Rainfed rice - IRRI books - International Rice Research Institute

Agro-Ecosystem Analysis
for Rainfed Environments
Rice ecosystems
E
cosystems are separated based on irrigation, hydrology and landform.
The subdivision of ecosystems into sub-ecosystems is based on flooding,
drought, water depth, length of growing season, climate and soil and
water quality parameters.
There are five rice ecosystems: irrigated, upland, rainfed lowland,
deepwater and tidal wetlands.
Rice-growing environments
The rainfed rice ecosystem is
characterised by diverse agro-climatic
and socio-economic conditions. It
covers areas with favourable as well
as unfavourable environments, e.g.,
drought, submergence/flood, adverse
soils, etc., which are complex, variable
and heterogeneous.
Irrigated
Irrigated ecosystems have good water
control, thereby allowing highyielding,
fertiliser-responsive varieties
to provide higher yields. This
ecosystem has been sub-divided into
three sub-ecosystems:
Irrigated, with favourable
temperature;
Irrigated, low-temperature,
tropical zone; and
Irrigated, low-temperature,
temperate zone.
Rice area has been
estimated to be about 148
million ha, 95% of which is
in South and Southeast
Asia. Rainfed lowlands
cover about 27% of the
world’s total rice area and
contribute 18% to the total
rice supply.
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