Soils In Arid Areas Research Articles

English

In order to promote the comprehensive production capacity and yield of farmland soil, the effects of subsoil tillage on soil structure, root activity, photosynthetic characteristics, dry matter accumulation, yield and water use through long-term positioning research in semi-arid areas were studied. This study was started in 2011 and investigated in the 2015–2016 research cycle. The experiment was conducted with five treatments including 30 cm subsoiling (SS-30) and 40 cm subsoiling (SS-40) before spring sowing, 30 cm (AS-30) and 40 cm (SS-40) between rows after autumn harvest and no subsoiling (CK). The effects of subsoiling on soil properties, crop growth, yield and water use of maize in semi-arid areas were investigated. The results showed that subsoiling significantly reduced the penetration resistance and bulk density of soil, and significantly increased the soil moisture content from subsoiling to the surface. Subsoiling increased GSand Ci, Tr, Pnand WUE in maize plants, and significantly increased root activity. Subsoiling significantly increased dry weight of aboveground part and root, significantly decreased root shoot ratio, and significantly increased WUE per plant. Subsoiling significantly increased 100 grain weight, yield and WUE of population. Subsoiling can effectively improve the soil structure, enhance the water storage capacity of the soil in arid areas, delay water loss, improve root activity, net photosynthetic rate, dry matter accumulation and WUE, and promote crop growth and yield of maize. Subsoiling in autumn has the best effect on soil improvement. Increasing the subsoiling depth properly can improve their effects, which will gradually less with the passage of time.© 2021 Friends Science Publishers

Regulating and intervening act of Cr chemical speciation effect on the electrokinetic removal in Cr contaminated soil in arid area

Heavy metals chemical speciation significantly effects the electrokinetic removal of heavy metals contaminated soil, but how to regulate and intervene the chemical speciation for improving the removal efficiency in the electrokinetic remediation of the contaminated soil is still an opened problem. In this study, we used increasing citric acid electrolyte concentration and soil pretreatment as regulating measures and the anolyte circulation and reduction wells as intervening act to explore the detailed transformation and migration of Cr speciation over time during electrokinetic remediation, the effect of the transformation and migration of Cr speciation in arid area contaminated soil on the removal efficiency. Based on the results of sequential extraction, the regulating measures can significantly improve the soil pH and the transformation of Cr speciation in arid areas, but the detailed transformation occurs in the early stage of remediation. The material flows showed that the transformation of other speciation to exchangeable (EXC) was higher than its migration to the electrode chamber and the EXC was not completely removed throughout the experiment. By adding HCl to the soil prior to the electrokinetic remediation, more Cr (III) can migrate to the cathode region. Regulating measure for pretreatment of real contaminated soil in arid area based on high concentration of citric acid and intervening act for the anolyte circulation could significantly reduce the bound to Fe/Mn oxides (FM), but the overall removal efficiency of the real contaminated soil (from 44.86% to 44.90%) was not improved, while the removal efficiency of artificially contaminated soil was higher. Furthermore, the multivariate linear regression analysis of the link between the five fractions and removal efficiency of Cr also shows that their correlation was much higher in artificially contaminated soils than in real contaminated soils. The scale effect would affect the transformation of the speciation, and the smaller the scale of the experiment is, the larger the influence on the migration and transformation of Cr speciation will be. The combination of regulating measures and intervening act provide a valuable reference for the specific transformation and migration of heavy metals speciation and the improvement of removal efficiency during EKR of contaminated soil in arid area.

Evaluating the Effects of Biochar and SAP Polymer on Soil Physical Quality Indices

ABSTRACT The aim of this study was to examine the effects of soil amendments to sandy loam and soil physical indices, mainly soil aggregates, soil retention curve, and pore size distribution. Date palm waste biochar at rates 2% (B1), 4% (B2), 6% (B3), and 8% (B4) and sorbent adsorption polymer (SAP) at rates 0.2% (P1), 0.4% (P2), 0.6% (P3), and 0.8% (P4) (w/w). In addition, the combination of both as B1:P1, B2:P2, B3:P3, and B4:P4, were added to the soil as amelioration materials. The results revealed that on the average, soil water content increased by 7.3%, 3.3%, and 15.0% with the addition of biochar, polymer, and the combination, respectively. The location parameters dmode, dmedian, and dmean decreased by 6.4%, 8.8%, and 10.6% for the biochar, and increased by 2.3%, 4.6%, and 3.4% for the polymer treatments, decreased by 4.8%, 4.4%, and 4.2% for the combination treatments, respectively. Shape parameters such as standard deviation (SD), (spread) skewness (asymmetry), and kurtosis (peakedness) were 2.2, – 0.27, and 1.6 for the biochar treatments, 2.17, – 0.27, and 1.6 for the polymer treatments, and 2.17, – 0.23, and 1.6, for the combination treatments, respectively. The aggregate stability (SA) of soils of size 0.25 and 0.13 mm increased by 50.8% and 50% with the application of biochar (B2 = 4%) and polymer (P2 = 0.4%) B2:P2 and polymer (P4 = 0.8%) P4 treatments, respectively. This study recommends using combination of biochar with polymer treatments on sandy loam soil in arid area due to its strong hydro-physical properties.

Estimation of Low Organic Matter Content in Desert Soil of Arid Area Based on Fractional Order Sprott Chaotic Circuit and Gray Theory

Weak spectral response and low model accuracy problems occurred in the process of quantitative inversion of low organic matter content of desert soil in arid areas. This study collects soil samples and field spectral data from different human interference regions in Fukang City, Xinjiang, to search the soil hyperspectral response law that based on the fractional Sprott chaotic system, and combined with the gray system theory to estimate organic matter content rapidly and accurately. Simulation shows that for those sampling soil with lower organic matter content, the range of X and Y components of the dynamic error motion curve distribution of the Sprott chaotic system is larger, and the motion curve of the non-integer order 1.9-order dynamic error is the most obvious. Since the chaotic attractors will appear as a linear trend according to different contents of the organic matter, so this thesis establishes a gray prediction model based on the 1.9 fractional order chaotic attractors. The R 2 , RPD, and RMSE of the low organic matter content in the region without human interruption are 0.995, 14.86, and 0.17, respectively. The R 2 , RPD, and RMSE of low organic matter content in the region with human interruption are 0.992, 11.95, and 0.11, respectively. This study demonstrates that it is feasible to estimate the low organic matter content of desert soils in arid regions via the gray prediction model that based on fractional chaotic attractors. This study provides a novel method for soil spectra signal analysis and estimation of the organic matter content.

Research Progress of CO2 Flux in Saline and Alkali soils in Arid area

Study on CO2 flux of saline and alkali soil in arid area is of great significance to greenhouse gas control. At present, the main research contents at home and abroad focus on the ways of CO2 sequestration and migration and transformation in saline-alkali soils in arid areas. The influencing factors of CO2 flux in saline-alkali soil in arid area include soil temperature, humidity, pH, EC and soil physical and chemical properties. Inorganic carbon equilibrium process of CO2(g)—CO2 (aq)—HCO3- (aq)—CaCO3(s) is common in soil, its dynamic process dominates the inorganic carbon exchange at the ground-gas interface. This is of great significance to the study of soil-atmospheric carbon circulation system for exploring the principle and mechanism of greenhouse gas change in order to slow down global warming and strengthen the management and control of greenhouse gases. It contributes to China’s energy conservation and emission reduction planning and international carbon balance negotiations.

Study on Environmental Effects of Different Covering Measures on Spring Maize Planting in the Loess Plateau

Covering farming techniques is an effective means of protecting and managing soils in arid, semi-arid and sub-humid and drought-prone areas, and is a change to traditional farming systems. This technology can regulate the “water, fertilizer, gas, heat” of farmland soil, change the physical and chemical properties and environmental quality of soil in arid areas, and effectively solve a series of problems caused by drought and irrational farming. Through different farming cover measures, In order to achieve stable production and high yield, it has important promotion value in the loess area. Through comprehensive research on the relevant research and demonstration experience of predecessors, this paper deeply studies the growth and development of spring maize and soil water and fertilizer effects under different cropping practices. It is found that different coverage measures have significant gain effects on soil moisture and fertility. The increase in corn production has a positive effect.

Evaluation of a Microwave Emissivity Module for Desert Regions With CMEM

To overcome deficiencies of current state‐of‐the‐art L‐band microwave emission models a microwave emissivity parameterization for desert regions, as derived by Grody and Weng (2008) using dense media theory, has been implemented in European Centre for Medium‐Range Weather Forecasts' Community Microwave Emission Modeling platform (CMEM). Simulations of L‐Band brightness temperatures were conducted over Africa for 2013 using the default CMEM parameterization of the soil dielectric constant from Wang and Schmugge, and using the desert emissivity parameterization from Grody and Weng. Results are evaluated against Soil Moisture and Ocean Salinity mission data. The Grody and Weng parameterization shows clear improvements over dry soil in arid areas with reduced bias and root‐mean‐square deviations at both polarizations. However deficiencies for semi‐arid areas, where the bare soil model of Wang and Schmugge shows best results in rainy conditions, suggest that hybrid implementation combining soil dielectric and desert emissivity models should be investigated for global scale applications.

Effect of a Mining and Smelting Plant on the Accumulation of Heavy Metals in Soils in Arid Areas in Xinjiang

Arid and semi-arid regions in West China are ecologically fragile zones. Increasing attention has been focused on soil pollution triggered by mining and smelting in those areas. Nine heavy metals in the soil around a mining and smelting plant in Xinjiang were investigated using multivariate analysis, the geoaccumulation index, and GIS techniques. The heavy metals Cu and As were identified as the main pollutants in the study area. The accumulation of the heavy metals Cr, Zn, Ni, and Cd is small and weakly disturbed by human activity. Anthropogenic accumulation of Co and Pb was observed at a few sampling sites; its degree was also small. Anthropogenic accumulation of Mn in soil was not apparent. The factor analysis indicates two sources for the nine heavy metals in the soils. Source 1 includes As, Cu, Ni, Cr, Zn, Cd, and Co, while Source 2 includes Mn and Pb. The spatial distribution suggests that the sites with the highest As, Cu, Ni, Cr, Zn, Pb, Cd, and Co concentrations are in areas close to the tailing dump. The sealing tailing dump is the prior way to prevent the spread of heavy metals. The results also reveal that the PCA/APCS receptor model is not applicable for the quantification of the contribution of heavy metals in soils in this case.

Experimental Study on Influence of Vaporous Water on Salt Expansion of Sulfate Saline Soil

The harm of salt expansion of saline soil in arid areas has always been a major problem to be solved urgently. According to the conversion rule between sodium sulfate and sodium sulfate decahydrate, sodium sulfate decahydrate crystals can be precipitated from sodium sulfate solution by cooling. Besides, when the relative humidity (RH) exceeds the critical relative humidity (CRH), sodium sulfate decahydrate can be formed by the combination of sodium sulfate and vaporous water, resulting in the salt volume expansion. However, at present, in the salt expansion mechanism of sulfate saline soil, only the influence of liquid water is considered while vaporous water is not involved. To study the effects of temperature, salinity, and ARH on salt expansion, the salt expansion test of dry sulfate saline soil under the action of vaporous water was conducted, and its composition was analyzed by X‐ray diffraction (XRD) technology. Experimental results showed that sodium sulfate decahydrate crystals were produced in the sulfate saline soil if the relative humidity (RH) of pore gas exceeded the critical one so that salt expansion occurred. Salt expansion and salt expansion rate of sulfate saline soil increased with the increase of RH and salinity but decreased with the increase of temperature. Therefore, the new salt expansion mechanism of sulfate saline soil under vaporous water is verified. The experimental results further perfected the original salt expansion mechanism of sulfate saline soil under the action of liquid water and guided the study of new treatment methods of sulfate saline soil.

Estimation of growth and exopolysaccharide production by two soil cyanobacteria, Scytonema tolypothrichoides and Tolypothrix bouteillei as determined by cultivation in irradiance and temperature crossed gradients.

Two filamentous cyanobacteria of the genera Scytonema and Tolypothrix were reported to be effective for stabilizing soil in arid areas due to the production of significant amounts of extracellular polysaccharides (EPS). These EPS may also have applications in the biotechnology industry. Therefore, two cyanobacterial species, Scytonema tolypothrichoides and Tolypothrix bouteillei were examined using crossed gradients of temperature (8-40°C) and irradiance (3-21 W m-2) to identify their temperature and irradiance optima for maximum biomass and EPS production. According to their reported temperature requirements, both strains were considered mesophilic. The optimum growth range of temperature in S. tolypothrichoides (27 to 34°C) was higher than T. bouteillei (22-32°C). The optimum irradiance range for growth of S. tolypothrichoides (9-13 W m-2) was slightly lower than T. bouteillei (7-18 W m-2). Maximum EPS production by S. tolypothrichoides occurred at similar temperatures (28-34°C) as T. bouteillei (27-34°C), both slightly higher than for maximum growth. The optimum irradiance range for EPS production was comparable to that for growth in S. tolypotrichoides (8-13 W m-2), and slightly lower in T. bouteillei (7-17 W m-2). The Redundancy Analysis confirmed that temperature was the most important controlling factor and protocols for field applications or for mass cultivation can now be developed.

Pretreatment of Total Phosphorus Content in Saline Soil in Arid Area by Fractional Differential Algorithm

Pretreatment of Total Phosphorus Content in Saline Soil in Arid Area by Fractional Differential Algorithm

Effect of clay amendment on physical and chemical characteristics of sandy soil in arid areas: the case of ground south - eastern Tunisian

Effect of clay amendment on physical and chemical characteristics of sandy soil in arid areas: the case of ground south - eastern Tunisian

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.

Plastic mulching with drip irrigation increases soil carbon stocks of natrargid soils in arid areas of northwestern China

A cotton field experiment was conducted to study the effects of plastic film mulching cultivation (PC) and non-mulching cultivation (NPC) on soil carbon content of an Aridisol, classified as a typic natrargid, in Xinjiang Uygher Autonomous Region, China. The use of PC enhanced the stock of soil organic carbon (SOC) at depths of 0–30cm, but not at depths of 30–70cm, compared with NPC. Furthermore, PC enhanced the stock of soil inorganic carbon (SIC) at depths of 30–70cm but not at 0–30cm. Overall, PC increased the total carbon (TC) stock at depths of 0–70cm. The TC stock was higher in PC (16.37kgCm−2year−1) than in NPC (15.89kgCm−2year−1). The contribution percentage of SIC (52%) to the net soil carbon (C) accumulation was higher than that of SOC (48%). Our results suggested that adoption of PC could be used as an effective way to increase the carbon sequestration of soils under cotton systems in arid areas.

Detecting soil salinity with arid fraction integrated index and salinity index in feature space using Landsat TM imagery

Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context (vegetation cover, moisture, surface roughness, and organic matter) and the weak spectral features of salinized soil. Therefore, an index such as the salinity index (SI) that only uses soil spectra may not detect soil salinity effectively and quantitatively. The use of vegetation reflectance as an indirect indicator can avoid limitations associated with the direct use of soil reflectance. The normalized difference vegetation index (NDVI), as the most common vegetation index, was found to be responsive to salinity but may not be available for retrieving sparse vegetation due to its sensitivity to background soil in arid areas. Therefore, the arid fraction integrated index (AFII) was created as supported by the spectral mixture analysis (SMA), which is more appropriate for analyzing variations in vegetation cover (particularly halophytes) than NDVI in the study area. Using soil and vegetation separately for detecting salinity perhaps is not feasible. Then, we developed a new and operational model, the soil salinity detecting model (SDM) that combines AFII and SI to quantitatively estimate the salt content in the surface soil. SDMs, including SDM1 and SDM2, were constructed through analyzing the spatial characteristics of soils with different salinization degree by integrating AFII and SI using a scatterplot. The SDMs were then compared to the combined spectral response index (COSRI) from field measurements with respect to the soil salt content. The results indicate that the SDM values are highly correlated with soil salinity, in contrast to the performance of COSRI. Strong exponential relationships were observed between soil salinity and SDMs (R 2>0.86, RMSE<6.86) compared to COSRI (R 2=0.71, RMSE=16.21). These results suggest that the feature space related to biophysical properties combined with AFII and SI can effectively provide information on soil salinity.

Reclamation and Utilization of Saline Soils in Arid Northwestern China: A Promising Halophyte Drip-Irrigation System

W the context of arable land and fresh water limits and a large population, the ability of China’s agriculture to meet demands for food, fodder, and fuel presents a falling tendency. Therefore, it is crucial for China to find appropriate methods and effective technologies to solve the food security problem, to achieve agricultural stability and sustainable development. Saline agriculture is proposed as one of the best solutions to deal with this threat. Success stories in saline agriculture have been documented in India and Pakistan. Nearly 70% of the total area of China’s saline soils occur in arid or semiarid regions, so developing water-saving saline agriculture is perhaps an efficient method for the optimized matching of agricultural water and soil resources. As an advanced irrigation technique with water-saving advantages, drip-irrigation is widely used in traditional agriculture throughout China. Here, we propose that planting halophyte crops under drip-irrigation conditions may be a promising approach for reclamation and utilization of saline soils in arid northwestern China. China’s National Mediumand Long-Term Program for Food Security (2008−2020) shows that China’s food security faces serious challenges, including rigid growth of commissary consumer demand, reduction of the arable land, and shortage of agricultural water resources. According to the Ministry of Land Resources of China, China is approaching the arable land “red line” (120 million hectare) because of urbanization, salinizaition and desertification. Saline soils, which are precious candidate arable land resources, occupy a significant strategic position in agriculture. Recently, rational reclamation and suitable utilization of saline soils in arid areas has become a major issue in China and has attracted increasing awareness from both government administrators and scientists. In China, about 25 million hectare saline soils in arid area remain uncultivable because of high salinity and water scarcity. Various approaches to reclaim saline soils including engineering, mechanical, chemical and biological are widely applied in northwestern China. However, such approaches have not yielded desirable results due to high costs or water limitations. Revegetation of saline soils with salt hyperaccumulating halophytes is a proactive phytoremediation method. Many halophytes such as Suaeda maritima and Sesuvium portulacastrum are reported to accumulate high contents of salt in their above ground tissues, and saline soils can be remediated by harvesting the plants regularly. To plant halophytes with limited water resources, this is a question of primary importance for arid saline soil recovery. Drip-irrigation is an effective irrigation technique to improve water use efficiency and is widely applied in traditional crops all over the world, especially in arid regions. This technology has the potential to plant halophytic crops and to obtain high-yield biomass with less irrigation water. Many halophytes have succulent leaves or small leaves, so we expect that water consumption for halophyte cultivation may be less than or similar to local crops grown under drip-irrigation. We hope that by using this system, a crucial step will be taken to break the bottleneck of biological reclamation of saline soils in arid areas. Not only can saline agriculture reclaim saline soils efficiently, it can also directly provide food, fodder, renewable energy and raw materials for industry. Scientists have found thousands of halophytes with great potential for development. Halophytes grown under saline conditions show levels of biomass and seed production comparable to conventional crops. For instance, Salicornia bigelovii, an oil-seed halophyte, could produce ca. 18 tons ha−1 of biomass and 2 tons ha−1 of seeds. Some halophytes have high nutritional value as forage or fodder crops. The restricting factor is their high salt content, but this limitation can be moderated by leaf protein extraction. Although the direct consumption of halophytic crops by humans and animals is limited, their seeds are being considered as new sources of grains or vegetable oils. Recent research carried out in Pakistan showed that some halophytes have potential as bioethanol crops.

艾比湖地区土壤呼吸对季节性冻土厚度变化的响应

As an special process for soils in the regions of high altitude,the freeze-thaw process directly or indirectly influences the physical,chemical and biological properties of soils. Under the background of the global warming,increasing attention has been paid to the effect of soil freezing-thawing alternation on carbon cycles. By measuring the changes of depth of seasonal frozen soil,of soil properties and soil respiration,our main objective was to provide insight into the responses of soil properties and soil respiration to changes in depth of seasonal frozen soil in arid area,and to further elaborate the effect of global warming on seasonal frozen soil and the resulted carbon release. Soil respiration rate( Rs) of Ebinur Lake area was measured from January to April in 2010 in the field using an automated CO 2 efflux system( LI-8100). Meanwhile, temperature( air temperature),atmospheric relative humidity and wind speed were measured 150 cm above the ground. Temperature,atmospheric relative humidity and wind speed were also measured at 10 cm above the ground,with a handheld weather instrument. Soil temperatures were measured at 5 cm,10 cm,15 cm,20 cm and 25 cm below soil surface with two geo-thermometers. The results showed that: during the frozen period,soil temperature is the most important factor determining the depth of frozen soil,while during thawing period,the depth of frozen soil was not influenced by temperature( P0.05). There was significant positive correlation between soil respiration rate and depth of frozen soil during most of the freezing period( R2= 0. 782,P0. 05),this correlation did not apply to the initial stage of freezing period( P0. 05). There was no significant difference in soil respiration rate between the freezing period and the initial stage of freezing period, but soil respiration rate significantly increased with the temperature during thawing period until the soil was unfrozen completely( the changes was 0. 14—0. 37μmol·m-2·s-1),indicating that permafrost melting significantly increased soil carbon emissions. Climate change impact on seasonal frozen soil depth,on the duration of frozen period,will change the seasonal crop production in permafrost regions. The natural vegetation biomass,spatial distribution pattern of vegetation and ranges of natural native plants distribution will also be changed. Even the plant community succession direction and patterns may also be altered by the changes in duration and depth of frozen soil. All those will affect the ecosystem carbon cycling process. The difference in soil respiration rate of different periods was influenced by soil organic content,snow-melt recharging to soil water and other factors,which may have a collectively effect on carbon cycle of the local ecosystem. Our preliminary findings in the current study revealed the impacts of seasonal frozen- thawing process on soil respiration in Ebinur Lake area,and provided theoretical basis for revealing carbon release mechanism during frozen-thawing processes under the background of global warming.

Laboratory experimental study of infrared imaging technology detecting the conservation effect of ancient earthen sites (Jiaohe Ruins) in China

As a new kind of inorganic reinforced material, potassium silicate can greatly improve the mechanical strength and the anti-wind erosion ability of ruins' soil in arid areas after being reinforced. The research developed a test device and test method of determining the thermal conductivity of earthen ruins' soil. The disturbed soil taken from the site of Jiaohe Ruins was made into soil specimens, and then, to study the reinforcement effect PS has on the thermal conductivity of ruins' soil by a thermal conductivity determination test and a laboratory model test. Test analysis showed that the thermal conductivity of PS reinforced specimens was reduced, furthermore, the larger the PS concentration, the smaller the thermal conductivity. Because PS decreased the soil's thermal conductivity, the heat transfer process of the reinforced soil was changed, and when external temperature had a change, the PS reinforced soil had a slower response to temperature than the unreinforced soil. From the analysis above, it is known that PS reinforced soil can slow down the physical weathering caused by temperature difference. And this viewpoint provides very useful scientific basis for studying the mechanism of PS and the earthen ruins' soil in northwest China arid regions.

Maximum surface temperature model to evaluate evaporation from a saline soil in arid area

In order to estimate soil evaporation from saline soil in arid area, a maximum surface temperature (MST) model was applied to Hetao Irrigation District (HID). The model was developed based on energy balance and sinusoidal function of surface soil temperature. Evaporation and surface temperature of drying soil columns and surface temperature of natural field were observed in each 1-h interval in daytime (from September 10 to 19, 2010) in a saline land in HID. The results indicated that the estimated evaporation shows a similar trend and in good agreement with the observed values. To quantitatively evaluate the performance of the model, some statistic parameters were calculated as well. These statistics could also indicate that the observed values perform similar trend to the estimated values. It is concluded that the MST model could be applied to estimate soil evaporation from saline land. The proposed method is hopeful to estimate soil evaporation over large scale area using only surface temperature available from the satellite image while assigning an effective exchange coefficient (ch).

SALINITY IN ARID-ZONE SOILS

Soil salinity is a factor that must be taken into account to characterize the environment of plants’ development. The reactions of cationic exchange regarding Na + , Ca +2 and Mg +2 cations have a great importance for soils of arid areas. Also, in these areas, the application of irrigation is a must. From the perspective of soil chemistry, all irrigation water are complex electrolyte solutions. In this context, the study presented in this work reveals a number of issues regarding: cationic exchange reactions and colloidal phenomena, the characterization indexes of salinity and alkalinity, irrigation water quality and its influence on the regime of saline soils, such as the irrigation systems supplied from the Siret and Buzau rivers.