沙漠研究 19-1, 277- 282 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

Rehabilitation of Salt Affected Soils with Chemical Geo-Textile
in Northeast Thailand
Machito MIHARA1, Kota SHOJI2, Lalita SIRIWATTANANON3
Abstract: Salt accumulation occurred due to capillary water rise from salt groundwater is one of
the major problems in Northeast Thailand. The salt accumulation is causing a serious farming
problem. So, this study dealt with the rehabilitation strategy on salt affected soils for sustainableagriculture in Phra Yun, Northeast Thailand. Application of chemical geo-textile wasinvestigated in the laboratory experiment using the soil column. The results indicated thatchemical geo-textile could intercept the capillary water rise in the laboratory experiment. Basedon the results of soil column experiment, chemical geo-textile was installed in the salt affected
fields of Phra Yun. The field experimental results showed that EC1:5 values in surface soils ofthe ridges installed the chemical geo-textile did not decrease, as sodium components existing insurface soils could not be washed out by leaching with rainfall. Therefore, leaching experiment
was conducted to discuss the effective leaching measures. Through the leaching experiment, it
became clear that soil permeability improvement is indispensable for washing sodium
components out. Also, the experimental results showed that EC1:5 values were reduced far below
the expected crop tolerance level if applying enough volume of water as same in water height assurface soil depth. In addition, the higher mixing ratio with gravel in surface soils showed thehigher effectiveness for reducing EC1:5 values with leaching.
Keywords: Chemical geo-textile, Leaching, Salt accumulation

1. Introduction
Salt accumulation occurred due to capillary water rise fromsalt groundwater is causing a serious farming problem in NortheastThailand (Fig. 1). There are many studies concerning salt
Khon Kaen
accumulation and suggestion for suitable strategies to be taken toBangkok
overcome the problems. Dissataporn et al. (2002) suggested that
Study area
the groundwater level should be managed below 1.5 m deep from(Phra Yun)soil surface to reduce salt accumulation. Also, Kanazawa et al.
Salt affected area
(2006) reported that the groundwater level in Nong Thung Mon
village of Phra Yun was 0.51 m deep from soil surface in August
2003 of rainy season. Anase et al. (1997) reported that thesub-soil drainage system in addition to the banking was effective
Fig. 1. Salt affected area in Thailand.
for keeping groundwater level lower. Also, Endo and Hara (2000)
reported that the stone layer in soils was suitable measures to intercept the capillary rise of saline water.
However, there are no studies concerning the application of geo-textiles to intercept capillary water risefrom salt groundwater in this area. Therefore, the objectives of this study are to evaluate the applicationof chemical geo-textile for intercepting the capillary water rise from salt groundwater and to discuss theeffective leaching measures.
2. Research site and Methods
2.1. Experiment on intercepting capillary water rise with chemical geo-textile
The effects of chemical geo-textile on intercepting capillary water rise were investigated using the soilcolumn. The soil column was filled with silica sand (Table 1) or Phra Yun soil (Table 2). Chemicalgeo-textile was installed at 23 cm deep from soil surface in the soil column of 50 cm high, and sodium
chloride (NaCl) solution at 6,740-6,820 μS/cm was supplied from the bottom of soil column for 96 hours.
1

Faculty of Regional Environment Science, Tokyo University of Agriculture, Japan, Email: m-mihara@nodai.ac.jp,
Fax: 03-5477-2620
2
Nippon Koei Co., Ltd., Tokyo, Japan
3
Graduate School of Agriculture, Tokyo University of Agriculture, Tokyo, Japan

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Soils were sampled above and below the chemical geo-textile in the soil column, also water content andelectric conductivity (EC1:5) were measured at 24, 48, 72 and 96 hours passed. Figure 2 shows the crosssection of experimental soil column.
Table 1. Physical properties of silica sand.
Particle size distribution (%)

Specific gravity
Silica sand

2.62

0.21 mm

0.149 mm0.105 mm0.074 mm0.053 mmunder 0.053 mm

0.1

0.1

13.7

56.8

23.7

5.6

Table 2. Physical properties of soils in Phra Yun, Northeast Thailand (rainy season).
Depth fromthe soil surface(cm)HorizonHorizon ofsoil deposit
A1A2A3
Horizon oftransitional
B1
B20-23-14
15-20
21-30
31-42
43-75
76-95

SpecificDry density

gravity(g/cm³)

Particle size distribution (%) *GravelCoarsesandFine
sandSilt

Clay

Soil

Saturated

Ignition

texturepermeability(×10-5) cm/s

loss
(%)

2.62

―

0

23.6

70.9

3.6

1.9

S

―

0.70

2.64
2.65
2.63

1.69
1.75
1.77

000

21.3
23.6
25.5

67.3
57
56.5

8
11.9
9.8

3.4
7.5
8.2

LSSLSL

0.25
2.51
1.62

0.88
1.25
1.79

2.64

1.80

022.8

59

10.4

7.8

SL

0.35

1.19

2.65
2.66

1.66
1.64

0025.2
23.2

57.3
55.7

8.8
11.4

8.7
11.4

SLSL

0.15
0.25

1.31
1.48

* ISSS method

Table 3. Chemical properties of soils in Phra Yun, Northeast Thailand (rainy season).
Depth fromthe soil surface
(cm)
0-2
3-14
15-20
21-30
31-42
43-75
76-95

HorizonSodiumCalcium

Electric

Total

Total

concentration

concentration

nitrogenPhosphorus(×10 kg/kg)-5(×10 kg/kg)

conductivity(μＳ/cm)(×10 kg/kg)-5(×10 kg/kg)

7.56

0.632

35.3

22.60

0.71

4.72
31.20
60.70

0.298
0.392
0.651

53.3
395.0522.0

15.90
19.65
27.50

0.57
1.05
0.47

69.30

1.288

629.0

14.71

0.72

76.10
81.40

0.812
0.483

695.0
683.0

12.57
11.70

0.58
0.27

Horizon ofsoil deposit
A1A2
A3
Horizon oftransitional
B1
B2-5-5

10 cm

46 cm

50 cm

Column filled with silica
sand or soil sampled at PhraYun

23 cm

Soil surface
Sampling points

Chemical geo-textile
Sampling points

Sodium chloride solution(6,740～6,820 μＳ/cm)
Column filled with soil sampled

Sodium cloride solution

at Phra Yun, ThailandμS/cm)(6740~6820
Fig. 2. Crosssectional view of experimental soilcolumn.

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2.2. Field experiment with chemical geo-textile
Salt accumulation is causing severe farming problems in Phra Yun. In August 2002, rainy season,
soil profile survey was conducted in salt affected area of Phra Yun to analyze the soil physical andchemical properties as shown in Tables 2 and 3. There was a tendency that EC values and sodium
concentration increased with depth. Also, soil permeability was low ranging from 0.1 × 10-5 to 2.6 × 10-5cm/s.
In salt affected area of Phra Yun, chemical geo-textile was installed at 20 cm deep from soil surface inthe ridge of 40 cm high in December 2002. Soils were sampled above and below the chemical geo-textile
in March 2004 to analyze water content and EC1:5 values. Figure 3 shows the cross section of the ridgewith chemical geo-textile in salt affected area of Phra Yun.

8 cm

20 cm

Samplingpoints
pointsSampring

Samplingpoints
pointsSampring

2cm 2cm 2cm 2cm

Soil surface

Chemical fiber geo-textile
8cm

40 cm

150 cmSampling point
Sampling point
Sampling point
Sampling point

50 cm

Fig. 3. Cross sectional view of ridge withchemical geo-textile.

Fig. 4. Cross sectional view of column
for leaching experiment.

2.3. Experiment on effective leaching measures
Salt affected soil sampled from 0 to 10 cm deep at a same point in Phra Yun during dry season of2004 was used for investigating the effective leaching measures. Although soil texture was sandy, thesoil showed low permeability as shown in Table 2. Only EC1:5 value of 6,710 μS/cm was higher than thatin rainy season in Table 3. For improving soil permeability, the soil was mixed with the gravel in whichdiameter was larger than 1 cm at the various ratios of soil : gravel at 7:1, 3:1 and 1:1. The column of 8
cm diameter and 20 cm high, 402 cm3 in volume, was filled with well mixed soil and gravel.
Total volume of 100.5, 201 and 402 ml of distilled water was supplied to the column at supplying rateof 5, 10 and 20 mm/h. The volume of 100.5, 201 and 402 ml was equal to quarter height of watercomparing to surface soil depth, half of water height comparing to surface soil depth and same height ofwater as surface soil depth. Soils were sampled from 4 layers at 0 to 2 cm, 2 to 4 cm, 4 to 6 cm and 6 to 8cm deep from soil surface, and then water content and EC1:5 values were measured. Figure 4 shows thecross section of the column for leaching experiment.
3. Results and Discussion
3.1 Effects of chemical geo-textile on intercepting capillary water rise
The results of soil column experiment with and without chemical geo-textile were summarized inFigure 5. In the experiment, chemical geo-textile was installed at 23 cm deep from soil surface in the soilcolumn of 50 cm high, and sodium chloride (NaCl) solution at 6,740-6,820 μS/cm was supplied from thebottom of soil column for 96 hours. Water content and EC1:5 values above the geo-textile in silica sandcolumn were significantly smaller than that without the geo-textile at 99% confidence level. It wasconsidered that chemical geo-textile worked well for intercepting capillary water rise.
Although water content above the geo-textile in the column filled with soil sampled at Phra Yun was
remarkably smaller than that below the geo-textile, the difference in EC1:5 values between above and below
the geo-textile was comparatively small.

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Soil surface

010

Depth, cm .

Depth, cm .

1020302030404050500102030
Water content, %40

100 200 300 400 500, ,μS/cm
ECEC
μS/cm
1.5
1:5

Soil surface020

Geo-textile

30

Depth, cm .

1010
Depth, cm .

0

Soil surface

04020

Geo-textile

30
4050500102030
Watre content, %040

100200300400500

EC1:5
μS/cm
1.5,, μS/cm

Soil surface

0

Soil surface

0101020Geo-textile

3040Depth, cmDepth, cm

Soil surface

020Geo-textile

304050500102030

Water content, %400500

1000

1500

2000

μＳ/cm
EC1:51:5,, μS/cm

Fig. 5. Changes in water content and EC1:5 values in soil column.
(1st and 2nd rows: silica sand, 3rd row: Phra Yun soil)

3.2 Effects of chemical geo-textile on reducing salt accumulation in fields
In salt affected area of Phra Yun, chemical geo-textile was installed at 20 cm deep from soil surface inthe ridge of 40 cm high in December 2002, and then soils were sampled above and below the geo-textile inMarch 2004 to analyze water content and EC1:5 values. As shown in Figure 6, water content above thegeo-textile was lower than that below the geo-textile, however EC1:5 values above the geo-textile werehigher than that below the geo-textile.
In addition, there was a tendency for EC1:5 values in the upper parts of the ridges above the geo-textile
to be higher than that without the geo-textile. It meant that rainfall events from January 2003 to February
2004 did not contribute well for leaching sodium components out from top layer of the ridges. Althoughsoil texture was sandy in salt affected area of Phra Yun, the soil showed low permeability as shown inTable 2. It was considered that soil permeability improvement is indispensable for leaching sodium
components effectively.

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3.3 Effective leaching measures
For improving soil permeability, the soil sampled at Phra Yun in dry season of 2004 was mixed withthe gravel in which diameter was larger than 1 cm at the various ratios. The column of 8 cm diameter and20 cm high, 402 cm3 in volume, was filled with well mixed soil and gravel.
The changes in water content and EC1:5 values under different leaching measures were summarized inFigures 7, 8 and 9. The experimental results showed that EC1:5 values were reduced far below theexpected crop tolerance level if applying enough volume of water as same in water height as surface soil
depth. In addition, the higher mixing ratio with gravel in surface soils showed the higher effective for
reducing EC1:5 values due to leaching. However, there was no certain tendency for the effects ofsupplying rate on reducing EC1:5 values.
without geo-textile
01030203005101520
W ater content, %10geo-textile

2040402501000

2000

03000

5EC 1:5, μS/cm

P oint 1geo-textile

2030304040

Soil surface

010Depth, cm

20

Soil surface

010Depth, cm .

Depth, cmwith geo-textile
Soil surface

Depth, cm

Soil
Soilsurface
s urface00101520W ater content, %25

P oint 2201000
2000
EC1:5 , μS/cm

3000

P oint 3Fig. 6. Water content and EC1:5 values in ridges of Phra Yun.
Soil surface

0

Soil surface

0

Original EC 1:5 values

42Depth, cm2466880

Soil surface

0

Original EC 1:5 values
Depth, cmDepth, cm

Original EC 1:5 values

2000 4000 6000 8000 10000 12000 14000 16000

2468002000 4000 6000 8000 10000 12000 14000 16000

2000 4000 6000 8000 10000 12000 14000 16000

EC 1:5 , μＳ/cm

EC 1:5 , μＳ/cm

EC 1:5 , μＳ/cm

Irrigation water depth 80 mm (402 ml)

Irrigation water depth 40 mm (201 ml)

Irrigation water depth 20 mm (100.5 ml)

5 mm/h10 mm/h

20 mm/hFig. 7. Changes in EC1:5 values due to leaching at 12.5 % gravel added.

Soil surface

0

Soil surface

0422446668882000 4000 6000 8000 10000 12000 14000 16000

Original EC 1:5 values
D epth, cm

D epth, cm

D ep th, cm

20

Soil
Soilsurface
surface0

Original EC 1:5 values

Original EC 1:5 values

02000 4000 6000 8000 10000 12000 14000 16000

02000 4000 6000 8000 10000 12000 14000 16000

EC 1:5 , μＳ/cm

EC 1:5 , μＳ/cm

EC 1:5 , μＳ/cm

Irrigation water depth 80 mm (402 ml)

Irrigation water depth 40 mm (201 ml)

Irrigation water depth 20 mm (100.5 ml)

5 m m /h

10 m m /h

20 m m /hFig. 8. Changes in EC1:5 values due to leaching at 25 % gravel added.

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Soil surface

0

Soil surface

0

Original EC 1:5 values

Original EC 1:5 values

4622

4

D ep th , cm

D ep th , cm

D ep th , cm

246

68

880

Soil
Soilsurface
surface0

Original EC 1:5 values

2000 4000 6000 8000 10000 12000 14000 16000

02000 4000 6000 8000 10000 12000 14000 16000

02000 4000 6000 8000 10000 12000 14000 16000EC 1:5 , μＳ/cm

EC 1:5 , μＳ/cm

EC 1:5 , μＳ/cm

Irrigation water depth 80 mm (402 ml)

Irrigation water depth 40 mm (201 ml)

Irrigation water depth 20 mm (100.5 ml)

5 m m /h

10 m m /h

20 m m /hFig. 9. Changes in EC1:5 values due to leaching at 50% gravel added.

4. Conclusions
Salt accumulation occurred due to capillary water rise from salt groundwater is causing a serious
farming problem in Northeast Thailand. This study dealt with the evaluation of chemical geo-textile
application for intercepting the capillary water rise from salt groundwater and the discussion of effective
leaching measures.
Chemical geo-textile could intercept the capillary water rise; however the geo-textile did not work for
decreasing EC1:5 values at field level. Sodium components existing in surface soils could not be washedout by leaching with rainfall. Therefore, leaching experiment was conducted to discuss the effective
leaching measures. Through the leaching experiment, it became clear that soil permeability improvement
is indispensable for washing sodium components out.
Also, the experimental results showed that EC1:5 values were reduced far below the expected croptolerance level if applying enough volume of water as same in water height as surface soil depth. Inaddition, the higher mixing ratio with gravel in surface soils showed the higher effective for reducing EC1:5values with leaching.
References
Anase M., Ai F., Narioka H., Fukumura K., Sugi S. (1997): Study on the production environment improvement for saline soil area,
The case of Khon Kaen, Northeastern Thailand. Bull. NODAI Res. Inst., 8: 8-21.
Dissataporn C., Yacouba K., Mihara M., Yasutomi R. (2002): Effect of groundwater level on salinity content and environmental land
classification. Journal of Japanese Society of Soil Physics, 89: 35-42.
Endo A., Hara M. (2000): Efficiency of salt leaching for inclined layered structures, For improve the cutting-off zone techniqueintroduced in Northeast Thailand. Trans. JSIDRE, 210: 13-18.
Kanazawa D., Mihara M., Noguchi Y., Dissataporn C. (2006): Effects of reforestation on reducing salt accumulation in Chi riverwatersheds, Northeast Thailand. Journal of Arid Land Studies, 15(4): 475-478.