methane and nitrous oxide emissions from an
TRANSCRIPT
METHANE AND NITROUS OXIDE EMISSIONS FROM ANMETHANE AND NITROUS OXIDE EMISSIONS FROM AN URUGUAYAN RICE FIELD
MSc Pilar Irisarri D t t f Pl t Bi lDepartment of Plant BiologyFacultad de AgronomíaUniversidad de la RepúblicaMontevideo URUGUAYMontevideo, URUGUAY
MARCO/GRA Joint Workshop on Paddy Field Management and Greenhouse Gases
BACKGROUND ‐ Uruguay
20%
10%
0%
10%
70%Temperature Oct‐Apr: 17. 6ºC
Rain: 1100 mm
Heliophany: 6.6 h
Area: 162000 ha
Yield: 7670 kg ha‐1
BACKGROUND ‐ GHG
GHG National Inventory, 2002
15000
5000
10000 C
O2
-5000
0
on /
kton
eq
-15000
-10000kto
-20000
Emisión neta (kton) -19157 688 31E i ió t (kt d CO2) 19157 14446 9697 4986
CO2 CH4 N2O Total
Emisión neta (kton eq. de CO2)100 años
-19157 14446 9697 4986
BACKGROUND – Non‐CO2 GHGCH4 emissions: 14.4 Mt CO2‐e N2O emissions: 9.7 Mt CO2‐e
Desechos - Residuos Sólidos
Urbanos8% Agricultura -
Cultivo de arroz A i lt
Agriculture:i
Agriculture:
Urban solid waste8%
Desechos - Efl t lí id
Cultivo de arroz4% Agricultura -
Manejo del estiércol
2%
Agricultura - Suelos
agrícolas (Emisiones indirectas)
33%
Agricultura - Suelos
agrícolas (Emisiones directas)
rice4%
Agriculture: manure management2%
indirect emissions from managed soils33%
Liquid
Agriculture:direct emissions from managed soils
Efluentes líquidos industriales y domésticos
2%Agricultura -
Fermentación entérica Desechos -
Excremento
directas)6%
Agriculture: enteric fermentation
Liquid waste2%
6%
84% Excremento humano
1%Agricultura - Suelos de pastoreo
(Emisiones directas por excreta de
fermentation84% Agriculture:
animal excreta inputs to grazed soils60% animales)
60%
60%
BACKGROUND – Rice production system
•Only one rice crop per year•Only one rice crop per year
The crop is dr direct seeded Depending on rainfall oc rrence•The crop is dry‐direct seeded. Depending on rainfall ocurrence, flushing (1 or 2) is required to prevent water stress, before establishing the permanent flood 30‐40 days after planting till15 20 days before harvest
•Starter fertilizers are normally applied at seeding and mainly
15 ‐20 days before harvest.
consist in N and P applications. One or two N top dressings are normally used (tillering /panicle initiation). Average 60 kg N ha‐1.
•Rice production rotates with 3 to 4 years of pastures.
OBJECTIVES
• To measure CH4 and N2O emissions in a ricefield of the Eastern production zoneEastern production zone.
• To assess the effect of paddy field management on CH4 and• To assess the effect of paddy field management on CH4 and N2O fluxes
– Flooding regime – Nitrogen fertilization
Winter cover crop– Winter cover crop
MATERIALS AND METHODS – Experimental design
• Greenhouse– Experimental Station INIA TyT– 3 treatments (DAE):
• Flooding 21 DAE, with N• Flooding 45 DAE with NFlooding 45 DAE, with N• Flooding 21 DAE, without N
• Field– Unidad “Paso de la Laguna” INIA TyT– 4 treatments:
• Ryegrasss as winter cover crop• Ryegrasss as winter cover crop –with or without N
• Without cover ‐ with or without N– Flooding 21 DAE– 9 x 4 m2 plots
OC %
Total N%
P Bray I (µg/g)
K (meq/100g)
pH (H2O)
Ap dens (g cm-3)
1.9 0.17 7.8 14.6 5.4 1.4
MATERIALS AND METHODS ‐ CH4 y N2O measurements4 y 2
“Closed chambers method”– Permanently installed bases, water‐sealy ,– Fan– Internal chamber temperature
Ai l ll t d t 0 30 60 i– Air samples collected at 0, 30, 60 min– Samples stored in vacutainers
A l i GCAnalysis: GC– CH4: flame ionization detector– N2O: electronic capture detector2 p
Mass flux (g/ha.d): F = ρ.h(dC/dt)
RESULTS ‐ Greenhouse
• N2O N O– Without N:
almost no emission– With N: 50
60
708090
N2O
2O (g/ h
a.d)
– With N:Highest when fertilization was inmediately after flooding (p<0 0001) 10
0102030
4050
20 0 20 40 60 80 100 120
Flujo N‐N
2
(p<0.0001)
• CH4
-10-20 0 20 40 60 80 100 120
Tiempo (DDE)
CH44– Emission begins 5 weeks after
flooding (21 DAE)– Date of flooding was not as
4000
5000
6000
7000 4
‐CH 4
(g /ha.d)
– Date of flooding was not as determinant as phenological stage of rice (emission begins at reproductive stage)
0
1000
2000
3000
-20 0 20 40 60 80 100 120
Flujo C‐
at reproductive stage)Tiempo (DDE)
RESULTS ‐ Field
N2O• N2O
5060
708090
N2O– Emission increases after
flooding and flushing– No significant differences 2O
(g/ h
a.d)
100
1020
304050
30 10 10 30 50 70 90 110 130 150 170
No significant differences (p<0.0964)
– Slight increase after drainage previous harvest
Flujo N‐N
2
-10-30 -10 10 30 50 70 90 110 130 150 170
Tiempo (DDE)
CH4
p
• CH4– Emission begins 5 weeks after
4000
5000
6000
7000
4gflooding with ryegrass earlier
– Ryegrass + N: highest H 4(g /
ha.d)
0
1000
2000
3000
-30 -10 10 30 50 70 90 110 130 150 170
Ryegrass N: highest (interaction p<0.0001)
– Decreases with drainage Flujo C‐CH
-100030 10 10 30 50 70 90 110 130 150 170
Tiempo (DDE)
DISCUSSION
CHCH4
Water soil content‐ redox potentialWater soil content redox potentialRyegrass and N fertilization Phenological stage of riceMETHANOGENESIS METHANOTROPHYMETHANOGENESIS – METHANOTROPHY
N2O2
N fertilizationW il d i lWater soil content – redox potentialNITRIFICATIONDENITRIFICATION
PRELIMINARY CONCLUSIONS
• CH4 major GHG
• Emission patterns for both gases followed inverse trends
• Rice after ryegrass cover crop emitted 2 times more methane than without cover crop
• No methane was detected during fallow or in the pasture‐rotation phase.
• CH4 emission predicted using IPCC methodology was 80 kg h ‐1 ‐1 hil th l l t d t fl 61ha‐1 yr‐1 while the calculated net mass flux was among 61‐112 kg ha‐1 yr‐1 for the field treatments