Properties Of Saline Soil Research Articles

Laboratory Investigation and Modelling of the Thermal-Mechanical Properties of Soil in Shallow Mineralized Groundwater Area

The capillary rise of shallow mineralized groundwater can contribute to the salinization of the soil layers. The excessive salt amounts adversely affect soil physical and mechanical properties, as well as the heat transfer performance, all of which are key factors with regard to the design of geothermal-related earth structures such as geothermal energy piles (GEP), ground source heat pumps (GSHP), and earth-air tunnel heat exchangers (EATHE). Therefore, in this study, the thermal-mechanical properties of saline soils are systematically investigated. A series of thermal and mechanical response tests were carried out under different salinity conditions, and the shear wave velocity-stress behavior of saline soil was measured using a modified oedometric cell coupled with an anchored bender element pair. Experimental results showed that saline soils generally have higher dry density and lower optimum moisture content at higher salt contents. The shear strength of saline soil increased about 5% while the salt concentrations of bulk solution increased from 0 mol/kg to 6 mol/kg, and the shear wave velocity increased by 50% to 83% when the normal load increased from 12.5 kPa to 250 kPa for sodium chloride- (NaCl-) treated soil and 39% to 52% for calcium chloride- (CaCl2-) treated soil. In addition, the thermal conductivity decreased by 0.121 W m-1 K-1 for NaCl-treated soil and 0.129 W m-1 K-1 for CaCl2-treated soil on average when the salt concentration increased from 0 mol/kg to 6 mol/kg. Finally, an elastic shear modulus (G0) model and a thermal conductivity (K) model were formulated for saline soil for the first time, and the effectiveness and feasibility of the proposed models were validated by comparisons of the model predicted values and experimental data.

Effects of rhus typhina and robinia pseudoacacia on physicochemical properties of saline soil in Dagang Area, Tianjin

In order to explore the effect of using two different afforestation tree species to improve soil in coastal saline-alkali land, the method of combining field sampling and indoor analysis and test was adopted. The physical and chemical properties of soils planted with Rhus typhina and Robinia pseudoacacia forest were determined. The results showed that afforestation could improve soil structure, decrease soil bulk density and increase soil fertility. To reduce soil salinization, the soil physical and chemical indexes of Robinia pseudoacacia plantation were better than those of growing Rhus typhina forest, so the planting area of Robinia pseudoacacia plantation in Dagang area could be increased. Planting Rhus typhina forest could also improve the soil in this area, but its effect was lower than planting Robinia pseudoacacia plantation.

Impacts of Rice Hull and Pistia on the Vegetative Growth of Rice and Physico-Chemical Properties of Saline Soil Under Variable Moistures

A pot experiment was conducted using BRRI Hybrid Dhan-6 variety of rice at the premises of the Department of Soil, Water and Environment, University of Dhaka, Bangladesh to evaluate the capabilities of rice hull (RH: 0, 2, 4 t ha-1) and pistia (PT: 0, 400, 800 kg ha-1) for the improvement of growth performances of rice grown under field moist (FM: 70% moisture) and 2 - 5 cm standing water (SW) conditions in saline soil. Among the vegetative growth, the plant heights, number of productive tillers, fresh shoot and shoot dry matter weights were found to be increased significantly (p ≤ 0.05) with the increased rates of rice hull and pistia treatments, and the increments were more striking by their combinations in most of the cases under both FM and SW conditions. The tallest plant heights (112 cm in FM and 120 cm in SW) and the maximum number of productive tillers (13 in FM and 16 in SW) were recorded at maturity stage of rice in the T8 (RH4PT8) treatment where rice hull and pistia were applied at the highest (RH: 4 t ha-1, PT: 800 kg ha-1) dosages. Based on superiority in both the plant heights and number of tillers, the amendments can be arranged in the sequence of T8 > T7> T6> T5> T2> T3>T4> T0 > T1. The analysis of variance on these data indicated that in the standing water condition, fresh shoot and shoot dry matter weights of rice plants were found to be increased significantly (p ≤ 0.05) by the application of the higher rates of the treatments and their combinations. Thus, the application of indigenous organic amendments such as, rice hull and pistia showed significant contribution for the growth performances of rice under variable moistures but further researches are needed under variable soil and climatic conditions to ensure food security under saline soil.
 Asiat. Soc. Bangladesh, Sci. 44(2): 173-183, December 2018

Using ANFIS and BPNN Methods to Predict the Unfrozen Water Content of Saline Soil in Western Jilin, China

Saline soil in seasonally frozen soil areas has caused tremendous damage to engineering and the ecological environment. The unfrozen water is the main factor affecting the properties of saline soil in seasonally frozen soil area and therefore needs to be studied. However, due to the high cost of laboratory measurement of the unfrozen water content, this study focuses on using an adaptive network fuzzy inference system (ANFIS) and a back propagation neural network (BPNN) to predict the unfrozen water content of saline soil in the Zhenlai area, Western Jilin. The data for the constructed model is obtained by nuclear magnetic resonance (NMR) testing. The initial water content (W0), salt content (S), and temperature (T) are used as input parameters for predicting the unfrozen water content (Wu). The results of the ANFIS and BPNN models are compared. The results show that although both methods are suitable for predicting the unfrozen water content of saline soil in the Zhenlai area, western Jilin, the prediction accuracy of the ANFIS model is higher.

Basic properties of saline soil in Da'an, western Jilin, China

This paper studied the basic properties of saline soil at different depths of a sampling site in Da’an, China, through field reconnaissance and laboratory analysis. A series of experiments which comprised the analyses of grain size distribution, mineral composition, soil physical properties, soluble salt concent, p H, organic content and cation exchange capacity were conducted. Through these experiments, the distribution rule of each property and their causes are discussed. These results could provide a fundamental base for the study of moisture migration.

Adaptive growth response of exotic Elaeagnus angustifolia L. to indigenous saline soil and its beneficial effects on the soil system in the Yellow River Delta, China

Our manuscript showed that Elaeagnus angustifolia L. can be introduced to the Yellow River Delta of China and planting E. angustifolia was beneficial effects on the soil system. The saline soil of the Yellow River Delta of China is not suitable for the growth of crop and afforestation seedlings due to high salt content, high underground water level, and deficiencies in organic matter, nitrogen and phosphorus, which limits urban road greening around the Yellow River Delta. Elaeagnus angustifolia L. (E. angustifolia) is a member of the Elaeagnaceae family, which is a deciduous shrub or small tree. Due to its good resistance, E. angustifolia has been planted widely in the western region of China, and it has been used for wind breaking, landscaping and sand stabilization. Furthermore, E. angustifolia seedlings were introduced to the Yellow River Delta due to its strong stress and adaptive growth response, which were studied in 2014 and 2015. The results revealed that the seedlings of E. angustifolia grew well with high relative growth rates, big crowns, thick basal diameter, thick diameter at the breast height, and many branches, especially during the second year. Planting E. angustifolia on the Yellow River Delta significantly decreased its salt content, and increased its content of organic matter, nitrogen and phosphorus, as well as the number of fungus, bacteria, salt-tolerant bacteria, actinomycetes and salt-tolerant actinomycetes, especially after planting E. angustifolia for two consecutive years. In conclusion, E. angustifolia seedlings can grow well in the saline soil of the Yellow River Delta with a large biomass. In turn, planting E. angustifolia could improve saline soil properties. Hence, E. angustifolia can be a potential local greening tree species.

Effect of freeze-thaw cycles on shear strength of saline soil

Freeze-thaw (F-T) cycle is an important external factor affecting the mechanical properties of saline soils in cold regions. In this study, the effects of F-T cycles (0, 1, 5, 10, 30, 60 and 120) and salt contents (0, 0.5, 1.0, 2.0 and 3.0%) on the shear properties of saline soil in western Jilin Province of northeastern China, including stress-strain behavior, peak undrained shear strength (τu), resilient modulus (ER), cohesion (cu) and internal friction angle (φu), were investigated by conducting unconsolidated-undrained (UU) triaxial compression tests. The results demonstrated that, when the salt content was the same, the τu, ER and cu basically showed a decreasing-steady-decreasing trend with increasing F-T cycles, and the dynamic evolutions of soil microstructure were mainly responsible for such variations. The Gouy-Chapman diffuse double layer together with matrix suction theories were employed to analyze the mechanism of the effects of salt content on the cu and φu at different freeze-thaw cycles; the thicker diffuse double layer induced by higher sodium ion contents and the decreasing matrix suction were deemed as the main reasons that led the cu to continuous reduction; the φu was believed to be successively affected by the enhanced lubrication effect and the salt crystallization process, and there was a threshold salt content (2.0%) which was influenced by the number of F-T cycles. Finally, by categorizing the different experimental combinations into relative undamaged, single-factor damaged and two-factor damaged states concerning the τu, an empirical mathematical equation of high reliability (R2 > 0.985) was established to describe the combining effects of F-T and salinity on the changes in τu.

Natural Biostimulants Improve Saline Soil Characteristics and Salt Stressed-Sorghum Performance

ABSTRACTHumus substances (HM) and Moringa oleifera leaf extract (MLE) are considered as biostimulants used for plant growing under normal and salt stress conditions. Therefore, effects of soil HM and foliar MLE applications on soil characteristics and on sorghum growth, physio-biochemical properties, and antioxidant defense system activity were investigated under salt stress using pot experiments. The experimental design was a split-split plot with three soil salinities (S1, S2, and S3) as main-plots, two HM levels (0 and 0.1 g kg‒1 soil) as subplots, and two MLE levels (0% and 3%) as sub-subplots, and each one of the 12 treatments was replicated 20 times. Saline soil properties were improved by HM. Under saline conditions, either HM or MLE increased growth characteristics, photochemical activity, contents of RNA, DNA, phytohormones, osmoprotectants and non-enzymatic antioxidants, and activities of antioxidant enzymes in sorghum plants compared to those in the untreated control plants. The interactive HM×MLE application was most effective at overcoming the harmful effects of soil salinity stress and further increased the abovementioned criteria. This study, therefore, recommends using the integrative HM+MLE treatment for growing sorghum plants in saline soils up to more than 6.12 dS m‒1 without loss in growth characteristics.

Dielectric and Radio-Emission Properties of Oil-Polluted Soils

The results of laboratory measurements of dielectric properties of oil-polluted sandy, clayey, and saline soils at variations of volume humidity and temperature in the range between 260 and 300 K at 1.41-GHz frequency are given. It is shown that dielectric and radio-emission properties of dry sand and oil within the error are temperature independent in the range from 260 to 315 K. The influence of oil on the microwave emission of soils is observed when volume humidity exceeds the maximum amount of bound water. The occurrence of oil additives in the soil leads to variations in dielectric and radio-emission properties of soils due to the change of the phase composition of soil moisture. Oil pollution of saline soils causes a dramatic change in their dielectric and radio-emission properties. Dielectric properties of the saline soils with the addition of oil in the range of positive temperatures depend on the ratio between humidity and soil salinity.

Saline soil properties, quality and productivity of wheat grown with bagasse ash and thiourea in different climatic zones

Soil salinity and atmosphere temperature change have negative impacts on crop productivity and its quality and can pose a significant risk to soil properties in semi-arid regions. We conducted two field experiments in North (first zone) and South (second zone) of Egypt to investigate the effects of soil bagasse ash (10 ton ha−1), foliar thiourea (240 g ha−1) and their combination in comparison to the control treatment on saline soil properties and productivity and quality traits of wheat. All studied treatments were received the recommended rate of N, P and K fertilizations. Combination of soil bagasse ash and foliar thiourea application resulted in a significant improvement of most studied soil properties (i.e. EC, compaction, hydraulic conductivity, OM and available P, K, N contents) after harvest in comparison to other treatments in both of zones. Also, it enhanced growth and grain yield of wheat in terms of photosynthesis related attributes and yield components. Moreover, combination of soil bagasse ash and foliar thiourea application resulted in superior grain quality traits in terms of carbohydrate, fibre, protein and ash contents than separated application of soil bagasse ash, foliar thiourea or even control treatment. In conclusion, combination of soil bagasse ash and foliar thiourea application can be used as suitable option to enhance plant nutrition, wheat productivity and improve wheat grain quality and soil traits in saline soil as well as can alleviate heat stress.

Responses of Saline Soil Properties and Cotton Growth to Different Organic Amendments

Application of organic waste to saline alkaline soils is considered to be a good practice for soil remediation. The effects of applying different organic amendments (e.g., cattle dung, vermicompost, biofertilizer) and earthworm inoculations (Eisenia fetida) on saline soils and cotton growth were investigated during 1 year of cotton cultivation. Compared to the control (applied with inorganic NPK fertilizer), applying organic amendments improved soil physicochemical properties. Biofertilizer application improved available nutrient content, reduced short-term soil electrical conductivity, and produced the highest cotton yield, whereas cattle dung and vermicompost applications resulted in higher soil organic matter content. Application of organic amendments significantly increased soil microbial biomass carbon during the flowering period, which sharply declined at harvest. This was especially true for the biofertilizer treatment, which also exhibited lower nematode abundance compared with the other organic materials. Earthworm inoculation following cattle dung application failed to significantly change soil physicochemical properties when compared to the treatments without earthworm inoculation. Results suggest that biofertilizer application to saline soil would improve soil nutrient status in the short-term, whereas cattle dung application would improve soil organic matter content and increase soil organism abundance to a greater extent. However, different strategies might be required for long-term saline soil remediation.

The Phase Change Process and Properties of Saline Soil During Cooling

Detrimental frost heave and salt expansion may occur in saline soils of cold regions. The severity of these processes depends on the amount of salt precipitation and ice crystal growth in the pore solution at different temperatures. By employing nuclear magnetic resonance, the liquid water fractions in different concentrations of sodium chloride and sodium sulfate saline soils were measured at different temperatures. Based on the theory of solution phase diagram and phase change in porous media, the differences and similarities of phase change between pore solution and free solution were analyzed. The phase change sequence and effects of salt on frozen soils are also discussed. The theoretical and experimental results confirm that the phase diagram can reflect the phase change of pore solutions roughly, and pore size distribution is the cause of differences between the pore solution and free solution. Sodium chloride can mitigate the frost heave of soil, and frost heave and salt expansion occur together when the sodium sulfate soil is frozen.

INFLUENCE OF SOME PROPERTIES CONCERNING WATER STABLE AGGREGATES OF SALINE SOILS

According to literature, aggregate stability of soils is influenced by: particle size and soil texture, soil structure, content of Ca2+ and Mg2+, mineral clay type, soil content of organic matter, soil processing degree. This paper aims to investigate the influence of some physical, microbiological and chemical properties of saline soil concerning water-stable aggregate. The hydro system stability of the aggregates appears in the specialized studies as having a positive correlation with microorganisms activity and thus with their behaviour in the soil. Our data support this theory, since according to our research there is a positive correlation between the percentage of stable aggregates and the amount of microorganisms. In samples from cultivated soil (noted in this paper by S), where the amount of microorganisms is higher, the percentage of water-stable aggregate is higher as well. In samples from uncultivated soil (noted in this paper by M), where the amount of microorganisms is lower, the percentage of water-stable aggregate is lower too. According to research studies and to the specialty literature, sodium is an element with a disruptive role on the stability of the aggregates. Our experimental data has shown that in samples from uncultivated soil (M), where sodium values are much higher, compared to samples from the cultivated soil (S), the percentage of water-stable aggregate is lower than the percentage of water-stable aggregate in the samples from the cultivated soil. Also, our results concerning porosity values ranging between 42.27% (the minimal value) to 49.86% the maximal value, show that these soils can be characterized as having low and very low porosity according to specialized literature. However, it must be taken into account the fact that in clay soils the porosity is very variable, depending on how the soil contracts, swells, disperses, compacts or cracks. In addition, the values describing the water permeability of the soil show that this characteristic for the control soil is small, the permeability coefficient k having values between 1.73 10-8 -7.19 10-8. For the cultivated soil, the permeability is medium, k having values between 4.97 10-7 - 7.83 10-8. Our data regarding soil physical properties, as well as the data about soil chemical properties that have been analyzed in this study show a weak quality of these soils, which cannot sustain a healthy crop with good economic yield.

Vineyard Compost Supplemented with Trichoderma Harzianum T78 Improve Saline Soil Quality

AbstractUnderstanding soil degradation is especially important in the Mediterranean Region where desertification is a serious problem, and soil salinization is one of the causes. Salinity reduces soil quality, limits crop productivity and brings on long term soil degradation. Therefore the restoration of degraded soils is necessary to reduce land degradation, improve soil fertility and achieve a sustainable food production. The addition of compost supplemented with the beneficial microorganism Trichoderma harzianum isolate T78 to saline soils (NaCl) was studied to determine the impact on soil microbiology, which is the key to restore and rehabilitate degraded soils. The selected Trichoderma harzianum isolate T78 showed high salt tolerance despite the low osmotolerance of the genus Trichoderma. Increasing salt concentration reduced Trichoderma sp colony‐forming units (CFU) from natural soil and adversely affected soil microbial biomass C as well as dehydrogenase, β‐glucosidase, phosphatase and urease activities. Simultaneous amendment of the saline soil with compost and inoculation with T. harzianum T78 improved the soil microbiological quality; the number of T. harzianum T78 CFU did not decrease as NaCl increased. As T. harzianum strain T78 is salt tolerant, increasing the relative abundance of this specific strain would contribute to the rehabilitation of saline soils. Vineyard composts supplemented with T. harzianum T78 represent a promising approach for the treatment and improvement of saline soil properties. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of biochar application on Suaeda salsa growth and saline soil properties

Pot experiments were conducted to study the effects of biochar application rates (5, 10, 20 g/kg) and types of wheat straw biochar (WS), corn stalk biochar (CS) and peanut shell biochar (PS) on Suaeda salsa (S. salsa) growth and properties of saline soil in Yellow River Delta. It was found that S. salsa yield increased from 11.7 to 115 % under WS application at a range of 5–10 g/kg compared with control. As biochar rate increased to 20 g/kg, the increment decreased to 102 %. The underground biomass of S. salsa only increased at 20 g/kg rate. The S. salsa growth respond to biochar followed the order of PS > WS > CS. Biochar application generally reduced saline soil pH and the effect was more obvious for WS. The content of total organic matter increased significantly at biochar rate of 10–20 g/kg. WS at higher application rate (20 g/kg) significantly increased available phosphorus content. At the same time, CS increased more available phosphorus content while PS decreased more of exchange sodium percentage. In generally, biochar application improved saline soil quality and enhanced plant growth although these effects should be tested in long-term period.

Changes in biological and chemical properties of saline soil amended with municipal solid waste compost and chemical fertilizers in a mustard–pearl millet cropping system

The restoration of microbial activities is a basic step in the reclamation of saline soil. For this reason, the ability of municipal solid waste compost (MSWC) to accelerate the microbiological and chemical properties of soil was evaluated in a field experiment. The aim of this study was to evaluate the efficiency of combined use of organic amendments viz. MSWC, gypsum enriched compost (GEC), rice straw compost (RSC) and chemical fertilizers as reclamation agents for improving biological and chemical properties of saline soil in a mustard–pearl millet cropping system. Integrated use of 25% recommended dose of fertilizer (RDF) along with organic amendments (RSC@3.5tha−1+GEC@3.5tha−1+MSWC@4tha−1) resulted significantly higher amount of microbial activities, Walkley and Black Organic Carbon (WBC) as well as available KMnO4-N, Olsen-P and NH4 OAc-K over unfertilized control plot after mustard and pearl millet harvest. Combined use of organic amendments along with 25% RDF increased by 50 and 56% higher microbial biomass carbon (MBC) over unfertilized control plot after harvest of mustard and pearl millet respectively. Treatment receiving 100% RDF improved dehydrogenase activity (DHA), alkaline phosphatase activity (APA) and urease activity by 39, 26 and 23%, respectively over unfertilized control plot after harvest of pearl millet crop. Balanced use of organic amendments plus 25% RDF maintained 9, 42 and 16% higher amount of available KMnO4-N, Olsen-P and NH4OAc-K, respectively over the alone use of 100% RDF after mustard harvest. After harvest of pearl millet soil EC (1:2) was significantly lower under treatment receiving organic amendments along with 25% RDF than other treatments.

Effects of municipal solid waste compost, rice-straw compost and mineral fertilisers on biological and chemical properties of a saline soil and yields in a mustard–pearl millet cropping system

We investigated the effects of organic amendments, municipal solid waste compost (MSWC) and rice-straw compost (RSC) with and without mineral fertilisers on biological and chemical properties of a saline soil. Field experiments were conducted for two consecutive years during 2012–14. In the first year, application of 8tha–1 of MSWC+50% of the recommended dose of fertilisers (RDF) resulted in higher microbial biomass carbon (MBC), enzyme activities, soil organic carbon (SOC), available nitrogen (N), phosphorus (P) and potassium (K) than 7tha–1 of RSC+50% RDF, after mustard (Brassica juncea) and pearl millet (Pennisetum glaucum) harvests. Combined use of 8tha–1 of MSWC+50% RDF resulted in 47% and 54% more MBC than the unfertilised control after mustard and pearl millet harvests, respectively. Dehydrogenase activity was significantly higher with 100% RDF than the control after 2 years of the cropping cycle. Among organic amendments, MSWC was superior to RSC in terms of MBC, and activities of dehydrogenase, alkaline phosphatase and urease. SOC was significantly increased under MSWC+50% RDF compared with 100% RDF alone. Significant build-up of soil fertility in terms of available N, P and K was observed with RSC+50% RDF compared with the control. During the second year of the cropping system, soil treated with RSC+50% RDF had 14%, 17% and 9% higher N, P and K than soil treated with 100% RDF, after pearl millet harvest. The magnitude of change in soil electrical conductivity and pH was low during 2012–13; however, soil salinity decreased by 55% and 48% with MSWC+50% RDF and RSC+50% RDF, respectively, relative to the control at 120 days of pearl millet growth in 2013–14. Application of MSWC +50% RDF produced 2.5 and 2.70tha–1 of mustard and pearl millet, and increased grain yield by 19% and 15%, respectively, compared with 100% RDF. Integrated use organic amendments and mineral fertiliser is recommended for promoting biological and chemical properties of saline soil in a mustard–pearl millet cropping system.

Hiệu quả của phân hữu cơ và vôi trong cải thiện năng suất lúa và đặc tính bất lợi của đất nhiễm mặn trong điều kiện nhà lưới

Saline soils need to be reclaimed to maintain fertility levels for sustaining food production as they are of soil chemical constraints, leading to rice yields reduction. The experiment was established in a greenhouse to evaluate the effect of compost amendment and lime on improving some selected soil properties and rice yield in saline soils. Soil samples were collected from the fields under a shrimp-rice farming system at An Biên district, Kien Giang province. The results showed that application of inorganic fertilizer (60-20–20), 5 ton/ha of sugarcane filter cake compost or Bio-pro and 0.5 ton/ha lime resulted in an improvement of adverse properties of saline soil. The changes were found as reducing exchangeable Na+, Exchangeable Sodium Percentage (ESP), and ECe, increasing of soil available nitrogen and phosphorus. Consequently, the growth rate and rice yield were increased significantly.

Dielectric properties of saline soil based on a modified Dobson dielectric model

Soil salinization is a major concern for agricultural development in arid areas. In this paper, a modified Dobson dielectric model was applied to simulate the dielectric constant of saline soil in the Ugan-Kuqa river delta oasis of Xinjiang Uygur autonomous region, northwestern China. The model performance was examined through analyzing the influences of its parameters on the soil dielectric constant and the relationship between radar backscattering coefficient and the dielectric constant of saline soil. The results of the study indicate that: (1) The real part of the soil dielectric constant is affected by soil water content at low radar frequencies; the imaginary part is closely related with both the soil water content and soil salt content. (2) The soil water and salt contents are related with the coefficient of dialectical loss, which is consistent with the natural conditions of saline soil in arid areas and provides valuable references for the study of soil dielectric properties. (3) The changes of soil water content and soil salt content have instant influences on the dielectric constant of saline soil. Subsequently, the radar backscattering coefficient is affected to respond to the dielectric constant of saline soil. The radar backscattering coefficient is most responsible to the radar’s cross polarization pattern with a correlation coefficient of R 2=0.75. This study provides a potential method to monitor soil salinization and soil water content by using a soil dielectric model and radar techniques.

Dielectric Properties of Saline Soils and an Improved Dielectric Model in C-Band

To retrieve the soil salinity by microwave remote sensing, we must clarify the relation of dielectric properties of saline soils with soil salinity. The objective of this paper was to determine how dielectric properties are affected by soil salinity in the remote sensing range and develop an improved model applying for the saline soil. Laboratory measurements of dielectric constant are made with a microwave vector network analyzer using soil mixture samples of various soil moistures and salinities prepared artificially from natural soils. The results confirmed that the real part is strongly affected by soil moisture, whereas the imaginary part depends on both the soil moisture and salinity, particularly at lower frequencies (1-6 GHz). Thus, as a key factor, soil salinity is introduced into the expression of the imaginary part of dielectric constant in the Dobson semiempirical dielectric mixing model, combining the dielectric model for saline water and the impact of electrical conductivity of soil solution. The improved model yields results, which are in good agreement with the laboratory measurements, the slopes of fitting curves between measurements and simulation nearly being equal to 1, and coefficient R 2 are higher than 0.89. In addition, the improve model is independent of soil-texture parameters. However, it should be noted that the improved model can be applied only to the C-band remote sensing.