Improvement Of Saline Soils Research Articles

Multi-Scenario Simulation of Optimal Landscape Pattern Configuration in Saline Soil Areas of Western Jilin Province, China

The Songnen Plain is a significant region in China, known for its high grain production and concentrated distribution of soda saline land. It is also considered a priority area for cropland development in the country. However, the Songnen Plain is now facing prominent issues such as soil salinization, soil erosion, and deteriorating cropland quality, which are exacerbated by climate change and intensified human activities. In order to address these challenges, it is crucial to adjust the quantitative structure and layout of different landscapes in a harmonious manner, aiming to achieve synergistic optimization, which is posed as the key scientific approach to guide comprehensive renovation policies, improve saline–alkaline land conditions, and promote sustainable agricultural development. In this study, four scenarios including natural development, priority food production (PFP), ecological security priority (ESP), and economic–ecological-balanced saline soil improvement were set up based on Nondominated Sorting Genetic Algorithm II (NSGA-II) and the Future Land Use Simulation (FLUS) model. The results demonstrated that the SSI scenario, which focused on economic–ecological equilibrium, displayed the most rational quantitative structure and spatial layout of landscape types, with total benefits surpassing those of the other scenarios. Notably, this scenario involved converting unused land into saline cropland and transforming saline cropland into normal cropland, thereby increasing the amount of high-quality cropland and potential cropland while enhancing the habitat quality of the region. Consequently, the conflict between food production and ecological environmental protection was effectively mitigated. Furthermore, the SSI scenario facilitated the establishment of a robust ecological security and protection barrier, offering valuable insights for land use planning and ecological security pattern construction in the Songnen Plain, particularly in salt-affected areas.

The Application of Straw Return with Nitrogen Fertilizer Increases Rice Yield in Saline–Sodic Soils by Regulating Rice Organ Ion Concentrations and Soil Leaching Parameters

Soil salinization is a severe environmental problem that restricts crop productivity. Straw amendment could increase the fertility of saline–sodic soils by improving soil physical properties and carbon sequestration; however, the chemical mechanism of saline soil improvement via straw reclamation is not clear. This study aimed to investigate the effects of straw return with nitrogen fertilizer on soil leaching characteristics, rice organ ion concentrations, and yield. Therefore, a soil column leaching experiment was conducted in 2021 in Baicheng, Jilin Province, using two straw application rate treatments (0 and 8 t hm−2) and three nitrogen application rate treatments (0, 180, and 360 kg hm−2). The results revealed the following: 1. The combination of straw return and nitrogen fertilizer significantly increased the soil leachate volume, leachate pH, Na+ concentration, and Na+/K+ ratio, thereby reducing Na+ stress on rice; 2. The application of nitrogen fertilizer during straw return effectively minimized soil nitrogen loss by lowering the ammonium and nitrate nitrogen concentrations in the soil leachate; 3. This combination also reduced plant Na+ concentrations while increasing plant K+ concentrations, thus improving the Na+/K+ ratio in the plants; 4. Straw return with nitrogen fertilizer significantly enhanced rice yield, which increased with higher nitrogen application rates. In summary, the integration of straw return with nitrogen fertilizer not only regulates rice salinity tolerance but also boosts rice yield, presenting a novel approach for improving saline–sodic soils.

Saline soil improvement promotes the transformation of microbial salt tolerance mechanisms and microbial-plant-animal ecological interactions

The improvement of coastal saline land would alleviate the problem of insufficient arable land and provide new solutions for guaranteeing food security and ecological environment modification. In this study, five typical soil samples were collected from Tongzhou Bay, China. The changes in bacterial, animal and plant community composition before and after improvement were comprehensively investigated by a combination of high-throughput sequencing and macro-barcode sequencing analysis of eDNA. The study aimed (1) to characterize the species composition and diversity of the bacterial communities in saline soils, (2) to elucidate the mechanisms of salt tolerance of the bacterial communities, and (3) to investigate the impacts of the microbial salt tolerance mechanisms on the regional bacteria and fauna. The results showed that over 15 years of improvement, the composition of the bacteria in the saline-alkaline plots evolved significantly, changing from Desulfovibrio (10.60%) and Campylobacter (11.20%), to Acidobacter (12.91%). After the improvement, salt stress on the bacterial phyla gradually decreased. The functional differentiation of the bacterial phyla became more pronounced. As ion concentrations decreased, the main mechanism of salt tolerance of the bacterial bacteria changed from mainly mechanism of inorganic ion accumulation (55.56%), supplemented by flexible halophilic enzymes (31.77%), to mainly mechanism of compatible solute (44.80%). The mechanism of microbial salt tolerance directly affected micro-diversity and indirectly influenced the diversity of environmental species (R = 0.54). The results of this study provide a scientific basis for coastal saline land as a microbiodiversity marker and for the exploration of microbial improvement of saline land.

Reclamation and Improvement of Saline Soils Using Organo–Mineral–Natural Resources, Treated Saline Water, and Drip Irrigation Technology

Reclamation and management of saline soil in arid regions fundamentally require more consideration to attain sustainable agriculture. Experiments were conducted at Abo-Kalam Farm, South Sinai, Egypt. Split-split-plot design experiments were carried out to study the effect of treatments on saline soil hydrophysical properties, sorghum, and cv. ‘Dorado’ plants during the summer season. Pea cv. ‘Entsar 3’ plants were cultivated during the winter season for the residual effect of treatments. Organo–mineral amendment (rice straw compost + mineral sulfur at different rates) was assigned as the main factor, natural rock or artificial fertilizers were assigned as subfactors, and humic acid at different rates was the sub-subfactor. Results showed that organo–mineral amendments improved the hydrophysical properties of the soil, plant nutrient uptake, crop yield, and crop water productivity; however, it diminished by 10 tons/fed (4200 m2) of compost plus 700 kg/fed of mineral sulfur. Therefore, it is recommended that economically using the combination of applying organic–mineral amendments of 4 tons/fed of compost plus 400 kg/fed of mineral sulfur and 5 kg/fed of humic acid plus natural rock fertilizer is the best safe management for reclamation and improvement of saline soils using partially treated saline irrigation water and natural resources.

Combined utilization of slag, fly ash, and polyacrylamide for sustainable saline soil improvement: a win-win strategy

Combined utilization of slag, fly ash, and polyacrylamide for sustainable saline soil improvement: a win-win strategy

Evaluation of hydrochar-derived modifier and water-soluble fertilizer on saline soil improvement and pasture growth

Soil salinization poses a serious threat to crop growth. The selection of appropriate soil modifiers and water-soluble fertilizers for saline soils represents a crucial method for enhancing crop yields. The modifiers and medium-element water-soluble fertilizers were prepared using hydrochar derived from rice straw. Two distinct experiments were designed to study the effect of modifiers and water-soluble fertilizers on saline soils. The first experiment, designated as the “Soil Cultivation Experiment” , sought to investigate the impact of various modifiers on soil quality. The second experiment, designated as the “Method of Field Micro-Area Experiment”, aimed to assess the influence of water-soluble fertilizers on saline soils. The results showed that the application of modifiers and water-soluble fertilizers significantly enhanced comprehensive soil physical and chemical properties, crop growth, soil enzyme activity, and other key indicators in saline and alkaline soils. The optimal dosage of the modifier was 20 g/kg, which reduced the pH value from 8.62 to 8.21 and the decreased alkalinity by 8.26%. Furthermore, their application effectively boosted nutrient levels, including organic matter, and increased soil enzyme activity. The biomass of alfalfa showed enhancements of 63.01% and 20.87% and the biomass of leymus chinensis increased by 29.39% and 9.02% for the two batches, respectively. Notably, the application of water-soluble fertilizer yielded achieved superior results. This study also provided a theoretical basis for their future application in soda saline–alkali soil.

Genome-wide identification and expression analysis of the PP2C gene family in Apocynum venetum and Apocynum hendersonii

BackgroundProtein phosphatase class 2 C (PP2C) is the largest protein phosphatase family in plants. Members of the PP2C gene family are involved in a variety of physiological pathways in plants, including the abscisic acid signalling pathway, the regulation of plant growth and development, etc., and are capable of responding to a wide range of biotic and abiotic stresses, and play an important role in plant growth, development, and response to stress. Apocynum is a perennial persistent herb, divided into Apocynum venetum and Apocynum hendersonii. It mainly grows in saline soil, deserts and other harsh environments, and is widely used in saline soil improvement, ecological restoration, textiles and medicine. A. hendersonii was found to be more tolerant to adverse conditions. The main purpose of this study was to investigate the PP2C gene family and its expression pattern under salt stress and to identify important candidate genes related to salt tolerance.ResultsIn this study, 68 AvPP2C genes and 68 AhPP2C genes were identified from the genomes of A. venetum and A. hendersonii, respectively. They were classified into 13 subgroups based on their phylogenetic relationships and were further analyzed for their subcellular locations, gene structures, conserved structural domains, and cis-acting elements. The results of qRT-PCR analyses of seven AvPP2C genes and seven AhPP2C genes proved that they differed significantly in gene expression under salt stress. It has been observed that the PP2C genes in A. venetum and A. hendersonii exhibit different expression patterns. Specifically, AvPP2C2, 6, 24, 27, 41 and AhPP2C2, 6, 24, 27, 42 have shown significant differences in expression under salt stress. This indicates that these genes may play a crucial role in the salt tolerance mechanism of A. venetum and A. hendersonii.ConclusionsIn this study, we conducted a genome-wide analysis of the AvPP2C and AhPP2C gene families in Apocynum, which provided a reference for further understanding the functional characteristics of these genes.

Effects of Environmentally Friendly Materials on Saline Soil Improvement and Sunflower Yields in the Hetao Irrigation Region, China

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.

Infiltration and Leaching Characteristics of Soils with Different Salinity under Fertilizer Irrigation

Salt and nutrient transport and transformations during water infiltration directly influence saline soil improvement and the efficient use of water and fertilizer resources. The effects of soil initial salinity (18.3 g/kg, 25.5 g/kg, 42.2 g/kg, 79.94 g/kg, and 165 g/kg, respectively, labeled S1 to S5) on the infiltration and leaching characteristics of water, salt, and nitrogen were analyzed via a one-dimensional vertical fertilizer infiltration experiment. Meanwhile, the estimation models of cumulative infiltration and wetting front, including the effect of soil initial salinity, were established. The results showed that, with the increase in soil initial salinity, the cumulative infiltration within the same time decreased, and the migration time of wet front to 45 cm was longer. The time required for S5 to reach the preset cumulative infiltration was more than six times that of S1, and, for the wet front migration to 45 cm, the time requirement for S5 was about four times that of S1. In the established Kostiakov model and wetting front model, the coefficients all decreased with the increase in soil initial salinity, and the test index R2 values both reached 0.999. In the Kostiakov model, coefficient K had a linear relationship with the natural logarithm of initial soil salt content, while index a had a direct linear relationship with initial soil salt content. The cumulative leachate volume decreased with the increase in soil initial salinity, and the corresponding data of S3 and S5 were reduced by 37% and 57.3%, respectively, compared with S1. The electrical conductivity values of S1, S3, and S5 were 15.4, 209.8, and 205.6 ms/cm, respectively, being affected by the initial content in soil, soil moisture transport rate, and exogenous potassium nitrate (KNO3) addition. The NO3−-N concentrations in the leachates of S1, S3, and S5 at the end of leaching were 55.26, 16.17, and 3.2 mg/L, respectively. Based on the results of this study, for soil with high initial salinity, the conventional irrigation amount (2250 m3/ha) of the general soil in the study area could not meet the requirements of leaching salt. These results can provide a reference for the formulation of irrigation and fertilization strategies for soils with different salinity and contribute to the sustainable development of saline soil agriculture and the ecological environment.

Genome-wide identification of bHLH transcription factors and functional analysis in salt gland development of the recretohalophyte sea lavender (Limonium bicolor).

Transcription factors with basic helix-loop-helix (bHLH) structures regulate plant growth, epidermal structure development, metabolic processes, and responses to stress extensively. Sea lavender (Limonium bicolor) is a recretohalophyte with unique salt glands in the epidermis that make it highly resistant to salt stress, contributing to the improvement of saline lands. However, the features of the bHLH transcription factor family in L. bicolor are largely unknown. Here, we systematically analyzed the characteristics, localization, and phylogenetic relationships of 187 identified bHLH family genes throughout the L. bicolor genome, as well as their cis-regulatory promoter elements, expression patterns, and key roles in salt gland development or salt tolerance by genetic analysis. Nine verified L. bicolor bHLH genes are expressed and the encoded proteins function in the nucleus, among which the proteins encoded by Lb2G14060 and Lb1G07934 also localize to salt glands. Analysis of CRISPR-Cas9-generated knockout mutants and overexpression lines indicated that the protein encoded by Lb1G07934 is involved in the formation of salt glands, salt secretion, and salt resistance, indicating that bHLH genes strongly influence epidermal structure development and stress responses. The current study lays the foundation for further investigation of the effects and functional mechanisms of bHLH genes in L. bicolor and paves the way for selecting salt-tolerance genes that will enhance salt resistance in crops and for the improvement of saline soils.

Investigation on Zoning Management of Saline Soil in Cotton Fields in Alar Reclamation Area, Xinjiang

Aiming at assessing the problems of the high land salinity, high spatial variability of soil nutrients, sloppy management, and low efficiency in the Xinjiang region, research on the precise delineation method of field management zones is being conducted to facilitate differentiated fertilizer management for farmers and increase the level of saline soil improvement. Taking the plots in the experimental area as the research object, traditional statistics, principal component analysis, and fuzzy c-mean classification were applied to divide the management zoning in the study area, and the suitability and effectiveness of the management zoning were evaluated. The study area was at a mild salinization level; the soil organic matter and total nitrogen content were at a low level; total phosphorus was at a medium level; and total potassium and pH reached a high level. pH had a coefficient of variation <0.1, which was weak, and the other soil attributes were of medium variability intensity. The spatial distribution of the soil attributes was highly variable. The results of the principal component analysis showed that the six soil attributes grouped into statistical factors could be divided into three principal components. The results of the fuzzy c-means classification showed that the study area could be divided into four management zones, and there were significant differences in the soil salinity, organic matter, soil nutrients, and other attributes in the different management zones. The different soil attributes could be utilized to determine the management zoning of farmland in the study area with the help of fuzzy c-mean classification.

Improvements in saline soil and the law of water-salt transport based on salt inhibition using MICP technology

Soil desertification and salinization are the main environmental disasters in arid and semi-arid areas. It is of great significance to study the water - salt migration law of saline soil and propose corresponding water- salt regulation and control measures. Microbial-induced calcite precipitation (MICP) technology was proposed to improve saline soil based on salt inhibition, and the water–salt–heat coupling migration law and salt-frost heave deformation law of saline soil before and after improvement were studied using soil column model tests. XR1#, XR2#（Saline-alkali-tolerant mineralization bacteria isolated from saline soil) and Sporosarcina pasteurii were used in the MICP improvement and the effect of XR1# was the best. Under high-temperature evaporation, the water migration change rate, water loss rate, accumulated evaporation amount, and accumulated salt content of the improved soil columns within a depth range of 0–40 cm were reduced by an average of 53.6 %, 47.3 %, 69.5 %, and 40 %, respectively, compared with the untreated soil column. During low-temperature cooling, the characteristics of water-salt migration changed significantly, and the deformation of salt-frost heave decreased significantly. The water-salt content at the freezing point (−4.5 °C) changed from a cliff-like steep drop (untreated saline soil) to a slow decrease at environmental temperature (MICP-treated saline soil), and the amount of water crystallization decreased from 81 % to 56.7 % at −5 °C. At the end of the cooling process, the amount of salt-frost heaving on the surface of the soil columns decreased by an average of 62.7 %. Based on the measured data, a numerical simulation was conducted using the HYDRUS-1D model, which had good reliability and accurately simulated and predicted the law of water-salt migration in saline soil under the conditions of microbial solidification and improvement. MICP technology significantly reduced the change rate of water-salt migration and water evaporation in saline soil, hindered salt accumulation, and reduced salt-frost heave deformation, which effectively improved saline soil. The research results provide an important innovation and theoretical basis for the improvement of saline soil.

Genome analysis of a plasmid-bearing myxobacterim Myxococcus sp. strain MxC21 with salt-tolerant property.

Myxobacteria are widely distributed in various habitats of soil and oceanic sediment. However, it is unclear whether soil-dwelling myxobacteria tolerate a saline environment. In this study, a salt-tolerant myxobacterium Myxococcus sp. strain MxC21 was isolated from forest soil with NaCl tolerance >2% concentration. Under 1% salt-contained condition, strain MxC21 could kill and consume bacteria prey and exhibited complex social behaviors such as S-motility, biofilm, and fruiting body formation but adopted an asocial living pattern with the presence of 1.5% NaCl. To investigate the genomic basis of stress tolerance, the complete genome of MxC21 was sequenced and analyzed. Strain MxC21 consists of a circular chromosome with a total length of 9.13 Mbp and a circular plasmid of 64.3 kb. Comparative genomic analysis revealed that the genomes of strain MxC21 and M. xanthus DK1622 share high genome synteny, while no endogenous plasmid was found in DK1622. Further analysis showed that approximately 21% of its coding genes from the genome of strain MxC21 are predominantly associated with signal transduction, transcriptional regulation, and protein folding involved in diverse niche adaptation such as salt tolerance, which enables social behavior such as gliding motility, sporulation, and predation. Meantime, a high number of genes are also found to be involved in defense against oxidative stress and production of antimicrobial compounds. All of these functional genes may be responsible for the potential salt-toleration. Otherwise, strain MxC21 is the second reported myxobacteria containing indigenous plasmid, while only a small proportion of genes was specific to the circular plasmid of strain MxC21, and most of them were annotated as hypothetical proteins, which may have a direct relationship with the habitat adaptation of strain MxC21 under saline environment. This study provides an inspiration of the adaptive evolution of salt-tolerant myxobacterium and facilitates a potential application in the improvement of saline soil in future.

Effects of Microbial Fertilizer on Physicochemical Properties and Bacterial Communities of Saline Soil Under Brackish Water Irrigation

The improvement of saline soil with microbial fertilizer has numerous advantages including high efficiency, green environmental protection, etc. At the same time, applying microbial fertilizer is an effective way to safely use brackish water. Based on the moderately saline soil in the Hetao irrigation area, four treatments of F1 (4500 kg·km-2), F2 (7500 kg·km-2), F3 (10500 kg·km-2), and CK without microbial fertilizer were applied under brackish water irrigation using Lycium barbarum as the indicator plants. The aim was to study the effects of different microbial fertilizer application rates on soil ions, soil moisture content, pH value, nutrients, and bacterial community in four key growth stages of L. barbarum (flowering stage, fruit expansion stage, full fruit stage, and deciduous stage). The results showed that, compared with that in CK, F1 only significantly decreased Na+ content in the first two growth stages (P<0.05), whereas F2 and F3 significantly decreased Na+ content in the whole growth period (P<0.05), with an average reduction of 33.66% and 57.98%, respectively, and F3 significantly increased soil moisture content (MC), organic matter (OM), alkaline hydrolysis nitrogen (AN), and available phosphorus (AP) contents (P<0.05) during the whole growth period. In the flourishing period of L. barbarum, the Shannon index of F3 increased by 4.41% compared with that of CK. The dominant bacterial phyla in the soil were Proteobacteria, Bacteroidetes, and Actinobacteria, and the dominant bacterial genera were Sphingomonas and Pseudomonas. The most abundant functions of bacterial communities in the study area were chemoheterotrophy and aerobic chemoheterotrophy, with an average relative abundance of 15.07% and 13.16%, respectively. The application of microbial fertilizer increased the chitinolysis function and chloroplast functions of soil bacteria, which F2 increased to the highest degree. Canonical correlation analysis (CCA) showed that MC, Na+, and OM were important factors affecting the composition of the bacterial community. The correlation heat map showed that MC was positively correlated with Planctomycetes (P<0.01), and Gp6 was positively correlated with AN (P<0.01). Compared with that in CK, the F3 treatment increased the relative abundance of Gp6 and optimized the community structure during the growth period. In conclusion, the application of 10500 kg·km-2 microbial fertilizer (F3 treatment) under brackish water irrigation could significantly reduce soil salinity, increase nutrients, and improve the diversity of the soil bacterial community structure, which is conducive to the safe utilization of brackish water and the maintenance of soil ecological health.

The Effect of Biochar on the Salinity Reduction in Mung Bean Plant

The aim of research was investigation of biochar effect on salinity reduction in mung bean plant. The experiment was performed in a randomized complete block design with two replications and three treatments of saline, non-saline and saline + biochar. A silty soil was used for the plant substrate while calcium chloride and sodium chloride salts were employed in order to create the salinity levels in it. The results of variance analysis associated with the studied traits showed that the simple effects of salinity and plant organs as well as the interaction of salinity×plant organs on the calcium, magnesium, chlorine, sodium, potassium, pH and electrical conductivity (EC) levels are significant at a level of 1%. Also, the results of comparing the mean interaction of salinity×organ indicated that the highest calcium content in most cases is associated with the shoots. The biochar consumption has been found to reduce the calcium adsorption at high salinity in leaves and roots and increase it in the stem and pod. Increasing the calcium chloride and sodium chloride salinities in plant organs, the concentration of potassium decreased compared to calcium and with increasing salinity levels, the concentration of all mentioned elements increased in most treatments. The results showed that EC value was found to be improved by applying biochar. According to the results, effect of organ, salinity and organ× salinity on all characteristics was significant. It has been found that the salinity resistance mechanism of this plant is the salt tolerance through the accumulation of ions in its organs. Therefore, biochar can be used in the improvement of saline soils, for the optimal use of soil resources and saline waters.

Numerical and experimental study on water-heat-salt transport patterns in shallow bare soil with varying salt contents under evaporative conditions: A comparative investigation

Soil salinization is aggravated by evaporation, resulting in salt crystallizing on the soil surface. Soil salinization is harmful to agriculture and has significant implications for the engineering and construction industry. Therefore, this paper investigates water and salt transport in saline soils through comparison of numerical simulations with indoor evaporation tests. Based on Darcy's law, ideal gas law, mass conservation law, and energy conservation law, a one-dimensional transient mathematical model of coupled water-heat-salt transport is derived. The bottom of the model represents a recharge boundary condition, the sides of the soil column are insulated and impermeable, and the top serves as a heat source. The results show that the greater the salinity of the soil, the more drastic the temperature change, and at the same time, the greater the water retention of the soil. The temperature gradient along the height of the soil column provides a tremendous driving force for water-salt transport, and although the volumetric water content of the soil column at 3 ∼ 4 cm dissipates quickly, there is a gradient of increasing salt concentration towards the ends and decreasing towards the middle. The modeled results agree with the experimental data, indicating that the model can effectively simulate the water-heat-salt transport process for different saline sites under evaporation conditions. The model is essential for the improvement of saline soils and for finding new methods to prevent further soil salinization.

Synergistic mechanisms of bioorganic fertilizer and AMF driving rhizosphere bacterial community to improve phytoremediation efficiency of multiple HMs-contaminated saline soil

The addition of Arbuscular mycorrhizal fungi (AMF) or bioorganic fertilizer (BOF) alone has been reported to enhance plant tolerance to heavy metals and salt stress and promote plant growth, while their synergistic effects on plant growth and rhizosphere microorganism are largely unknown. This study explored the effects of AMF (Rhizophagus intraradices), BOF and BOF + RI assisted phytoremediation on heavy metals contaminated saline soil improvement and revealed the microbial mechanism. For this purpose, a pot trial consisting of four treatments (CK, RI, BOF and BOF + RI) was carried out. The results showed that the biomass, nutrient element contents, the accumulation of heavy metals and Na of Astragalus adsurgens and soil properties were most significantly improved by BOF + RI. BOF + RI significantly impacted rhizosphere microbial diversity, abundance and community composition. Chloroflexi and Patescibacteria at the phylum level and Actinomadura, Iamia, and Desulfosporosinus at the genus level were significantly enriched in BOF + RI. Network analysis revealed that BOF + RI significantly changed the keystone and enhanced complexity and interaction. Most of the keystones had roles in promoting plant growth and stress resistance. This study suggested that phytoremediation assisted by BOF and AMF is an attractive approach to ameliorate heavy metals contaminated saline soil.

Biochar Amends Saline Soil and Enhances Maize Growth: Three-Year Field Experiment Findings

Soil salinization is a significant obstacle to agricultural development in arid and semiarid regions. While short-term experiments have demonstrated the effective improvement of saline soils through biochar amendment, the long-term efficacy in sustainably ameliorating such soils remains uncertain. Addressing this knowledge gap, this study investigated the long-term effects of biochar amendment in a field setting by applying different rates of biochar to a salt-affected soil and cultivating silage maize for three consecutive years. The comprehensive assessment includes not only maize growth but also changes in soil physical and chemical properties over the study period. The results reveal a notable elevation in maize above-ground dry matter, directly correlated to the enhanced uptake of nitrogen, phosphorous, and potassium. Additionally, biochar application improves saline soil physical properties, including reduced bulk density (1–23%), increased soil large pores (0.7–12%), and macroaggregates (24–141%), and chemical properties, including a decrease in exchangeable sodium percentage (35–48%), and an increase in soil total organic carbon (112–857%), total nitrogen (9–198%), available nitrogen (12–49%), phosphorus (141–538%) and potassium (57–895%). These improvements ultimately resulted in better maize growth. However, the amelioration effect of biochar on these soil properties gradually diminished over the three-year study. Consequently, this study suggests that biochar is a promising soil amendment that can enhance maize growth in saline soil for at least three years in a field experiment, providing valuable insights for sustainable agricultural practices in salt-affected regions.

Effects of Phosphogypsum and Suaeda salsa on the Soil Moisture, Salt, and Bacterial Community Structure of Salinized Soil

The improvement of saline soil is an important issue that cannot be ignored in the farmland soil environment. The change in soil salinity will inevitably affect the soil bacterial community. This experiment was based on moderately saline soil in the Hetao Irrigation Area, conducted by applying phosphogypsum (LSG), interplanting Suaeda salsa with Lycium barbarum (JP) and applying phosphogypsum and interplanting S. salsa with L. barbarum (LSG+JP),and the local unimproved soil of a L. barbarum orchard was used as the control (CK), to explore the effects of different improvement methods on soil moisture, salinity, nutrients, and bacterial community structure diversity during the growth period of L. barbarum. The results showed that compared with that under CK, the LSG+JP treatment significantly decreased the soil EC value and pH value from the flowering stage to the deciduous stage (P<0.05), with an average decrease of 39.96% and 7.25%, respectively; the LSG+JP treatment significantly increased soil organic matter (OM) and available phosphorus (AP) content during the whole growth period (P<0.05), with an average annual increase of 81.85% and 203.50%, respectively. The total nitrogen (TN) content was significantly increased in the flowering and deciduous stages (P<0.05), with an annual average increase of 48.91%. The Shannon index of LSG+JP in the early stage of improvement was increased by 3.31% and 6.54% compared with that of CK, and the Chao1 index was increased by 24.95% and 43.26% compared with that of CK, respectively. The dominant bacteria in the soil were Proteobacteria, Bacteroidetes, Actinobacteria, and Acidobacteria, and the dominant genus was Sphingomonas. Compared with that in CK, the relative abundance of Proteobacteria in the improved treatment increased by 0.50%-16.27% from the flowering stage to the deciduous stage, and the relative abundance of Actinobacteria in the improved treatment increased by 1.91%-4.98% compared with that in CK in the flowering and full-fruit stages. Redundancy analysis (RDA) results showed that pH, water content (WT), and AP were important factors affecting bacterial community composition, and the correlation heatmap showed that Proteobacteria, Bacteroidetes, and EC values were significantly negatively correlated (P<0.001); Actinobacteria and Nitrospirillum were significantly negatively correlated with EC values (P<0.01). In conclusion, the application of phosphogypsum and interplanting S. salsa with L. barbarum (LSG+JP) could significantly reduce soil salinity, increase nutrients, and improve the diversity of soil bacterial community structure, which is beneficial to the long-term improvement of saline soil in the Hetao Irrigation Area and the maintenance of soil ecological health.

Organic Materials and AMF Addition Promote Growth of Taxodium ‘zhongshanshan’ by Improving Soil Structure

Soil salinization is considered a type of global-scale soil degradation, whereby excessive salinity severely diminishes soil health, which is primarily manifested through disrupted soil structures and reduced fertility. Furthermore, plant growth capacity is inhibited, and productivity is diminished. Consequently, the improvement of saline soils is regarded as a particularly important aspect of enhancing land production. To elucidate the roles of organic amendments and mycorrhizal fungi in the improvement of saline soils, seven treatments were set up, including biochar alone (B), straw alone (S), arbuscular mycorrhizal fungi alone (A), biochar in combination with arbuscular mycorrhizal fungi (BA), straw in combination with arbuscular mycorrhizal fungi (SA), and a control (CK). The results revealed that the seedling height growth rate under the BA treatment was significantly higher than that of the CK by 31.66%. The capillary porosity of the soil under the addition of BA was significantly higher than the CK by 3.17% in the 0–20 cm soil layer. The BA treatment reduced the fractal dimension of soil aggregates considerably by 19.06% in the 0–20 cm soil layer, and 13.71% in the 40–60 cm soil layer in contrast to the CK, respectively. In addition, the positive effects of the BA treatment were significant in the 20–40 cm soil layer. Overall, the application of biochar alone promoted the water stability of soil aggregates. The combination of arbuscular mycorrhizal fungi and biochar promoted plant growth, improved soil pore structures, promoted agglomerate water stability, and led to improved microbial activities. The results showed that organic amendments applied in conjunction with AMF improved the environment of salinized soil, which is a key factor in the promotion of plant growth and the long-term stability of soil health. This study provides a key technical basis for remediation of salinized soil.