Problem soils & its management

Satira Udomsri, LDD

Kingdom of Thailand

Population: 64.8 million people (2014)

Elevation extremes:

lowest point: Gulf of Thailand 0 m

highest point: Doi Inthanon 2,576 m

Location: Southeast Asian mainland

5o-20oN 97o-105oE

Area total: 513,120 sq km land: 510,890 sq km

water: 2,230 sq km

Capital: Bangkok

Aver. Rainfall (mm)

Average Annual Rainfall (30 years: 1973-2002)

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

Climate of Thailand

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 oC & 75% humidity);

3. the rainy season from May through October during the

Southwest monsoon. (32 oc -< 20 oc + a drop in humidity)

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

Soil Moisture Regimes

Land Use of Thailand

2008-2009

Agriculture area

Build up area

Forest area

Water area

Other

Physiographic Regions of Thailand

24

53

1

6

1. North & West Continental Highlands

2. Central Plain

3. Central Highlands

4. Southeast Coast

5. Northeast Plateau

6. Peninsular South

Soil and Landform Relationship:Based on the combination of

+ landforms

+ soil parent material

+ vegetation cover

+ climatic conditions

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.

6

24

53

1

6

Physiographic Regions of Thailand

Consist of hilly to mountain and with narrow

intermontaneous valleys

Fertile soils and vary in profile characteristics

according to the differences in rock

North & West Continental Highlands

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

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

The Peninsular South:

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

WHY?

Soils resources of Thailand depending on clorpt

cl = climateo = organism

r = relief/topographyp = 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

DEM

Hill shade

GEO

Orthophoto

Slope class

Data gathering

Satellite map, topographical map, geology map, soil map, present land use map, forest map, conservation zone district map, climatic data etc.

GIS to produce soil map

Soil Survey of Thailand

For futureSoil map 1:25,000(except Sloping area)

1:4,000 (specific area)

Suitable Soils

There are 6 main soils with severe constraint for agronomic productions:

Problem soils (Degraded Soils)

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)

+ prone to erosion

+ toxicity (Al and Mn)

+ deficient in minerals; P K Mg Ca

+ occurrence of plant diseases

problem

+ broadcasting lime

+ adding organic matter/plant nutrients

+ mulching soil

+ selecting tolerant crops

+ “Good Agricultural Practices”

Way to improving

Acid soils

Acid sulfate soils

+ accumulation of partly or completely

decomposed plant residues

+ swamp/ lagoon

+ low pH

properties

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

Acid sulfate soils

+ 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)

Way to improving

Organic soils

+ accumulation of partly or completely

decomposed plant residues

+ swamp/ lagoon

+ low pH

properties