Webpages with more detailed information.
Thesis, CO2 adsorption/emissions
Land Classes and Areas
Impact, including CO2 emission
Problems, including CH4 emissions
Water Management System
Good rice yields in
swampland require an intensive drain and water control system, this should include an
on-farm water management system.
Note: It should
be realized that most recommendations discussed here apply to Schemes suitable for
so-called second stage development. Second Stage
Development is a term used to indicate Government sponsored schemes in swamps for
which it is feasible to upgrade them with an improved water control system. However this
system is still without pumped irrigation. (Third Stage Development)
Most poorly drained
soils in the reclaimed Swamplands of Indonesia do not have sufficient percolation for high
yields of rice. By the absence of an on-farm water management system and lack of
understanding how to operate the water management system, the upgraded swamp schemes
deteriorate again as a result of insufficient maintenance of the
canals related to the low farmer's interest. (caused by the low yields)
This main cause of
the insufficient percolation relates to:
The Canal Supply system. The water supply is not adequate to
provide sufficient water for percolation. An intensive tertiary canal system with
ample shallow field ditches will be a solution for good water supply. The more intensive
the lay-out of the canal system, the larger the extent of the potential areas for good
water supply will be. This water supply system is based on irrigation at high tide.
Irrigation for wetland rice requires that land levels should not be higher than 20 cm
above mean high tide level during springtide during periods of dry spells. Further the
distance of the rice field to the adjoining tertiary canal should preferable not be more
than 100 m. to reduce the distances for the on-farm water supply system.
The On-farm Water Management system. In most cases an intensive field ditch system for supply and drainage
does not exists. This has two negative effects. Insufficient water reaches the fields and
insufficient drainage occurs for leaching of the toxic components in the groundwater.
Drainage of excess rain & tidal water occurs often only in the upper 20 cm of the
soil, because of a ditch-wall effect in
the tertiary canals and field ditches. (ditch wall effect= clogging of holes and cracks on
the walls of the ditches, causing extreme low permeability). This prevents the leaching of
the deeper subsoil and is a main cause of the extreme high toxicity's, often found in the
fields. A subsurface drainage system will improve percolation considerably (there are no
ditch wall effects ) and will reduce the workload for farmers to maintain the water
The Operation of the Control gates. Training of Water User's
Associations and gate operators is required and by means of the Model Areas the farmer's
should be convinced the system based on leaching/percolation is working. This needs time
for implementation. At present farmers tend still to operate the system for water
retention as much as possible as soon there is high rainfall. This planting season there
is ample prove that farmers who planted early with high rainfall and lots of
leaching/percolation found much better yields than farmers who planted later with even
higher rainfall but with mainly water retention in their fields during early growth of the
See also proposed improvements.
See also WebPage
Thesis for information concerning
the need for percolation.
The Water Management system consists of three components:
Water supply and
drainage system. This is the most critical part for good water management and high yields.
Often the water supply is experienced as the most critical part of the water management
system. As a cure for the insufficient water supply the control structures are closed.
However this will work counter-productive, because it will decrease percolation and
consequently increases the toxicity levels in the field. The system should aim at
increasing both water supply and improving drainage.
and information on the recommended water supply/drainage system see Web page System.
Soil/water management and
operation system. A proper operation of the irrigation/drainage system should benefit the
yield levels and the potentials for crop diversification. The soil/water management should
aim to promote the ripening of the soft soils by permitting the drying of the surface
layers during the dry season. Deep plowing followed by intensive puddling for land
preparation will benefit the yields. The water levels in the field should not drop below
30 cm below the surface during the growth period of the rice. For that reason ample water
supply is crucial.
description of the factors important for a good soil/water management is given in Web page
system. The traditional developed areas usually have a well organized
institutional infrastructure. It are usually the more difficult to operate areas where
there are problems. Lack of understanding to apply the proper Soil and Water Management
system and the lack of Operation & Maintenance budget and facilities are the key
limitations for improvement.
For more information
see Web page Institutions.
See also Table of Contents.