Transcript What is climate change?

IMPACT OF CLIMATE CHANGE
ON WATER RESOURCES AND
AGRICULTURAL PRODUCTIVITY
BY
REV. FR. PROF. MENSAH BONSU
DEPARTMENT OF CROP AND SOIL SCIENCES
FACULTY OF AGRICULTURE
KNUST, KUMASI
Outline of presentation
•
•
•
•
What is climate change?
Green house effect and climate change
Sources of green house gases emissions
Factors leading to potential vulnerability to
climate change
• Indicators of climate change
• Climate change and water resources
• Planning for future response to water resources
and climate change
• Climate change and its impact on agricultural
productivity
• Analysis of climate change impact on
agriculture
• Application of GCM in Ghana
• Adaptations to climate change
• Socio-economic factors and climate change
What is climate change?
A change in climate which is attributed directly
or indirectly to human (anthropogenic) activity
that alters the composition of the global
atmosphere and which is in addition to natural
climate variability observed over a given or
noticeable period of time.
INTRODUCTION
The green house effect and climate change
• Estimates indicate that since 1991, the global
atmosphere concentration of carbon dioxide has
been increasing at a rate of about 1.8 parts per
million or 0018% per year.
• These trace gases in the atmosphere notably carbon
dioxide, nitrous oxide and methane called
“greenhouse gases” can absorb the heat radiated
from the earth (i.e. Long wave radiation or infrared).
• The greenhouse gases prevent the heat radiated from
the earth from being escaped into space.
INTRODUCTION
The green house effect and climate change
• Human activities have led to an increase in the
concentration of these greenhouse gases in the
lower atmosphere, resulting in anthropogenic
greenhouse effect which is resulting in global
warming and its attendant “climate change”.
• The major greenhouse gases are carbon
dioxide (CO2), Methane (CH4), Nitrous Oxide
(N20), hydrofluorocarbons (H FCs).
Perflurocarbons (PFCs) and Sulphur
hexafluoride (SF6).
Sources of Anthropogenic
Greenhouse Gases Emissions
The key sources of anthropogenic
greenhouse gases emissions are:
• The energy sector
• Agricultural sector and
• Waste management sector
Sources of Anthropogenic
Greenhouse Gases Emissions
The Energy Sector
• In the energy sector, greenhouse gases
emissions emanate from fuel combustion
through the energy, manufacturing and
construction industries as well as vehicular
emissions.
• Other sources are through fugitive
emissions from fuels in the form of solid
fuels (e.g. coal and oil and natural gas).
Sources of Anthropogenic
Greenhouse Gases Emissions
The Energy Sector
• The industrial processes also contribute
significantly to green house gases emissions such
as:
– mineral production
– chemical industries
– cement production
– metal production
– production and use of halocarbons and sulphur
hexafluoride, and the production and use of solvents
Sources of Anthropogenic
Greenhouse Gases Emissions
The Agricultural Sector
The sources of emissions of greenhouse gases are:
• Enteric fermentation of ruminants (CH4)
• manure management (anaerobic decomposition)
• rice cultivation (flooded rice fields)
• mineralization in agricultural soils (CO2, N20)
• use of nitrogenous fertilizers (N20)
Sources of Anthropogenic
Greenhouse Gases Emissions
Waste Management
• Sources of anthropogenic greenhouse gases
emissions are through waste management.
• Anaerobic as well as aerobic decomposition of
wastes results in the emissions of carbon
dioxide, methane and nitrous oxide (or other
nitrogen oxides NOx).
Indicators of climate change
• High solar radiation intensities and global
warming
• Elevated air temperatures
• Reduced rainfall amounts and occurrence of
droughts
• Unreliable and erratic rainfall events
• Poor rainfall distribution
• Extreme climate events – floods and storms
• Hurricanes and tornadoes
Factors Leading to potential
vulnerability to climate change
• Unsustainable use of natural resources
• Lack of mitigation of greenhouse gas
emissions in the industrial sector
• Weak waste management systems and
poor environmental sanitation
• Imports of over-aged vehicles
Climate change and Water Resources
•
•
•
•
Sources of water resources
natural precipitation
groundwater resources
freshwater rivers, streams, rivulets and lakes,
dams and reservoirs and
marine and estuarine water resources
Natural precipitation is the key source of water
that feeds all the other water resources. Therefore
a decrease in rainfall due to climate change will
deleteriously affect all the other water resources.
Climate change and Water Resources
Runoff
• Runoff or overland flow is the major source of
water feeding rives, streams, rivulets, dams,
lakes and reservoirs.
• It is estimated as amount of precipitation
minus infiltration (i.e. the amount of
precipitation that enters the soil).
• The current low levels of water in dams
indicate the sensitivity of reservoirs storage to
variations in runoff due to climate change and
drought.
Climate change and Water Resources
Groundwater Resource and Climate Change
Groundwater is an important source of global water
requirements for:
• Domestic use
• Agricultural use and
• Industrial use
Groundwater is recharged through:
• Seepage from rainfall events
• Seepage from dams and reservoirs, and
• Seepage from rivers and lakes
Climate change and Water Resources
Marine and Estuarine Water Resources and
Sea Level Rise due to climate change
Table 1. Expected sea level rise in Ghana due to
climate change
Year
Expected sea level
rise (cm)
2020
2050
2080
5.8
16.5
34.5
Marine and Estuarine Water Resources
and Sea Level Rise due to climate change
Causes of sea level rise
• Volumetric expansion of sea water due to rise
in sea water temperature
• Melting of polar ice due to rise in temperature
• Melting of ice-bergs due to rise in temperature
• Melting of mountain glaciers due to rise in
temperature
Marine and Estuarine Water Resources
and Sea Level Rise due to climate change
Effects of sea level rise
• Accelerated coastal erosion. For example, the
annual coastal erosion in the Keta area of
Ghana is estimated to be 3m.
• Inundation of low-lying coastal zones and
• Increased tidal waves which favour further
inland penetration of the sea water through
internal lateral flow, which will increase
salinisation of coastal aquifer and streams.
Planning for the future response to water
resources and climate change
• Climate change must be factored into water-resource
planning and policies for the future on a contingency
basis.
• A global climate change often results in linking of
environmental factors that favour evaporative
demand of the environment such as:
• Increase in air temperature
• Increase in net radiation
• Decrease in atmospheric relative humidity, and
increase in windiness
In planning for the future response to water resources and
climate change, the following factors must be considered:
• A change in regional water resources must be
considered holistically.
• The dynamic nature of water resource management must
be fully considered physically and socially.
• Lessons from past development effects in connection
with water resource management, especially past
failures should be referred to and applied judiciously.
• The approaches should consider current water problems
in the context of political and cultural perspectives.
Climate change and its impact on
agricultural productivity
The adverse effects of climate change on
agricultural productivity are due to:
• Increased temperatures (global warming)
• Decreased rainfall
Climate change and its impact on
agricultural productivity
Stresses due to these two climatic variables result in
reduced crop yields because of the following
reasons:
• The plant tries to complete its life cycle more
rapidly resulting in reduced storage of food
product.
• Heat stress and reduced water availability could
result in the death of the plant.
• Extreme climatic events such as storms and
windiness can be devastating to plants through
logging and flooding.
Climate change and its impact on
agricultural productivity
• Higher temperatures increase the rate of water
loss through evaporation and transpiration.
• With high temperatures, nutrient release through
organic matter decomposition is not synchronized
with the time when the plants nutrient
requirement is at its peak.
• If climate change results in excessive rainfall,
nutrient losses through leaching and erosion
result in soil fertility decline.
• Higher temperatures with moisture favour the
germination of spores and spread of bacteria,
fungi and nematodes.
Climate change and its impact on
agricultural productivity
Impact of climate change on Animal Production
Increased temperatures and animal physiology:
• High temperatures accelerate metabolic processes
requiring high oxygen consumption, which if not
met can reach final stage resulting in death.
• Higher surrounding temperatures could result
intake of less food and more water and reduced
gain-weight of the animal.
Impact of climate change on Animal
Production
Increased temperatures and animal
physiology:
• At high temperatures proteins and nucleic
acids are denatured and protein synthesis in
the animal is drastically reduced.
• High temperatures may change the
membrane fluidity of the animal from gel
phase to liquid crystalline phase leading to
reduced performance and death.
Analysis of Climate Change Impacts
on Agriculture
The analysis of future climate change
impacts on agriculture demands
multifaceted approaches involving:
• The study of biophysical processes
• Socioeconomic processes
Analysis of Climate Change Impacts
on Agriculture
The approaches employed include:
• Climate change Scenarios:
These involve projections of what values climate
parameters may assume in the future and how
agriculture might fare in the new circumstances. This
approach addresses the question: “What will
agriculture be like in a given changed climate.
In this approach, chain of causalities from the
biophysical responses of crops and livestock at the
farm level to socio-economic effects are constructed.
Analysis of Climate Change Impacts
on Agriculture
There are different types of scenarios for the
analysis of impacts of climate change on
Agriculture. But the commonest ones are:
• Global circulation models (GCMs)
• Regional climate (Simulation) Models
(Reg CMs)
Application of GCM in Ghana
• GCMs are normally used to generate future climatic
parameters based on current climatic parameters of a
specified period. The generated future climatic
parameters are fed into a given Dynamic Crop
Growth Model to generate future crop responses to
the changed future climatic parameters.
• This approach was used in Ghana to simulate the
impact of climate change on maize and roots and
tubers production.
Application of GCM in Ghana
Model simulation (GCMs)
The GCMs used were the ‘Linked Model’
adopted from:
• The Hardly Centre Model 2 (HADCM 2)
• The U.K. Meteorological Office Transient
Model (UKH 1)
Application of GCM in Ghana
Dynamic Crop Growth models:
• Maize: IBSNAT Crop simulation models
(DSSAT) (specifically CERES-Maize) was
used
• Cassava/Cocoyam: DSSATV4 (specifically)
CROPSIM-Cassava/CROPGRO (ARGR
0980) were used
Table 2. Expected average increase in
temperature and decrease in rainfall
Year
Increase in
Decrease in
Temperature (⁰C) rainfall (%)
2020
0.6
2.8
2050
2.0
10.9
2080
3.9
18.6
Application of GCM in Ghana
Simulated mean temperature and rainfall
variations for all the agro-climatic zones of
Ghana up to the year 2080
As temperature increased, rainfall also decreased
systematically.
Application of GCM in Ghana
Using the 2020 data, average maize yield in
Ghana would decrease by 7%.
• National maize production in Ghana
declined by 30% in 1982 due to drought.
• Poor seed set in maize at temperatures
above 38oC.
Application of GCM in Ghana
Table 3. Projected yield Reduction of Cassava
and Cocoyam
YEAR
CASSAVA
(%)
COCOYAM
(%)
2020
13
11.8
2050
23
29.6
2080
58
68
Adaptations of Agriculture and
Water Resources to climate change
• Altering the crops to be grown
• Early maturing and drought tolerant crops may be
grown
Change the methods of cultivation
Conservation tillage may be used instead of conventional
tillage systems
Increased use of irrigation in areas prone to drought
• Altering timing of planting to make use of shifts in
rainfall regimes
• Integrated soil fertility management
• Integrated pest and disease control measures
Socio-Economic Factors
These socio-economic factors should be
tackled and resolved through government
policy under changing climate conditions:
• Farm land values and tenure arrangements
• Crop produce market prices
• Cost of irrigation
• Cost of other inputs of production
• Government subsidy
• Improving the economic situation of farmers
CONCLUSION
Mitigation and adaptive measures are
needed to offset any future impact of
climate change on agriculture and
water resources
Estimation of Green House Gases
Estimating methane emission
from enteric fermentation
Summary
STEP 1
• Divide the livestock population into subgroups
and characterize each subgroup.
• To prevent bias, it is recommended to use three
year averages of activity data if available.
STEP 2
• Estimate emission factors for each subgroup in
terms of kilograms of methane per animal per
year.
Estimating methan emission from
enteric fermentation
Summary
STEP 3
• Multiply the subgroup emission factors by the
subgroup populations to estimate subgroup
emission.
• Sum across the subgroups to estimate total
emission.
Enteric fermentation emission
factors for Africa
Livestock
Emission factor (kg per head per
year)
Dairy cattle
36
Non-dairy cattle
25
Buffalo
55
Sheep
5
Goats
5
Camels
46
Horses
18
Mules/Asses
10
Swine
1
Poultry
Not estimated
Emissions from prescribed burning
of savannas
Background
• The growth of vegetation in savannas is controlled by
alternating wet and dry seasons.
• Man-made and/or natural fires generally occur during
the dry season.
• Savannas are intentionally burned during the dry
season primarily for agricultural purposes such as:
 ridding the grassland of weeds and pests
 promoting nutrient cycling: and
 Encouraging the growth of new grasses for animal
grazing.
Emissions from prescribed burning
of savannas
Emissions through savanna burning include:
• CO2 – net CO2 released is assumed to be zero
because of regrowth of vegetation between
burning cycles.
• Methane (CH4)
• Carbon monoxide (CO)
• Nitrous oxide (N2O)
• Oxides of nitrogen (NOx), i.e. (NO and NO2)
• Non-methane volatile organic compounds
(NMVOCs)
Emissions from prescribed burning
of savannas
Estimates of annual instantaneous gross release of
carbon from savanna burning are uncertain because
of lack of data on:
• The above ground biomass density
• The savanna areas burned annually
• The fraction of above-ground biomass which
actually burns, and
• The fraction which oxidizes
• The methodology takes these factors into
account.
Emissions from prescribed burning
of savannas
Calculations
• First, it is necessary to estimate the total amount
of carbon released to the atmosphere from savanna
burning as these are needed to derive non- CO2
trace gas emissions.
• It is recommended to use three-year averages of
activity data
• If data are not directly available, estimates can be
derived as shown in Table 4.14 (IPCC Guidelines)
Table 4.14 Default factors for regional
savanna statistics (IPCC)
Region
Fraction of
total
savanna
that is
burned
annually
Above ground
biomass density
(t dm/ha)
Fraction
of
biomass
actually
burned
Fraction of
above ground
biomass that
is living
Tropical Africa
0.75
6.6 ± 1.6
Sahel zone
0.05 – 0.15 0.5 – 2.5
0.95
0.20
North Sudan
zone
0.25 – 0.50 2 – 4
0.85
0.45
South Sudan
zone
0.25 – 0.50 3 – 6
0.85
0.45
Guinea zone
0.60 – 0.80 4 – 8
0.9 – 1.0
0.55
Emissions from prescribed burning
of savannas
Step 1: Total carbon released from savanna burning.
These data are required for each category
• Total area of savanna;
• Fraction of savanna area burned annually;
• Average above-ground biomass density (tonnes dry
matter/hectare) of savannas;
• Fraction of above-ground biomass which actually burns;
• Fraction of above-ground biomass that is living;
• Fraction of living and of dead above-ground biomass
oxidized; and
• Fraction of carbon in living and dead biomass.
Equations for calculations of estimates of
total carbon released due to burning of
savannas
Equation 1: Area of savanna burned Annually (ha) =
Total area of savanna (ha) x Fraction burned annually
Equation 2: Biomass burned (t dm) = Area of savanna
burned annually (ha) x above-ground biomass
density (t dm(ha)) x Fraction actually burned
Equation 3: Carbon released from live biomass (tC) =
Biomass burned (t dm) x Fraction that is live x
Fraction oxidized x carbon content of live biomass
(tC/t dm)
Equations for calculations of estimates of
total carbon released due to burning of
savannas
Equation 4: Carbon released from dead biomass (t C) =
Biomass burned (t dm) x Fraction that is dead x Fraction
oxidized x carbon content of dead biomass (tC/t dm)
Equation 5: Total carbon released (t C) = carbon released
from live material (t C) + carbon released from dead
material (t C)
Equations for calculations of estimates of
total carbon released due to burning of
savannas
STEP 2:
Once the carbon released from savanna burning has been
estimated, the emissions of CH4, CO, N2O and NOx can be
calculated using emission ratios. Default values are given in
Table 4.15.
CH4 Emissions = (carbon released) x (emission ratio) x 16/12
CO Emissions = (carbon released) x emission ratio x 28/12
N2O Emissions = (carbon released) x (N/C ratio) x (emission
ratio) x 44/28
NOx (NO2) Emissions = (carbon released) x (N/C ratio) x
(emission ratio) x (46/14)
Table 4.15. Default Emission Ratios for
Savanna Burning Calculations
Compound
CH4
CO
N2O
NOx
Ratios
0.004 (0.002 – 0.006)
0.06 (0.04 – 0.08)
0.007 (0.005 – 0.009)
0.121 (0.094 – 0.148)
Field Burning of Agricultural Residue
1. Calculations
STEP 1: Total carbon released
Data required to calculate the amount of carbon
burned in agricultural residues are listed below:
• Amount of crops produced with residues that are
commonly burned;
• Ratio of residue to crop product;
• Fraction of residue burned;
• Dry matter content of residue;
• Fraction oxidized in burning, and
• Carbon content of the residue
Field Burning of Agricultural Residue
Total carbon released (tonnes of carbon) = Ʃ annual
production (t of biomass per year) x the ratio of residue to
crop product (fraction) x the average dry matter fraction of
residue (t of dry matter/ t of biomass) x the fraction actually
burned in the field x the fraction oxidized x the carbon
fraction (t of C/t of dm).
STEP 2: Based on carbon released the emissions of CH4, CO,
N2O and NOx can be calculated as follows:
CH4 = carbon released x emission ratio x 16/12
CO = carbon released x emission ratio x 28/12
N2O = carbon released x (N/C ratio) x emission ratio x 44/28
NOx = carbon released x (N/C ratio) x 46/14
Table 4.16 Default factors for emission
ratios for agricultural residues
Compound
CH4
CO
N2O
NOx
Ratios
0.005 (0.003 – 0.007)
0.06 (0.04 – 0.08)
0.007 (0.005 – 0.009)
0.121 (0.094 – 0.148)
Table 4.17 Selected Crop Residue
Statistics
Product
Residue/Crop Dry matter
product
fraction
Carbon
fraction
Nitrogen –
Carbon (N-C)
ratio
Maize
1
0.30 – 0.50
0.4709
0.02
Rice
1.4
0.78 – 0.88
0.4144
0.014
Millet
1.4
0.016
Sorghum
1.4
0.02
Bean
2.1
Soybean
2.1
Groundnut
1
0.05
I. N2O emissions from manure
management
• This deals with N2O produced during the storage
and treatment of manure before it is applied to
land.
• Manure collectively include both dung and urine
produced by livestock.
• Factors that influence emission of N2O from
manure during storage and treatment are:
 the nitrogen and carbon content of manure
 the duration of the storage, and
 the type of treatment given to the manure.
II. THE IPCC GUIDELINES
The IPCC Guidelines method for estimating
nitrous oxide (N2O) from manure
management entails:
• Multiplying the total N excretion (from all
animal species/categories) in each type of
manure management by an emission factor
for the type of manure management system.
N2O emission = N excretion x Emission factor
III. METHODOLOGY
• The animal population must first be divided into
species/categories.
• Collect population data from livestock population
characterization.
• Determine the annual average nitrogen excretion
rate per head (Nex(T)) for each defined livestock
species/category T;
• Determine the fraction of total annual excretion
for each livestock species/category T that is
managed in each manure management system S
(ms(Ts))
III. METHODOLOGY
Determine the N2O emission factors (EF) for
each manure management system S (EF3 (s)):
• For each manure management system type
S, amount of nitrogen excretion (from all
animal species/categories) in that system,
to estimate N2O emissions from that
manure management system. Then sum
over all manure management systems.
IV. EQUATION FOR CALCULATING N2O
EMISSIONS FROM MANURE MANAGEMENT
(N2O – N) (mm) = Ʃ(s) [(Ʃ(T) (N(T) x Nex (T) x MS(Ts) )) x EF3 (s) ]
(N2O – N) (mm) = N2O – N emissions from manure
management in the country (kg N2O – N/year)
N(T) = number of head of livestock species/category T in
the country
Nex (T) = Animal average N extraction per head of
species/category T in the country (kg N/animal/year)
MS(Ts) = Fraction of total annual excretion for each
livestock species/category T that is managed in
manure management system (S) in the country.
IV. EQUATION FOR CALCULATING N2O
EMISSIONS FROM MANURE MANAGEMENT
EF3 (s) = N2O emission factor for manure
management system S in the country (kg N2O
– N/kg N in manure management system (S).
S = manure management system
T = species/category of livestock
• Conversion of N2O – N (mm) emission to
N2O(mm) emissions
N2O(mm) = (N2O – N) (mm) x 44/28
V. CHOICE OF EMISSION FACTORS
• Accurate estimate will be obtained
using country-specific emission
factors.
• If appropriate country-specific
emission factors are unavailable,
default emission factors are
encouraged to be used.
VI. DEFAULT EMISSION FACTORS FOR N2O
FROM MANURE MANAGEMENT
System
Description
EF3 (kg N2O – N/kg nitrogen
excreted
Pasture/range/Paddock
Manure is deposited directly
on soils by livestock
(unmanaged)
0.02
Solid storage
Dung and urine is collected
and stored in bulk for a long
time (months) before
disposal
0.02
Dry lot
Manure is allowed to dry
until it is periodically
removed. Upon removal the
manure may be spread on
fields
0.02
Liquid/slurry
Combined storage of dung
and urine in tanks
0.001
VI. DEFAULT EMISSION FACTORS FOR N2O
FROM MANURE MANAGEMENT
System
Description
EF3 (kg N2O – N/kg
nitrogen excreted
Anaerobic lagoon
Manure residues in the
0.001
lagoon for periods from 30
days to over 200 days. The
water from the lagoon may
be recycled or used to
irrigate and fertilize soils
Open pits below animal
confinements
Combined storage of dung
and urine below animal
confinement
Anaerobic Digester
Dung and urine is
0.001
anaerobically digested to
produce CH4 gas for energy
Burned for fuel
Dung is collected and dried 0.007
in cakes and burned for
heating or cooking
0.001
VI. DEFAULT EMISSION FACTORS FOR N2O FROM MANURE
MANAGEMENT (JUDGEMENT BY EXPERT GROUP)
System
Description
Cattle and swine deep
litter
Cattle/swine dung and urine
are excreted on stall floor. The
accumulated waste is removed
after a long time
<1 month
> 1 month
EF3 (kg N2O – N/kg
nitrogen excreted
0.005
0.02
Composting - intensive
Dung and urine are collected
and placed in a vessel or
tunnel, there is forced aeration
of the waste
0.02
Composting – extensive
Dung and urine collected,
stacked and regularly turned
for aeration
0.02
Poultry manure with
bedding
Manure is excreted in floor
with bedding. Birds walk on
waste
0.02
VI. DEFAULT EMISSION FACTORS FOR N2O FROM MANURE
MANAGEMENT (JUDGEMENT BY EXPERT GROUP)
System
Description
EF3 (kg N2O – N/kg
nitrogen excreted
Poultry manure
without bedding
Manure is excreted in floor 0.005
without bedding. Birds do
not walk on waste
Aerobic treatment
Dung/manure is collected 0.02
as a liquid. The waste
undergoes forced aeration,
or is treated in aerobic
ponds or wetland systems
to provide nitrification and
denitrification
VII. ACTIVITY DATA FOR ESTIMATING N2O EMISSIONS
FROM MANURE MANAGEMENT SYSTEM
The three main types of activity data required are:
• Livestock population data
• Nitrogen excretion data for each animal
species/category, and
• Manure management system usage data
(i) Livestock population data (N(T))
• If default nitrogen excretion rates are used, a basic
livestock population characterization is sufficient.
• If calculated nitrogen excretion rates are used, an
enhanced characterization must be performed.
VII. ACTIVITY DATA FOR ESTIMATING N2O EMISSIONS
FROM MANURE MANAGEMENT SYSTEM
(ii) Annual average nitrogen excretion rates Nex (T)
• Country-specific rates may be taken directly from
documents on reports from agricultural industry and
scientific literature; or
• Derived from information on animal nitrogen intake
and retention, or
• IPCC default excretion rates should be used with
defaults adjustment factors.
• In order to adjust the values for young animals, it is a
good practice to multiply the N-excretion rates by
the default adjustment factors (Table 4.14).
Table 4.20 Calculation of manure – N excretion and
N2O emission factors for different animal waste
management systems in Africa
Type of animal
Non-dairy cattle
Dairy cattle
Poultry (E)
Sheep
Swine
Other animals (F)
Number of
animals
(x 106)
133198
18734
646000
179171
12445
162194
N-excretion (kg
N/animal/year)
40
60
0.6
12
16
40
Nex (T)
Table 4.14 Default adjustment factors when
estimating N – excretion rates fro young animals
Animal
Age range (years)
species/category
Non-Dairy cattle
0–1
Non-Dairy cattle
1–2
Dairy cattle
0–1
Dairy cattle
1–2
Poultry
0 – 0.25
Sheep
0–1
Swine
0 – 0.5
Adjustment
factor
0.3
0.6
0.3
0.6
0.5
0.5
0.5
Table 4.20 Emission factors for AWMSs EF3 (%
of manure N excreted that is lost as N2O)
Type of
animal
AL
(EF3)
LS (EF3)
DS (EF3) SS + Dry PRP
Wt
(EF3)
(EF3)
Used
Fuel
(EF3)
Other Total N
system excreted
(EF3)
(Tg N)
Non-dairy
cattle
0.1
0.1
0.0
2.0
2.0
0.0
0.5
5.3
Dairy
cattle
0.1
0.1
0.0
2.0
2.0
0.0
0.5
1.1
Poultry (E)
0.1
0.1
0.0
2.0
2.0
0.0
0.5
0.4
Sheep
0.1
0.1
0.0
2.0
2.0
0.0
0.5
2.2
Swine
0.1
0.1
0.0
2.0
2.0
0.0
0.5
0.2
Other
0.1
animals (F)
0.1
0.0
2.0
2.0
0.0
0.5
6.5
AL = Anaerobic lagoon LS = Liquid systems
SS + Dry wt = Solid storage and dry lot
DS = Daily spread
PRP = Pasture, Range, Paddock
CALCULATION OF ANIMAL N EXCRETION RATES
• The annual amount of N-excreted by each
animal species/category depends on the total
annual N intake and total annual N retention
of the animal.
• Annual N intake depends on:
 the annual amount of feed digested by the
animal
 and the protein content of that feed
• Total feed intake depends on the production
level of the animal (e.g. growth rate, milk
production, draft power).
CALCULATION OF ANIMAL N EXCRETION RATES
• Annual N retention (i.e. the fraction of N
intake that is retained by the animal for the
production of meat, milk and wool) is a
measure of the animal’s efficiency of
production of animal protein from feed
protein.
• N-intake and retention data for specific animal
species/categories may be available from
national statistics or from animal nutrition
specialists
ANIMAL N EXCRETION RATES
Nex (T) = N intake (T) x (1 – N retention (T))
Where:
Nex (T) = animal N excretion rates, kg
N/animal/year
N intake (T) = The annual N intake per head of
animal of species/category T, kg N/animal/year
N retention (T) = Fraction of annual N intake that is
retained by animal of species/category T kg N
retained/animal/year per kg N
intake/animal/year
DEFAULT N RETENTION VALUES
Table 4.15. Default fraction N-intake retained
by the animal
Animal Category
N retention (T)
(kg N retained/animal/year per kg N
intake/animal/year)
Dairy Cattle
0.2
Non-Dairy Cattle
0.07
Buffalo
0.07
Sheep
0.10
Goats
0.10
Camels
0.07
Swine
0.3
Horses
0.07
Poultry
0.3
GREENHOUSE GAS EMISSIONS FROM
AGRICULTURAL SOILS
1. Nitrous Oxide (N2O) Emissions
Three sources of N2O distinguished are:
• Direct emissions from agricultural soils
• Direct soil emissions from animal production
• N2O emissions indirectly induced by
agricultural activities.
GREENHOUSE GAS EMISSIONS FROM
AGRICULTURAL SOILS
2. Anthropogenic input of N into agricultural
systems include:
• Synthetic fertilizer;
• Nitrogen from animal wastes;
• Nitrogen from increased biological N-fixation;
• Nitrogen derived from cultivation of mineral
and organic soils through enhanced organic
matter mineralization.
I. Direct N2O emissions from
agricultural soils
• Anthropogenic sources of N2O can be biogenic (e.g.
enhanced N2O production by bacteria in fertilized fields)
• Or abiogenic (e.g. formation during burning processes)
Biogenic production of N2O in the soil results primarily
from:
• Nitrification process – the aerobic microbial oxidation of
ammonium to nitrate;
• Denitrification – anaerobic microbial reduction of nitrate
to nitrogen.
• Nitrous oxide is a gaseous intermediate in the reaction
sequences of both processes.
GREENHOUSE GAS EMISSIONS FROM
AGRICULTURAL SOILS
1.1 Anthropogenic input into agricultural systems include:
• Synthetic fertilizer
• Nitrogen from animal wastes
• Nitrogen from biological N-fixation
• Nitrogen derived from enhanced organic matter
mineralization
• N2O emitted directly in agricultural fields, animal
confinements or pastoral systems or transported from
agricultural systems into ground and surface waters
through runoff, nitrogen leaching etc.
GREENHOUSE GAS EMISSIONS FROM
AGRICULTURAL SOILS
1.2 Direct N2O emissions from agricultural soils
Anthropogenic sources of N2O can be:
• Biogenic (e.g. N2O production by bacteria in fertilized fields) and
• abiogenic (e.g. N2O formation during burning)
Biogenic production of N2O in the soil results primarily from:
• Nitrification – the aerobic microbial oxidation of ammonium to
nitrate; and
• Denitrification – the anaerobic microbial reduction of nitrate to
nitrogen gas.
• In both processes, Nitrous oxide is a gaseous intermediate in the
reaction sequence.
• These reactions are controlled by temperature, pH and soil
moisture content.
Summary of sources of N2O
The following sources and sink of N2O can be
distinguished:
• Synthetic fertilizers;
• Animal excreta nitrogen used as fertilizers;
• Biological nitrogen fixation;
• Crop residue and sewage sludge application;
• Cultivation of high organic content soils;
• Soil sink for N2O.
1.3 Methodology for estimating direct N2O
emissions from agricultural fields
The total direct annual N2O emission is:
N2O direct [(FSN + FAW + FBN + FCR) x EF1] + FOS x EF2
N2O direct = direct emissions from agricultural soils in country
(kgN/yr)
FSN = synthetic nitrogen applied (kgN/yr)
FAW = manure nitrogen used as fertilizer in country (kgN/yr)
FBN = N fixed by N-fixing crops (kgN/yr)
FCR = N in crop residues returned to the soil (kgN/yr)
EF1= emission factor for direct soil emissions (kg N2O-N/kgN-input)
FOS = area of cultivated organic soils within country
EF2 = emission factor for organic soil mineralization due to
cultivation (kg N2O-Nha/yr)
1.3 Methodology for estimating direct N2O
emissions from agricultural fields
FSN = N fert x (1-Frac GASF)
FAW = (Nex x (1- Frac Fuel + Frac GRAZ + Frac GASM)
FBN = 2 x CropBF + Frac NCRBF
FCR = 2 x [Crop O x Frac NCRO + Crop BF x Frac NCRBF] x (1- Frac R) x (1Frac BURN)
N fert = synthetic fertilizers used in country (kgN/yr)
Frac GASF = fraction of synthetic fertilizer nitrogen applied to soils
that volatilizes as NH3 and NOx (kg NH3 –N and NOx –N/kg of N
input
Nex = amount of nitrogen excreted by the livestock within a country
(kgN/yr)
Frac Fuel = fraction of livestock nitrogen excretion contained in
excrements burned for fuel (kgN/kgN totally excreted)
1.3 Methodology for estimating direct N2O
emissions from agricultural fields
Frac GRAZ = fraction of livestock nitrogen excreted and deposited onto
soil during grazing (kg N/kg N excreted) country estimate
Frac GASM = fraction of livestock nitrogen excretion that volatilises as
NH3 and NOx (kg NH3 –N and NOx –N/kg of N excreted)
CropBF = seed yield of pulses + soybeans in country (kg dry biomass/yr)
Frac NCRBF = fraction of nitrogen in N-fixing crop (kg N/kg of dry
biomass)
Crop O = production of all other (i.e. non-N fixing) crops in country (kg
dry biomass/yr)
Frac NCRO = fraction of nitrogen in non-fixing crop (kgN/kg of dry
biomass)
Frac R = fraction of crop residue that is removed from the field ad crop
(kgN/kg crop-N)
Frac BURN = fraction of crop residues that is burned rather than left on
the field
Table 4.19 Default values for parameters
Frac BURN
0.25 (in developing countries (kg N/kg crop N)
Frac R
Frac Fuel
Frac GASF
0.45 kg N/kg crop-N
0.0 kg N/kg N excreted
0.1 kg NH3 –N + NOx –N/kg of synthetic
fertilizer N applied
Frac GASM
0.2 kg NH3 –N + NOx –N/kg of N excreted by
livestock
Non-dairy cattle – 96; dairy cattle – 83; poultry
– 81; sheep – 99; swine – 0; other animals - 99
Frac GRAZ
Frac NCRBF
Frac NCRO
0.03 kg N/kg of dry biomass
0.015 kg N/kg of dry biomass