Page 153 - E-BOOK English

(Profile features

Vertisols are heavy clay soils with dark colour, fine texture, and deep-wide cracks from
the surface downward when they dry out. Deep and wide cracks allow soil material from the
surface to fall deeper, causing churning and, consequently, an undulating surface. These soils
mostly have low development and unclear horizons in their profiles.

Environment and landforms

Vertisols frequently occur in tropical, subtropical, semi-arid to sub-humid regions where
the process of alternative wetting and drying is pronounced. These soils are often found in
lower landscape positions of plains to undulating terraces. They also occur under natural
grassland and/or woodland and can develop on base-rich parent materials, such as limestone,
in the tropical regions.

Use and management

Vertisols are one of the productive soils of Thailand but still have limitations. In dry
areas, cracks of Vertisols negatively influence agricultural applications such as tillage, whereas
this problem is less in humid or irrigated areas. These soils are being cultivated for corn and
sugarcane in uplands. At the same time, large areas of Vertisols in lowlands are used for paddy
rice production, and some areas are for growing vegetable plants.

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