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Mitigation Strategies for Dissolved Phosphorus Transport: Emerging Science

Kevin W. King USDA-ARS

Soil Drainage Research Unit Columbus, OH

Ohio Nutrient Forum: Visioning Workshop November 14, 2012

Can We Avoid Unintended Consequences? Agricultural Systems are Leaky!

Farmers provide society with food, feed, fiber, and fuel with economical efficiency! How do we equilibrate between economic efficiency and ecological impact? Requires a shift in scale: More efficient agronomics need to be better combined with practices that provide healthier soils and approaches that effectively manage LANDSCAPES and their natural variability. Integrate knowledge about landscape variability, hydrology, and ecosystem processes into production agriculture. Accept that agricultural systems do leak – incorporate upland, EOF, and downstream approaches to minimize the impact of agriculture.

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Excerpts from Farm Drainage, by Henry French published in 1860:

•"The agriculture of Ohio can make no farther marked progress until

a good system of under-drainage has been adopted.“ - John H. Klippart,

Esq., the learned Secretary of the Ohio Board of Agriculture

•"One of two things must be done by us here. Clay predominates in

our soil, and we must under-drain our land, or sell and move west.“

- A writer in the Country Gentleman, from Ashtabula County, Ohio

Necessity of Tile Drainage

25% of cropland in US and Canada could

not be farmed without tile drainage (Skaggs et

al., 1994)

- soils with the greatest inherent production

potential

Tile Drainage (Fausey et al., 1987):

- provides trafficable conditions for field

operations

- promotes root development by preventing

exposure of plants to excess water

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Why Drainage is Required - glacially derived, fine

textured soils - low gradient (flat)

J F M A M J J A S O N D

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lum

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th (

mm

)

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180Precip > PET

PET

2005-2010 Precip

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Effect of Drainage on Discharge

Solid = undrained Dashed = drainage

(Robinson and Beven, 1983)

Sandusky, Ohio (Schwab et al., 1963) Discharge from replicated 0.23 ha plots, Toledo silty clay

(March to September) Surface drained only (81 mm) Surface and subsurface (88 mm)

Tota

l Dis

char

ge (

mm

/hr)

Current Research

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Watershed

0.0 0.2 0.4 0.6 0.8 1.0

Su

mm

ed

Tile

0.0

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0.8

1.0discharge (y = 0.47 x)

dissolved phosphorus (y = 0.42 x)

nitrate-nitrogen (y = 0.60 x)

1:1 line

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Time

6/10/11 6/14/11 6/18/11 6/22/11 6/26/11

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(l/s)

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lub

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mg

/L)

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flow rate

soluble P

Chemograph of soluble P concentration in tile flow (Mercer County, OH) Positive correlation between peaks in concentrations and tile discharge indicate fast flow processes (preferential flow) and connection to surface sources

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surface runoff

tile discharge

precipitation

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s)

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surface discharge

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precipitation

Two different tile systems with different responses

0.5 inch rainfall 1.25 inches rainfall

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Mitigation Strategies

What Determines Watershed Condition and Response? How Do We Measure and Monitor?

How Do Watersheds Function to Transport and Process Pollutants?

Uniqueness - Landscape and geomorphology

(drainage density, shape factors) - Management - Soils and geological deposits - Climate - Hydrologic alteration (drainage, impoundments) Complexity - Lag time - Seasonality - Land use change - Riparian function and processes - Interacting cycles of water, carbon, and nutrients

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Upland/In-field Edge-of-field Downstream

% R

edu

ctio

n in

Po

llu

tan

t Tr

ansp

ort

4-R approach

Scale

What is the most effective scale to address water quality? How do we avoid tradeoffs among pollutants? How does it depend on the

ecoregion? How do we convince landowners to look at their individual fields in a larger environmental context?

Strategies for Addressing Agricultural Induced Phosphorus Transport

Upland Management 4Rs Interruption of connection to surface Structural Hydrologic Control Drainage water management blind inlets Filtration End-of-tile and in-stream Enhanced bioreactors Edge-of-field Buffers wetlands Ditch Design and Management Two stage, natural, and over-wide ditches Dredging Vegetated channels

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Upland Management (4 Rs) • Rate - adhere to soil test recommendations - apply only what is needed in crop year; avoid multi-year applications (Algoazany et al., 2007)

• Source - manure vs. commercial (Phillips et al., 1981)

• Placement - incorporation - precision application - banding vs. broadcast • Timing - be cognizant of weather predictions and avoid application prior to rainfall - avoid winter time manure applications – winter applied manure had greatest concentrations of dissolved P in tile effluent (Phillips et al., 1981)

Potential Practices to Investigate • Cover crops

• Banding vs broadcast

• Spring vs fall vs split application

• Incorporation

• Deep injection

• Tillage vs no-till

• Tri state recommendation vs reduced rate

• Manure vs commercial fertilizers

• Controlled traffic and variable rate application

• Other

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• More frequent, lower rates of fertilizer result in less loss

• Longer rotations lose less P

• No-till may result in > SP loss, but must balance that with < TP loss

• More P lost with corn (due to P applications)

• Tillage increases buffering capacity and disrupts macropores

Cropping & Tillage

Provided by Doug Smith USDA-ARS, West Lafayette, IN

SP Load by Management

No-Till Rotation Till Conv Till/8yr Rot

SP

Lo

ad

(g

ha

-1)

0

100

200

300

400

500

TP Load by Management

No-Till Rotation Till Conv Till/8yr Rot

TP

Lo

ad

(g

ha

-1)

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1400

Fertilizer Source, Placement, and Rate • DRP conc. peaks occurred after broadcast appl. (Turtola and Jaakkola 1995)

• Greater appl. rate and applying P after crop harvest had greater soluble P transport in tile (Algoazany et al 2007)

• Sites where P was applied every 2 years had greater P concentration in tile drainage (Algoazany et al 2007)

• Poultry and swine manure generally had greater proportions of DRP compared to dairy manure and commercial fertilizers (Kinley et

al 2007)

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Promote soil biological diversity

• Soil organisms control transformation between inorganic and organic P forms (Frossard et al., 2000; Illmer et al., 1995)

• Addition of microbial energy sources increased mobility of P by 38 times (Hannapel et al., 1963a)

• Mobilization of P by microbial population was most important factor in P transport (Hannapel et al., 1963b)

Structural Hydrologic Control

Drainage Water Management Blind Inlets

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Drainage Water Management

• Conventional Subsurface Drainage

• Controlled Drainage

• Subirrigation

- reduced total phosphorus losses in NC by 35% (Evans et al., 1990)

- DRP losses reduced by 63% and TP losses by 50% in MN (Feser et al., 2010)

- 85% reduction in TP losses from small plots in Sweden (Wesstrom et al., 2001)

- 18% reduction in median DRP concentrations in Ohio from 8 paired fields (unpublished data from Norm Fausey)

Blind Inlets Must be a practice farmers will implement

• Reduce sediment & phosphorus loads

• Minimize loss of productive land

• Allow farm traffic (don’t like risers)

• Minimal/easy maintenance

• Approved for cost share

• Effectively drain landscape

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April 2010 Hydrology

4/25/1

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char

ge (

L s-1

)

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Precipitation Intensity (m

m hr -1)

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Blind Inlet

Tile Riser

RF Intensity

33.5 mm precip total

Soluble P Concentrations During April 2010 Storm

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Blind Inlet

Tile Riser

Tile Riser = 3.12 g ha-1

Blind Inlet = 0.88 g ha-1

2009 2010

Soluble P 64 72

Total P 52 78

Percent Reduction (blind inlet vs. tile riser)

Provided by Doug Smith USDA-ARS, West Lafayette, IN

Filtration End-of-tile and in-stream

Enhanced bioreactors

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End-of-Tile Filters Laboratory and Field Results - 50% reduction in DRP concentrations and loads across 3 flow rates Constraint(s) - Flow Rates

Flow Rate (L/s)

0.0 0.5 1.0 1.5 2.0

% R

ed

ucti

on

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Dissolved ReactivePhosporus

Ditch filters

Provided by Peter Kleinman USDA-ARS, State College, PA

FGD Gypsum Ditch Filter P removal efficiency

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0 2000 4000 6000 8000 10000

P r

em

ova

l Eff

icie

ncy

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Flow Rate Through Gypsum Filter L Day-1 m2

Maximum flow rate

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- approximately 70% reduction in DRP over 2 years in New Zealand (McDowell et al., 2008)

- > 70% of DRP in milkhouse wastes removed with steel slag (Bird and Drizo, 2010)

- DRP concentrations reduced by 50 to 99% using in-stream gypsum (Penn et al., 2010)

- 50% reduction in DRP concentrations and loads using end-of-tile filters (King et al., 2010)

- bioreactors enriched with steel slag (Brown et al., in progress)

- flow rate is limiting factor both in-stream and end-of-tile systems

In-stream or end-of-tile treatment summary

Edge-of-field Buffers wetlands

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Forested Buffer

Ditch - No Buffer

Ditch - Buffer

Me

an

an

nu

al c

on

ce

ntr

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g/L

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Buffer Type

Dissolved Reactive Phosphorus Total Phosphorus

a b b a ab b

NB GB FB NB GB FB

Mean annual (2006-2010) stream side nutrient

concentrations for dissolved reactive

phosphorus and total phosphorus for

streams with no buffers (NB), grassed buffers

(GB), and forested buffers (FB). (unpublished

data in UBWC provided by Kevin King).

Buffers

Buffers • Many buffers along streams

serve predominately as setbacks

• Current buffering in Indiana watershed reduces TP loading by ~8% but could increase to 50% reduction if all field buffered (Mega $$$)

• FB > GB > NB

• Primarily addresses surface transport

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Wetlands Braskerud et al. (2005):

•17 constructed wetlands

•Sweden, Norway, Finland,

Switzerland, USA (Illinois)

•Surface area (400 to 10000 m2)

• Limited in addressing large

flows

Braskerud et al. (2005)

Ditch Design and Management Two stage, natural, and over-wide ditches Dredging Vegetated channels

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Agricultural Ditch Design Approaches

Trapezoidal Design

Two-Stage Design

Self-Forming Design

Provided by Jon Witter Ohio State University

• DRP not as variable; reduced in 3 streams

• Using paired data: two-stage reduced SRP concentrations (paired t-test, p=0.04)

Tank, Davis et al. unpublished data University of Notre Dame

Two-stage reduced SRP concentrations, but site dependent

Two-Stage vs. Trapezoidal Design

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B Ditch Dredging

April 2004

January 2005

Not Dredged

Provided by Doug Smith USDA-ARS, West Lafayette, IN Year

2003 2004 2005 2006 2007 2008

Stu

dy R

each

So

lub

le P

Lo

ad

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)

-20

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B

C

In-situ P loads for monitored study reaches

Dredging

VEGETATED DRAINAGE DITCHES

Water / nutrient / sediment mixture amendment flow: 600 gallons/minute for 7 hr

Load Reduction (%) Vegetated DIP 99 TP 86

Provided by Robbie Kroger (MSU)

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- vegetated drainage ditches or linear wetlands reduced DRP in growing season by 61% in MS (Kroger et al., 2008)

- two-stage ditches - promotes denitrification in the benches (Roley et al., 2011)

- preliminary findings suggest greater than 30% reduction of DRP in 3 ditches while 3 other ditches had no reduction (Tank et al.,

unpublished data)

- dredging reduced intermediate term (approx 1 year) total and soluble P losses (Smith and Huang, 2010)

Ditch Design and Management Summary

Can We Avoid Unintended Consequences? Agricultural Systems are Leaky!

Farmers provide society with food, feed, fiber, and fuel with economical efficiency! How do we equilibrate between economic efficiency and ecological impact? Requires a shift in scale: More efficient agronomics need to be better combined with practices that provide healthier soils and approaches that effectively manage LANDSCAPES and their natural variability. Integrate knowledge about landscape variability, hydrology, and ecosystem processes into production agriculture. Accept that agricultural systems do leak – incorporate upland, EOF, and downstream approaches to minimize the impact of agriculture.

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How to Implement • Market approach

Supply/Demand: increase price of fertilizer to limit unnecessary or insurance applications Trading: accepts status quo and does not consider spatial location Watershed based Co-op (Novak, 2012)

• Incentives and Voluntary Implementation - somewhat effective but only affect maybe 20% of land and maybe not critical source areas

• Regulation - may work but don’t necessarily have resources to

implement and greater societal problems will arise (i.e. food prices will soar)

kevin.king@ars.usda.gov (614) 292-3550 (office) (740) -815-9710 (cell)

Contact Information

‘‘Everybody talks about environmentalists, well, I do not really think very much of the environmentalists, per se, because I feel like I am one. I am involved with it everyday, I do it everyday, I do not go to work in an office and do things like that. I feel like we are the active environmentalists, not environmental activists.’’ (Illinois

Farmer/Producer quoted in Urban, 2005)