Wetting and Drying: Reducing GHG Emissions

and Saving Water

from Rice Production

Installment 8 of “Creating a Sustainable Food Future”World Resources ReportWRI.org/WRR

Photo: IRRI.TAPAN K. ADHYA, BRUCE LINQUIST, TIM SEARCHINGER, REINER WASSMANN, AND XIAOYUAN YAN

WRI.org/WRR

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)

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)

Mid-season drainage reduces GHG emissions

from rice production in Punjab by one-thirdTons of CO2e per hectare

Note: Solid bars show state-wide averages. Error bars represent one standard deviation.

Source: Pathak et al. (2012).

Water tables have been falling across most of

PunjabDepth in meters, 1998–2006

Source: Kaur et al. (2011).

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

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

‘Opportunities for Change of Practice’

In rice fields

affected by water

scarcity:

Stabilizing yields

in dry periods

In rice fields

relying on

groundwater

supply: Reducing

pumping costs

Mitigating

methane

emissions from

rice through

AWD Angat Reservoir (near Manila)

‘Opportunities for Change of Practice’

In rice fields

affected by water

scarcity:

Stabilizing yields

in dry periods

In rice fields

relying on

groundwater

supply: Reducing

pumping costs

In new or

renovated

irrigation systems:

Staggered water

supply

Mitigating

methane

emissions from

rice through

AWD

‘Opportunities for Change of Practice’

In rice fields

affected by water

scarcity:

Stabilizing yields

in dry periods

In rice fields

relying on

groundwater

supply: Reducing

pumping costs

In support of

national climate

change policies:

Setting feasible

mitigation targets

In new or

renovated

irrigation systems:

Staggered water

supply

Mitigating

methane

emissions from

rice through

AWD

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.

UCDAVISUniversity 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

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

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

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

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.

传统栽培

Traditional

覆膜栽培Plastic Mulch

Significant drought

resistance effect

Film MulchingConventional

Film Mulching Conventional

Warmer temperature

to better early growth

of rice

Why film mulching with ridge and furrow

0

10

20

30

40

50

0 30 60 90 120

Days after flooding (Apr. 18, 2010)

CH

4 f

lux (

mg C

H4 m

-2 h

-1)

TF

TF-DCD/HQ

PM

PM-DCD/HQ

Transplanting0

10

20

30

40

50

CH

4 e

mis

sio

n (

g C

H4 m

-2)

TF TF-DCD/HQ PM PM-DCD/HQ

Convent

NI+UI

Film

FM+NI+UI

CH4 and N2O emissions

Convent

NI+

UI

Film

FM

+N

I+U

I

0

300

600

900

1200

1500

0 30 60 90 120

Days after flooding (Apr. 18, 2010)

N2O

flu

x (

μg

N2O

-N m

-2 h

-1)

TF

TF-DCD/HQ

PM

PM-DCD/HQ

Transplanting

0

100

200

300

400

500

600

N2O

em

issi

on

(m

g N

2O

-N m

-2)

TF TF-DCD/HQ PM PM-DCD/HQ

Integrated GWP

More durable plastic film

is easier to remove and

prevent the land from

white pollution.

What to do with the plastic film

Thank you

Discussants

Marcus Wijnen (Senior Water Resources

Management Specialist, World Bank)

Robert Bertram (Chief Scientist, USAID

Bureau for Food Security)

“Wetting and Drying: Reducing

GHG Emissions and Saving Water

from Rice Production”

Download at: WRI.org/WRR

World Resources Report:

Creating a Sustainable Food Future