Soil Carbon in Grazing Lands: What's been done and we need to do and Highlights from Nitrogen...
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Agricultural and climate change Emissions and solutions in context Presented by Richard Conant
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Soil Carbon in Grazing Lands: What's been done and we need to do and Highlights from Nitrogen Efficiency Study in Cropping Systems
Transcript of Soil Carbon in Grazing Lands: What's been done and we need to do and Highlights from Nitrogen...
Agricultural and climate change
Emissions and solutions in context
Presented by Richard Conant
1860 1880 1900 1920 1940 1960 1980 2000
Mm
tC y
r-1
0
2000
4000
6000
8000
10000
Fossil fuel emissions
Tropical LUC
Temperate LUC
CO2 concentrations are increasing: Human activities are driving increases in atmospheric CO2
1860 1880 1900 1920 1940 1960 1980 2000
Mm
tC y
r-1
0
2000
4000
6000
8000
10000
World population
Fossil fuel emissions
Tropical LUC
Temperate LUC
CO2 concentrations are increasing: Population and CO2 emissions
person
CO2CO2 emissions ≡people
Deriving the Kaya Identity:Understanding the driving forces for CO2 emissions
• Decreased populations• Abstention• contraception/abortion• Small families• Stop immigration• Disease• War• Murder/violence• Famine• Accidents• Pollution (smoking)
• Increased populations• Procreation• Motherhood• Large families• Immigration• Medicine• Public health• Sanitation• Peace• Law and order• Scientific agriculture• Accident prevention (drive 55)• Clean air• Ignorance of the population
problem
Problems Solutions
Deriving the Kaya Identity:Understanding the driving forces for CO2 emissions
GDP
person
CO2CO2 emissions ≡people
GDP
Deriving the Kaya Identity:Understanding the driving forces for CO2 emissions
EnergyGDP
personCO2 emissions ≡
peopleperson
Deriving the Kaya Identity:Understanding the driving forces for CO2 emissions
GDP
CO2
Energy
Food
Food
GDP
personGHG emissions ≡ people
person
GDP EnergyEnergy
The REVISED Kaya identity:Agriculture is different
CO2
Food
five
foodfood production system
food
+food
GHG
of food prod.
GHG intensity CO2, N2O & CH4 per unit food
CO2 emissions ≡
The REVISED Kaya identity:
Food
FoodpersonGHG emissions ≡ people
person
EnergyEnergy
The REVISED Kaya identity:Agriculture is different
CO2 +food
GHG
GHG intensity
food consumption is increasing (a good thing)
increasing in developing countriesslight declines in developed countries
GHG intensity CO2, N2O & CH4 per unit food
slow improvement until recently…
Evaluating intensity and efficiency:N2O/crop and N recovery efficiency (REN)
food
N2OGHG ≡ N inputs × Ef
yield
constant
If crop [N] is constant food
N2O
≡
≈ N inputs N in
yield
REN
N inputs N in
yield
Cassman et al. 2003Ann. Rev. Environ. Reourc.
Field-scale N recovery efficiency
Increased fertilizer use >> increased yield decreased efficiency
Cassman et al. 2003Ann. Rev. Environ. Reourc.
Increased fertilizer use Decreased efficiency
Field-scale N recovery efficiency
Tilman et al. 2002 Nature
Increased production
Decreased efficiency
Field-scale N recovery efficiency
Increased fertilizer use
Frink et al. 1999 PNAS
changes in^Field-scale N recovery efficiency
N recovery efficiency: what do we know?
1. Knowledge derived at the field-scale suggests that as fertilizer application rates increase in the field, N use efficiency decreases
2. Global-scale analysis of fertilizer data suggests that as application rates increased over time, N use efficiency decreased – dramatically
3. But the growth rate for fertilizer application rates has declined over time.
Evaluating efficiency:N2O/crop and N recovery efficiency (REN)
≡REN
Challenges:1.Crop composition has changed over time, [N] varies by crop2.N inputs arise not just from fertilizer, but from legumes, manure; N input mix has changed over time3.Therefore, we need a database on N inputs and yield by crop, over time to evaluate temporal and spatial trends in REN (and N2O/food)
N inputs N in
yield
Maize (kgN/ha)
wheat
rice
oats
…
1961 1962 1963 … 2006 2007 2008
Country total(tN/yr)
2019 2120 2199 4993 5193 5318
1998
4761
45
27
54
18
…IPNIS, IFIA
We used a Bayesian model to integrate information on fertilizer appilcation rates (IPNIS, IFA – average and variation) and constraints from total N fertilizer rates by country to fill in this matrix
Evaluating efficiency:Allocating fertilizer N to each crop
Maize (kgN/ha)
wheat
rice
oats
…
1961 1962 1963 … 2006 2007 2008
Country total(tN/yr)
2019 2120 2199 4993 5193 5318
1998
4761
45
27
54
18
…IPNIS, IFIA
Evaluating efficiency:Allocating fertilizer N to each crop
We generated a new database of N fixation rates by crop, by country to generate new estimates of N-fixation inputs
877 903 910 1311 1355 13981201
22
13
12
11
We generated a new database of manure N inputs by allocating total N manure (from FAOstat livestock data)
soybeans
lupin
572 596 610 744 784 819712
22
13
The REVISED Kaya identity:Efficiency of N use
The REVISED Kaya identity:Efficiency of N use and N2O production
Yie
ld(M
g D
M h
a-1 y
r-1)
0
1
2
3
4
5
6
1960 1970 1980 1990 2000 2010
N in
puts
(kg
N h
a-1 y
r-1)
0
20
40
60
80
100
120
140
160
180
RE
N
(N h
arve
ste
d /
N in
puts
)
0.0
0.2
0.4
0.6
0.8
1.0
1960 1970 1980 1990 2000 2010
N2O
per
uni
t yi
eld
(g N
2O-N
Mg
DM
-1)
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
OECD BRICS non-OECD World average
0.2
0.4
0.6
0.8
1.0
0.2
0.4
0.6
0.8
1.0
N inputs(kg N ha-1 yr-1)
0100200300400
Pro
port
ion
of to
tal p
rodu
ctio
n
0.0
0.2
0.4
0.6
0.8
1.0
REN
(N harvested in crops / N inputs)
0.5 1.0 1.5 2.00.0
0.2
0.4
0.6
0.8
1.0
India
China
China
India
USA
USA
former USSR
former USSR
Indonesia
Brazil
Brazil
FranceBangladesh
Japan
Argentina
Canada
France
CanadaArgentina
Bangladesh
The REVISED Kaya identity:Efficiency of N use and N2O production
OECDBRICSnon-OECD
2005
1963
1. Emissions are non-point sources of multiple greenhouse gases.
2. Opportunities for C sequestration and CO2 drawdown.
3. Reducing food consumption is unlikely and increasing food consumption is often a good thing.
4. Decarbonization of energy sources has a role in reducing emissions, but it is limited.
5. Increasing efficiency of our food production systems is central to reducing agricultural GHG emissions.
Agriculture and climate change Emissions and solutions in context – agriculture is different
Source: IPCC 2007
Agricultural is different
1. Practical reasons:1. Less important (focus first on large sources)2. Uncertainty in measurements
2. Political reasons:1. No desire to limit food production2. Most emitters with a large ag GHG footprint are developing countries
(low emitters)3. Detracts focus from reducing largest sources4. A cynical reason: ag can’t be outsourced
3. Implications of ag being on the outside:1. Greater risk2. Accounting issues3. Limited investment
Why isn’t agriculture on the agenda? And implications
1. Address practical limitations 1. Measurement/uncertainty
1. Expand sampling networks2. Conduct more/better syntheses
2. Feasibility1. Carry out demonstration projects
3. Address offset limitations head on1. Develop protocols for existing trading programs
2. Address political concerns:1. Argue for an all-in approach (working on the energy sector is not a
reason to forego work on the ag sector)2. ID win-win scenarios (production, adaptation, etc.)3. A kaya-ag framework focused on overall systematic improvement4. Understand limits to progress
3. Reduce risk: 1. quantify co-benefits, production/adaptation benefits2. Pilot projects to demonstrate feasibility
Why isn’t agriculture on the agenda? How can we get it there?
