Effects of Conservation Tillage Systems on Dissolved Phosphorus

Dr. David BakerHeidelberg University

Tiffin, Ohio 44883

November 15, 2012

Davenport, IA

Building Science Assessments for State-Level Nutrient Reduction

Stategies

This talk -- Lessons learned from agricultural

phosphorus control programs in the Lake Erie BasinThe 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.mileSandusky – 1,250 sq. mileCuyahoga - 708 sq. mile

1. Suspended solids2. Total phosphorus3. Dissolved reactive phosphorus4. Nitrate5. Nitrite6. Ammonia7. Total Kjeldahl Nitrogen8. Chloride9. Sulfate10. Silica11. Fluoride12. Conductivity

Seasonally pesticidesSelected metals

Bioavailable Phosphorus

Analytical Program at the NCWQR

• 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/ncwqr/data

Program Characteristics:

Total Phosphorus

Load

Total Particulate

PhosphorusLoad

Total Dissolved

PhosphorusLoad

+=

TotalBioavailablePhosphorus

Load+=

BioavailableParticulate

PhosphorusLoad

BioavailableDissolved

PhosphorusLoad

Management Options for Phosphorus Load Reduction

Focus of reduction programs

Nonpoint phosphorus control programs were planned in the 1980s and initiated in the 1990s.

ParticulatePhosphorus

82%

Dissolved Phosphorus

18%Forms of

phosphorus transported in northwestern Ohio rivers, 1975-1987.

Phosphorus reduction programs focused on reducing erosion and particulate phosphorus loading through fostering adoption

of no-till and reduced till crop protection methods.

Particulate phosphorus during storm

runoff is attached to soil

particles.

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

Internet Explorer.lnk

From here

To here

With some very good years in

between!

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.

Total Phosphorus Tributary Loads to Lake Erie, 2005

MaumeeSanduskyCuyahogaThamesCattaraugus CreekGrand (Ont)ChagrinHuron (OH)VermilionGrand (OH)BlackDetroit 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

How does nutrient export from the Northwestern Ohio rivers compare with the export from other areas?

Land use in study watersheds, as percent

Watershed Agricul-ture Forest

Grass_Hay_

Pasture

Open Water Urban Wetland Other

Maumee 73.3 6.5 6.3 0.7 10.6 2.3 0.2Sandusky 77.6 8.8 4.3 0.5 8.1 0.3 0.3Cuyahoga 9.0 33.6 11.8 2.6 39.5 3.1 0.4

Average annual nutrient export rates, 1996-2011

River SS TP, DRP, Nitrate-N TKN,

lbs/acre lbs/acre lbs/acre lbs/acre lbs/acreMaumee 504 1.21 0.25 21% 17.08 5.23Sandusky 642 1.46 0.29 20% 18.73 5.76Cuyahoga 1,175 1.26 0.18 14% 7.59 4.86

DRP as % TP

Data for 2004-2008 Water Years

WatershedPoint source Phosphorus

Non-Point Phosphorus

Maumee 5% 95%

Sandusky 3% 97%

Trends in tillage practices in northwestern Ohio: 1989-2004

Tillage Practices Corn,(1142 fields)

Soybeans (1147 fields)

Wheat (945

fields)

Hay(52 fields)

1 Moldboard plow, < 5% cover

5% 1% 1% 4%

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%

Tillage Practices in the Sandusky Watershed: 2009-2010

“Rotational no till”

Phosphorus fertilizer sales in Ohio, 1955-2007

Heidelberg Monitoring started

Start of Heidelberg monitoring

Long-term trend in average phosphorus soil tests in Northwest Ohio

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 1,030 100%

How will the majority of phosphorus fertilizer be applied to this field?

Sandusky Watershed Soil Stratification Studies

Timing of fertilizer application # of fields

% of fields

1 In spring (April to June), prior to planting

86 8.4 %

2 In spring (April to June), at planting 513 50.0 %

3 In late summer or fall (August – November) after wheat or hay harvest.

92 9.0 %

4 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 %

Total Responses 1,026

When will the majority of phosphorus fertilizer be applied?

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 phosphorus27% dissolved phosphorus

Bioavailable Phosphorus (275 metric tons/year)46% particulate phosphorus54% dissolved phosphorus

Management choice impacts--• Trading• TMDLs• BMP selection

93% bioavailable

29% bioavailable

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.

5. changes in rainfall patterns that have resulted in increases in winter rainstorms and resulting stream flows, especially in December and January.

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.

Phosphorus stratification in cropland of the Sandusky Watershed

Analysis of dilute aqueous soil suspensions

Analysis of dilute aqueous soil suspensions

Questions?

NCWQRPhosphorus

Analyses

Sample PretreatmentPortion

Analyzed acidadded

oxidant added

auto-clave

Dissolved Phosphorus (DP) (filter sample through 0.45 micron filter)

Total Phosphorus (TP) whole sample x xx

NaOH Extractable PP (extract residue on filter with NaOHand analyze as DRP)

Particulate Phosphorus (PP) calculated as TP - TDP

Dissolved Organic P (DOP) calculated as TDP - DHP

Total Dissolved P (TDP) xxxfiltrate

Dissolved Hydrolyzable P (DHP) x xfiltrate ---

Dissolved Reactive P (DRP) filtrate --- ------

all samples extra analyses for bioavailability studies

BioavailableForms