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The deterioration of soil fertility due to the salt pollution of agricultural fields has been a major concern since the 26th of December 2004 when the tsunami ravaged thousands of kilometers of coast along the shore of the Indian Ocean penetrating from 0.5 km up to several kms inland.

Agriculture is the second sector affected after fisheries. FAO estimates that in the countries hardest hit by the disaster (Indonesia, Sri Lanka, Maldives, India and Thailand) a total of 47,000 ha of agricultural land has been damaged by huge waves and sea floods leading to massive crop losses and deterioration of land fertility.

"38,000 ha of the affected areas can be recovered for cultivation in 2005 while the remaining 9,000 ha should be regarded as lost to the sea or in such a bad state that alternatives other than agriculture need to be examined" says Daniel Renault FAO Agriculture Coordinator for tsunami.

This devastation has adversely affected more than hundreds of thousands of farmers and families in the region whose livelihoods depend on agriculture. Furthermore in many countries bordering the Indian Ocean, home gardens although small in terms of area, are very important in helping people to sustain their livelihoods, providing additional nutrients and medicinal plants. In addition to the countless homes that need rebuilding, more than 40,000 home gardens have been devastated and salinized by the tsunami and need to be created from scratch.

Tsunami salinity pollution has two origins:
  • sea water infiltration during the flood and resulting salt fixation along the top soil profile

  • and

  • saline sea deposits (sand or clay).

The duration of the inundation had a direct impact on the quantity of infiltrated salt and this depends mainly on the local post-tsunami drainage capacity.

The fear of a massive decrease in fertility due to soil salinization has prompted many actors to carry out survey campaigns and careful monitoring of the local situation. In the days following the disaster there were wide-spread alarmist reports on the impact of saltwater on the soil and how reclaiming the land would take many years. Fortunately this fear is unfounded, or more precisely it is founded on salinity problems that are very different. It is true that reclaiming soils in arid countries, which have become salinized due to irrigation practices or natural accumulation, can take years, but in the case of sea flash floods it is obvious that the nature, duration and type of impact are very different.

In early January FAO predicted that in general in the tropical humid conditions of the Indian Ocean salt-affected fields would return to their pre-tsunami state in a matter of months. Since then, this prediction has been largely verified, and recent surveys show that where fields are well watered by rain or irrigation and well drained, the situation has returned to normal and farmers have already started to recultivate their fields.
To help governments and communities tackle the challenges, FAO has carried out 3 main types of action for salinity issues:
  • several survey campaigns of soil and water resource salinity
  • provision of hundreds of Ec meters and training to help local actors deal with the salinity issue
  • coordination of efforts for assessment and strategies for recovery.

More than two-thirds of affected arable land is salt cleaned

FAO estimates that for the coming crop season starting in most places in April and May, more than 2/3 of the affected arable land throughout the region has been cleaned of salt through precipitation and irrigation. For the areas yet to be cleaned, the problem is not so much the severity of the salt pollution but the absence of a means of cleaning the soil.

"To leach out accumulated salt on the top soil layers you need to water your field either using natural precipitation or irrigation water and then you need good drainage, either vertical (on sandy soil for instance) or surface drainage for paddyfields to evacuate the saline water " says Daniel Renault, FAO Agriculture Coordinator for tsunami.

With respect to these means of rehabilitation, i.e. watering and drainage, the situation varies on the ground. In the Maldives, the FAO survey shows that the top soil has been largely cleaned from salinity by recent rains. With the Monsoon in sight, the problems have receded as far as salt is concerned. On the dry East Coast of Sri Lanka, heavy precipitations in Trincomalee and Batticaloa districts immediately after the tsunami, respectively 100 mm and 350 mm, have been a real blessing in terms of land cleaning, whereas in the nearby district of Mullataivu lack of precipitation and irrigation facilities associated with very poor drainage will leave depressions along the coast uncultivated for months to come.

Along the Indian coast of Andra Pradesh and Tamil Nadu, farmers are waiting for the onset of the monsoon around July, to leach out their land so that they can begin to cultivate. On the dry East Coast of Aceh, the recovery from salt contamination is strongly dependent on irrigation and drainage, while along the severely damaged West Coast, heavy precipitation has already leached out most of the contaminated lands.

Sigli District East Coast Aceh Province - Indonesia
Left picture: (24th February 05) a field still salinized and water logged 2 months after the disaster, due to lack of irrigation and proper drainage. The drainage canal shown at the bottom of the picture is full of sediment and trash.

Right picture: (same day), near-by fields well served by irrigation and drainage systems on which farmers have started transplanting immediately, rice is developing well.

Special efforts needed for the areas that are still polluted

FAO recommends that a special effort should be made to provide a water supply and drainage to areas that have not yet been cleaned. This of course depends on the local situation, with respect to water resources and the ability to transport and distribute fresh irrigated water. Tapping upstream water storage and using natural streams and pumping facilities for transport and distribution to provide water to affected fields should be funded through the tsunami recovery plans.

A Regional Workshop to consolidate assessments, design land reclamations and plan agricultural recovery

In line with the coordination intervention FAO - through its Regional Office for Asia and the Pacific - is convening a regional workshop to bring together interested parties involved in post-tsunami soil salinity assessment and rehabilitation work. The workshop will be held in Bangkok FAO Office the 31st of March and 1st of April, and will provide participants with an opportunity to share information, collectively assess initial findings related to rehabilitation needs and opportunities, share plans and proposals for future rehabilitation work, and develop mechanisms for collaboration and joint activities.

About 50 experts representing 7 countries are expected at the regional workshop. It is anticipated that the workshop will lead to a comprehensive and consolidated assessment of the situation regarding salinity as well as practical solutions for land reclamation interventions targeting salt, deposits and erosion. Since salinity is only one aspect of land rehabilitation and agricultural recovery it is the intention of the workshop to place the recommendations within a comprehensive regional framework for agriculture recovery, dealing with this issue within a much broader perspective.

Salinity is only one of the many constraints affecting the return to cultivation

Although today we can say that soil salinity is declining progressively and a return to normal conditions for crops can be expected within a few months for the remaining land that has not yet been cleaned, a return to cultivation depends on many other factors. Affected agricultural fields have been damaged by massive erosion, sediment and trash deposits along with salinity contamination. Leaching out salts is only one of the issues to be tackled in reclaiming the land. To revive a healthy agricultural community along the coasts of the Indian Ocean the perspectives should be further broadened in order to achieve an integrated approach to repairing the physical damage, but beyond that to revitalizing the farming systems as well.

"Salt-cleaned lands of the West coast of Aceh may be kept fallow for different reasons, for example because households have not returned to their villages/fields; due to shortage of labour to clean and cultivate the land; and because people have other priorities such as building/repairing their homes; or are suffering from psychological trauma; because there is no capital for inputs; and no equipment and tools" reports Ronald Dijk FAO Agronomist Banda Aceh.

Along with the positive message that initial problems like salinity are being overcome, the challenges ahead require the continuous attention of all actors involved.

As rice is the main crop in the region FAO-AGLW proposes below an example of approach developed for paddyfield but which can be easily extrapolated to any particular other crop.

 contact: tsunami@fao.org © FAO, 2005