IJERD – International Journal of Environmental and Rural Development (2011) 2–1

Research article
erdInfluence of Soil Salinization on Growth of Cotton in an
Arid Area in Northwest of China
YAMAMOTO TADAO
Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido Japan
Email: tady@env.agr.hokudai.ac.jp

HASEGAWA SHUICHI
Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, JapanKAMIYA MITSUHIKO
Hokkaido Institute of Technology, Sapporo, Hokkaido, JapanABDISALAM JALALDIN
College of Resources and Environmental Sciences, Xinjiang University, Xinjiang China

ANWAIRE MAIMAIDI
Xayar Water Resource Agency, Xayar, Xinjiang, China

NAGASAWA TETUAKI
Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
Received 8 December 2010

Accepted 28 January 2011

Abstract This paper discusses the influence of soil salinization on cotton plant growth andthe factors that cause salinization in irrigated farmland located along the northern part ofthe Tarim River, Xinjiang Uygur Autonomous Region, China. A field survey wasconducted in a cotton field in Nuerbake Township, Xayar County. The physical propertiesof the soil, fluctuations in groundwater level, the growth of cotton plants and electricalconductivity (EC) of the soil saturation extract were investigated. The quality of irrigationwater and groundwater was also measured at the study area. The groundwater level was
low in the summer and high in early spring; this high level was due to thawing of the soil
and irrigation for planting. However, use of border irrigation temporarily raised thegroundwater level. Even within the same field, the EC of the soil saturation extract
differed depending on locations and soil depths. An EC of the surface soil exceeding 8.0
dSm−1 retarded cotton growth. We found that irrigation water quality did not affect thegrowth remarkably because the EC of the irrigation water was lower than 4.0–6.0 dS/m.
On the other hand, the existence of a less permeable subsurface soil damaged cotton
growth. The difference in hydraulic properties of the subsurface soil is influenced by theamount of clay that affects water and saline movement toward the surface.
Keywords electrical conductivity, soil saturation extract, salinization, irrigation

INTRODUCTION
The degradation of fields by soil salinization causes decrease in crop production. Soil salinization
is a serious problem in arid and semi-arid regions (Jan van S., 1994), and it is a chronic problem in
Xinjiang, northwest China. In Xinjiang, the agricultural field under salinization influence is about
one-third of the total cultivated field (Hou, Z. et al., 2007). At the same time, soil salinization
becomes a serious problem with the increase in irrigation agriculture (Yamamoto, T. et al., 2006).
The factors affecting soil salinization have been delineated in several past studies. In this areaof China, soil salinization is the result of several factors, namely; 1) soil and groundwater contain© ISERD

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IJERD – International Journal of Environmental and Rural Development (2011) 2–1

large amount of saline; 2) the groundwater level is kept high and 3) soil moisture and saline moveto the surface by evapotranspiration under the above-mentioned conditions.
However, the groundwater level may not be a direct factor of soil salinization in Xayar, China,
because salt accumulates in the farmland where groundwater level is sufficiently deep (Nagasawa,T. et al., 2008). Moreover, little research has been done on crop growth and soil salinization, andfundamental data are needed to counter this problem in the future. Therefore, in this study, we
considered the factors involved in soil salinization and its influence on cotton growth in the Tarim
River Basin.
METHODOLOGY
Outline of the investigation area
The investigation targeted Nuerbake Township of Xayar County, which is located in theTaklimakan Desert in the northern border region of Xinjiang Uyghur Autonomous Region. Xayar
County is located downstream of the Ugen River, which is a branch of the Tarim River (Fig. 1).
The   temperature   ranges   from   −30°C   to   40°C,   and   annual   precipitation   is   about   50   mm   in   this  region. Here, soil freezes during the winter. The primary local crop is cotton, and irrigation water
relies on the Kyzyl Dam located upstream of the Ugen River. The method of irrigation is mainly
border irrigation.

Fig. 1 Outline of Xayar CountyFig. 2 Investigation field

The sampling of the irrigation, drainage, groundwater and well water was performed in Xayar,
particularly in the Nuerbak Township in 2006–2010. The electrical conductivity (EC) wasmeasured onsite, and water quality was analysed for anions and cations with Japanese IndustrialStandards (JIS).
The EC of soil saturation extracts in a farmland damaged by salt accumulation was measured.
In addition, a soil survey of the farmland and groundwater level measurement was conducted. The
surveyed farmland was located near a drainage ditch and consisted of cotton fields where thegrowth of cotton was uneven and salt accumulation was relatively troublesome (Fig. 2). We
measured plant heights and collected soil samples from this farmland. The survey was conductedduring the flowering period in early August 2008 at two places, namely: along the A Lineextending in the east to west direction at 40 m north of the farm road where the growth of cotton© ISERD

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IJERD – International Journal of Environmental and Rural Development (2011) 2–1

flowers was uneven and sporadic bare areas could be seen on the ground; and, along the B Lineextending in the east to west direction at 12 m north of the road where plant growth was relatively
even. Along both the lines, from points 1.5, 4.5, 7.5, 10.5, 13.5, 16.5 and 19.5 m from the westernend, soil samples were collected from the depth of 45 cm using a 50 cm long, thin steel pipe withan inner diameter of 2.7 cm at the tip and 3.0 cm along the rest of the pipe. At each point, soil
samples were collected three times and divided them into five layers (0-5, 10-15, 20-25, 30-35 and40-45 cm from soil surface); each layer was then collected in a separate plastic bag. These samples
were transferred to a polyvinyl chloride container, saturated from the bottom with water taken fromthe main irrigation channel (EC value: 0.45 dSm−1) and absorbed with an unglazed cup to measure
the EC value. Soil samples were collected from the depth of 1.0 m in each line with a hand auger.
Measurement of EC1:5 values (1 part soil with 5 parts water) and screening tests were performed
with these samples.
RESULTS AND DISCUSSION
Cotton growth and EC in the farmland
Along the A Line, 40 m from the road where the growth was bad (Fig. 3), there were sporadic bareareas on the ground and the heights of cotton flowers were uneven. In contrast, along the B Line,
12 m from the road side where the growth was relatively even, there were no bare areas on theground and the plant heights were comparatively even, albeit with differences of approximately 10cm. Cotton is a salt-tolerant crop, comparable to beet and alfalfa, and capable of producing abumper harvest up to an EC value of 8 dSm−1.

Fig. 3 Growth situation of cotton on each transect line

Fig. 4 EC of soil saturation extracts at each depth on farmland
Figure 4 shows the EC values along the A Line in parallel with the heights of cotton. At somepoints, the EC value exceeded 20 dSm−1, which is the measurement limit of the EC metre used. In© ISERD

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IJERD – International Journal of Environmental and Rural Development (2011) 2–1

such cases, the EC value was recorded uniformly as 20 dSm−1 on the figure. In the bare areas, inparticular, the EC value of shallow parts exceeded 20 dSm−1.
With the exception of the easternmost point, the EC value exceeded the threshold value forsurvival at all points and depths along the A Line. Besides, at most points, the shallower the depth,
the higher the EC value tended to be, thus indicating an accumulation of salt near the groundsurface due to evaporation. On the other hand, along the B Line where the growth of cotton wasrelatively even, the EC values fluctuated considerably even at the same point depending on thedepth. However, the EC value never exceeded 15 dSm−1. Furthermore, with the exception of one
point, the EC value of the 0-5 cm layer was below the threshold value of 8 dSm−1; however, at mostpoints, the EC value of the 10-15 cm layer was in the vicinity of the threshold value. Therefore, thedeeper the depth, the higher the EC value tended to be (Fig. 4). This suggests that unlike the A Line,the influence of eluviation by irrigation water was greater than that of salt accumulation caused bysoil surface evaporation in the B Line.
Because EC is influenced by grain size composition in soil deeper than the target layer, wecould not find a tendency in the relationship of the EC value and the percentage of a specific grain
size (<3.8 × 10−5 m). However, in the relationship between the EC value of the 0-10 cm layer andthe relative elevation of the ground on each sampling point, the EC1:5 value increased as the relativeelevation increased (P<0.05, Fig. 5). From this result, since the dissolved matters move with soil
moisture by a capillary power with aridity, saline matters accumulation were estimated in thehigher elevation point where is susceptible to such effect.

Fig. 5 Relationship of EC1:5 and relative
elevation of the farmland

Fig. 6 Changes of EC in irrigation water

Table 1 Water quality of groundwater (Aug 2006)
No.

EC(dSm-1)

12
3
4
56
7
89
10

4.6
1.6
2.2
2.0
1.4
2.6
5.1
4.0
3.3
0.6

Cation (meq L-1)
Na+
16.0
5.2
6.4
8.6
4.4
10.8
17.9
12.3
8.7
2.9

Ca2+
13.7
3.7
7.9
2.0
3.9
4.2
11.0
12.9
11.3
1.4

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Mg2+
15.1
4.6
9.2
2.0
4.1
7.4
14.1
14.8
15.0
0.0

Type
Shallow groundwater (<4.0 m)Well water (<30 m)

Well water (120 m)

IJERD – International Journal of Environmental and Rural Development (2011) 2–1

Water quality in the area
The EC value of irrigation water changes seasonally, and it ranged from 0.4 to 0.7 dSm−1 in thisarea (Fig. 6). According to the standard of United States Department of Agriculture (USDA) (SoilSurvey Division Staff, 1993), this value shows an intermediate salt density disorder. The EC valuesof the groundwater were basically more than 2.0 dSm−1 in our research. This result is appropriate
because Chen, W. et al. (2010) shows that the salinity levels of most of the shallow groundwater
sources in Xinjiang are greater than 2.0 dSm−1. Dissolved cations are shown in Table 1. It showsNa+ value is higher at the time of EC is lower, and Mg2+ is higher as to be high value of EC. Whenthe EC value of groundwater is compared, the tendency is for the EC value to be higher in theshallow groundwater of a field and to be lower in a deeper well. The influence of the leachingeffect by irrigation is the likely cause that EC is higher in shallow groundwater.
Changing of groundwater level
In this area, it is assumed that a groundwater level of more than –2.0 m carry a high risk of soil
salinization. The change of groundwater level in research target farmland is shown in Fig. 7.

Fig. 7 Change of groundwater level in farmland
It shows groundwater level is higher in the winter and early spring and sufficiently lower insummer. Certainly, groundwater level is higher in the planting period (March to early April), but it
is not high enough to be a problem during the cotton growing season.
Why does unevenness of soil salinization occur?
In the case wherein irrigation water was very saline, soil salinization may have occurred due to thesalinity being supplied to the field by irrigation water. However, the EC of irrigation water wasmuch lower than that of the groundwater in this study. This suggests that irrigation water is not a
direct factor in soil salinization.
According to the USDA standard, the EC value of the irrigation water can be classified as
causing moderate salinity damage. Nevertheless, when compared with the EC value and positive
ions of shallow underground water, the effects of leaching are evident. This implies that the supplyof salts by the irrigation water was not directly connected with salt accumulation. Saline in the soilof the farmland migrates by capillary attraction. In particular, it is believed that the presence of soil
stratum containing clay beneath the Ap layer contributes to the maintenance of dampness in the soil,
thereby promoting capillary attraction.
When the groundwater level is sufficiently deep, the supply of salts and water from beneath isscarce. However, in this region, irrigation and the thawing of ice in the soil, especially in early
spring, causes the groundwater level to rise. Moreover, soil moisture is kept in the soil layer
containing clay. In other words, the rise of shallow groundwater supplies the soil with saline frombeneath in the annual groundwater fluctuation. This should be a major factor causing soil
salinization, as the capillary action of the soil attracts the salts to the surface.
As for the unevenness of cotton growth that occurs in the same farmland, it was considered awaterlogging by inequality of ground surface during the planting period, partial difference of soil
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IJERD – International Journal of Environmental and Rural Development (2011) 2–1structure (soil layer including large amount of clay exists in comparatively shallow depth) anddeviation in fertilizer application could be the factors causing the same.
CONCLUSION
The influence of soil salinization on cotton growth in an arid area was observed. Based on theresults, in the bare areas, the EC of soil saturate extract exceeded the threshold value (8 dSm−1) forsurvival at all points and depths. In the area where the growth of cotton was relatively even, the EC
values did not exceed the threshold value in 0–5 cm depth. In other words, it is clear that saline
accumulation influences cotton growth. On the other hand, it was suggested that the causes ofunevenness of soil salinization in the same farmland are soil composition (e.g. clay content) andmicrorelief (land elevation) on the farmland. Moreover, irrigation water was not a direct factor insoil salinization.
It is thought that soil improvement and the introduction of under-drainage in farmland would
be an effective solution for the problem of soil salinization, but this is difficult when cost isconsidered. For realistic correspondence, it was suggested that crops are grown on furrow. Thisway should make saline matters beneath the plants move to the ridge direction. It is necessary toverify this hypothesis by further experiments.
ACKNOWLEDGEMENTS
Xayar County Government, Xayar Water Management Agency and Xinjiang Uyghur AutonomousRegion Water Resource Management Bureau supported this research.
This study is a part of the academic research (No.21405031) supported by Grant-in-Aid for
Scientific Research (B) from Japan Society for the Promotion of Science (JSPS), Japan.
REFERENCES
Jan van, S. (1994) Irrigation-a blessing or a curse. Agricultural Water Management, 25, 203-219.
Hou, Z., Li, P., Gong, J. and Wang, Y. (2007) Effect of different soil salinity levels and application rates ofnitrogen on the growth of cotton under drip irrigation. China. Journal of Soil Science, 38, 681-686.
Chen, W., Hou, Z., Wu, L., Liang, Y. and Wei, C. (2010) Evaluating salinity distribution in soil irrigatedwith saline water in arid regions of northwest China. Agricultural Water Management, 97, 2001-2008.
Soil Survey Division Staff (1993) Soil survey manual, Soil Conservation Service. U.S. Department ofAgriculture Handbook, 18, 108.
Yamamoto, T., Nagasawa, T. and Abudisalam. J. (2006) Irrigated agriculture and the environment in theTarim River watershed: Case study of the Shaya irrigation district in the Ugen River basin. Sustainable
Irrigation Management, Technologies and Policies, WIT press, 303-312.
Nagasawa, T., Yamamoto, T. and Abudisalam, J. (2008) Salinization of farmland in northern region ofTaklamakan Desert, Relationship of salinization and agricultural wateruse in semi-arid zone (1).
Conference Proceeding of Japanese society of Irrigation, Drainage and Rural Engineering, 808-809.

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