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

2. 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

3. Degraded land covers approximately 22.88 %, (11.7 mil.ha) comprising five major soil problems, acid sulfate soils peat soils sandy soils shallow soils inland saline soils.

4. Peat soils soil has major stress with high organic matter

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

6. Sandy soils soil has major stress with low water holding capacity

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

11. Shallow soils soil has major stress with shallow soils

14. Laterlite layer

15. Saline soils soil has major stress with salinity

23. 4 Apr.2003 6 years ago

24. 9 Oct.1976 33 years ago

25. 31 Dec.1953 56 years ago

26. Assessment from - soils group data - mapping salt crust

27. Soil information of Thailand - Soil Taxonomy system - 300 Soil series - Each soil series show > 20 properties landformparent materialdepth drainageslopetexture colormottlestructure %BSpH CEC %OMPK NaCaMn ECfertility

32. From 300 series grouping to 62 soil series groups Group properties relate to land degradation group 2 9 10 11 14 : acid sulfate soils group 57 58: peat soils group 41 44: sandy soils group 46 47 48 49: shallow soils group 20 : saline soils

33. group 2 9 10 11 14 : acid sulfate soils C, acid layer / marine clay C, acid layer < 50 cm C, acid layer 50 -100 cm C, Acid + saline C, acid layer > 100 cm

34. 13.526.93shallow 3.982.04sandy 0.800.04peat 1.710.88 acid sulfate %Mil.ha problem

35. acid sulfate

36. Peat soils

37. Sandy soils

38. Shallow soils

39. New soil map 1:25,000

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

41. Method 1.Grouping Lowland soils, separate from Upland soils 2. Image analysis by Supervise Classification, TM band 1 4 7 3.Take draft map to do field check 4.Correct draft map to fit field condition 5. Input corrected map data 6. Layout map

42. Geolog y

43. Band 1 - 7

45. SOILS MAP

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

52. 3.59 %1.84 mil.haSaline soil

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

54. The Land Development Department has been responsible for various studies on the occurrence and improvement of degraded lands since 1963. 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.

55. Thank you