potentials for soil carbon sequestration in different livestock feed strategies
DESCRIPTION
Seminar on Landscapes in a Carbon Focused World 26 October 2012 SIANI, Focali & Naturskyddsföreningen organized a one-day seminar in Gothenburg. Summary: Grassland for silage, hay and pasture has for long been the traditional roughage feeding strategy for cattle in northern Europe. There is an increasing interest for substituting this with maize silage and more concentrates which probably lead to different soil carbon balances. There are great difficulties to calculate such changes in estimates of GHG emissions from livestock production systems which will be discussed in this section. Christel Cederberg's research is mainly about environmental impact of livestock production systems in developed countries and focus on GHG emissions and land-use issues. Cederberg has a Master in Agriculture, a PhD in Environmental Science and now works at SIK and is adjunct professor at Chalmers.TRANSCRIPT
Potentials for soil carbon sequestration in different livestock feed strategies
Christel Cederberg SIK, the Swedish Institute for Food and Biotechnology
Department of Energy and Environment, Chalmers University of Technology
Focali 26 oct 2012
Chalmers University of Technology
Feeding livestock ~ 75 % of world agricultural land
23%
12% 65%
Arable land,human food
Arable land,feed forlivestock
Permanentpasture,livestock
Calculating the carbon footprint of milk
Primary production Transport Processing Packaging Retail & consumer
CO2 x 1 CH4 x 25 N2O x 298
CO2 x 1 CO2 x 1 CO2 x 1 CO2 x 1
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0,4
0,6
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Prim prod Process Pack Transport Retail&cons
CO2
CH4
N2O
kg C
O2
e p
er
kg m
ilk
0.8
0.6
0.4
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Prim prod Processing Packaging Transport Retail&cons.
CO2
CH4
N2O
-1000
-500
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500
1000
1500
2000
Milk
Meat
Accounting for affected systems – total emissions globally
553 Mtonnes milk
34 Mtonnes meat
Dairy sector:
GHG emissions (Mtonnes CO2e) associated with the dairy sector
290 Mtonnes CO2e ‘saved’ ~
Meat dairy sector
Meat cow-calf system
Gerber et al., 2010
Gerber et al., 2010
Agricultural GHG emissions 1990-2020 (no LULUC)
Källa: Smith et al 2007. Agriculture, Ecosystems and Environment 118: 6-28.
0
1000
2000
3000
4000
5000
6000
7000
8000
1990 2005 2020 1990 2005 2020 1990 2005 2020
Developing countries Developed countries Total
milj
on
er
ton
CO
2e
/år
Biomass burning,CH4&N2O
Manure management,CH4&N2O
Rice cultivation, CH4
Enteric fermentation,CH4
Soils, N2O
Global technical mitigation potential by 2030 in global agriculture
Smith et al, 2007 Phil Trans R Soc 363:789-813; IPCC 2007
-200
0
200
400
600
800
1000
1200
1400
1600
Mto
n C
O2
e/y
ear
Lustgas
Metan
Koldioxid
Close to 90% of mitigation potential in 2030 is estimated to
be Soil Carbon Sequestration!
Soil carbon sequestration: Some basics
Carbon storage, Ton C per ha
TIME
Arable soil at equilibrium
Measure: conversion from cropland to grassland
Soil C sequestration
Carbon sink saturation
10 to 100 years…….
Carbon sink permanence
?
Affects soil carbon sequestration
• Carbon input – crop residues
– organic material (e.g. manure)
• Initial carbon stock in soil
• Temperature
• Clay content
• Water content
• Carbon/Nitrogen ratio
• Tillage(?)
Carbon in harvest products and crop residues
-8
-6
-4
-2
0
2
4
6
C in harvest
C in crop residues
Ton C/ha
Important limitations for soil carbon sequestration as a GHG mitigation option
• Carbon sink saturation – soils reach C saturation after 20-50(100) yrs
• Achieved C sequestration is reversible – the same land use must go on ”forever” to avoid C loss
• Displacement effects – e.g. if peatlands are taken out of production to reduce GHG emissions, foregone food production must take place elsewhere, maybe by ploughing grasslands (releasing carbon) or on deforested land
• Monitoring – verification that a particular measure has increased soil carbon stock is costly
• C sequestration potentials in feed production
Energy from grain Protein
pulses
Protein
Co-products from oil crops
Syntetiska aminosyror för snabb tillväxt
Enmagade djur – generellt om deras foder Feeding monogastric animals
Cropland management for increased C sequestration
• Agronomy practices >higher yields >more crop residues (e.g. extending crop rotations with perennial
crops) ~0.88 t CO2/ha*yr
• Improved nutrient management ~0.55 tCO2/ha*yr
• Minimal – no tillage ~0.5 t CO2/ha*yr
• Agroforestry ~0.5 t CO2/ha*yr
• Land cover change, cropland to native vegetation/grassland ~3 t CO2/ha*yr
Smith et al, 2007 Phil Trans R Soc 363:789-813; IPCC 2007
Idisslare – generellt om deras foder
Energy and proteins from grassland
Energy from grains Protein
from oil seed crops
Feeding ruminants
Observed effects on C-seq in grassland soils
Net C seq (+) or emission (-)
t CO2e/ha yr
Referens
Variable C stock change, several studies +13 till -6 Soussana m fl (2010)
Predicted range, C stock change, European grasslands
+6 till -2a Janssens m fl (2005)
Conversion cropland to pasture +3,7 Conant m fl (2001)
Conversion cropland to grass +1,8 Soussana m fl (2004)
Conversion more leguminous plants +1,1 till +1,8 Soussana m fl (2004)
Conversion from short to permanent grasslands
+1,1 till +1,5 Soussana m fl (2004)
Increased duration ley/grassland +0,7 till +1,8 Soussana m fl (2004)
Improved pasture management +1,3 Conant m fl (2001)
Fertilisation +1,1b Conant m fl (2001)
Reduction of N-input +1,1c Soussana m fl (2004)
Higherplantdiversity in grasslands +15 till +2,1 Steinbeiss m fl (2008)
Management of grasslands for C sequestration
Cederberg m fl 2012. Jordbrukets potential som kolsänka, SIK-report in publication
Milk and beef can be produced with different feed rations…..effects on soil carbon changes?
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Baseline Maize & grass More&BetterGrass
kg D
M f
ee
d p
er
kg m
ilk
Concentrates
Grain
Super-pressed pulp
Maize silage
Grass/clover silage, pasture
Production level 9000 kg milk/cow*year
Wirsenius & Cederberg, ”Soil carbon sequestration as a greenhouse gas mitigation option in dairy production”, manus in prep
Experiences from modelling soil C changes for different feed rations in milk production
• Initial soil carbon status is very important for the soil´s carbon sequestration potential
• The estimated soil carbon changes are significant, but not of great importance for milk´s total GHG balance
• Feed rations with more maize silage seem to loose soil carbon
• Reasonably correct data on crop residues from grasslands are needed – big lack of data!
Landscape focus with a carbon approach
• Develop knowledge and understanding on carbon fluxes and stocks
• System analysis, going from product and farm level to landscape level - up-scaling?... Interaction effects?…….
• Risk for displacement effects?
Thank you!