Page 9 - Final Report Improving information and developing a repository of sustainable soil management practices in Asia

ห้องสมุดกรมพัฒนาที่ดิน

The coastal salt-affected soils are found scattered along the coast of the Southern and Eastern

regions. These areas are subject to tidal influences and brackish or sea water intrusion. These soils
are very young heavy clay or silty clay with little profile development. They are very saline and

most of them are flooded during spring tides only. Factors limiting plant growth include not only
salinity but also potential acidity and degree of ripening of the soil. Therefore, sea barrier gate has

been recommended to prevent an encroachment of sea water and then the salts from root zone will
be leached by rain or water which has lower salt concentration.

Management of coastal salt-affected soils needs to cope with the specific characteristics of the soil,
crop and water regimes. Rice cultivation is common in these areas. Beside rice cultivation,

economic salt tolerant crops such as tomato, cabbage, sweetpotato, corns, cantaloupe and taro were

suggested with organic amendments and chemical fertilizer application. Moreover appropriate
irrigation with mulching and use of farmyard manure plus chemical fertilizer gave higher crop

yield. In addition the removal of soluble and exchangeable sodium from the root zone was
necessary. Dikes were constructed to prevent high tides from inundating the lands, with flood gates

to regulate brine and fresh water flows. Farmers have also used indigenous technologies to reclaim

their lands.

The last few decades, the rapid increase in numbers of shrimp ponds and salt flat displacing
mangrove forests and agricultural lands. Although inappropriate land use gives farmers high profit,

these land use activities has caused serious soil deterioration and environmental problems in salt

affected soils. It would lead to a long term economic value, investment cost increasing, soil
problems and water management. Several government agencies and related agencies have

therefore set high priority in the research on the impacts of shrimp farming on coastal ecosystems

particularly nutrients and sediment discharged from shrimp ponds on soil and water quality as well
as performance of adjacent economic crops.

SELECTION CRITERIA OF TECHNOLOGIES AND APPROACHES FOR

SUSTAINABLE SOIL MANAGEMENT PRACTICES

The following criteria have been agreed by National Consultancies during LDD regional meetings

to inventory and select technologies for documentation using FAO-WOCAT tools for salt affected

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