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