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The application of green manure is a traditional and valuable practice to improve the fertility of saline soil. However, the impact of environmental factors, green manure types and returning methods on the changes in soil fertility and soil salinity remain poorly quantified at a large scale. In the present study, we conducted a meta-analysis to generate a comprehensive evaluation of the effects of green manure on soil organic carbon (SOC), soil salt content, and soil nutrients compared to bare soil in China. The results showed that compared with bare soil, green manure planting could significantly increase the SOC content of saline soil, reduce salt content, and improve the soil total nitrogen (N), soil available phosphorus (P) and soil available potassium (K) contents. On average, green manure significantly enhanced SOC by 34.82% (percentage change), soil total N by 32.23%, soil available P by 34.34% and soil available K by 17.43%, while reducing soil salt content by 47.75%, compared to bare soil. In areas with a mean annual temperature (MAT) of <10 °C or a mean annual precipitation (MAP) of 200–400 mm, green manure had the largest increase in SOC, soil total N, soil available P, and soil available K. The smallest increases were observed in areas with an MAT above 15 °C and MAP greater than 800 mm. Green manure types influenced the improvement effect of green manure on saline soil. Green manure mixtures were more conducive to increases in SOC, while the increases in soil total N resulting from mixed green manure were lower in comparison to those from both legumes and non-legumes. In addition, the initial salt content, experimental years, and returning method influenced the improvement effect of green manure on saline soil. Therefore, this meta-analysis identified green manure as a promising practice for significantly improved saline soil in China. [ABSTRACT FROM AUTHOR]

Nakhon Ratchasima Province faces significant challenges due to saline soil and water, resulting from natural salt rock deposits and salt mining activities. This study investigates the physicochemical properties, salinity distribution, and surface water quality in Non Thai and Phra Thong Kham District. A total of 75 samples were collected, with 48 from Non Thai and 27 from Phra Thong Kham. The analysis focused on properties such as temperature, electrical conductivity (EC), pH, total dissolved solids (TDS), salinity, chloride, sodium, calcium, and magnesium. Water quality was assessed using standards from the Thai Department of Health and the World Health Organization. Additionally, the Sodium Adsorption Ratio (SAR) was employed to evaluate irrigation suitability, and ArcGIS 10.5 was utilized to map salinity and water quality distribution. Results indicated that surface water pH remained relatively neutral and within acceptable limits. However, salinity levels varied from 0.5 to 30 ppt, indicating brackish to saline conditions. In several areas, concentrations of salinity, sodium, and chloride exceeded standard limits. Factors such as proximity to salt mines, water flow direction, lower terrain, and smaller reservoirs were linked to increased salinity, with Phang Thiam Subdistrict in Phra Thong Kham District showing the highest levels. The SAR index further indicated that water quality in Phra Thong Kham was unsuitable for domestic use and irrigation, unlike Non Thai. Further research in other salt mine areas are essential for a deeper understanding of salinity distribution, which is crucial for assessing risks and making informed decisions to protect public health and the environment. [ABSTRACT FROM AUTHOR]

Soil salinity is one of the major problems that threaten the soils in Jordan, which led to a decrease in the percentage of arable land in Jordan. The phytoremediation process is concerned with the restoration of contaminated soils using tolerant plants, such as halophyte plants. In this context, the potential short-term phytoremediation ability of Panicum Mombasa and Salicornia Europaea was evaluated and measured. A field experiment was conducted over two consecutive years to study the ability of these previous two crops for the phytoremediation of saline soils induced by treated wastewater irrigation. Both crops with bare soil as a control were irrigated together from the effluent of the Ramtha Wastewater Treatment Plant at the same time. Soil electrical conductivity was identified as the main parameter for measuring the plant's ability for salt absorption. The results for both seasons show a higher accumulation of salts in bare soil significantly as expected since no plants were present to absorb these salts and no leaching requirements were added with irrigation water. The absorption rate for each crop was measured at the 1st season for comparison. It is measured for each crop depending on the length of the growing season. Salicornia's absorption rate was greater than Panicum, and it reached 36 ppm/day for salicornia, whereas it reached 33 ppm/day for panicum. In the 2nd season, both crops are planted and harvested together. Salt absorbed percentage from the soil under Salicornia was greater than Panicum and it reached 73 % as compared to bare soil. However, in the soils under Panicum, the amount of salts absorbed reached 37 % as compared to bare soil. Plant analysis for both crops shows higher salt ions accumulation in Salicornia tissues than Panicum, and this explains the higher absorption rate for Salicornia than Panicum. Microbiological analysis for Panicum shows some contamination, whereas no contamination occurs in Salicornia. This is explained by the high salinity environment in Salicornia which is not favorable for e-coil, total, and fecal coliform to grow. The obtained Results from this research state that both crops have the ability for phytoremediation, with greater ability for Salicornia. [ABSTRACT FROM AUTHOR]

To study the effects of conventional biochar and acid modified biochar on water infiltration, with no biochar as the control (CK), 2 kinds of biochar with 3 additive amounts of 2%, 4% and 8% (mass fraction) were set up to conduct vertical one-dimensional water infiltration test. The dynamic changes of cumulative infiltration amount and wetting front migration were measured and discussed. The results showed that biochar increased the cumulative infiltration volume, shortened the wetting front transport time and improved the infiltration rate, and the larger the amount of biochar added, the more obvious the effect. Biochar improved the water holding capacity of coastal saline soils, and the effect of acid modified biochar on increasing the water content of shallow soil was more obvious. The one dimensional algebraic model was suitable for the water content of the tillage layer of coastal saline soil after the addition of biochar, and simulated the water distribution of the soil tillage layer after the infiltration test. Overall, the addition of 4% acid modified biochar was beneficial for improving the infiltration capacity and water holding characteristics of coastal saline soils. [ABSTRACT FROM AUTHOR]

Soil salinization poses a great threat to global agricultural ecosystems, and finding ways to improve the soils affected by salt and maintain soil health and sustainable productivity has become a major challenge. Various physical, chemical and biological approaches are being evaluated to address this escalating environmental issue. Among them, fully utilizing salt-tolerant plant growth-promoting bacteria (PGPB) has been labeled as a potential strategy to alleviate salt stress, since they can not only adapt well to saline soil environments but also enhance soil fertility and plant development under saline conditions. In the last few years, an increasing number of salt-tolerant PGPB have been excavated from specific ecological niches, and various mechanisms mediated by such bacterial strains, including but not limited to siderophore production, nitrogen fixation, enhanced nutrient availability, and phytohormone modulation, have been intensively studied to develop microbial inoculants in agriculture. This review outlines the positive impacts and growth-promoting mechanisms of a variety of salt-tolerant PGPB and opens up new avenues to commercialize cultivable microbes and reduce the detrimental impacts of salt stress on plant growth. Furthermore, considering the practical limitations of salt-tolerant PGPB in the implementation and potential integration of advanced biological techniques in salt-tolerant PGPB to enhance their effectiveness in promoting sustainable agriculture under salt stress are also accentuated. [ABSTRACT FROM AUTHOR]

Freezing points play a crucial role in distinguishing between salt expansion and frost heave in frozen saline soil. Through a series of cooling experiments, the freezing points of sodium chloride and sodium sulfate saline soils were measured, considering various salt concentrations and ratios of c(Cl−)/2c( SO 4 2 - ). The results revealed a three-stage cooling process: rapid cooling, constant cooling, and decreasing cooling. The freezing point of saline soil decreases with increasing salt concentration ranging from 1.5 to 4.9 times, attributed to the presence of more hydrated water molecules. Furthermore, influenced by the solubility of sodium sulfate, the freezing point of saline soil decreases with an increasing ratio of c(Cl−)/2c( SO 4 2 - ) in the range of 0.7–4 times. The reduction of water content, on the other hand, enhances capillary action and soil particle adsorption, causing the freezing point of the soil to decrease by 0.5 to 1.7 times. To accurately predict the freezing point of saline frozen soil, a prediction model was proposed and validated, taking into account the effects of salt types, salinities, and water contents. This research serves as a valuable theoretical reference for predicting the freezing point of saline frozen soil. [ABSTRACT FROM AUTHOR]

The matric suction of saline soil is the driving force that causes water migration, and it is of great significance for exploring the mechanism of water and salt migration in saline frozen soil. In order to investigate the effect of phase transition of soil pore solution induced by temperature on the matric suction of saline soil, the matric suction of different types of saline soils was measured by pF meter under different temperature conditions. The natural soil was first washed to obtain the desalinized soil, then different salt mass ratios of sodium chloride and sodium sulfate (0:6, 4:2, 2:4, 6:0) were added into the desalinized soil to model the composite saline soil, the salt content and water content were set to 6% and 20%, respectively. Subsequently, the remolded saline soil was compacted into the test chamber (0.37 m×0.25 m×0.22 m), and its dry density was controlled at 1.6 g/cm³. Hydra Probe II and pF meter were embedded at 11cm of the sample to measure the liquid water content and matric suction versus temperature. Freezing-thawing box (TMS 9 018-R30), produced by Zhejiang Tomos company, was employed to control the experimental temperature by step cooling method. The temperature range was from 30 to -24 °C, and the temperature interval was 3 °C. The data was collected by CR300 at an interval of 6 h. When the experiment was complete, the temperature effect of saline soil matric suction was analyzed and the effect of water/salt phase transition was explored. The experimental results reveal that the matric suction of saline soil increases almost linearly with the decrease of temperature when no phase transition occurs, which is caused by surface tension and wetting coefficient. Different types of saline soils have different effects on the phase transition process of pore solution, resulting in significant differences in the matric suction of different types of saline soils. The mirabilite crystallizes at 19 °C and the second phase transition occurs at -9 °C for the composite saline soil with 2% NaCl+4% Na2SO4, and the phase transition of composite saline soil with 4% NaCl+2% Na2SO4 occurs at 11 and -16 °C.Sodium chloride can inhibit the occurrence of ice formation, then the matric suction caused by ice formation is reduced, and the segregated frost heave caused by water migration is restrained indirectly. Besides, sodium sulfate is prone to crystallization at positive temperatures, and ice is also produced in the secondary phase transition process, both salt crystallization and ice formation increase the matric suction in sodium sulfate soil, and water and salt redistribute in this process, salt expansion and frost heave are induced. For composite saline soil, sodium sulfate mainly affects the salt crystallization of the soil at a positive temperature, while sodium chloride mainly affects the ice formation of the soil at a negative temperature. The different proportions of the two salts cause significant differences in the salt crystallization temperature and the secondary phase transition temperature, resulting in more complex phase transition laws in composite saline soil, and it is more difficult to predict the matric suction of composite saline soil. In addition, this paper further explores the contribution of ice and salt crystallization to the variation of matric suction, providing effective references for a deeper understanding of the relationship between phase transition processes and matric suction in saline soils. [ABSTRACT FROM AUTHOR]

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The relationship between unfrozen water content and temperature, called as soil freezing characteristic curve (SFCC), is of importance for hydrologic, engineering, environmental issues related to frozen soil. The SFCC of saline soil is essentially a result of phase equilibrium of pore solution, which is similar but not identical to that of bulk solution. However, there is still a vacancy of study on the phase equilibrium of pore solution in frozen soil. In this study, image transformation was used to establish the relationship of phase equilibrium between bulk solution and pore solution, with four introduced parameters. Then, the new model of SFCC for saline soil was proposed based on the equivalent state of bulk solution with Pitzer model and SFCC of nonsaline soil. The model was validated by the experimental data from published articles and showed good performance in calculating SFCC of saline soils regardless of soil type, phase transition path, and soil initial water‐salt condition, and some advantages when compared to other three models. All the four introduced parameters have clear physical meanings and their relationships with soil type and initial salt concentration were discussed. Finally, the evolution of phase diagram from bulk solution to pore solution at icing stage was figured out. Further studies are needed for their relationship at salt crystallization stage. Shifting the research perspective from unfrozen water content to pore solution, this study gives a new approach to research of freezing characteristic of saline soil and could promote hydrological and engineering research in cold regions. Plain Language Summary: The freezing temperature of pure water declines in soil like in solution. There is a reason to believe that the chemical equilibrium of pore solution differs from that of bulk solution. The chemical equilibrium of pore solution, to a certain extent, determines the amount of unfrozen water content, which affects the thermal, hydraulic and mechanical properties of soil. Two phase transition stages have been found in some saline soils with high salt content, which does not appear in nonsaline soils. The relationship of chemical equilibrium between pore solution and bulk solution is the vital interface to apply mature results of chemical characteristics of bulk solution into research of freezing characteristic of saline soils. However, it is still ambiguous for most researchers ignore the soil matrix effect on chemical equilibrium of pore solution. This paper used the transformation of phase diagram from pore solution to bulk solution, sounds like coordinate conversion, to establish their relationship and proposed an intuitive model to calculate the unfrozen water content of saline soil with equivalent state of bulk solution. The performance of the proposed model is good for various saline soils. This study provides an interesting perspective for frozen soil research. Key Points: A soil freezing characteristic curve (SFCC) model for saline soil is proposed with the equivalent bulk solution and SFCC of nonsaline soilGood performance of the new model at predicting SFCC of saline soil both in ice‐eutectic and crystallization‐eutectic pathsThe evolution of phase diagram at icing stage from bulk solution to pore solution is discovered with the proposed model [ABSTRACT FROM AUTHOR]

Nakhon Ratchasima Province faces significant challenges due to saline soil and water, resulting from natural salt rock deposits and salt mining activities. This study investigates the physicochemical properties, salinity distribution, and surface water quality in Non Thai and Phra Thong Kham District. A total of 75 samples were collected, with 48 from Non Thai and 27 from Phra Thong Kham. The analysis focused on properties such as temperature, electrical conductivity (EC), pH, total dissolved solids (TDS), salinity, chloride, sodium, calcium, and magnesium. Water quality was assessed using standards from the Thai Department of Health and the World Health Organization. Additionally, the Sodium Adsorption Ratio (SAR) was employed to evaluate irrigation suitability, and ArcGIS 10.5 was utilized to map salinity and water quality distribution. Results indicated that surface water pH remained relatively neutral and within acceptable limits. However, salinity levels varied from 0.5 to 30 ppt, indicating brackish to saline conditions. In several areas, concentrations of salinity, sodium, and chloride exceeded standard limits. Factors such as proximity to salt mines, water flow direction, lower terrain, and smaller reservoirs were linked to increased salinity, with Phang Thiam Subdistrict in Phra Thong Kham District showing the highest levels. The SAR index further indicated that water quality in Phra Thong Kham was unsuitable for domestic use and irrigation, unlike Non Thai. Further research in other salt mine areas are essential for a deeper understanding of salinity distribution, which is crucial for assessing risks and making informed decisions to protect public health and the environment.

Soluble phosphorus (P) and P uptake are heavily affected by adverse conditions, such as salinity and acidity. The study aimed to evaluate the effects of P-solubilizing purple nonsulfur bacteria (PSPNSB) Cereibacter sphaeroides on soil characteristics, P uptake, growth, and yield of rice planted in saline soil in Thoi Binh – Ca Mau under greenhouse conditions. The pot experiment was completely randomized in blocks with two factors. Factor A was the rate of phosphorus chemical fertilization at 0, 25, 50, 75, and 100% P according to the recommendation. Factor B was the PSPNSB including a single strain of C. sphaeroides ST16 or C. sphaeroides ST26 and a mixture of them. The soluble P in soil increased by 16.4–18.2% when C. sphaeroides ST16 and ST26 were supplied singly or in the mixture, leading to the increase in total P uptake in rice by 19.2–30.1% in two continuous crops. Moreover, the growth and yield components of rice were also improved, leading to an increase in rice grain yield by 7.20–17.7%. Moreover, supplying the C. sphaeroides strains reduced Na+ in soil and Na content in stem, leaves, and grains, leading to the reduction in proline content in rice. Supplying the C. sphaeroides ST16 and ST26 or their mixture replaced 100% P fertilizer but still ensured the rice grain yield. Further approaches should be made to investigate the possibility of the potent strains replacing chemical P fertilizers under field conditions.

Land use in arid and semi-arid regions is a serious challenge for sustainable production, owing not only to drought and climate change but also to water availability. Irrigated perimeters in these regions are subject to secondary salinization that negatively impacts soil quality and agricultural productivity. Monitoring and diagnosing the extent of soil contamination requires a more innovative approach to optimize rehabilitation of affected areas. In the present study, diagnosing of saline soil degradation is conducted by using two key indicators: electrical conductivity of saturated paste extract (ECe) and saturated hydraulic conductivity (HCs). The results of the study reveal that the value of ECe in 85% of the Lower Chellif Plain area (north-west Algeria) is ECe < 2 dS m−1, while 78% of the area is moderately permeable. These findings underscore high spatial variability in salinity distribution, indicating that the process of salinization has not yet reached a critical stage. Furthermore, it is concluded that ECe and HCs are appropriate indicators for diagnosing salinity of soil in relation to its structural and permeability characteristics.

The coastal areas of western Taiwan feature acidic and saline soils with low fertility. Sodium bicarbonate (NaHCO3), produced readily by carbon capture and storage technologies, could be suitable for the neutralization of acidic soils, but its effects on plant growth and the ability of Bacillus subtilis var. natto to confer salinity tolerance remain unclear. In this study, we examined the potential of sodium bicarbonate and B. subtilis var. natto (NTU18) to improve the growth of tobacco (Nicotiana tabacum L.) under salt stress conditions. We found that salt stress was the main factor affecting tobacco growth, resulting in shorter roots and shoots, a reduced leaf area and leaf number, and clustered dark green leaves. The addition of sodium bicarbonate exacerbated the symptoms of salinity stress. Inoculating the soil with B. subtilis did not enhance salinity tolerance, but intriguingly it increased shoot and root growth under normal conditions and in the presence of sodium bicarbonate. The mechanism of growth promotion mediated by the bacteria is unknown and should be investigated in more detail.

The morphological adjustments of euhalophytes are well-known to be influenced by the soil-soluble salt variation; however, whether and how these changes in morphological traits alter the biomass allocation pattern remains unclear, especially under different NaCl levels. Therefore, an allometric analysis was applied to investigate the biomass allocation pattern and morphological plasticity, and the carbon (C), nitrogen (N), and phosphorus (P) stoichiometric characteristics of the euhalophyte Suaeda Salsa (S. salsa) at the four soil-soluble salt levels of no salt (NS), light salt (LS), moderate salt (MS), and heavy salt (HS). The results showed that soil-soluble salts significantly change the biomass allocation to the stems and leaves (p < 0.05). With the growth of S. salsa, the NS treatment produced a downward leaf mass ratio (LMR) and upward stem mass ratio (SMR); this finding was completely different from that for the salt treatments. When S. salsa was harvested on the 100th day, the HS treatment had the highest LMR (61%) and the lowest SMR (31%), while the NS treatment was the opposite, with an LMR of 44% and an SMR of 50%. Meanwhile, the soil-soluble salt reshaped the morphological characteristics of S. salsa (e.g., root length, plant height, basal stem diameter, and leaf succulence). Combined with the stoichiometric characteristics, N uptake restriction under salt stress is a vital reason for inhibited stem growth. Although the NS treatment had the highest biomass (48.65 g root box−1), the LS treatment had the highest salt absorption (3.73 g root box−1). In conclusion, S. salsa can change its biomass allocation pattern through morphological adjustments to adapt to different saline–alkali habitats. Moreover, it has an optimal biological desalting effect in lightly saline soil dominated by NaCl. [ABSTRACT FROM AUTHOR]

The application of biochar to improve the quality of saline soils has attracted widespread attention. However, the impact of saline soil amendments with biochar prepared at different pyrolysis temperatures remains unclear. Therefore, we conducted a two-year (2022–2023) field experiment in the Hetao Irrigation District, China, to evaluate the effects of the biochar pyrolysis temperature (C1: 300 °C, C2: 500 °C, and C3: 700 °C) and application rate (T1: 10 t/ha and T2: 20 t/ha) on the soil quality and maize yield. The results indicated that (1) all biochar treatments significantly decreased the soil bulk density and increased the soil porosity; (2) treatment C3T1 significantly increased the soil moisture content and decreased soil salinity. The C3T2 treatment significantly increased the soil's organic carbon content, and the soil's available phosphorus content was greatest in the C1T2 treatment. (3) The maize yield increased linearly with the soil quality index (SQI), which was attributed mainly to improvements in the soil water–salt conditions and increases in the soil organic carbon content. In summary, biochar produced at high pyrolysis temperatures, when applied at a low application rate (C3T1), can result in high corn yields and improve saline soil quality. [ABSTRACT FROM AUTHOR]

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This article explores the potential benefits of using zinc lysine and biochar to enhance the growth and physiological performance of wheat plants under saline stress. The study found that the combined application of biochar and zinc lysine significantly improved various physiological attributes and reduced oxidative stress indicators. The authors suggest that this combined treatment could be a practical solution to mitigate salt stress in plants, but further field studies are needed to validate these findings [Extracted from the article]

The widespread abandoned saline-alkali soils in the Manas River Basin in northwest China have been reclaimed for cotton cropping in recent decade. However, the temporal dynamics of soil microbial functional genes during the reclamation of abandoned salinized farmlands remains unclear. In this study, the abandoned salinized cotton fields that had been reclaimed for 1, 3, 5, and 7 years were selected to study the temporal dynamics of soil microbial functional genes through metagenomic technology. The abundance of genes involved in C, N, P, and S cycles increased significantly since the reclamation, among them, the abundance of KEGG Pathway genes and Enzymes after the reclamation increased by 29.10 and 30.20%, respectively compared with those of the CK (abandoned salinized farmland). The Shannon index of KEGG Pathway and Enzyme-annotated genes after the reclamation increased by 0.82 and 1.10%, respectively compared with those of the CK. The permutational multivariate analysis of variance (PERMANOVA) and correlation analysis showed that the decrease in soil Na+ content and the increase in soil C/N ratio induced by the reclamation increased the abundance and diversity of soil microbial functional genes. After the reclamation, continuous straw incorporation and fertigation increased the soil C/N ratio, and reduced salinity, thus improving soil quality and soil microbial ecological functions. This study will provide reference for the rational development and utilization of abandoned salinized soils in arid areas. [ABSTRACT FROM AUTHOR]

Saline soils limit plant growth due to high salinity. Straw returning has proven effective in enhancing soil adaptability and agricultural stability on saline lands. This study evaluates the effects of different straw-returning methods—straw mulching (SM), straw incorporation (SI), and straw biochar (BC)—on soil nutrients, water dynamics, and salinity in a barley–cotton rotation system using field box experiments. SM improved soil water retention during barley's jointing and heading stages, while SI was more effective in its filling and maturation stages. BC showed lesser water storage capacity. During cotton's growth, SI enhanced early-stage water retention, and SM benefited the flowering and boll opening stages. Grey relational analysis pinpointed significant water relationships at 10 cm and 20 cm soil depths, with SM regulating water across layers. SM and BC notably reduced soil conductivity, primarily within the top 20 cm, and their effectiveness decreased with depth. SI significantly lowered soil conductivity at barley's jointing stage. SM effectively reduced salinity at 10 cm and 20 cm soil depths, whereas BC decreased soil conductivity throughout barley's jointing, filling, and heading stages. For cotton, SI lowered soil conductivity at the seedling and boll opening stages. SM consistently reduced salinity across all stages, and BC decreased conductivity in the top 30 cm of soil during all growth stages. Both SM and BC significantly enhanced the total nutrient availability for barley and cotton, especially improving soil organic carbon and available potassium, with BC showing notable improvements. At barley's heading stage, SI maximized dry matter accumulation, while SM boosted accumulation in leaves, stems, and spikes during the filling and maturation stages. Straw returning increased barley yield, particularly with SM and BC, and improved water use efficiency by 11.60% and 5.74%, respectively. For cotton, straw returning significantly boosted yield and water use efficiency, especially with SI and SM treatments, enhancing the total bolls and yield. In conclusion, straw returning effectively improves saline soils, enhances fertility, boosts crop yields, and supports sustainable agriculture. These results provide a robust scientific foundation for adopting efficient soil improvement strategies on saline lands, with significant theoretical and practical implications for increasing agricultural productivity and crop resilience to salt stress. [ABSTRACT FROM AUTHOR]

The Hetao irrigation region is located in Inner Mongolia, China, within a dry and semi-dry region. This region suffers from poor agricultural productivity and environmental damage due to the presence of saline soil. To explore the growth of salty lands using a more environmentally friendly method, this research employed three eco-conscious amendments to improve the soil. These include flue gas desulfurization gypsum (S), humic acid (H), and biochar (C). During a two-year study, the amendments were utilized to enhance the soil quality for planting sunflowers. Humic acid was used prior to every seedling season, whereas the remaining two substances were only used once. These additions increased the soil's water-holding capacity, reduced soil salinity during sunflower growth, and improved the macroaggregate proportion. The most effective treatment for decreasing the soil's salt content after the seedling stage was the application of humic acid (0.6 t ha−1). Biochar (15 t ha−1) decreased the soil's bulk density (from 1.49 to 1.34 g cm−3) and mostly increased the sunflower seed yield up to 3133−3964 kg ha−1. Humic acid addition significantly increased the aggregate (>0.25 mm) content up to 27.88% after the experiment, but it led to a lower seed yield (2607−3686 kg ha−1). In 2019, the temperature was lower compared to 2018, which may have led to a reduction in the yield. However, these three amendments could potentially increase yields by more than conventional methods. These three environmentally friendly amendments are useful for improving saline soil and increasing yields. More studies are required to understand their impacts on larger areas and over extended periods. [ABSTRACT FROM AUTHOR]

Soil's hydraulic properties are an essential characteristic that influences the hydrologic cycle by influencing infiltration and runoff and the transport of soil water and salt in the process of vegetation rehabilitation in coastal saline soils. To date, few studies have specifically addressed the soil's hydraulic properties and root–soil interactions of coastal saline soil under revegetation. This study aimed to identify the unique hydraulic characteristics of soil, the pore size distribution parameter, Gardner α, and the different contributions of soil's physical properties and vegetation's root morphological characteristics with regard to soil infiltration. For this purpose, disc infiltration experiments at different pressure heads were performed on three vegetation types, Salix matsudana (SM), Hibiscus syriacus (HC), and Sabina vulgaris (SV), after two years of vegetation rehabilitation. The results demonstrated that the initial and steady infiltration rate, Gardner α, and soil porosity fraction exhibit significant differences among the three plant species. A correlation analysis indicated that the soil water content, surface area, density, and dry weight of roots had inverse relationships with soil infiltration at heads of pressure of 0 cm and 9 cm. The regulation of soil infiltration was influenced by the root dry weight and root average diameter, which played crucial roles in determining the roots' morphological properties and the formation of pathways and soil pores. [ABSTRACT FROM AUTHOR]

Soil salinization poses a critical problem, adversely affecting plant development and sustainable agriculture. Plants can produce soil legacy effects through interactions with the soil environments. Salt tolerance of plants in saline soils is not only determined by their own stress tolerance but is also closely related to soil legacy effects. Creating positive soil legacy effects for crops, thereby alleviating crop salt stress, presents a new perspective for improving soil conditions and increasing productivity in saline farmlands. Firstly, the formation and role of soil legacy effects in natural ecosystems are summarized. Then, the processes by which plants and soil microbial assistance respond to salt stress are outlined, as well as the potential soil legacy effects they may produce. Using this as a foundation, proposed the application of salt tolerance mechanisms related to soil legacy effects in natural ecosystems to saline farmlands production. One aspect involves leveraging the soil legacy effects created by plants to cope with salt stress, including the direct use of halophytes and salt-tolerant crops and the design of cropping patterns with the specific crop functional groups. Another aspect focuses on the utilization of soil legacy effects created synergistically by soil microorganisms. This includes the inoculation of specific strains, functional microbiota, entire soil which legacy with beneficial microorganisms and tolerant substances, as well as the application of novel technologies such as direct use of rhizosphere secretions or microbial transmission mechanisms. These approaches capitalize on the characteristics of beneficial microorganisms to help crops against salinity. Consequently, we concluded that by the screening suitable salt-tolerant crops, the development rational cropping patterns, and the inoculation of safe functional soils, positive soil legacy effects could be created to enhance crop salt tolerance. It could also improve the practical significance of soil legacy effects in the application of saline farmlands. [ABSTRACT FROM AUTHOR]

Purpose: Biochar, as a stable carbon-rich material, has received concentrated attention in soil quality improvement, especially in soil carbon sequestration. This study aimed to find out the effects of biochar application on carbon stock in the whole salt-affected soil ecosystems. Methods: This study was conducted in a heavy salt-affected soil, aiming at investigating biochar application effects on salt-affected soil organic carbon (SOC), soil inorganic carbon (SIC), as well as plant (Tamarisk chinensis) biomass carbon stocks. Results: After 4 years of biochar application of 30, 60, and 90 t ha−1, the results showed that biochar increased soil total organic carbon (STOC) stock by 54.78, 160.44, and 198.33%, and biochar increased soil total inorganic carbon (STIC) stock by 13.85, 11.04, and 16.03%, respectively. Further, it is calculated that biochar increased native SOC (extra SOC excluding biochar carbon) by 7.63, 66.15, and 56.90% and SIC by 13.55, 10.44, and 15.12%, respectively. In addition, biochar application accelerated Tamarisk chinensis growth by 10.03, 23.54, and 11.28%, respectively. Combining all the SOC, SIC, and plant-derived carbon, it is concluded that biochar application enlarged salt-affected soil-vegetation ecosystem carbon stock by 23.36, 47.80, and 58.10%, respectively. Conclusion: These results indicated that applying biochar in salt-affected soil can enhance salt-affected soil-vegetation ecosystem carbon stocks. The mechanisms behind this phenomenon may be that biochar improves soil water content and bulk density, which promotes Tamarisk chinensis growth. Biochar has a good potential to improve salt-affected soil quality and mitigate climate change. [ABSTRACT FROM AUTHOR]

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Soil salinity, a severe environmental factor, significantly reduces the productivity of crop plants by increasing salt and mineral fertilizer concentrations in the soil. As a result, the development of sustainable slow-release mineral fertilizers (SRFs) is critical for addressing salt-affected soils. This study aimed to synthesize struvite (MgNH4PO4·6H2O) into hydrogel beads made from sodium alginate-poly (acrylic acid) in the absence (Sa@S) and presence (Sa@SHa) of humic acid (HA). The optimal conditions for struvite formation were at pH 9.0, resulting in a remarkable 73.21 %, 98.74 %, and 99.20 % for Mg, NH4-N and P removal, respectively. The SRFs study demonstrated that struvite had a significant release of Mg, P, and NH4-N, notably higher (P ≤ 0.05) than Sa@S and Sa@SHa. Experiments on swelling and soil water loss demonstrated that Sa@S yielded higher results in comparison to Sa@SHa. Furthermore, an experiment was conducted to study the impact of Sa@S and Sa@SHa on saline soil parameters over 20 days of incubation. The results showed both encapsulated struvite hydrogel beads reduced soil salinity, as indicated by the sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). Additionally, a significant reduction (P ≤ 0.05) in soil electrical conductivity (EC) and sodium (Na) was observed for both hydrogel bead encapsulation treatments compared to the control soil. However, no apparent variance was observed in pH and soil organic carbon (SOC). Moreover, the levels of available phosphorus (P), ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N), cation exchange capacity (CEC), and exchangeable cations (Ca, Mg, K) in the soil were observed to be increased (P ≤ 0.05).

Increasing soil salinization and microplastics (MPs) pollution of farmland have become global agricultural issues that have to be faced, destabilizing plant-soil systems and bringing threats to ecosystems. Few studies have focused on the effects of MPs on saline soil water evaporation and desiccation crack formation, and the underlying influencing mechanisms of MPs and salts in soils. A mechanism test was conducted to explore the effects of MPs concentrations (0.5 %, 1 %, 3 %, w/w) on the simultaneous changes of water evaporation and cracking patterns of saline soils with different salinities (0, 0.1 %, 0.3 %, 0.5 %, w/w). Quantitative findings showed that (1) the MPs significantly reduced saturated conductivity by 14.9–46.8 % and 4.6–54.5 % in non-saline soil and lightly saline soil, respectively, which showed a decreasing trend with increasing MPs concentration; besides, soil salts also significantly reduced saturated conductivity, but the inhibition weakened with increasing soil salinity. (2) The MPs significantly reduced total porosity by 2.2–7.9 % and 1.8–6.6 % in non-saline and saline soils, respectively, which exhibited a slight decreasing trend with increasing MPs concentration. (3) The MPs reduced total evaporation by 0.4–6.1 % and 0.9–6.5 % in non-saline and saline soils, respectively. As the MPs concentration increased, the total evaporation of non-saline soil decreased, and the total evaporation of saline soils firstly decreased and then increased. After evaporation, both soil salt and MPs inhibited cracking. Correlations indicated that the presence of soil salt and MPs and their interactions explained more than half of the variability of soil and water characteristics and crack parameters. Mechanism exploration suggested that the MPs affect the evaporation process and crack behavior by changing soil pore size distribution, damaging soil structure, and the water repellency of the MPs particles; besides, the salts inhibit the soil water evaporation and surface cracking through increasing osmotic suction, blocking soil macropores, and promoting inter-microaggregate cementation. Our findings provide evidences for MPs influences on saline soil physical properties, water evaporation, and crack development, deserving attentions to the regulations and developments of soil-crop systems that facing salinization and plastic pollution.

To investigate the synergistic effect of IAA and melatonin (MT) on three plants to alleviate the effects of salt damage on plants, we aim to determine the optimal concentrations of exogenous hormone treatments that improve salinity resistance for each species. In this experiment, three desert plants, Sarcozygium xanthoxylon, Nitraria tangutorum, and Ammopiptanthus mongolicus, which are common in Wuhai City, were used as plant materials. Two time periods (12 h,24 h) of exogenous hormone IAA (100 μmol/L) and exogenous melatonin concentration (0, 100, 200, 300 μmol/L) were used to treat the three desert plants in saline soil under different conditions of exogenous IAA and exogenous melatonin. The results indicate that under different concentrations of exogenous IAA and melatonin, the germination rate and vigor of the three desert plant species in saline-alkaline soil improved. However, as the concentration of melatonin increased, the germination rate and vigor of these desert plants were inhibited. Whereas, plant height, root length, leaf length, fresh weight, dry weight, and root vigor of the three desert plants were alleviated under different conditions of exogenous IAA and exogenous melatonin. under the action of two exogenous hormones, the low concentration of melatonin decreased their malondialdehyde content and increased their proline content. As melatonin levels increased, the activity of antioxidant enzymes also rose initially, followed by a subsequent decline. This study highlights the synergistic effects of two exogenous hormones on the critical role of cell osmomodulators and antioxidant enzyme activity in combating salinity damage in three desert plants.

Against the backdrop of saline soil solidification and the resource utilization of solid waste and aeolian sand in cold and arid regions, this study employs locally accessible fly ash and aeolian sand to solidify saline soil. By combining unconfined compressive strength tests, X-ray diffraction analysis, scanning electron microscopy, orthogonal experiments, and single-factor analysis, the strength characteristics, mineral composition, and interfacial structure changes of saline soil solidified with different freeze-thaw cycles and varying amounts of fly ash, aeolian sand, and alkali activators were investigated. The effects of each factor were analyzed to determine the optimal mixture ratio and to explore the solidification mechanism.The results indicate that the unconfined compressive strength of saline soil is most significantly enhanced when solidified with a combination of fly ash, aeolian sand, and alkali activators. The optimal mixture ratio was found to be 24 % fly ash, 7 % aeolian sand, and 4.5 mol/L alkali activator. With the incorporation of these solidifying materials, the failure mode of saline soil transitions from plastic to brittle, and the stress-strain curve exhibited a strain-softening behavior. The combined solidification method demonstrated the most pronounced effect in mitigating freeze-thaw damage, with the unconfined compressive strength of the solidified soil reaching 7.01 MPa after seven freeze-thaw cycles, compared to 0.03 MPa for the untreated soil, an increase by a factor of 234.This significant enhancement is attributed to the formation of substantial gel substances, which mitigate the strength loss caused by freeze-thaw cycles. The gel locking mechanism between particles in the solidified soil far exceeds the detrimental effects of freeze-thaw cycles, effectively inhibiting freeze-thaw deterioration. Additionally, the reaction pathways involving AFt and AFm phases reduce the content of SO42- and Cl- in the solidified soil, effectively suppressing salt expansion and significantly improving the soil's strength.

ABSTRACTSoil salinisation has led to increasing abandonment of farmlands in the arid region of northwest China, and the cultivation of cash crops has become an important way to reuse abandoned farmlands and remediate saline soils. In this study, the effects of cotton (Cot), alfalfa (Alf), and rapeseed (Rap) cropping on the bacterial and fungal communities in saline soil were compared based on high-throughput sequencing. The results showed that soil pH and electrical conductivity (EC) of the Cot, Alf, and Rap groups decreased significantly compared with those of bare land (CK). Especially, soil pH (8.3) and EC (0.93 mS cm-1) of the Alf group decreased the most, and the contents of total nitrogen (TN) and total phosphorus (TP) increased the most, which increased by 250% and 91.4%, respectively compared with those of the CK (p < 0.05). Actinobacteriota and Proteobacteria were the dominant bacterial phyla in the three groups, Ascomycota and Basidiomycota were the dominant fungal phyla. The diversity of soil bacterial and fungal communities in the Alf group was higher than that in the Cot and Rap groups. The results of RDA and PERMANOVA analysis showed that soil pH, EC, C/N ratio, and TN were the main factors affecting soil bacterial and fungal communities in the three groups. In general, Cot, Alf, and Rap cropping all could reduce soil pH and EC and improve soil microbial community structure and diversity, but Alf cropping had the best effects in improving saline soil quality and bacterial and fungal diversity.

Studies have demonstrated that the physicochemical properties of saline soils can be improved, and crop growth can be promoted by fly ash saline and alkaline soil amendment materials. Herein, the effects of fly ash saline and alkaline soil amendment materials on the physical and chemical properties of saline soil and growth conditions of Arrhenatherum elatius at room temperature were evaluated. Meanwhile, planting experiments of Zea mays L. were conducted in the demonstration field of saline–alkaline land amendment in Yinchuan, Ningxia. The results showed that the application of amendment materials significantly (p < 0.05) improved saline soil's physical and chemical properties. The saline soil pH decreased from an average of 10.51 to 8.89; the Na+ content decreased from an average of 2.93 g·kg−1 to 0.7 g·kg−1 after 25 days of action. In addition, the soil bulk density decreased from an average of 1.49 g·cm−3 to 1.36 g·cm−3, and the total porosity increased by 15.60%. Soil available phosphorus and available potassium content also increased significantly, with mean values increasing from 6.74 mg·kg−1 and 173 mg·kg−1 to 58.30 mg·kg−1 and 330.76 mg·kg−1, respectively. In addition, the plant height and stem thickness of Arrhenatherum elatius increased from an average of 11.76 cm, 1.28 mm to 21.72 cm, 1.59 mm with the application of 2.5 wt% amendment material. The plant height and stem thickness of Zea mays L. increased from mean values of 210 cm and 21.94 mm to 315.7 cm and 26.75 mm, respectively, when 0.07 t·hm−2 of amendment material was applied in the field. Overall, it was concluded that applying fly ash saline and alkaline soil amendment materials improves the physicochemical properties of saline soils, reducing saline stress and promoting the growth of Arrhenatherum elatius and Zea mays L. [ABSTRACT FROM AUTHOR]

Potassium (K) is a crucial element required for the healthy growth of plants, as it activates many enzymatic reactions in the plant body. Nowadays, K-deficiency is widespread worldwide. The high cost of potassium fertilization and less awareness about the pros of external nutrition from K fertilizer application are possible reasons for K-deficient soils in Pakistan. Efforts are ongoing to improve the potassium use efficiency (KUE) and bioavailability of K from commercial potassium sources. Therefore, a field experiment commenced to minimize the bioavailable K losses using carbon sequestering fertilizer (CSF) under saline soil conditions (4 dS m-1) using wheat as a test crop in Pind Dadan Khan, Punjab, Pakistan. The experiment ran in a three-replication randomized complete block design (RCBD) statistical scheme using four treatments, i.e., T1 = Control; T2 = Filter cake press mud (FCP) as CSF; T3 = Sulphate of potash (SOP); and T4 = SOP + FCP, using two wheat varieties, namely, Faisalabad 2008 (FSD-08) and Chakwal-50. Results implied that SOP application in combination with FCP (T4) performed best treatments with Faisalabad 2008 as the better variety than Chakwal-50 under saline growth environment. Maximum spike length (8.85 cm), the number of grains/spike (45), shoot dry weight (2.75 g), soil K contents (310 ppm), soil C content (1.03%), chlorophyll content (2.18 µmol m-2), and H-ATPs (99.5) resulted in Faisalabad 2008 when applied with the combination of SOP and FCP (T4). Thus, the combined application of mineral and organic sources of CSF improved the wheat growth parameters and nutritional status of the soil. [ABSTRACT FROM AUTHOR]

Sandy saline soils are widely distributed and commonly experience seasonal or long‐term freezing, yet the freezing process in these soils is rarely studied. This research utilized in situ X‐ray computed tomography (CT) to visualize pore‐scale freezing processes in sandy saline soils under various initial water and salt contents. Micron‐resolution observations of pore ice and unfrozen water produced new insights into the preferential orientation and grouping of pore ice crystals, intersections between different pore ice crystal groups causing anisotropic behavior, decreasing pore ice crystal size under faster freezing rates, and the formation of interconnected networks of both pore ice and unfrozen water upon freezing. From a thermodynamic perspective, the salt content in the unfrozen liquid is dependent on the local temperature as described by water–salt phase diagram. Furthermore, the local volume ratio between unfrozen water and pore ice reflects the initial salt content and salt mass transfer occurring due to both diffusion and fluid flow processes. This work improves the understanding of complex freezing phenomena in sandy saline soils through high‐resolution evidence of crystallization patterns, transformation mechanisms, and coupled heat‐mass transfer. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Gelbana district, Sahl El-Tina (latitude of 30.57º N and longitude of 32.20º E), North Sinai Governorate, Egypt, in 2021/2022 and 2022/2023 to find out the optimal level of nitrogen fertilization and some combinations of Spirulina platensis extract and potassium silicate on growth, yield, and quality of sugar beet. This work included 21 treatments of three nitrogen levels and seven foliar combinations of Spirulina extract and potassium silicate. A complete block design in a split-plot arrangement with three replicates was used. Results indicated that fertilizing beets with 288.0 kg N ha-1 increased proline content, root diameter, fresh weight, root impurities, and sugar lost to molasses. Enriching beets with 230.4 and/or 288.0 kg N ha-1 gave the highest leaf area index, photosynthetic pigments, sucrose, extracted sugar percentages, quality index, root and sugar yields ha-1 in both seasons. Spraying beet tops with (3.60 g L-1 ha-1 Spirulina extract combined with a fixed dose of potassium silicate) resulted in a significant increase in leaf area index, photosynthetic pigments, root diameter, fresh weight, α-amino-N content, yields of root and sugar ha-1. However, proline, potassium, and sodium content decreased compared to other single doses of algal extract. Application of 230.4 kg N ha-1 and spraying beet tops with a combination of (3.60 g L-1 algal extract and 7.20 cm3 L-1 potassium silicate) led to a significant increase in sucrose %, quality index, root and sugar yields ha-1 with a reduction in sodium and potassium contents. [ABSTRACT FROM AUTHOR]

Purpose: The contamination of soil with antibiotics has become a hot issue for the environment and global public health. However, there are scarcely any studies on the occurrence forms of antibiotics in saline soil. Occurrence forms of antibiotics are related to bioavailability. Therefore, this study facilitates the evaluation of the ecological risk of antibiotics in saline soil. Materials and methods: An experiment with artificial antibiotic contamination of soil and salinization simulations was conducted. The changes in the occurrence forms of oxytetracycline (OTC) and sulfamethoxazole (SMX) in saline soil were analyzed by continuous ultrasonic extraction. The factors for occurrence forms, including aging time and particle size fraction, were considered. Results and discussion: Soil salinization promoted the conversion of OTC and SMX from acid-soluble and bound states to water-soluble and locked states. Oxytetracycline in saline soil was predominantly in the water-soluble and acid-soluble states, accounting for 54.9–83.7% of the total. Sulfamethoxazole as well is accounting for 66.1–82.1%. In addition, the aging process from 7 to 63 days facilitated the conversion of OTC and SMX from the water-soluble, acid-soluble, and bound states to the non-extractable locked states, resulting in reduced bioavailability. Since the content of extractable forms of OTC and SMX in saline clay was high, it favors conversion to a locked state. Conclusions: Oxytetracycline and sulfamethoxazole in saline soil were mainly in bioavailable states. The aging effect reduced the bioavailability of OTC and SMX in saline soil. Clay had the low proportion of OTC and SMX in the bioavailable state, reducing environmental risks. [ABSTRACT FROM AUTHOR]

Soil salinization poses a global threat to terrestrial ecosystems. Soil microorganisms, crucial for maintaining ecosystem services, are sensitive to changes in soil structure and properties, particularly salinity. In this study, contrasting dynamics within the rhizosphere and bulk soil were focused on exploring the effects of heightened salinity on soil microbial communities, evaluating the influences shaping their composition in saline environments. This study observed a general decrease in bacterial alpha diversity with increasing salinity, along with shifts in community structure in terms of taxa relative abundance. The size and stability of bacterial co-occurrence networks declined under salt stress, indicating functional and resilience losses. An increased proportion of heterogeneous selection in bacterial community assembly suggested salinity's critical role in shaping bacterial communities. Stochasticity dominated fungal community assembly, suggesting their relatively lower sensitivity to soil salinity. However, bipartite network analysis revealed that fungi played a more significant role than bacteria in intensified microbial interactions in the rhizosphere under salinity stress compared to the bulk soil. Therefore, microbial cross-domain interactions might play a key role in bacterial resilience under salt stress in the rhizosphere. [ABSTRACT FROM AUTHOR]

The current species of Halosegnis and Salella within the class Halobacteria are closely related based on phylogenetic, phylogenomic, and comparative genomic analyses. The Halosegnis species showed 99.8–100.0% 16S rRNA and 96.6–99.6% rpoB′ gene similarities to the Salella species, respectively. Phylogenetic and phylogenomic analyses showed that Salella cibi CBA1133T, the sole species of Salella, formed a single tight cluster with Halosegnis longus F12-1T, then with Halosegnis rubeus F17-44T. The average nucleotide identity (ANI), digital DNA–DNA hybridization (dDDH), and average amino acid identity (AAI) values between Salella cibi CBA1133T and Halosegnis longus F12-1T were 99.2, 94.2, and 98.6%, respectively, much higher than the thresholds for species demarcation. This genome-based classification revealed that the genus Salella should be merged with Halosegnis, and Salella cibi should be a later heterotypic synonym of Halosegnis longus. Halophilic archaeal strains DT72T, DT80T, DT85T, and DT116T, isolated from the saline soil of a tidal flat in China, were subjected to polyphasic taxonomic characterization. The phenotypic, chemotaxonomic, phylogenetic, and phylogenomic features indicated that strains DT72T (= CGMCC 1.18925T = JCM 35418T), DT80T (= CGMCC 1.18926T = JCM 35419T), DT85T (= CGMCC 1.19049T = JCM 35605T), and DT116T (= CGMCC 1.19045T = JCM 35606T) represent four novel species of the genera Halorussus, Halosegnis and Haloglomus, respectively, for which the names, Halorussus caseinilyticus sp. nov., Halorussus lipolyticus sp. nov., Halosegnis marinus sp. nov., and Haloglomus litoreum sp. nov., are proposed. [ABSTRACT FROM AUTHOR]

More than two-thirds of the arable land in the Hetao Irrigation District of Inner Mongolia, China, is suffering from various soil salinization and alkalization, which has seriously restricted the local agriculture and animal husbandry economy. Among them, biochar and flue gas desulfurization (FGD) gypsum have been widely used as soil amendments in the saline-alkali soils. The amendments can often be applied on the surface and then mixed with the topsoil. However, the large investment and high cost of the traditional practice cannot fully meet the large-scale production in recent years. There is a high demand to develop more effective practices in soil amendments. In this study, a field experiment was conducted in Wuyuan County, Bayannur City, Inner Mongolia Autonomous Region, China, in order to cultivate healthy and fertile soil for less soil salinization. Three treatments were designed: 1) covering the planting holes with sand (S), 2) strip application of biochar in topsoil and then covering the planting holes with sand (B+S), and 3) strip application of biochar in topsoil and then covering the planting holes with FGD gypsum (B+G). In biochar treatments, 3750 kg biochar per hectare was buried in strips at a depth of 5-10 cm below the soil surface, and 5-10 cm away from the planting strip. In coverage treatments, the planting holes were covered completely with 750 kg sand or FGD gypsum per hectare. The soil samples were collected at a depth of 0-40 cm from the sunflower planting strip after harvest. The soil quality was then determined among the three treatments, in terms of salinity, alkalinity, organic matter, and nutrient status. Meanwhile, the sunflower yield and its components were also analyzed to deduce their relationship with soil quality. The results showed that the biochar and FGD gypsum in the root zone improved the water-soluble cations composition of the 0-40 cm soil layers, resulting in a higher Ca2+ concentration, while lower Na+ concentration after the experiment. As expected, the B+S and B+G treatments significantly decreased the sodium adsorption ratio (SAR) of the 0-40 cm soil layers and the pH value of the 20-40 cm soil layer, but increased the soil desalination rate (Ds), compared with the S treatment. In addition, the B+S and B+G treatments shared the higher contents of organic matter (OM), nitrate nitrogen (NO3--N), available phosphorus and available potassium (AK) in the 0-40 cm soil layers, indicating the better soil environment for sunflower emergence and growth. The entire dataset of soil parameters showed that the soil quality index (SQI) of B+S and B+G treatments increased by 35.7% and 88.5%, respectively, compared with the S treatment. The SQI parameters (such as SAR, Ds, Ca2+, Mg2+, AK, NO3--N and OM) achieved high scores after the B+S and B+G treatments. The reason was that the higher soil quality was obtained to reduce the salinity stress for the high nutrient levels. By contrast, the B+G treatment showed better performance than the B+S treatments, resulting in a higher seed yield of sunflower. Therefore, the combination of biochar strip application and FGD gypsum covering planting holes in saline-alkali land can be expected to intensively regulate the root zone soil, for the high soil quality and sunflower yield. The findings can also provide technical support to the amelioration and utilization of saline-alkali soils in the Hetao Irrigation District. [ABSTRACT FROM AUTHOR]

Soil salinization is a major problem affecting agriculture globally. One approach to restore saline soil is through the application of biochar which is great at adsorbing salt ions and thus amending salt-affected soils. Biochar produced using forestry wastes (Gigantochloa levis and Melaleuca cajuputi) were pyrolyzed at 300, 450 and 600 ℃ for 2 h. Proximate and ultimate analyses were done followed with physical and chemical analyses of the biochar and their raw materials before undergoing the sodium adsorption study. The fixed carbon was observed to increase from 9.636 to 72.919% (G. levis) and 9.473–69.950% (M. cajuputi) upon carbonization of the raw materials. These values correlated with the increasing C content of the samples, which also resulted in lower H/C value especially for G-600 and M-600 samples. It was found that biochar aromaticity and stability increased with increasing temperature. In addition, field emission scanning electron microscopy (FESEM) elucidated that higher pyrolysis temperature increased the porosity and surface area. The pH observed to increase from 5.36 to 7.97 (G. levis) and 4.19–9.05 (M. cajuputi) following higher pyrolysis temperature. From the analyses conducted, the biochar produced was identified to have a potential for sodium adsorption. [ABSTRACT FROM AUTHOR]

The soil freezing characteristic curve (SFCC) describes the relationship between the freezing point and unfrozen water content, which are two critical parameters in depicting the heat, solute, and water transport in frozen soil. In this paper, we propose a novel Generalized Clapeyron Equation (GCE)-based model, the GCE-Salt Model, to better capture the SFCC in frozen soil in the presence of solute. It keeps the matric potential Ψf in the GCE as its original meaning and incorporates the effect of solute potential in the equilibrium freezing temperature. The performance of our GCE-Salt Model was validated by both lab and field experimental data and compared with related models (Combined Model and GCE-Tan Model). The GCE-Salt Model performed exceptionally well in extremely saline soil and it performed well in both non-saline and saline soil. (1) Our GCE-Salt Model could capture the SFCC of non-saline soil equally as well as the Combined Model (NSE = 0.866); (2) our GCE-Salt Model performed similarly well as the Combined Model and a little better than the GCE-Tan Model for the slightly to highly saline soil (NSE ≥ 0.80 for three models); and (3) our GCE-Salt Model (NSE = 0.919) beat the Combined Model (NSE = 0.863) and the GCE-Tan Model (NSE = 0.62) in capturing the SFCC of extremely saline soil, mainly because the inherent expression of our GCE-Salt Model can more accurately capture the freezing point. Our findings highlight the effect of solute potential on the ice–water change and could improve the understanding of the effect of freezing and thawing on the thermal–hydrological processes, structure of saline soil, and landscape evolution in cold regions. [ABSTRACT FROM AUTHOR]

The decline in agricultural productivity because of soil salinization has become a global problem in recent years. Biofertilizers show great potential for soil improvement as a sustainable strategy; however, their effectiveness in improving saline soils and enhancing plant growth under saline stress is poorly understood. We assessed the effectiveness of biofertilizers in improving saline soils and enhancing crop growth under saline stress and investigated the related potential mechanisms. Changes in soil physicochemical properties, plant physiological parameters, and soil microbial communities were analyzed using pot experiments. The results showed that biofertilizer application reduced total soluble salts in the soil by 30.8% and increased Brassica rapa L. biomass by 8.4 times. Biofertilizer application increased soil organic matter, total nitrogen, and available phosphorus by 56.1%, 57.0%, and 290%, respectively. Simultaneously, superoxide dismutase, catalase, chlorophyll a, chlorophyll b, total soluble sugar, and proline levels also increased by 89.5%, 140%, 110%, 190%, and 130%, respectively. Biofertilizers increased the abundance of Bacillus and Planococcus and decreased the abundance of Mortierella and Aspergillus, which could potentially be the underlying reason for the promotion of plant growth. Overall, the results of this study demonstrate the efficacy of biofertilizers in improving saline soils and that the application of biofertilizer could greatly promote agricultural production. [ABSTRACT FROM AUTHOR]

Applying biochar to saline soil is a novel strategy for improving soil quality. However, how biochar addition amount affects soil nutrients, bacterial communities, and cotton growth at different stages remains unclear. Three biochar treatments, no biochar (BC0), 1% biochar (BC1, w/w), 3% biochar (BC3), and two cotton varieties, salt‐sensitive (SS) and salt‐tolerant (ST), were used in pot experiments, analyzing biochar effects on saline soil nutrients, bacterial communities, and cotton growth. The study found that biochar increased only organic carbon (SOC), total nitrogen (TN), and available potassium (AK) at the seedling stage. However, at the flowering‐boll stage, biochar also increased nitrate (NO3−–N) and available phosphorus (AP) and reduced soil salt content. Biochar did not affect α‐diversity at the seedling stage, but BC3 reduced α‐diversity at the flowering‐boll stage. The principal coordinate analysis revealed changes in the soil bacterial community composition that were closely associated with biochar added. From the redundancy analyses, SOC and AK were the leading environmental factors for soil bacterial community composition changes. SOC, TN, and AK correlated positively with Proteobacteria, which increased their relative abundance through biochar addition and correlated negatively with Bacteroidetes, Chloroflexi, and Acidobacteria, which decreased their relative abundance due to biochar. Furthermore, the random forests analysis showed that SOC, Shannon index, and β‐diversity were significant predictors of cotton biomass. In summary, biochar drives changes in bacterial communities in saline soils by increasing nutrients such as SOC and AK, which affect cotton growth. This study provides data to support the application of biochar on saline soils. [ABSTRACT FROM AUTHOR]

The soil dielectric constant model is essential for retrieving soil properties based on microwave remote sensing. However, the existing saline soil dielectric constant models perform poorly in simulating the dielectric constant of soil with high water content and salinity. In this study, the Wang Yueru (WYR) saline soil dielectric constant model, which was demonstrated to perform well in describing the effect of salinity and moisture on the dielectric constant, was validated based on experimental measurements of soil samples under different water content and salinity degrees. Furthermore, we adjusted the model form, refitted the empirical coefficient in the model, and finally acquired a two-stage model for simulating the soil dielectric constant. The enhanced model was validated under different soil moisture and salinity ranges using experimental measurements of soil samples. Compared to the original model, the proposed model exhibits a larger improvement in simulating the soil dielectric constant, and the RMSE of the simulated results dramatically decreased from 7.3 to 1.6, especially for soil with high salinity and water content. On this basis, a model suitable for L-band microwave was established. This model is of great significance for studying soil dielectric characteristics and retrieving soil parameters based on L-band data. Furthermore, this model can be used to retrieve soil salinity and water content using microwave remote sensing under a broadened application situation, such as in saline-alkali soils, wetlands, and salt marshes. [ABSTRACT FROM AUTHOR]