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Green Week 2012 Nitrates hotspots – prevention and cure Monitoring and modelling nitrogen cycling in rural landscape to mitigate nutrient surface water Chantal GASCUEL-ODOUX
Global Change More Reactive Nitrogen in Environment Nitrogen synthesis & Animal density
N2(g) + 3H2(g) → 2 NH3(g) From Galloway et al. (2003) and J.W. Erisman (2006)
Wor
ld P
opul
atio
n (m
illiar
ds)
Reactive nitrogen (Tg = M
tonnes)
Industriy, transport, Energy
Agriculture
Population
Nitrate Hotspots North Western Europe + regional spots in south
N agricultural input per
agricultural area
N balance per agricultural area
- N surplus - Livestock
& - Effective rainfall
as the main factor controlling N retention
From JRC reports
Surplus Brittany: 2500 kg/km² Seine Basin: 1160 kg/km² Loire Basin: 830 kg/km²
0
20
40
60
80
100
120
140
160
180
1971
/72
1973
/74
1975
/76
1977
/78
1979
/80
1981
/82
1983
/84
1985
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1987
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1989
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1991
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1993
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1995
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1997
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1999
/00
2001
/02
flux
spéc
ifiqu
es (k
g/ha
/an)
N Fluxes on 30 catchments 60% of the regional drinking water
Increasing trend, then stabilisation High inter-annual variations High variability between catchments
Brittany region, France
Gascuel-Odoux et al., Stoten, 2010
Cattle Surplus
Crop export
Resorption Mineral
Poultry
Pork
Regional N Budget
Total N surplus: 84 800 t
Concentrations in targets regarding drinking water with a high variability
Observed nitrate load(kgN.ha-1.yr-1)
1-BFIN
surplus
[NO3-] aquifer
PS
L
BFI
Bsoil Brain Briparian
Ldgw
R
N retention [0.2 – 1]
specific runoff mean distance to stream hydromorphic soils
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 100 200 300 400 500 600 700 800
flux/surplus vs lame d'eauN flux/Nsurplus versus specific runoff
Specific discharge
N fl
ux/N
surp
lus
Dupas et al., EGU 2012 Nitrogen Workshop 2012
Low retention due to shallow aquifer and short stream network
flux
• Drinking water: 50 mg/l • Intensive agriculture
• Vulnerable ecosystem: around 10 mg/l
Targets
Current mitigation measures
Manure treatment 35 000t / 84 000 t Manure transport (local to regional)
Wetland management Buffer in landscape
– Fertilisation plan at farm level – Upper limit: 210 Kg N/ha/year, 170 of organic N – Closing period (manure spreading) – Spatial restrictions (high slopes, saturated conditions) – Vegetation cover in winter - Grass strip along rivers
Current Regulation
Mitigation at farm level
-
outcome : Catchment Nitrate notation
Reduction in wet areas
= Catc
hmen
t
=
N leaching estimation per rotation type (optimized fertilization)
Environment Sensitivity : soil depth x water drainage x
+
N leaching estimation with real fertilization
+
x
x n fields
8
Dilution by non agricultural areas (woods, urban areas…)
Designing new mitigation options – Territ’eau
Participative diagnostic tool BRETAGNE
http://agro-transfert-bretagne.univ-rennes1.fr/Territ_eau/
N leaching references under some rotations (equilibrium fertilization) from Agrotransfert TERRIT’EAU 2010, drainage > 400 mm)
CC : catch crop, undersown or sow before 1st oct. Low grazing < 300 LSU.grazing days.ha-1, High grazing > 800 LSU.grazing days.ha-1
Effet destruction
125 100
85 70
60 50
45 40 40
35 30
15 10
Permanent grassland, high LSU/ha
Maize silage / cereal+ CC
permanent grassland extensive grazing
Cut grassland
grassland 9 yrs, extensive grazing, wheat permanent grassland moderate grazing
Maize silage + CC/ maize / cereal+ CC Maize silage / cereal / rape / cereal + CC
grassland 6 yrs, mean LSU/ha /Ms+CC/Ms/wheat Idem but grassland 4 yrs
grassland 6 yrs, high LSU/ha /Ms+CC/Ms/wheat Idem but grassland 4 yrs
Idem renewed every 6 yrs
A starting Point
Environmental, Technical & Social difficulties
• Environmental: water transit time, response time • Technical:
– Organic fertilisation (various organic products, farm plot plan ) – High mineralisation in autumn and winter (50-100 kg/ha) – Maize / winter wheat rotation (unefficient intercrop) – Grassland in rotation : up to 300 kg/ha after grassland
destruction
• Social and economic: livestock farming, particularly poultry and pork: Heavy infrastructure. Price volatility.
Difficulties
• Drinking water : 50 mg/l • Intensive agriculture • Regulation & Optimization ...changes and time in highly degraded situations
• Vulnerable ecosystem : around 10 mg/l • New agricultural systems :
agroecosystem approach
Targets
Northern Coast
N as main control (Menesguen et al.)
A large set of small coastal catchments Various features: depth, closeness,..
Dramatic effects at local scale: vulnerable to marine eutrophication - Green tides
14 coastal catchments, i.e. 7% of the agriculturals surface area
A human health problem Local high H2S emission
3500 farms, i.e. 10%
KgN.ha-1.total area-1 KgN.ha-1.Agric.area-1
A diversity of situations
Green algae plan Objective: 30% of the « way » to go down to 10 mg/l before 2015 4 projects already accepted. A scientific council to analyze each plan
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50
juil.
-98
janv
.-99
juil.
-99
janv
.-00
juil.
-00
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.-01
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.-07
juil.
-07
janv
.-08
NO
3 (m
g/L)
ddass AEP bvlg aep
Ecosystem health
Drinking water
120 km², 170 farmers 85% animal breeding
70% in agricultural land 50% in grassland
Average conc. 26 mg/l
100
120
140
160
180
200
220
1997 2006
kg N total /ha SAU
Optimization almost achieved
Moreau et al 2012 (Agee)
Disturbing results….
0
10
20
30
40
5019
98
2000
2002
2004
2006
2008
2010
2012
2014
2016
2018
Années
Nitr
ates
rivi
ère
mg/
L
Current situation
Agri. Environ. Measures
« Zero leaching »
objective N control by vegetation
Years
Nitr
ate
Con
c. In
rive
rs m
g/l
Which agriculture in such environment ?
Exports Internal
Fluxes
Inputs
Reduce N input & Increase N internal recycling
Water
Atmosphere
N sorties
- Farm level pratices at risk
- Catchment level Buffer areas
Animal feeding
Animal density Fertilisers Crop Manure
Légumineuses (N fixation)
Animal production strongly linked to C & N soil storage accumulation
Grassland (grazing, storage)
Compléments protéiques
Agroecologic transition in livestock areas
N recycling
N input
N losses
Systemic indicators
Systemic approach
Agroecologic transition
Farms in transition
Systemic modelling
Global input: 100 kg N par ha of agricultural area N mineral + (0,75 ou 0,65) N feed + Δ N organic (export – import)
Feeding animals without risk: 1,40 UGB / ha on grasslands
Include farm constraints in environmental N modelling
CASIMOD’N : Catchment and Agricultural Systems Integrated
MODel for Nitrogen
climate
Biophysical characteristics
of the catchment
Output per catchment map, data series,….
Farm.1 (TF)
strategy
contraints
Agricultural practices
Crop spatial distribution Manure spatial distribution
itk scheduler
Farm.2 (TF)
Farm.n (TF)
Output per farm (yield, …)
Coupling different models : TOURNESOL (Garcia et al., 2005) - FUMIGENE (Chardon et al., 2008) - TNT2 in a plateform RECORD-VLE (Bergez et al., 2009; Quesnel et al., 2009)
N and water catchment
model (TNT2)
19
Systemic models
0
20
40
60
80
100Mineral fertilisation
Organic fertilisation22/18
Grazing 31 / 34
Symbiotic fixation
Deposition
Soil storagevariation 25/21
Crop export
Woodland export
Volatilisation
denitrification
Groundwaterexport 6/2
stream export27/21
Input Output
N Cycling Kg N.ha-1.year-1 Same production N recycling
Different N Lower
N losses
Comparison - 2007 versus - Sytemic approach (two systemic indicators)
• Drinking water • Mitigation and regulation measures
• Vulnerable ecosystem : Conception of new agroecosystems Closing N cyling in landscape But also coherent regulation, specific funding for vulnerable areas, control at plot, farm & catchment level
Hotspots
A L I M E N T A T I O N A G R I C U L T U R E E N V I R O N N E M E N T
Photo G. le Hénaff, UMR SAS
Thank for your attention [email protected] Thanks to P. Aurousseau, L. Delaby, P. Durand, R. Dupas, P. Moreau, L. Ruiz, F. Vertes National Agency for Research ANR-Systerra – Acassya Project