沙漠研究 22-1, 33 -36 (2012 )"ICAL 1 / DT X"

Journal of Arid Land Studies－Refereed Paper－Soil Physical Properties to Grow the Wild Licoriceat Semi-arid Area in Mongolia
Atsushi MARUI*1), Tomoaki NAGAFUCHI1), Yoshiyuki SHINOGI1), Noriyuki YASUFUKU2),
Kiyoshi OMINE2), Taizo KOBAYASHI3), Atsushi SHINKAI2), Indree TUVSHINTOGTOKH4),
Bayart MANDAKH4) and Battseren MUNKHJARGAL4)
Abstract: Wild licorice (Glycyrrhiza uralensis) is an important medicinal plant. It is grown in Asia, especially in the semi-arid
region of China and Mongolia. Recently, overharvesting of wild licorice has caused land deterioration and/or desertification, andsome exporting countries have begun restricting the export of wild licorice. The objective of this study is to prevent desertification byestablishing a method for cultivating high quality licorice. First, a field investigation of the habitat of high quality wild licorice wasconducted in the semi-arid region of Southern Mongolia in May 2010 and in Northeastern Mongolia in September 2010. Second, toevaluate the soil properties of the areas where wild licorice grows, physical experiments such as soil particle size distribution, soil waterretention, saturated hydraulic conductivity, and unsaturated hydraulic conductivity were conducted. Third, to research therelationship between soil water content and the transpiration of licorice from saturation to the wilting point was observed in a potexperiment. As a result, many large areas of wild licorice were found in Southern Mongolia with well-drained sandy soil and little
available moisture. These results will contribute to effective water management in semi-arid regions for growing wild licoricebecause the optimum soil properties for growing high quality licorice have been clarified.
Key Words: Semi-arid region, Soil permeability, Transpiration, Water retention, Wild licorice

1. Introduction
Glycyrrhiza uralensis (L) (hereinafter, called licorice)
grows wild in Asia, especially in the semi-arid region of Chinaand Mongolia. Licorice is an important medicinal plant
because 70% of traditional Kampo medicines contain
Glycyrrhizin (hereinafter, called GL) which is derived fromlicorice. Recently, the overharvesting of wild licorice has
caused land deterioration and/or desertification, and some
exporting countries have begun restricting the export of wildlicorice. Yamamoto and Tani (2005) reported that in 1984 theChinese government restricted the collection of licorice bypeople living in regions other than the 3 northern regions, andin 2000, the Chinese government restricted the collection ofwild licorice nationwide (Yamamoto and Tani, 2002).
Therefore, the exhaustion of medicinal plant resources is ofconcern. However, there is a continuing high demand forlicorice. Hayashi and Sudo (2009) summarized the economic
importance of licorice extracts used for cosmetics, foodadditives, tobacco flavors, and confectionery foods.
There are two suggested means to increase the supply oflicorice. One is to cultivate licorice in the semi-arid regions ofChina and Mongolia while combating desertification, and theother is to cultivate licorice in Japan. Abe et al. (2005)
indicated that the cultivation of medicinal plants in arid regions
was expected to be an alternative income source. Yamamotoand Tani (2005) reported that licorice harvested in the 4th year
after seeding conformed to the JP XV standard (The JapanesePharmacopoeia XV, 2006) for GL content in China (In order touse licorice as a medicinal plant in Japan, the GL content must
exceed 2.5%). In another approach, Zhang and Xiong (2008)
reported that N+ ion beam irradiation made licoricesalt-tolerant.
Kusano et al. (2003) suggested that selecting a superiorstrain of the licorice plant produced high quality licorice.
Shibano and Ozaki (2011) indicated the possibility of
producing high quality licorice in 2 years by selecting superior
types. In another approach, nutriculture has been studied.
Kakutani et al. (1997) reported that nutriculture usingRockwool could increase the GL content of licorice. Sato etal. (2004) reported that increasing nutrient concentration
increased the GL content of licorice. These efforts haveadvanced cultivation methods.
The objective of this study is to prevent desertification andto establish cultivation methods for producing high quality
licorice in semi-arid regions. First, field investigations of highquality licorice were conducted in semi-arid regions of* Corresponding Author: marui.atsushi.281@m.kyushu-u.ac.jp
6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581 Japan1) Faculty of Agriculture, Kyushu University, Japan

3) Faculty of Engineering, University of Fukui, Japan

2) Faculty of Engineering, Kyushu University, Japan

4) Institute of Botany, Mongolian Academy of Sciences, Mongolia

NE2Mongolia

・NE5S1NE3NE4S2S3Fig. 1. Map of investigation area in Mongolia.

Southern Mongolia in May 2010 and in Northeastern
Mongolia in September 2010. Second, to evaluate soil
properties in the area of growing wild licorice, physical soil
experiments such as particle size distribution, soil water
retention, saturated hydraulic conductivity, and unsaturatedhydraulic conductivity were conducted. Third, to research therelationship between soil water content and the transpiration oflicorice from saturation to the wilting point was observed in apot experiment.

2. Materials and Methods
2.1. Investigation for soil properties growing wild licoricein Mongolia
Field investigations of soil properties for growing wildlicorice were conducted in the Bayankhongor prefecture,
Southern Mongolia, in May 2010 and in the Dornod prefecture,
Northeastern Mongolia, in September 2010. Figure 1 shows
the location of the fields under investigation designated as sites
S1-S3 at Bayankhongor and sites NE2-NE5 at Dornad. Therewas some licorice as well as other native plants at site S1, which
had an area of 25 × 5 km. Only licorice was growing in highdensity at site S3, which had an area of 15 × 5 km. There
were no plants growing at site S2. The ground water level
was –3.0 m near site S1 and –1.9 m near site S3. The total
precipitation near the investigation site S was 129.6 mm/year,
making it an arid region. However, there was some licoricealong with more than 50 species of weeds around site NE, anarea classified as meadow and steppe. Site NE had a low
density of licorice. The ground water level was –3.0 m near site
NE3, and the total precipitation near site NE was 207.6 mm.
Soil samples near wild licorice roots were collected at sites
S1 and S3, and at sites NE2-NE5. For comparison, Japanesesoil, silica sand (size 7), and decomposed granite soil wereanalyzed. These samples were analyzed for saturated
hydraulic conductivity, unsaturated hydraulic conductivity, soil
texture, and soil moisture characteristic curve. Saturated
hydraulic conductivity was measured using a falling head
permeability test. The soil moisture characteristic curve wasmeasured using a suction plate method and a centrifuging
method. The unsaturated hydraulic conductivity was measured
using the one-step method (Doering 1955). The unsaturated
hydraulic conductivity of the low moisture area could not bemeasured by the one-step method, so the capillary tube model(Jury and Horton, 2004) was used for estimation Eq. (1).

K (θ s − ∆θ ) =τs 2 ∆θ12hρ w g J =i +1 h J2M∑(1)

where τ is tortuosity, σ is surface tension, ρw is the density ofwater, g is the acceleration due to gravity, η is viscosity, θ is thevolumetric water content, and h is the potential head.
2.2. Pot experiment of licorice transpiration
Plastic tube cultivation experiments to evaluate thetranspiration rate of licorice from a saturated condition to dry
were conducted over 50 days at the Phytotron at Biotron
Institute, Kyushu University. Silica sand (size 7) was placedin a plastic tube made of polyvinyl chloride (φ = 10.74 cm, h =50 cm) at a bulk density of 1.4 (g/cm3). Licorice wascultivated for 1 year in a greenhouse and then transplanted tothe tube where it was grown for a month before the experiment.
The air in the greenhouse was maintained at an eventemperature of 25ºC, and the relative humidity was 70%. The
soil water content was measured by TDR at depths of 10 cm,20 cm, 30 cm, and 40 cm. The soil surface was covered withvinyl to prevent evaporation so the cultivation pot could beweighed with an electronic balance to determine transpiration.

3. Results and Discussions
3.1. Soil properties
The soil textures of all samples from the southern site S3contained high percentages of sand according to the standard ofInternational Society of Soil Science (Table 1). In thenortheast site, almost all of the soil textures were “loam” or “siltloam.” As a result, the soil best suited for growing wildlicorice was sandy soil with good drainage and little water
retention, though licorice can be grown with lower yields inother conditions.
Figure 2 shows the soil moisture characteristic curves ofeach site. The volumetric water content of the southern sitewas 1-3.6 % at sampling time. The graphs of sites S1 and S3
were similar, and the soil at site S3 was similar to silica sandabove 130 cm of H2O. The readily available moisture at site
S1 (60 cm), site S1 (80 cm), and site S3 was 8.4%, 7.9%, and13.0% respectively. These values were low compared withgeneral farmland. The metric potential at the sampling timewas 1300-10,000 cm of H2O, which is more than the wilting
point (1000 cm of H2O). This indicated the possibility that

Table 1. Soil separation and soil texture classification
Cf.: ISSS (International Society of Soil Science)sand silt clay(%) (%) (%)

sampleSite S3

soiltexture

0cm

10000S

30cm

9451S

60cm

94

51

S

100cm
decomposed soil

80
96

16341

SS

silica sand (7size)

10000

S

5cm

66

286

SL

10cm
20cm

46
44

43
45

1111L
L

Site NE2-1

sampleSite NE3

Site NE4

sand silt clay(%) (%) (%)

Table 2. Saturated hydraulic conductivities (Ks) of soil at each site.

10cm

6233

5L

20cm

48

439L

30cm

365212SiL

40cm

364618

SiCL

5cm
10cm

5959323299LL20cm

513811L

30cm
40cm

46364443

1021SiL
SiCL

30cm

3652

12SiL

60cm

1261

27SiL

40cm
80cm

293857491413SiL
SiL

5cm

57

367L10cm

47

4211L

10cm

60

328L

Site NE5-1 20cm

44471111LL

Site NE2-2 20cm

3454

12SiL

30cm

45
4230cm

3256

12SiL

40cm

50

419L

5cm
10cm

6464

283185LL

10cm
Site NE5-2 30cm

57433546811LL

20cm

470

26

SiC

40cm

3850

12SiL

Site NE2(N-H)

Ks (cm/s)

samplesoil
textureSite S1
Site S3

licorice can grow in severe dry conditions or that its roots canextend deep into the earth, sufficient to reach groundwater.
However, the soil at sites NE2-NE5 had saturated water content
and water holding capacity that were better than the soil at thesouthern site. The volumetric water content of the northeast

9.5×10-380cm-350cmdecomposed
granite soil

7.6×10-3

sampleSite NE3

9.5×108.7×10‐3‐3Ks (cm/s)
10cm

2.4×10-320cm

6.0×10-330cm

1.4×10-340cm

7.1×10‐410cm

5.5×10-320cm

6.1×10-330cm

6.5×10-3

silica sand (size 7)

1.8×1010cm

5.4×10‐320cm

9.3×10‐340cm

1.5×10-330cm‐360cm

6.6×10-4‐310cm

2.4×10-320cm

2.6×10-330cm

3.5×10-3

Site NE2-1

40cm
80cm
10cm
Site NE2-2
Site NE2(N-H)

Fig.3.
Fig.2. Soil water characteristic curves of each site.

60cm

Site NE4

3.0×10
1.8×10‐4

2.5×10-3

Site NE5-1

1.5×1020cm-3

2.0×1040cm

2.9×10-430cm

2.2×10-310cm

1.0×10-310cm

1.2×10-630cm

2.0×10-420cm-440cm

2.7×10-4

3.0×10Site NE5-2

Unsaturated hydraulic conductivities (K (θ)) using capillary
tube model for soil at each site.

site was 6.8-19.5% at sampling time. Almost all of the metricpotential at that time was 1000-10,000 cm of H2O indicating
severe dry conditions, especially at the southern site.
Table 2 shows saturated hydraulic conductivity (Ks). The
results of Ks measurements showed good drainage for all

20

total transpiration

total transpiration (g)

40cm
10cm

1500

1520cm
100010500

530cm0volumetric water content (%)

2000

0010203040

semi-arid regions, because the optimum soil properties for
growing high quality licorice have been clarified.
Acknowledgement
This research was supported by the Grant-in-Aid for
Scientific Research (A) Ministry of Education, Culture, Sports,
Science and Technology, Japan, Grant number: 22246064,
Project leader: Prof. Yasufuku Noriyuki, Kyushu University.

50DaysFig. 4. Total transpiration of licorice and soil water content at eachdepth.

samples except for the deeper layer at the northeast site and allof NE2-1(N-H) (N-H indicates a non-habitat of licorice).
Figure 3 shows the unsaturated hydraulic conductivity (K (θ))
of each sample. Sites S1 and S3 showed the same variationand good drainage, which were different from the decomposed
granite soil. The deeper the soil layer was, the lower K (θ)
became at the northeast site.
3.2. Transpiration of licorice in dry conditions
Figure 4 shows the transpiration rate of licorice and soil
water content at each depth during the drying process. Water
consumption was large at 30 cm because of root density.
Dead leaves were observed by the 30th day when thevolumetric water content at 30 cm was 6%. The metricpotential at that time was about –1000 cm of H2O, which issame as the generally used wilting point. Transpiration
stopped by about the 40th day when volumetric water content
at 30 cm was 4% and the metric potential was –4000 cm ofH2O. After the experiment, the metric potential of the rootzone was more than –15,000 cm of H2O. All the leaves
appeared to have died, but exhibited signs of life after irrigation.
This indicated that the licorice could survive in severe drought
conditions.

4. Conclusions
In this study, the soil properties for growing wild licorice inMongolia were investigated, and transpiration experiments on
licorice were conducted. We found that there were manylarge licorice-growing areas in Southern Mongolia, and thatthese regions had sandy soil, good drainage, and little available
moisture. However, the northeast site, where the soil
comprises loam and silt loam, had low density of licorice.
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wilting point. We hope that these results will contribute toeffective water management for growing wild licorice inReferences
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