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Runoff Mitigation A toolbox approach for effective
and flexible mitigation of risks
Volker Laabs BASF SE, Germany
& MAgPIE Runoff Subgroup:
Colin Brown, University of York, UK
Jeremy Dyson, Syngenta, Switzerland
Katja Knauer, Bundesamt für Landwirtschaft, Switzerland
Björn Röpke, Bayer CropScience, Germany
Manfred Röttele, Better Decisions, Germany
SETAC Europe 12th Special Science Symposium Risk mitigation measures, risk assessment and labelling in the EU 28: Introduction to the MAgPIE toolbox
Society of Environmental Toxicology and Chemistry Environmental Quality through Science®
Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
Photo: Julie Maillet-Mezeray, TOPPS-prowadis 2
Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
3 Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Runoff Mitigation - Background
Pesticide transfer with runoff from agricultural streams to surface water has the potential to cause adverse environmental effects
Zonal registrations make basic risk mitigation options necessary for countries
Risk mitigation measures that are to be applied by farmers need to be
o Applicable to the crop rotation
o Practical and economically viable (cost, time)
o Robust enough to be effective in most of the local cases
4
Runoff Mitigation – Status in EU
So far, many MSs have different regulatory measures available to mitigate runoff: e.g.
Vegetated filter strips (different widths): BE, CZ, DE, ES, FI, FR, IT, LI, PL
Retention systems for runoff (edge of field): DE, IT
Reduced tillage: IT
Soil incorporation: IT
Band spraying: IT
No-till strips: BG
A few MSs stated that no regulatory option for runoff mitigation exists: DK, GR, NO, UK.
(Source: MAgPIE survey among participating authorities, 2013) 5
Runoff Mitigation - Goals
For zonal registrations of products that need runoff risk mitigation for a safe use…
o …a basic risk mitigation need in respect to an exposure pathway / protection goal should be defined by the zonal RMS
o … countries should establish a toolbox of measures, accepted at country level, to meet a mitigation need
o … whenever possible, farmers should be allowed to choose one/several measures from this toolbox, which - meet(s) the required mitigation need AND - fit(s) to their production system
X %
6
Influencing Factors for Runoff
• Climatic conditions
• Soil type and condition
• Soil profile permeability
Other factors:
• Slope/landscape parameters
• Pesticide water-soil distribution
• Timing of pesticide use (season / weather)
Run-off mitigation measures are complex to design and explain
Fig
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Surface
Run-off
Interflow /
Drainage
Soil-
Surface
Topsoil
Subsoil
Leaching
7
Influencing Factors for Runoff
Mitigation measures can only influence soil permeability and speed of run-off water
Key Factors Higher Risk Lower Risk
Precipitation event Large volume / Intense Small volume / Weak
Soil infiltration capacity &
Soil permeability
Low Fine soil texture
Capping/crusted soil
Subsoil compaction
High
Soil moisture High Low
Speed of run off water High High slope
Smooth soil surface
No barriers
Low
Distance to water Short Long
8
Runoff Types
Runoff is sub-divided into how it tends to move downslope:
… in a uniform manner (diffuse) down the whole field or part of the field
… in a concentrated manner in discrete channels
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Concentrated Runoff
Concentrated runoff & erosion channels…
„Extend“ surface water channels into fields: this often causes the highest diffuse pesticide contamination
Lead to soil loss and land degradation
May also reduce the efficiency of other
mitigation measures
(e.g. vegetative buffer strips)
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Concentrated runoff is not considered in regulatory runoff
risk assessments, being addressed by general GAP
Concentrated runoff & erosion channels need managing as a priority via GAPs (BMPs), e.g.
Mitigating Concentrated Run-off
o Ploughing across the slope
o Managing tramlines
o Establishing vegetated buffers in talwegs
o Creating edge-of-field bunds or vegetated ditches
o Constructing fascines
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Diffuse Runoff Generation
Diffuse runoff is caused by precipitation not being able to infiltrate through soil fast enough key factor to influence: soil properties on the surface and/or sub-surface
Surface Infiltration Restriction - heavy texture - poor structure - capping - low cover - topsoil compaction
Saturation Excess - heavy subsoil - plow pans & sub- surface compaction - shallow groundwater
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Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
13 Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Perspectives for Runoff Mitigation
Farmers: Aim to reduce runoff within the field first and then buffer the rest to be compliant with legislation and maximize land in production.
Regulators: start working from mitigating calculated transfer rates/effects in surface water, defining e.g. buffer widths for standard field scenarios.
Goal of flexible mitigation concept: enable regulators to ensure safe uses & meet environmental protection goals, while farmers mitigate runoff & farm productively
&
14
Objectives of Runoff Mitigation
1. Reducing risk to an acceptable level (requirement under EC 1107/2009)
2. Sound scientific reasoning for risk mitigation effects of measures and their combinations
3. Enable a flexible approach to runoff risk mitigation in the field let farmers choose from different measures & combination of measures
4. Translation into legally acceptable and understandable label language
5. Control of implementation of measures in the field must be possible
6. MSs shall have freedom to establish specific solutions/measures in MS
7. Ideally, measures should be eligible for promotion/funding under other pieces of EU legislation (e.g. CAP, WFDir, SUDir)
15
Basic Toolbox of Mitigation Measures
The following basic runoff mitigation measures are proposed:
Runoff Mitigation Measure Strength of Scientific Evidence
Basic* Mitigation
Effectiveness
Proposed Modelling Tools or Parameter Modifications
No-till / reduced tillage ++ 50% Curve number reduction: -3
In-field bunds (in row crops)
+ 50% Curve number reduction: -3
Vegetated filter strip 5 m (in field)
++ 50% Adaptation of modelling approaches needed
Inter-row vegetated strips (in permanent crops)
++ 50% Proportionate consideration of curve numbers
Vegetated filter strip 5 m +++ 40% VFSMOD
10 m +++ 65% VFSMOD
20 m +++ 80% VFSMOD
Edge-of-field bunds + 40% Calculation of water retention, infiltration, and environmental fate
Artificial wetland / Retention pond
+++ 75% Calculation of water retention, infiltration, and environmental fate
Vegetated ditch ++ 50%
In-field
Edge-of- field
Off-field
* May be differentiated according to substance polarity class (see MAgPIE Proc. Appendix 2, Table 2.3) 16
Basic Toolbox Measures No-till / Reduced Tillage
Runoff mitigation mechanism
Enhanced infiltration capacity of soil: Increased - pore continuity - soil structure - soil organic matter content
Reduced rain-splash erosion /soil capping plant residues on soil surface
Critical factors
Number and type of tillage operations
Time period of establishment
Constraints
Amount of plant residues on soil surface must be kept high (≥30%)
Depending on crop, weed and phyto-sanitary problems may arise
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Basic Toolbox Measures In-field Bunds (Row Crops)
Runoff mitigation mechanism
Small bunds between cropping rows stop water flow and enable infiltration
Critical factors
Distance and height of bunds must be adapted to rainfall and soil/slope conditions
Cropping should be done across slope
Constraints
Until now, well-tested for potatoes only
If slope becomes too steep, effectiveness limited
Bunds No bunds
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Basic Toolbox Measures Inter-row Vegetated Strips (Perennial Crops)
Runoff mitigation mechanism
Enhanced - water infiltration - sedimentation of eroded soil - in-situ erosion prevention …in grassed/vegetated areas.
Critical factors
Plant species need to be adapted to climate/soil
Regular mowing may be needed (erect stems)
Constraints
Competition for water and nutrients with perennial crop needs to be managed P
ho
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Basic Toolbox Measures Vegetated Filter Strips
Runoff mitigation mechanism
Enhanced - water infiltration - sedimentation of eroded soil - in-situ erosion prevention in grassed/vegetated areas.
Critical factors
Placement near runoff source critical
Plant species need to be adapted to climate/soil
Regular mowing may be needed (erect stems)
Constraints
Wet soil and concentrated flow impede effects
Loss of land for agricultural production Ph
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Basic Toolbox Measures Edge-of-field Bunds
Runoff mitigation mechanism
Retaining and infiltrating runoff volume in embanked area at downslope edge of field
Critical factors
Retention volume needs to be adapted for each field (standard volume per ha to be defined)
Regular inspection after rainfall needed (danger of concentrated flow generation)
Constraints
Works best on soils of heavier texture
Annual re-establishment needed
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Imag
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ideo
Basic Toolbox Measures Vegetated Ditch
Runoff mitigation mechanism
Retaining and infiltrating runoff volume in vegetated ditch (not connected to streams)
Critical factors
Retention volume needs to be adapted for each slope (standard volume per ha to be defined)
Plant species need to be adapted to floodings
Regular inspection after rainfall and occasional removal of sediments needed
Constraints
Legal status as habitat for species to be clarified
Loss of land for agricultural production
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Basic Toolbox Measures Artificial Wetland / Retention Pond
Runoff mitigation mechanism
Slowing down, retaining, and infiltrating runoff volume in wetlands/ponds
Pesticide removal also via in-situ sorption and degradation (plants, sediments)
Critical factors
Retention volume needs to be chosen for each slope (standard volume per ha to be defined)
Plant species need to be adapted to floodings
Yearly removal of sediments needed
Constraints
Legal status as habitat for species to be clarified
Loss of land for agricultural production
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Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
24 Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Runoff Assessment Methodology
Basic runoff risk assessment for Zonal Annex III
(EU FOCUS tiered modeling)
Farmers choose mitigation measure(s) from national runoff mitigation toolbox
Outcome: XY % runoff mitigation needed for reasonable worst case
Outcome: Basic runoff mitigation need (% of baseline)
Specific runoff risk assessment for MS Authorization
(National risk assessment schemes)
Farmers choose from product-specific list of mitigation
measure(s) and combinations
- General effectiveness values - Maximum flexibility - No additional regulatory work
- Product-specific calculations - Pre-determined options - Extra regulatory modelling
MS Option 1 MS Option 2
Option 1 reflects the fact that runoff reduction is key to mitigate pesticide transport. Option 2 uses specific modeling to also consider influence of substance properties.
25
Runoff Assessment Option 1 Basic toolbox approach
Runoff risk mitigation
need for product: XY pts
Farmer selects single or
combination of measures to
achieve necessary number
of mitigation pts
Toolbox List
Measure 1: 70 pts
Measure 2: 50 pts
Measure 3: 50 pts
Measure 4: 40 pts
Measure 5: 30 pts
Field evidence approach: General, average effective-
ness values per measure
Farmers choose mitigation measure(s) from national runoff mitigation toolbox
Conversion function
reflects conservativeness
and combinatory rule
Simple & flexible scheme, based on general runoff reduction potential of measures.
+
Runoff risk mitigation need for
product: % of baseline
26
Runoff Assessment Option 2 Modelling Approach
Modeling 1 (e.g. using FOCUSsw,
VFSMOD, other
national models)
Modeling 2 (calculating combinatory effects,
e.g. via curve number ajdustments
for in-field measures)
Farmers choose from product-specific list of mitigation
measure(s) and combinations
Farmer chooses from list of
approved measures or their
combinations
Measure 1: 62 %
Measure 2: 50 %
Measure 3: 48 %
Measure 4: 36 %
Measure 5: 25 %
Measures 1+2: 82 %
Measures 1+3: 75 %
Measures 2+4: 55 %
List of Measures
Measure 1: 62 %
Measures 1+2: 82 %
Measures 1+3: 75 %
Modelling approach: product-specific
calculations per measure
Modeling-based scheme, based on specific calculations for measures/combinations.
Runoff risk mitigation need for
product: % of baseline
27
Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
28 Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Example for Flexible Runoff Mitigation
Example: The virtual herbicide Super-Antiherb is evaluated at zonal level for use in corn and winter wheat.
The regulatory risk assessment for the product identified a risk mitigation need for surface runoff: 75% reduction of runoff needed in winter wheat 90% reduction of runoff needed in corn
Photos: TOPPS-prowadis 29
Flexible Runoff Mitigation Implementation in Country A
National risk mitigation approach: Basic toolbox of measures
The % mitigation need is translated into mitigation points: Winter wheat: 75% = 56 pts Corn: 90% = 86 pts Combination of measures result in additive points.
Defined national toolbox of measures for farmers to choose from, e.g.
No-till 30 pts Edge-of-field VFS 10 m 44 pts
In-field VFS 5 m 30 pts Edge-of-field VFS 20 m 64 pts
Edge-of-field VFS 5 m 21 pts Vegetated ditch 30 pts
Runoff mitigation
effectiveness
(%) Points
40 21
45 25
50 30
55 34
60 39
65 44
70 50
75 56
80 64
85 73
90 86
95 106
99 130
30
Farmers‘ choice to manage risks at field level:
Winter wheat (56 pts needed)
o Field 1 (Farmer X): 10 m VFS & vegetated ditch
o Field 2 (Farmer Y): no-till & 5-m in-field VFS
Corn (86 pts needed)
o Field 1 (Farmer X): no-till & 5-m in-field VFS & vegetated ditch
o Field 2 (Farmer Y): 5 m in-field VFS & & 10 m VFS & vegetated ditch
+
+
+
in field edge of field
in field edge of field
Flexible Runoff Mitigation Implementation in Country A
+
+
+
31
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Flexible Runoff Mitigation Implementation in Country B
National risk mitigation approach: Modelling-based mitigation tools
Modelling approach to evaluate the measures or combinations that cover the required % mitigation need ( acceptable TER)
Example results for modelling exposure calculations (e.g. for corn):
The product label would then list the acceptable measures/combinations, e.g.
o Winter wheat: 10 m VFS, 5 m VFS & no-till, 5 m VFS & vegetated ditch
o Corn: 20 m VBS, 10 m VFS & no-till, 5 m VFS & vegetated ditch & no-till
Modelling Step FOCUS scenario (acceptable conc.: 7 µg/L)
R1 pond R1 stream R2 stream R3 stream R4 stream
FOCUS Step 3 0.33 16.7 15.3 31.2 41.4
Step 4: 20-m VFS 0.09 0.42 0.56 5.15 0.42
Step 4: no-till 0.21 3.62 12.1 17.2 39.1
Step 4: no-till & 10-m VFS 0.14 0.81 1.07 6.28 0.08
32
Farmers‘ choice to manage risks at field level:
Winter wheat (list of options on label)
o Field 1 (Farmer X): 5 m VFS & vegetated ditch
o Field 2 (Farmer Y): no-till & 5 m VFS
Corn (list of options on label)
o Field 1 (Farmer X): 20 m VFS
o Field 2 (Farmer Y): no-till & 10 m VFS
+
+
in field edge of field
in field edge of field
+
Flexible Runoff Mitigation Implementation in Country B
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Risk Phrases for Runoff Mitigation
Option 1: Basic runoff mitigation toolbox
SPe X1: To protect [aquatic organisms] only apply to fields [adjacent / within Y m to surface water] where approved mitigation measures(s) with [X% reduction of runoff potential / XY runoff mitigation points] are implemented. The official reference for approved mitigation measures is [detail official reference].
Option 2: Product-specific list of runoff mitigation measures/combinations
SPe X2: To protect [aquatic organisms] only apply to fields [adjacent / within Y m to surface water] where one of the following measures / measure combinations to mitigate runoff are implemented: [detail the list of appropriate measures or combinations thereof].
For both options, an official list/toolbox of accepted mitigation measures is needed: to specify in detail the correct establishment & maintenance procedures for each measure to define auditable criteria for adequate measure implementation
34
Control of Measures in the Field
Prerequisites of efficient control are well-defined mitigation measure criteria and maintenance rules
Most measures are easy to control during the season, e.g.
o No-till / reduced tillage
o Vegetated filter strips
o Edge-of-field bunds
o Artificial wetland /retention pond
o Vegetated ditch
Other measures might need right-on-time control or photo documentation (time & GPS tracked), e.g.
o In-field bunds Ph
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35
Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
36 Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Ideas on Concentrated Runoff
In principle, concentrated runoff should be prevented by farmers based on GAP (soil & water protection)
If this pollution pathway shall be covered via pesticide legislation, a risk phrase may be defined (either for all or only for specific products)
SPe Y: To protect [aquatic organisms] only apply to fields [within Y m to surface water] where concentrated runoff is prevented by appropriate measures (see [detail official reference for concentrated flow mitigation measures]).
An official list of mitigation measures, detailing correct implementation and maintenance is needed
Control can also be based on diagnosis of erosion traces in the field
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Ideas on Holistic Runoff Prevention
In reality, the major part of runoff is caused by only a few fields in a catchment
To stimulate field-specific runoff diagnosis/ prevention schemes (e.g. Aquavallee, TOPPS- prowadis) the following risk phrase could be used:
SPe XY: These product-specific runoff mitigation obligations may be superseded by implementing field-specific runoff mitigation measures on the field/farmland, based on the participation in an officially approved national runoff risk diagnosis and management scheme ([detail names of officially accepted diagnosis systems]).
Control is based on documentation of diagnosis and control of implementation of measures on the ground
Fig.: TOPPS-prowadis
38
Catchment Risk Diagnosis TOPPS / Aquavalle Concept*
Catchment Catchment (field visit) Plot (field visit) Plot & Catchment
Adapt tillage
practices and
cropping
Position and
establish buffer
zones, wetlands,
hedges, etc….
Adapt application
timing and pesticide
use
1 3 4 5 Plot (field visit)
2
Climate, soils, geology,
landscape elements,
cropping, farms …
Basic run-off risk during
spring/summer and
autumn/winter time
Data collection: Identification of soil
water flow regime:
Refinement of the basic
run-off risk for each plot
Identification of water
flow pathways & critical
landscape elements:
Tillage practices, crop
rotation, pesticide use
Mapping of farmer
practices:
Assign mitigation
measures to fields &
establish catchment
management plan:
Fig. : Arvalis Institute de Vegetal, FR 39
* TOPPS concept based on Aquavalle concept by Arvalis Institute de Vegetal, FR
Outline
Introduction
Basic toolbox of proposed regulatory mitigation measures
Methodologies for risk assessment
Implementation examples
Further ideas
Conclusions
40 Photo: Julie Maillet-Mezeray, TOPPS-prowadis
Conclusions
Effective runoff mitigation must consider highly variable pedo-climatic conditions, catchment topographies, and application-precipitation timing
Due to the complexity of crop rotations and farming conditions, farmers should be able to choose from a list of mitigation measures and their combinations
A risk mitigation concept and risk phrases were proposed to accommodate this flexibility
MSs would need to define a national list of appropriate measures and to re-evaluate the proposed mitigation effectiveness values/modelling approach
41 Photo: Julie Maillet-Mezeray, TOPPS-prowadis