Problem soils & its management Satira Udomsri, LDD
Kingdom of Thailand Location: Southeast Asian mainland 5 o -20 o N 97 o -105 o E Area total: land: water: Capital: 513,120 sq km 510,890 sq km 2,230 sq km Bangkok Population: 64.8 million people (2014) Elevation extremes: lowest point: Gulf of Thailand 0 m highest point: Doi Inthanon 2,576 m
Climate of Thailand Climate regimes: Mainly Savanna climate and tropical monsoon in the Peninsular south and southeast coast Annual temperature: 24-30 o C Average annual rainfall: 1,100-1,500 mm. Major high rainfall zones Peninsular South & Southeast coast The low rainfall zone is found in the rain shadow of the Western mountains 1. the dry season or cool season from November through February during the Northeast monsoon. 2. the hot season of March, April and May with hot weather and variable winds. (34 o C & 75% humidity); 3. the rainy season from May through October during the Southwest monsoon. (32 o c -< 20 o c + a drop in humidity) Average Annual Rainfall (30 years: 1973-2002) Aver. Rainfall (mm)
Soil Moisture Regimes Aquic soil moisture regime (water) Udic soil moisture regime (moist) Ustic soil moisture regime (dry)
Soil Moisture Regimes Aquic soil moisture regime low-lying areas used for rice cultivation Soils are saturated by ground water or by impounded water for at least 6 months Udic soil moisture regime dominates in upland soils of Peninsular South and the Southeast cost regions where rainfall is high and well distribution during the year. Ustic soil moisture regime mainly found in upland soils of Northeast Plateau, Central Plain, North&West continental Highlands and Central Highlands
Land Use of Thailand 2008-2009 Agriculture area Build up area Forest area Water area Other
Physiographic Regions of Thailand 6 1 2 3 4 5 Soil and Landform Relationship: Based on the combination of + landforms + soil parent material + vegetation cover + climatic conditions 1. North & West Continental Highlands 2. Central Plain 3. Central Highlands 4. Southeast Coast 5. Northeast Plateau 6. Peninsular South
Physiographic Regions of Thailand 1 2 66 3 4 5 Area No. 1&3 Northern ranges and valleys and western mountains: high mountains alternate with plains, with large flood plains along the major rivers. Area No. 2 Central Plain: flood plains of the major rivers and their tributaries such as Chao Phraya river. Some highlands, mountains and hills at the western and eastern limits of the central region. Area No. 5 Northeast Plateau: an extensive plateau, with lowlands alternating with uplands. Area No. 4&6 Southeast Coast and Peninsular South: mountainous ridge extends along the length of the peninsula and coast, and coastal areas.
Fertile soils and vary in profile characteristics according to the differences in rock North & West Continental Highlands Consist of hilly to mountain and with narrow intermontaneous valleys Recent and semi-recent alluvial in basins of Ping Wang Yom and Nan rivers are mostly narrow
The Central Plain: The alluvial plain of the Chao Phraya River and tributaries and the surrounding piedmont belts; The Bangkok Plain The surface layer are composed of the recent and semi-recent alluvial deposits, then The plain has a deep with fertile soil
The Central Highlands: Fertile soils/produce a good yield; best for chemical properties, worst in physical properties (heavy soils, shrink-swell properties, high in bulk density
The Southeast Coast: The southeast coast is rolling land with rolls to its north and Mountains to its east, and with narrow coastal plains Dominated by terrace formations, numerous separate hills and ranges
The Northeast Plateau: > 200 masl Sandy-loamy soils with low fertile some problems; skeletal (lateritic), saline soils, sandy soils
The Peninsular South: continuation of the western mountains and river and coastal plain Due to the mount of rainfall; High in leaching + very low in plant nutrient content
WHY? Many kind of soils Differ in thickness, texture, draining capacity, fertility, degree of flooding, etc.. Suited for wetland rice, forest trees Differ from places to places
Soils resources of Thailand depending on clorpt cl = climate o = organism r = relief/topography p = parent material t = time/ profile development
How to get the soil data? To obtain soil information; Soil survey and classification techniques Soil survey activities were first introduced to Thailand in 1935
Provisional Map of the Soils and Surface Rocks of the Kingdom of Thailand by R.L. Pendleton The first general soil map of Thailand
GIS to produce soil map Data gathering Soil Survey of Thailand Slope class Orthophoto GEO Hill shade DEM Satellite map, topographical map, geology map, soil map, present land use map, forest map, conservation zone district map, climatic data etc.
For future Soil map 1:25,000 (except Sloping area) 1:4,000 (specific area)
Suitable Soils
Problem soils (Degraded Soils) There are 6 main soils with severe constraint for agronomic productions: Moreover, the mountainous soils, where slope are steeper than 35%, are also considered as problem soils due to steepness of the area which results in erosion and other environmental problems.
+ ph < 7.0 (ph < 5.5 = unsuitable) problem + prone to erosion + toxicity (Al and Mn) + deficient in minerals; P K Mg Ca + occurrence of plant diseases
Acid soils Way to improving + broadcasting lime + adding organic matter/plant nutrients + mulching soil + selecting tolerant crops + Good Agricultural Practices
Acid sulfate soils properties + accumulation of partly or completely decomposed plant residues + swamp/ lagoon + low ph
Acid sulfate soils
Acid sulfate soils problem + Acidic to very strongly acid + nutrient deficient/ imbalance of plant nutrients + toxicity in plants (high in Al Fe Mn)
Acid sulfate soils Way to improving + flushing the ground with water + using liming materials (marl, lime, dolomite) + adding organic matter/nutrients (fertilizers)/ bioextract (super LDD2) + selecting plants (pineapples, guava, palm oil)
Organic soils properties + accumulation of partly or completely decomposed plant residues + swamp/ lagoon + low ph