Soil Profiles: Chat
Chat Series
The Chat Series is a member of the Lanchang Family which is a very fine, kaolinitic, isohyperthermic, red-yellow Tipik Lutualemkuts. It is developed over fine grained sedimentary rocks. The soils have brown to yellowish brown clay to clay loam A horizons. The B horizons are deep and uniform with strong brown to yellowish brown colours and heavy clay textures. At depths below 70 cm the colours may become yellowish red. At depth, occasionally a layer of vein quartz may be present. The structures are weak to moderate, medium subangular blocky with friable consistence and patchy to discontinuous clayskins occur on ped faces. These soils have been identified over iron-rich shales sometimes having veins quartz. These soils have a kandic horizon and hence must have a CECclay of less than 16 cmol (+) kg–1 clay in all subhorizons between 25 to 100 cm depth. No significant clay decrease to 100 cm depth is permissible.
Type Location
The Chat Series was first established by Lim (1977). The above pedon was from the type locality along a timber tract between Benta town and Kampong Chat near Jerantut, Pahang, on rolling topography (6–12°) at an elevation of about 80 metres (250 ft). Location: Topographic Sheet 3860, 3°58’50” N, 101°59’20” E (Grid Reference 3860 – 435395 m).
Range in Characteristics
The Chat Series was formerly mapped as the Munchong Series. In the past the Munchong Series included soils with both with an oxic as well as an argillic or kandic horizons. Those having a deep kandic horizon and predominantly strong brown colours are now reclassified as the Chat Series. These soils also must have a CECclay of less than 16 cmol (+) kg–1 clay in all subhorizons between 25 to 100 cm depth. The A horizons of the Chat Series have colours ranging from brown yellowish brown to dark yellowish brown (10YR4/4, 4/6, 5/3, 5/4, 5/6, and 7.5YR5/4) and clay to clay loam textures. The upper part of the B horizons of the Chat Series often has yellowish brown, strong brown and rarely reddish yellow colours (10YR5/6, 5/8; 7.5YR5/6, 5/8, 6/6, 6/8) and uniformly clay textures. Hues of 5YR may be permitted but cannot occur within 50 cm of the surface. Very often the strong brown colours (7.5YR5/8) colours extend uniformly to great depths. The clay contents in the B horizon average over 65% and increase slightly with depth. The structures in the B horizons are weak to moderate medium subangular blocky and consistence is friable. The structures become slightly stronger and consistence slightly firm with depth. A stoneline often of fine nodular petroplinthite and/or stones of vein quartz may be present at depths below 1.25 m. Clayskins which are often patchy in the upper but discontinuous in the lower part of the B horizon are a distinctive feature of these soils.
Competing Soils and Their Differences
The 10YR and 7.5YR hues of the Chat Series in the upper part of the B horizon distinguishes this soil from the Segamat, Prang, Kampong Kolam and other redder soils. The presence of an kandic horizon separates the Chat Series from the Munchong, Jerangau and Katong Series. The Lanchang Series has similar colours but appears to have more medium to coarse sand than the Chat Series as it is developed over granodiorite. The Yong Peng Series on the other hand has textures which are more silty. The Lanchang and Yong Peng are developed from igneous rocks – granodiorite and dacite respectively while the Chat from shales. A soil referred to by some surveyors as the Razak Series is similar to the Chat Series and is hence this name should no longer be used. The clay content of more then 60% separates the Chat Series from the Bungor, Bedup, Kumansi/deep and Serdang Series. The Ulu Dong Series has redder colours and has more than 60% clay. Soils of the Melugu, Stass and Padawan Series also have more than 60% clay but have CECclay values exceeding 16 cmol (+) kg–1 clay in some subhorizon within 25 to 100 cm depth.
Setting
Soils of the Chat Series have been mapped on undulating to hilly terrain. They have been mapped at elevations ranging from 15–100 m (50–300 ft).
Principal Associated Soils
The Chat Series is often associated with soils of the Munchong, Serdang, Malacca, Gajah Mati and Prang Series. The Serdang Series is developed over quartzites and sandstones and has sandy clay loam textures and brownish yellow to yellowish brown colours. The Malacca and Gajah Mati Series are characterized by a thick band of lateritic nodules occurring within 50 cm of the surface. The Prang Series has hues which are much redder (2.5YR and 5YR) within 50 cm of the soil surface and has an oxic horizon. The Bungor Series has a fine sandy clay texture with more fine sand, consistence is firmer and structures are better developed. The colours of the Bungor Series are also often yellower than that of the Chat Series.
Drainage and Permeability
Soils of the Chat Series are well drained and have a good permeability.
Use and Vegetation
Rubber, oil palm and fruit trees are the main crops grown on this soil. In parts of Pahang and Kelantan, some of these soils may still be under primary forests.
Distribution and Extent
The actual distribution of these soils is not known. However, it appears that many of the areas mapped as Munchong Series in the past may be Chat Series. These soils have so far been identified in Selangor, Pahang, Johore and Kelantan. They may also be present in Sabah and Sarawak.
Series Established
This soil was established near Kampong Chat just south of Benta town in Pahang. The source of name is Kampong Chat, Pahang, Peninsular Malaysia.
Remarks on Classification
The Chat Series is classified here according to the Malaysian Soil Taxonomy – Second Approximation (Paramananthan 1998) as a member of the very fine, kaolinitic, isohyperthermic, red-yellow family of Tipik Lutualemkuts. They are classified as soils have a thick kandic horizon in which the clay contents increases or remains constant to a depth of over 100 cm and have a CECclay of less than 16 cmol (+) kg–1 clay between 25 to 100 cm depth. In the Keys to Soil Taxonomy – Eighth Edition (Soil Survey Staff 1998) the Chat Series are probably Typic Kandiudults. In the FAO/UNESCO Soil Map of the World – Revised Legend (FAO 1990) these soils would be classified as Haplic Nitisols.
Suitability for Agriculture
The Chat Series appears to be a highly suitable soil for agricultural development. The terrain is probably the major limitation in these soils. In areas where droughts or low rainfall is experienced these soils can give rise to moisture problems particularly during the establishment of the crop.
