations ,
agribusinesses and the fertilizer industry . Special thanks to the EPA’s Great Lakes
National Program Office and the Great Lakes Protection Fund for recent support for
bioavailability studies and phosphorus stratification studies.
15 stations
All at USGS Stream Gages
Today’s data from
three rivers:
Maumee – 6,330 sq.mile
Sandusky – 1,250 sq. mile
Cuyahoga - 708 sq. mile
Analytical Program at the NCWQR
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Suspended solids
Total phosphorus
Dissolved reactive phosphorus
Nitrate
Nitrite
Ammonia
Total Kjeldahl Nitrogen
Chloride
Sulfate
Silica
Fluoride
Conductivity
Seasonally pesticides
Selected metals
Bioavailable Phosphorus
Program Characteristics:
• Program started in 1975
• ~ 500 samples analyzed per
station per year
• Annual loads calculated by
integration with corrections
for final USGS daily
discharge
• Data available at
Heidelberg’s web site:
http://www.heidelberg.edu
/academiclife/distinctive/nc
wqr/data
Management Options for Phosphorus Load Reduction
Focus of reduction programs
Total
Phosphorus
Load
Total
Bioavailable
Phosphorus
Load
=
Total
Particulate
Phosphorus
Load
=
Bioavailable
Particulate
Phosphorus
Load
+
Total
Dissolved
Phosphorus
Load
+
Bioavailable
Dissolved
Phosphorus
Load
Nonpoint phosphorus control programs were
planned in the 1980s and initiated in the 1990s.
Forms of
phosphorus
transported in
northwestern
Ohio rivers,
1975-1987.
Dissolved
Phosphorus
18%
Particulate
Phosphorus
82%
Particulate
phosphorus
during storm
runoff is
attached to soil
particles.
Phosphorus reduction programs focused on reducing erosion
and particulate phosphorus loading through fostering adoption
of no-till and reduced till crop protection methods.
1. What does the water quality
monitoring data look like?
2. What changes in agricultural
practices could explain the loading
changes?
3.What changes in hydrology could
help explain the loading changes?
Trends in annual loads and flow weighted mean concentrations of
particulate phosphorus in the Maumee and Sandusky rivers
• Note the close
relationship
between variations
in annual discharge
and variations in TP
load.
• Discharge increased
by 41% while TP load
increased by 31%.
• Weather and
hydrology drive
nonpoint pollution
from cropland.
Trends in annual loads and flow weighted mean concentrations of
dissolved reactive phosphorus in the Maumee and Sandusky rivers
Dissolved Reactive Phosphorus
50% decrease from 1982-2011
Total Phosphorus
24% decrease from 1982-2011
From here
To here
Phosphorus reduction
programs in the Lake Erie
Basin have been driven by
the lake’s eutrophication
problems.
Point source control
problems were initiated
first and quickly resulted
in substantial reductions
in phosphorus loading.
How does nutrient export from the Northwestern Ohio
rivers compare with the export from other areas?
Total Phosphorus Tributary Loads to Lake Erie,
2005
Maumee
Sandusky
Cuyahoga
Thames
Cattaraugus Creek
Grand (Ont)
Chagrin
Huron (OH)
Vermilion
Grand (OH)
Black
Detroit R Canada
Maumee and Sandusky
•
26% of land area
•
51% of total phos. load
•
Export rate 3x higher than
average for rest of drainage
area
Land use in study watersheds, as percent
Watershed
Maumee
Sandusky
Cuyahoga
Agricul
-ture
Forest
73.3
77.6
9.0
6.5
8.8
33.6
Grass_
Open
Hay_
Urban Wetland Other
Water
Pasture
6.3
0.7
10.6
2.3
0.2
4.3
0.5
8.1
0.3
0.3
11.8
2.6
39.5
3.1
0.4
Average annual nutrient export rates, 1996-2011
River
Maumee
Sandusky
Cuyahoga
DRP, DRP as
% TP
SS
TP,
lbs/acre
lbs/acre
lbs/acre
1.21
1.46
1.26
0.25
0.29
0.18
504
642
1,175
21%
20%
14%
NitrateN
TKN,
lbs/acre
lbs/acre
17.08
18.73
7.59
5.23
5.76
4.86
Data for 2004-2008 Water Years
Watershed
Point source Non-Point
Phosphorus Phosphorus
Maumee
5%
95%
Sandusky
3%
97%
Trends in tillage practices in northwestern Ohio:
1989-2004
Tillage Practices in the Sandusky Watershed:
2009-2010
Tillage Practices
Corn,
(1142
fields)
Soybeans
(1147
fields)
Wheat
(945
fields)
Hay
(52 fields)
5%
1%
1%
4%
1
Moldboard plow,
< 5% cover
2
Reduced tillage, soil
heavily mixed, < 30%
cover
72%
9%
3%
48%
3
Mulch tillage, soil lightly
mixed, > 30% cover
15%
17%
12%
13%
4
No till, strip till
8%
73%
84%
35%
“Rotational no till”
Phosphorus fertilizer sales in Ohio, 1955-2007
Heidelberg Monitoring started
Long-term trend in average phosphorus
soil tests in Northwest Ohio
Start of Heidelberg monitoring
How will the majority of phosphorus
fertilizer be applied to this field?
Fertilizer application method
# of
fields
% of
fields
1
Broadcast and unincorporated
211
20%
2
Broadcast and incorporated within one
week
212
21%
3
Broadcast and incorporated after one
week or more
115
11%
4
Banded with corn planter
496
46%
5
Banded more than 2 inches deep with a
coulter/knife injection tool
23
2%
Total number of reported fields
Sandusky Watershed Soil Stratification Studies
1,030
100%
When will the majority of phosphorus
fertilizer be applied?
Timing of fertilizer application
# of
fields
% of
fields
86
8.4 %
513
50.0 %
92
9.0 %
In fall (September – November) after
soybean harvest
283
27.6 %
5
In fall, (September – November) after
corn harvest
47
4.6 %
6
In winter (December – March)
4
0.4%
7
In winter (December – March) on snow
covered or frozen soils.
1
0.1 %
1
In spring (April to June), prior to
planting
2
In spring (April to June), at planting
3
In late summer or fall (August –
November) after wheat or hay harvest.
4
Total Responses
1,026
Total Phosphorus
Loading
Total Bioavailable
Phosphorus Loading
A bottom line …
1. After 20+ years of efforts to reduce
phosphorus loading to Lake Erie from
cropland, we now have more bioavailable
phosphorus entering Lake Erie from
cropland than ever.
2. The increases in bioavailable phosphorus
loading are due to increases in dissolved
phosphorus runoff.
3. The increases in dissolved phosphorus
loading appear to be contributing increased
harmful algal blooms in Lake Erie.
Characteristics of average annual export of phosphorus
from the Sandusky River, 2002-2011
Total Phosphorus
(594 metric tons/year)
73% particulate phosphorus
27% dissolved phosphorus
93%
bioavailable
29%
bioavailable
Management
choice impacts-• Trading
• TMDLs
• BMP selection
Bioavailable Phosphorus
(275 metric tons/year)
46% particulate phosphorus
54% dissolved phosphorus
Why has the dissolved phosphorus loading from
the Sandusky and Maumee rivers dropped and
then increased so much?
Potential causes of the increasing dissolved phosphorus export
1. increasing fall and winter broadcasting of phosphorus fertilizers,
often without timely incorporation.
2. phosphorus stratification in the soil associated with widespread
adoption of no-till and reduced-till production and the
accompanying lack of inversion tillage.
3. increased tile drainage coupled with macropore flow that carries
surface water to tile drains and increases total discharge.
4. increasing trends in flashiness of northwestern Ohio streams.
5. changes in rainfall patterns that have resulted in increases in
winter rainstorms and resulting stream flows, especially in
December and January.
Phosphorus stratification in cropland of the
Sandusky Watershed
Analysis of dilute aqueous soil suspensions
Analysis of dilute aqueous soil suspensions
Questions?
NCWQR
Phosphorus
Analyses
Bioavailable
Forms
Portion
Analyzed
Total Phosphorus (TP)
whole sample
Dissolved Phosphorus (DP)
Sample Pretreatment
acid
added
oxidant
added
autoclave
x
x
x
(filter sample through 0.45 micron filter)
Dissolved Reactive P (DRP)
filtrate
---
---
---
Dissolved Hydrolyzable P (DHP)
filtrate
x
---
x
Total Dissolved P (TDP)
filtrate
x
x
x
Dissolved Organic P (DOP)
Particulate Phosphorus (PP)
NaOH Extractable PP
all samples
calculated as TDP - DHP
calculated as TP - TDP
(extract residue on filter with NaOH
and analyze as DRP)
extra analyses for bioavailability studies