Analysis on the Salt Content Characteristics of Southern Saline-Alkali Soil in Datong Basi

Analysis on the Salt Content Characteristics of Southern Saline-Alkali Soil in Datong Basin and Its CausesQing YI, Yan-pei CHENG*, Jian-kang ZHANGThe institute of Hydrogeology and Environmental Geology,CAGS, Shijiazhuang 050061,ChinaAbstract: This paper studies the southern part of Datong Basin and investigates, in combination with a survey on the soil properties, the salt content characteristics of the soil in the region using relevant analysis methods. The results showed that the soil salinization type of the soil in the study area is soda saline-alkaline soil, and the salt content of the profile soil tends to assemble in the soil surface. As the overall salt content is low, it is classified as moderately saline soil. However, being highly alkaline, it thus basically belongs to the moderate-to-severe level; a significant positive correlation is found between total salt quantity and exchange sodium and degree of alkalization. Exchange sodium is a factor that determines the size of alkalization degree and it also indirectly affects the pH value; special climate, topography and parent material, groundwater and soil properties, and tillage management of the region explain the formation of the large area of saline-alkali soil. This study will provide an important theoretical basis for the sustainable use of soil resources in the southern saline-alkali soil in Datong Basin.Keywords: Soil salinization, Datong Basin, Salinity characteristics, Cause analysisSoil salinization and secondary salinization are one of the most prominent environmental problems in the world. Saline soil destroys land resources, seriously affecting agricultural production and sustainable development. There is a large area and widely distributed saline soil in China from coastal areas to inland areas, from tropical zone to cold temperate zone, and from humid regions to extremely arid regions (Zun-qin WANG et al., 1993). As a semi-arid windy and sandy saline area, Datong Basin is one of the key saline and desert regions to be treated in the “Twelfth Five-Year Plan” of the Treatment Project of Sandstorm Sources of Beijing and Tianjin. It has high degrees of salinization and desertification, while the saline land there is poor utilized or even left idle, which accounts for 68.1% of the total area (4.5195 million mu) of saline land in Shanxi Province. Shuozhou City, located in the south of Datong Basin, has about 40% saline land of the total in the province, about 1.876 million mu (including abandoned farmland). The land is mainly distributed in both banks of Sanggan River, Huihe River, Huangshui River, Cangtou River, and Maying River.Studying the salt content, salinization degree and causes of saline soil is the prerequisite for the treatment of saline soil. Currently, scholars have studied the relations of salt content, electrical conductivity and soil ion in different regions (Zhen-zhen LYU et al., 2013; Guline Halimulati et al., 2012; Xin-guo LI et al., 2012; Guang-ming LIU et al., 2011; Yong-ling WENG et al., 2006; Yan-feng LIU et al., 2004). However, due to the differences in the terrain, soil parent material, and soil texture in different regions, the salt content characteristics and distribution, and the relations between electrical conductivity, ions and soil salt content are different. The study on the saline soil samples taken from the study area is aimed to understand the salt content, ion condition and salt*Corresponding author. E-mail: yanpeicheng@composition of the topsoil in the region and analyze the salt content characteristics of saline soil to provide a reference for the design of saline soil management program.Overview of Study AreaShuozhou is located in the northwest of Shanxi Province, with a longitude of 111°53'-113°34' and latitude of 39°05'-40°17', between the inner Great Wall and the Outer Great Wall. It belongs to the zone of temperate continental monsoon climate and is characterized by little rain or snow, windy and sandy, great evaporation, and frequent dry weather in spring; concentrated rainfall, occasional heavy rain, downpour and hail in summer; little rain, cool in the morning and at night while hot at noon in autumn; frequent wind and little snow and cold weather in winter. The average annual temperature is generally 3.6℃-7.3 and the℃annual average rainfall for multiple years (from 1956 to 1984) is 421.2 mm. The maximum annual rainfall is 806.7 mm (in 1964) and the minimum is 193 mm (in 1965).The study area is located in Agricultural Park of Zijin Mount, Shuocheng District, Shuocheng City, while the pilot site is located in the piedmont sloping plain with small changes in topography. From south, central, north to northwest, the ground elevation of the test area decreases, and the test area covers an area of 333,500 m2 (500 mu). Four trial trenches are constructed in the northeast, central and south part of the test area, and 11 shallow holes in vadose zone are implemented within the test area for detailed investigation of lithology and structure the vadose zone: the main components of the saline-alkali soil are exchange sodium salt, carbonate ions, and bicarbonate ions with strong alkaline reaction. Sometimes they form into a solid columnar deposited layer and physical and chemical properties of soil seriously deteriorate, resulting in difficult germinating, seedling missing, seedlingless ridges, growth retardation, and sharply reduced production. In extremely serious cases, arrest of crop growth and plant death may result. Research MethodologySample Collection and PretreatmentThe Working Group collected samples of field soil in the test area in 2011 and 2012, respectively, and 99 soil samples were collected. The sampling sites were chosen with consideration to the uniformity of spatial distribution of point location. Depending on the uniformity of field soil characteristics within the scope of 90 m×90 m, the sampling depths were determined as 10 cm, 20 cm, 30 cm, 40 cm, 50 cm, 70 cm, 90 cm, 120 cm, 150 cm, 180 cm, 210 cm, and 220 cm.After being sealed in the wild, the soil samples were air-dried in the lab. Intrusive bodies (such as plant debris, stones and other impurities) were taken out of the soil, and the soil was thoroughly mixed after being ground and sieved and was put into containers for future use.Sample Testing MethodThe collected 99 samples were measured by the Ground Water, Mineral Water and Environment Monitoring Center of Ministry of Land and Resources of PRC in total salt quantity, pH, content of exchange sodium content, cation exchange capacity (CEC) and degree of alkalization of the soil according to the requirement of soil agricultural chemistry analysis (Ru-kun Lu, 2000). The salt accumulation of soil was tested by oven dry method with 1:5 soil-water solution; the exchange sodium [cmol (Na+)/kg] was tested by ammonium acetate-ammonium hydroxide exchange-flame photometry; the CEC [cmol (+) / kg] was tested by ammonium chloride- ammonium acetate exchange; the degree of alkalization = (exchange sodium/CEC) × 100%; the measurement of soil pH was done by extraction under a soil-water ratio of 2:1 using pH meter.Data ProcessingDue to the differences in the causes for salinization and soil parent material in different regions, the relations between the total salt content, pH value and degree of alkalization and the salt content ofsoil are different. Therefore, Excel2007 was used for statistics, analysis and plotting of characteristic indexes of soil samples; the statistical software of SPSS17.0 was used for statistical analysis (Li-ren HAO et al., 2003) to understand the soil content of soil and classification of salt content in the soil samples. The correlations between characteristic indexes of soil were analyzed through analysis of variance and significance test of correlation analysis.Results and AnalysisCharacteristic Indexes of SoilThe alkali soil in the study area contains negative anions including chloride (Cl-), sulfate radical (SO42-), carbonate (CO32-) and bicarbonate (HCO3), and positive ions including sodium (Na+), kalium (K+), calcium (Ca2+), and magnesium (Mg2+). The salt composed of positive ions and chloride (Cl-) and sulfate radical (SO42-) is called neutral salt, while that composed of positive ions and carbonate (CO32-) and bicarbonate (HCO3) is called alkaline salt. The neutral salt content in topsoil, when reaching a certain level (usually 2 g/kg), can cause different degrees of harm to most crops. This type of soil is called saline soil. The degree of salinization will increase with the increase in the content of neutral salt. When the salt content exceeds a certain amount (usually chlorides 6 g/kg and sulfate sulfur 20 g/kg), only a small number of salt-tolerant wild plants will grow. This type of soil is called solonchak. If the soil content in topsoil is predominantly alkaline salt, when the soil is subject to strong alkaline reaction (pH≥8.5) and its degree of alkalization (or sodium ratio, i.e. the percentage of exchange sodium ion in the total exchange cation) exceeds 5%, the soil is called alkalized soil. Table 1 shows the statistical values of different indexes of sampling soil taken from 6 sampling sites.Table 1 Statistical Value of Different Soil Characteristic IndexesIndex of Soil Characteristics Minimum Maximum Average StandardDeviationVariable Coefficient (%)Salt Content (%) 0.026 0.586 0.120 0.125 1.042 pH Value 7.62 10.78 9.34 0.692 0.074 Exchange Sodium (cmol/kg) 0.076 4.978 1.054 1.165 1.105 CEC (cmol/kg) 8.043 18.587 11.905 2.164 0.182 Degree of Alkalization (%) 0.69 45.35 9.40 10.944 1.164Overall, the average total salt quantity of soil in the study area was at a low level of 0.120%, with a maximum value of 0.586% and a coefficient of variation (CV) of 1.042%, presenting strong variability (the dispersion degree of CV reaction sampling site was as follows: CV<0.1 represented weak variability; 0.1<CV<1 represented moderate variability; and CV>1 represented strong variability) (Zhi-dong LEI et al., 1988). The average pH value reached 9.34, indicating generally strong alkalinity in the soil. The pH value even reached 10.78, at which point the variability was the lowest, indicating weak variability; there was a high content of exchange sodium content, which was one of the main causes for high pH of the soil. There was a large range and strong variability was displayed; due to the high pH in soil, the CEC was maintained at a high level and moderate variability was displayed; as there were great differences in the degree of alkalization, strong variability was displayed, although the average value reached 9.40%. Thus, the salt content of the soil in the study area was moderate, but there was a higher alkaline content. Depth Distribution of Soil IndexesTable 2 shows a comparison of the average values of different soil indexes under different depths of lithology. Fig.1, Fig.2, and Fig.3 show the comparison of total salt quantity, pH values and degrees of alkalization of sampling sites at different depths.Table 2 Average Values of Soil Indexes at Different DepthsSoil Depth (cm)Main Soil TypeSalt Content(%)pH ValueExchange Sodium (cmol/kg) CEC (cmol/kg) Degree ofAlkalization (%)10 Sandy loam 0.238 9.35 1.697 11.630 16.07 20 Sandy loam, mediumloam 0.218 9.34 1.665 11.486 15.03 30 Sandy loam, mediumloam 0.179 9.37 1.654 12.120 14.96 40 Sandy loam, light clay 0.1099.451.442 11.359 13.02 50 Sandy loam 0.120 9.66 1.190 11.612 11.2470 Sandy loam, sandy soil 0.098 9.56 1.101 11.685 10.25 90 Sandy loam, sandy soil0.092 9.42 0.908 10.833 7.98 120 Light clay, clay 0.106 9.25 0.859 13.696 6.28 150 Light clay, sandy loam 0.084 9.22 0.562 12.065 4.66 180 Light clay, clay 0.052 9.17 0.522 13.442 3.90 210 Light clay, clay 0.059 9.20 0.411 11.486 3.70 220Light clay, clay0.0528.880.22110.9782.03As can be seen from Table 2, the lithology in thevadose zone in the study area was clearly layered. At a level of 50-70 cm, sandy loam and medium loam were predominant, interlined with thin layers of sandy soil and silty sand; at a level from about 50-70 cm to 150 cm, light clay was predominant, interlined with clay layers; at a level from 150 cm to above groundwater, clay was predominant.The average total salt quantity of soil decreased with the increase of depth and the change wasobvious. The average pH value did not vary significantly with the depth, except that high average pH values appear at depths from 40 cm to 90 cm; the average exchange sodium regularly decreased with the increase of depth and the change was obvious; the variation of average CEC with the depth fluctuated at the level of 1-12 cmol/kg; the average degree of alkalization decreased with the depth and the change was even and obvious.02040608010012014016018020022000.10.20.30.40.50.6D e p t h （c m ）Total Salt Quantity （%）Samling site 1Samling site 2Samling site 3Samling site 4Samling site 5Samling site 6Fig.1 Comparison of Total Salt Quantity of Sampling Sites at Different Depths020406080100120140160180200220789101112D e p t h （c m ）pH ValueSamling site 1Samling site 2Samling site 3Samling site 4Samling site 5Samling site 6Fig.2 Comparison of pH Value of Sampling Sites at Different Depths020406080100120140160180200220051015202530354045D e p t h (c m )Exchange Sodium Percentage (%)Samling site 1Samling site 2Samling site 3Samling site 4Samling site 5Samling site 6Fig.3 Comparison of Exchange Sodium Percentage of Sampling Sites at Different DepthsAs can be seen from Fig.1, Fig.2 and Fig.3, thetotal salt quantity in the saline-alkali soil in the study area was at a low level, generally less than 0.5%. Alkalized soil and alkaline soil were predominant soil there, and they were typical soda saline soil, whose degree of alkalization was basically higher than 10% at a level of 0-50 cm and pH value was higher than 9.5. According to the relevant classification standard of saline-alkali soil (Shou-quan Zhu et al., 1989): generally degree of alkalization > 5% represents alkalized soil, 5-10% represents light alkalized soil, 10-15% represents moderate alkalized soil, 15-20% represents strong alkalized soil, and degree of alkalization >20% represents alkali soil. Obviously, the study area mainly contains moderate to strong alkalized soil. The soil mainly contains negative ions including carbonate (CO 32-), bicarbonate(HCO3-) and sulfate radical (SO42-), and positive ions including sodium (Na+). There were large numbers of sodium ions that are hardly soluble in water in the soil colloid and they were strongly alkaline. The pH values of soil were generally greater than 9.0, and some were even as high as 11. This was a typical characteristic of soda saline-alkali soil.The total salt quantity of the soil in Sampling Site 1, 3, and 6 was at a low level, in spite of different degrees of volatility. The peak appeared at depths of 50-90cm in Sampling Site 2, and the maximum value (0.145%) in Sampling Site 3 appeared at a depth of 120 cm. Similar volatility appeared in Sampling Site 5, where the maximum value, 0.208%, appeared at a depth of 120 cm. The cases were different in Sampling Site 2 and Sampling Site 4. High numbers of total salt quantity appeared at depths of 0-30 cm and the maximum value reached 0.572%. As the depth increased, the total salt quantity stayed at a low level. It changed dramatically at the depths of 0-40 cm and varying degrees of volatility appeared at depths of 0-40 cm, but the variability decreased with the increase of depth.In Sampling Site 2 and Sampling Site 4, the pH values varied consistently with depth. In the depth range of 0-120 cm, the pH values decreased with the increase of depth. When the depth was over 120 cm, the pH values remained substantially constant. The cases were opposite in Sampling Site 1 and Sampling Site 3. In the depth range of 0-70 cm, the pH values increased with the increase of depth and were over 10; in the depth range over 70 cm, the pH values decreased with the increase of depth. Sampling Site 5 and Sampling Site 6 showed similar volatility in certain pH ranges (8-9 and 9-10). In the depth range of 0-90 cm, the variability of pH values became stronger, while in the depth range of 90-220 cm it decreased with the increase of depth.The degree of alkalization did not vary greatly with the depth in Sampling Site 6 and were constantly maintained at a low level. The soil was non-alkaline. Sampling Site 1, 3 and 5 shared similar trend of alkalization degree changes with the increase of depth, and the peaks and changing process appeared obviously at the depths of 30 -150 cm. in Sampling Site 2 and Sampling Site 4, the alkalization degree sharply decreased with the increase of depth in the depth range of 0-90 cm and the change became insignificant beyond the depth of 90cm, where the alkalization degree stayed at a low level. The variability of alkalization degree of soil gradually decreased with the increase of depth and was reflected in a funnel shape. The most dramatic change could be observed in the depth range of 0-90 cm. Classification of Soil Salinization and Soil Distribution CharacteristicsDifferent classification standards of soil salinization reflect the differences in various regions. The classification of saline soil in this paper is based on the classification standard of salt content. Table 3 shows the classification standard of salt content in saline soil (Shi-biao CHANG et al., 1992).Table 3 Classification Standard of Saline Soil by Salt ContentName of Saline SoilAverage Salt Content (%)Chlorine Saline Soil and ChlorousSaline SoilSulphate Saline Soil andSulfurous Saline SoilAlkalineSaline SoilNon-saline Soil < 0.5Weak Saline Soil 0.5~1.0Moderate Saline Soil 1.0~5.0 0.5~2.00.5~1.0 Strong Saline Soil 5.0~8.0 2.0~5.0 1.0~2.0Super Saline Soil > 8.0 > 5.0 > 2.0The test results showed that the alkalization degree, pH and total salt quantity at the superficial layer (0-50 cm) of some sampling soil were lower than those at the deep layer. For example, the average alkalization degree of the soil layer at 50-90 cm in Sampling Site 1 was 14.4 % and the average pH value was 9.9, indicating moderate alkaline soil, while the average alkalization degree of the soil layer at 0-50 cm was 5.2 % and the average pH was 4, indicating light alkaline soil. The reason why the alkalization degree, pH and total salt quantity at the superficial layer were lower than that at the deep layer was that soil layers with higher alkalization degree were ploughed deep into the lower layer as the lot where Sampling Site 1 was located had been cultivated in the previous year. However, overall, the soil layers at the depths of 0-90 cm still contained moderate to light saline-alkaline soil. The average alkalization degree of soil layers at the depths of 0-50 cm in Sampling Site 2 reached 30.9%, far greater than the limit value, 20%, for alkaline soil. The average pH value was 10.4, indicating strong alkalinity. The total salt quantity of soil at surface layers (0-30 cm) was up to 0.5%, reflecting moderate saline soil according to the classification of salinization. The average alkalization degree of soil layers at the depths of 0-50cm in Sampling Site 4 reached 32.7%, indicating strong alkaline soil. The average pH value was 10.5, and the total salt quantity of soil at surface layers (0-30 cm) was up to 0.49%, reflecting moderate saline soil. The average alkalization degree in the sampling points of Sampling Site 5 was slightly weaker than that in Sampling Site 2 and 4, yet the average alkalization degree of its soil layers at the depths of 0-50 cm reached 11.1%, indicating moderate alkaline soil, and the average pH value was up to 9.7. The average total salt quantity of soil in Sampling Site 6 was 0.08%, with weak violability. Its pH value stayed around 8-9 and its alkalization degree was below 5%. No salinization problem was reflected. Correlation Analysis of Soil IndexesThe characteristic values of saline soil are correlated. In order to understand their relations, this study analyzes the internal correlations between total salt quantity, pH value, exchange sodium content, CEC, degree of alkalization and depth. Table 4 shows the SPSS analysis result of correlations between soil indexes.Table 4 Analysis Matrix of Soil Characteristic ValuesTotal Salt Quantity pH ValueExchangeSodiumCECDegree ofAlkalizationDepthTotal Salt QuantityPearson correlation1 Significance (two sides)pH ValuePearson correlation .631**1 Significance (two sides) .000Exchange SodiumPearson correlation .888** .832**1 Significance (two sides) .000 .000CECPearson correlation -.155 -.380** -.1801 Significance (two sides) .203 .001 .140Degree of AlkalizationPearson correlation .896** .844** .990** -.278*1 Significance (two sides) .000 .000 .000 .021DepthPearson correlation -.400** -.180 -.404** .102 -.414**1 Significance (two sides) .001 .138 .001 .406 .000Note: ** Means extremely significant correlation at p <0.01 level (two sides). * Means significant correlation at p>0.05 (two sides).The analysis results showed that there was highly significant positive correlation between total salt quantity and pH value, exchange sodium content and degree of alkalization, especially between exchange sodium and degree of alkalization, with correlation coefficients of 0.888 and 0.896, indicating that total salt quantity was greatly affected by exchange sodium content and that degree of alkalization was also closely related to total salt quantity. There was significant positive correlation between pH value and exchange sodium content and degree of alkalization. The highest positive correlation was found between exchange sodium and degree of alkalization, with a correlation coefficient of 0.990, indicating that exchange sodium was a factor that determined the degree of alkalization while indirectly affecting the pH value.Cause Analysis of Saline-alkali SoilThe emergence and development of saline soil can be explained by the specific environment or basic conditions, or certain natural and artificial factors, under which it is nurtured. Different saline-alkaline soil is formed under certain natural conditions and its formation is essentially due to the reallocation of different easily soluble salts at horizontal direction and vertical direction on the ground, which enables the salt to gradually build up in the topsoil of salt concentration areas.The terrain in Shanxi presents a pattern of highness in the east and west part while lowness in the middle. A series of fault basin of different sizes are developed between two mountain systems of Taihang Mountain and Lvliang Mountain. Among them, the largest is Datong Basin, which extends more than 5,000 km2. Sanggan River and Nanyang River in the basin belong to the water system of Haihe River. As Shuozhou is located in the southern part of Datong Basin, its evaporation is much greater than precipitation due to the dry climate. Owing to the poor leaching performance of soil and worsened by the unfavorable terrain, underground water, soil parent material, ground vegetation and tillage management, plenty of saline-alkaline soil has been developed.Climatic FactorsShuozhou has the typical continental monsoon climate, with four distinct seasons, great wind and little rain in winter and spring. The salt in underground water rises along with the capillary water to assemble in topsoil, or the salt dissolving in water can easily accumulate in the ground surface due to strong evaporation of surface water to form the first peak of salt accumulation. This is the main season when salt is accumulated in the surface soil; in summer, there is plenty of rain and it is concentrated, making a great deal of soluble salt seep into the lower layer or flow away. This is the season of desalination. In the late autumn and early winter, most of the surface water would evaporate, leading to the second peak of salt accumulation in the soil in early winter. This process is described by the local people as “whitened winter and watering summer”. This is also a major factor that leads to the formation of saline-alkaline soil in Shuozhou.Terrain and Parent MaterialWhen the rocks in the mountainous region around the basin were weathered, various types of salt were formed and among them soda saline-alkaline soil was predominant. The weathered and corroded matters in the mountainous region formed into surface runoff as a result of rain wash and finally converged into low-lying land to become saline-alkaline soil over time. Therefore, the saline-alkaline soil in Shuozhou is soda saline-alkaline soil, mainly composed of exchange sodium, carbonate ions and bicarbonate ions. Underground Water and Soil Texture Where the underground water is buried beyond a depth of 3 m under the ground in Shuozhou, no obvious salt accumulation can be found. Typically, when the underground water level reaches the threshold of 1-1.5 m and the degree of mineralization is 2-4 g/l, the salt will rise with the water under a dry climate and form intosaline-alkaline soil easily. The higher the degree of mineralization is, the more salt will accumulate in the topsoil. Soil texture can affect the speed and height of capillary water movement in the soil. In general, capillary water in loamy soil rises faster and higher, while the salt accumulation in sandy soil and clay is slower. According to preliminary field investigation, the vadose zone in Shuozhou is mainly constituted by loamy soil.Vegetation and Farming Management Halophytes like suaeda heteroptera kitag, suaeda glauca, chenopodium album, lamb’s-quarters, ixeris japonica and Chinese tamarisk mainly contain chlorine, sodium, potassium and other ions, with a content of generally 20-25%. When they die, salt will accumulate on the earth surface, which in essence is a process of special biological salt accumulation. The extensive farming practice, surface irregularities, and serious deficiency of fertilizer will exacerbate salt accumulation in soil and earth surface. Especially in the case of broad irrigation in the river irrigated area during irrigation, the low-lying would only receive irrigation without drain, leading to rapid increase of underground water level and salt accumulation. As a result, the previously sound land will turn into saline-alkaline soil. This process is called secondary salinization.The above is a single-factor analysis on the causes for the saline-alkaline soil in Shuozhou. In fact, the formation of the saline-alkaline soil in Shuozhou is the result of long-term effects of multiple factors. ConclusionsThis study builds on the investigation on soil properties and adopts correlation analysis to explore the salt content characteristics of the southern saline-alkaline soil in Datong Basin. It also goes on to discuss the causes for the formation of such soil. The conclusions of this study are as follows:The salt content of the profile soil tends to assemble in the soil surface. The salt content at the depths of 0-40 cm varies most dramatically in the soil profile, while the salt content at the depths of 40-220 cm shows volatility of varying degree, but its variability shows a slowdown trend. In the horizontal direction, variability of soil salt content gradually decreases as the depth increases, and the variability at the depths of 0-30 cm is strong.The pH value of soil shows strong variability in the depth range of 0-90 cm. In the depth range of 90-220 cm, its variability gradually decreases with the increase depth. The variability of alkalization degree of soil gradually decreases with the increase depth in a funnel shape, and the most dramatic changes appear at the depths of 0-90 cm.There are extremely significant correlations between total salt quantity and exchange sodium and alkalization degree. The total salt quantity is greatly affected by exchange sodium. There is an extremely significant correlation between exchange sodium and alkalization degree. Exchange sodium is a factor that determines the degree of alkalization while indirectly affecting the pH value.The salt content of the soil in the study area is generally moderate, but alkalinity is generally strong. Most of the soil is moderate to severe alkaline or moderately saline soil. The large saline-alkaline soil is explained by the local special climate, terrain and parent material, underground water and soil texture, and vegetation and tillage management.ReferencesZun-qin WANG, Shou-quan ZHU, Ren-pei YU, et al.Saline soil in China (In Chinese) [M]. Beijing:Science Press, 1993: 400-515Zhen-zhen LYU, Guang-ming LIU, Jin-song YANG.Soil salinity characteristics of Manas RiverValley in Xinjiang [J]. Acta Pedologica Sinica,2013, 50(2): 289-295Guline Halimulati, Muhtar Turhong, Yu Kun, et al.Analysis on the characteristics of saline soil onKashghar River Valley (In Chinese) [J]. Journalof Arid Land Resources and Environment, 2012,26(1): 169-173。