Installment 8 of “World Resources Report: Creating a Sustainable Food Future” explores the potential to improve water management in rice production in order to reduce agricultural greenhouse gas emissions and save water. Find out more at http://www.wri.org/blog/2014/12/more-rice-less-methane

1. Wetting and Drying:
Reducing GHG Emissions
and Saving Water
from Rice Production
Installment 8 of “Creating a Sustainable Food Future”
World Resources Report
WRI.org/WRR
Photo: IRRI.
TAPAN K. ADHYA, BRUCE LINQUIST, TIM SEARCHINGER, REINER WASSMANN, AND XIAOYUAN YAN

2. WRI.org/WRR

3. Menu for a sustainable food future
Consumption  Reduce food loss and waste (Installment 2)
 Shift diets (Installment 11)
 Achieve replacement level fertility (Installment 3)
 Reduce biofuel demand for food crops (Installment 10)
Production  Sustainably increase crop yields
 Boost yields through crop breeding (Installment 7)
 Improve soil and water management (Installment 4)
 Expand onto low-carbon degraded lands (Installment 9)
 Sustainably increase “livestock” productivity
 Increase productivity of pasture and grazing lands
 Reduce then stabilize wild fish catch (Installment 5)
 Improve productivity and environmental performance
of aquaculture (Installment 5)
Production
methods
 Improve livestock feeding efficiency
 Increase the efficiency of fertilizer use
 Manage rice paddies to reduce emissions (Installment 8)

4. Authors
• Tapan K. Adhya (Professor, KIIT University)
• Bruce Linquist (Research Scientist, University of
California at Davis)
• Tim Searchinger (Senior Fellow, World Resources
Institute; Research Scholar, Princeton University)
• Reiner Wassmann (Climate Change Coordinator,
International Rice Research Institute)
• Xiaoyuan Yan (Professor, Institute for Soil Science,
Chinese Academy of Sciences)

6. Mid-season drainage reduces GHG emissions
from rice production in Punjab by one-third
Tons of CO2e per hectare
Note: Solid bars show state-wide averages. Error bars represent one standard deviation.
Source: Pathak et al. (2012).

7. Water tables have been falling across most of
Punjab
Depth in meters, 1998–2006
Source: Kaur et al. (2011).

8. Basic Facts on Philippine Rice Production
• 4.4 million ha harvested rice in 2010
(up from 3.8 million ha in 1995)
• One of the major rice importing
countries
• Rice is typically grown in double
cropping systems (dry season: Jan to
Apr; wet season: July to Oct)
• About 70% of rice area is irrigated,
but irrigation infrastructure is generally
inefficient with often unreliable water
supply during the dry season
• Low degree of mechanization –
almost all the rice is transplanted
manually

9. AWD in the Philippines
Adoption:
• Introduced to farmers as ‘safe AWD’ (in combination with PVC
tubes) as a means to save 15-30% irrigation water
• Unfeasible in wet season (corr. to 56% of harvested rice)
• Challenges in gravity-driven irrigation schemes, because farmers
pay flat irrigation fees (and not volume-based fees)
Research on GHG emissions:
• As of now, no published data on GHG emissions under AWD as
such, but three published studies have identified large reduction in
emissions by a single drawdown
• Several ongoing studies indicate significant reduction (>50%) in
methane emissions by AWD vs. continuous flooding
• Emissions of nitrous oxide are generally low -- even under AWD

10. ‘Opportunities for Change of Practice’
In rice fields
relying on
groundwater
supply: Reducing
pumping costs
In rice fields
affected by water
scarcity:
Stabilizing yields
in dry periods
Mitigating
methane
emissions from
rice through
AWD Angat Reservoir (near Manila)

11. ‘Opportunities for Change of Practice’
In rice fields
relying on
groundwater
supply: Reducing
pumping costs
In rice fields
affected by water
scarcity:
Stabilizing yields
in dry periods
In new or
renovated
irrigation systems:
Staggered water
supply
Mitigating
methane
emissions from
rice through
AWD

12. ‘Opportunities for Change of Practice’
In rice fields
relying on
groundwater
supply: Reducing
pumping costs
In rice fields
affected by water
scarcity:
Stabilizing yields
in dry periods
In new or
renovated
irrigation systems:
Staggered water
supply
In support of
national climate
change policies:
Setting feasible
mitigation targets
Mitigating
methane
emissions from
rice through
AWD

13. Rice production in the US
• In the US there are four
regions
– Arkansas Grand Prairie,
– Mississippi Delta, (parts
of Arkansas, Mississippi,
Missouri, and Louisiana);
– Gulf Coast (Texas and
Southwest Louisiana);
and
– Sacramento Valley of
California.

14. UC DAVIS
University of California
Rice establishment systems
Establishment Region practiced Water management
Transplanting Asia Continuously flooded after
transplanting. China uses mid-season
drain.
Dry seeding Mississippi Delta;
increasing in Asia
Irrigated like upland crop for 4 wk
then continuous flood
Wet seeding California, Louisiana,
Spain, Italy, Australia
Continuously flooded from before
planting

15. AWD Research in US
• Arkansas and California
– 2011-present (6 site years)
– Dry-seeding has lower GWP than water-seeding
– 80-90% reductions in GWP possible
– No yield reductions
• Requires good management of fertilizer and water
• Large yield reductions when too dry
– In Arkansas, this was accompanied by 20-30% water
savings
– Lower grain arsenic concentrations

16. Challenges for adoption
• Despite potential for water savings, even small
yield reductions make uneconomical
• Requires good water management to avoid
yield loss
• Fields are large and heterogeneous
– Need water quickly
– Need ability to apply fast

17. Best opportunity for expansion
• Southern US
– In regions where the aquifer is
receding presenting serious water
limitations as well as expensive water
(due to pumping depth).
– Where fields are irrigated with a pump
(this is most fields) using side inlet or
poly pipe
• California
– Opportunities are limited due to
surface irrigation (gravity feed)
• Not independently managed
• Slow to fill fields
• Fields hydrologically connected

18. Plastic film mulching rice cultivation
Early spring drought is a
problem to rice cultivation in
southwest China, plastic film
mulching is a practice for
water saving.

19. Why film mulching with ridge and furrow
传统栽培
Traditional
覆膜栽培
Plastic Mulch
Significant drought
resistance effect
Conventional Film Mulching
Film Mulching Conventional
Warmer temperature
to better early growth
of rice

20. 50
40
30
20
10
0
CH4 and N2O emissions
-2
)
-1
)
-2
h
0 30 60 90 120
Days after flooding (Apr. 18, 2010)
-1
)
-2
h
CH4 flux (mg CH4 m
TF
TF-DCD/HQ
PM
PM-DCD/HQ
Transplanting
50
1500
40
1200
30
900
20
600
10
N2O 0
0 30 60 Days after flooding (Apr. 18, CH4 emission (g CH4 m
TF TF-DCD/HQ PM PM-DCD/HQ
Convent
NI+UI
Film
FM+NI+UI
Convent
NI+UI
Film
FM+NI+UI
300
0
flux (μg N2O-N m
TF
TF-DCD/HQ
PM
PM-DCD/HQ
Transplanting

21. Integrated GWP

22. What to do with the plastic film
More durable plastic film
is easier to remove and
prevent the land from
white pollution.

23. Thank you

24. Discussants
Marcus Wijnen (Senior Water Resources
Management Specialist, World Bank)
Robert Bertram (Chief Scientist, USAID
Bureau for Food Security)

25. World Resources Report:
Creating a Sustainable Food Future
“Wetting and Drying: Reducing
GHG Emissions and Saving Water
from Rice Production”
Download at: WRI.org/WRR