Land Degradation Assessment in Thailand Somsak Sukchan and Rungsun Im-Erb Land Development Department, MOAC

21 million ha are currently under crops 13 million ha are forests 17 million ha compose of urban area, public area, sanitation, swamp land, railroads, highways, real estates and others Landuse map Thailand 51 mil. ha

Degraded land covers approximately %, (11.7 mil.ha) comprising five major soil problems, acid sulfate soils peat soils sandy soils shallow soils inland saline soils.

Peat soils soil has major stress with high organic matter

Acid sulfate soils soil has major land stress with acid sulfate condition

Sandy soils soil has major stress with low water holding capacity

Arial photo in 1954Arial photo in 1996 Ban Phai, Khon Kaen

Shallow soils soil has major stress with shallow soils

Laterlite layer

Saline soils soil has major stress with salinity

4 Apr years ago

9 Oct years ago

31 Dec years ago

Assessment from - soils group data - mapping salt crust

Soil information of Thailand - Soil Taxonomy system Soil series - Each soil series show > 20 properties landformparent materialdepth drainageslopetexture colormottlestructure %BSpH CEC %OMPK NaCaMn ECfertility

From 300 series grouping to 62 soil series groups Group properties relate to land degradation group : acid sulfate soils group 57 58: peat soils group 41 44: sandy soils group : shallow soils group 20 : saline soils

group : acid sulfate soils C, acid layer / marine clay C, acid layer < 50 cm C, acid layer cm C, Acid + saline C, acid layer > 100 cm

shallow sandy peat acid sulfate %Mil.ha problem

acid sulfate

Peat soils

Sandy soils

Shallow soils

New soil map 1:25,000

Inland Soils salinity assessment by RS and GIS technique + ground survey Data – LANDSAT TM – soil – ground water quality – geology – contour line

Method 1.Grouping Lowland soils, separate from Upland soils 2. Image analysis by Supervise Classification, TM band Take draft map to do field check 4.Correct draft map to fit field condition 5. Input corrected map data 6. Layout map

Geolog y

Band 1 - 7

SOILS MAP

Salt crust % Salt crust > 50 % Salt crust 1-10 % 50 % 10 % 1 %

3.59 %1.84 mil.haSaline soil

Soil erosion degradation : USLE Nutrient degradation ? Almost cultivated land found nutrient degradation

The Land Development Department has been responsible for various studies on the occurrence and improvement of degraded lands since The highlight outputs of its product have been used to conduct and disseminate to the stakeholders in the degraded lands including to increase awareness of decision-makers, which would be a better chance for having sustainable use of marginal lands, particularly to enhance good agricultural production to meet the fast- increasing demand.

Thank you