Page 8 - Final Report Improving information and developing a repository of sustainable soil management practices in Asia

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reported that more than 0.6 million hectares or 1.31% of the total area in Thailand is salt affected

soils, comprising of the inland and the coastal salt-affected soils. The inland salt-affected soils in
Thailand are formed through geochemical process and distributed in the northeastern part of the

country while coastal salt-affected soils originated from seawater scattered along the coastal lines.
The salt-affected soils are classified as slightly, moderately, severely salt-affected soils and

potential salt source area and the management practices are in line with this classification.

The wide spread inland salt-affected soils in the Northeast of Thailand caused by both natural and

anthropogenic salination processes. Management of inland salt-affected soil depends upon the
degree of salinity and the prevalent local salination processes. In general, salt-affected soils in the

northeast are high in sodium and chloride content, sandy and low in fertility. For the slightly to

moderately salt affected soils, the areas are generally used for rice cultivation or other cash crops.
Salt affected soil improvement practices mostly applied in these areas involve the use of

appropriate technology packages, including the selection of salt-tolerant crop species and the use
of organic amendments such as compost, organic matter, and green manure.

Numerous studies showed that application of organic amendments such as green manure, farmyard
manure or compost to increase soil fertility and improve soil physical properties. The use of

organic amendments in combination with reshaping the paddy field was another effective method
that LDD promotes to farmers to increase rice yield in salt affected land. Furthermore, land

leveling with planting salt tolerant trees on the ridge was successfully remediated the moderately

salt affected soils.

Prevention and reclamation practices are used in strongly saline soils. In the Northeastern where

strongly salt-affected soils occur, biological control as reforestation which include screening of
suitable salt-tolerant varieties of plants with a deep rooting system and high consumptive use of

water are recommended to prevent spread of soil salinization. These plants have been grown in
saline areas to reduce amount of excess water that flows to water table, this saline which is lower

from the groundwater table will not up to soil surface. For salt-tolerant trees, Acacia ampliceps,

Casuarina glauca and Melaleuca acaciodes, grew successfully well in the severely salt-affected
soils. While some native species namely Azadirachta indica, Cassia siamea, Tamarindus indica

and Pithecellobium dulce could also tolerate at high salinity level.

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