Rice and the environmentRice and the environment

Crop and Environmental Sciences DivisionCrop and Environmental Sciences DivisionInternational Rice Research InstituteInternational Rice Research Institute

Los BaLos Bañños, Philippinesos, Philippines

• RICE: most important staple food in Asia Annually 550-600 million ton => 3 billion people

Floating Floating ricerice DeepwaterDeepwater

Rainfed lowland Rainfed lowland Drought/Drought/

flash floodsflash floods Irrigated Irrigated

Upland riceUpland rice

Rice ecosystems

Rice is unique in its abilityto grow in a wide range ofhydrologic environments,some of which where other crops can not grow

Irrigated lowland rice (paddy)

Lowland rice

Upland rice

Floodprone rice

Rice production in Asia

Area

(106 ha)

Production (%/106 ton)

Yield

(t ha-1)

Irrigated Lowland

79 75% 3-9

Rainfed lowland

54 19% 2.3

Upland 14 4% 1

Deepwater 11 (overlap)

2%

1.5

Salt-affected

9-12 (overlap) 1

Total 150 550-600

Rice environments and production

0

20

40

60

80

100

120

140

160

1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001

0

250

500

750

1000

1250

1500

1750

2000

2250

Note: Rice Export Prices were adjusted for inflation (2000=100)

World rice price (US$ tonne-1)Per capita production (kg person-1)

Price

Production

Year

World rice production and price

Irrigated lowland rice (“paddy”):

• Land soaking • Puddling• Levelling• Bunded fields• Transplanted or direct seeded• “Permanently” flooded

Soaking and puddling

Puddling

Land levelling

Bund construction

Seed bed in main field

Ready for transplanting

Transplanting

Just transplanted fields

Direct (wet) seeding

Direct (wet) seeding using drum seeder

Wet-seeded rice

Lowland rice landscape

Lowland rice landscape

Where does all the water come from?

Where does all the water come from?

Main reservoir

Spilling

Water tunnels

“Natural” main canal

Lined main canal

Water control

Aquaduct

Water distribution

Smaller and smaller canals…

Finally at farmers’ fields

Plot-to-plot irrigation after water gets deliveredto farmers

Scooping water

Smaller scale: pumping from canals, creeks,..

Pumping from smallreservoirs to store water

Millions of Asian farmers now use shallow tubewells to pump from groundwater

Harvest time: Finally dry land

Environment and ecosystem services

Irrigated lowland rice

• 75% of the world’s rice production • Highly sustainable in terms of yield• Environmental impacts (traditional systems):

• Ecosystem services: fish, snails, groundwater recharge, flood buffer, biodiversity, temperature buffer, prevent soil erosion and landslides, cultural aspects,..

Methane (3-6% globally)

Ammonia volatilization (acid rain)

Little N2O

Danger chemical outflow in surface water

No/little Nitrate leaching

Pesticides degrade rapidly

Low herbicide use

Raise groundwater table => risk salinization

Efficient to leach salts

Acts as wetland in removing N and P

Fish in irrigation ponds

Ducks Fish in irrigation canals

Food production: fish and ducks

Lowland rice landscape: specific biodiversity?

Mountain terraces• Ground water recharge• Mitigate erosion• Mitigate run-off, floods

Steve McCurry, 1988.Steve McCurry, 1988.

Deltas: flood buffer with production potential