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The water potential in drying soils, comprising both matric potential and osmotic potential components, can be measured using the dew point method (DPM). By combining DPM data with retention curve data acquired from techniques such as the suction plate method or the simplified evaporation method (SEM), it becomes possible to determine the soil water retention curve across the entire moisture spectrum. However, as the latter methods only determine the matric potential, the osmotic potential component in DPM data must either be negligible or known so that osmotic and matric potential components can be separated. This study aims to critically analyse common approaches for calculating the osmotic potential. To achieve this, we measured the water retention properties of a silt loam, a sandy loam and a sand across the entire moisture range by combining SEM and DPM. By using almost salt‐free soil material, we characterized reference water retention curves with negligible osmotic potential components. The impact of salt on water potential was analysed by conditioning soils with MgCl2 solutions of different concentrations, drying them, and measuring the water potential at different water contents using the DPM. The resulting water potentials were compared to the reference potentials and differences were interpreted as the osmotic potential component. The DPM‐measured water potentials in drying soils can be significantly affected by osmotic potential, especially at higher matric potentials (low suctions). Two models accounting for ideal and one model accounting for non‐ideal electrolyte behaviour were used to compare osmotic potential predictions with measurements. At low to medium salt concentrations, all models performed fairly well. At high concentrations, only the model accounting for non‐ideal behaviour predicted the osmotic potential satisfactorily, whereas at very high concentrations, all models underestimated the impact of osmotic potential on water potential. This suggests that the surface properties of the soil matrix, such as the specific surface area and surface charges, may lead to a decrease in osmotic potential beyond what is expected in pure solutions. [ABSTRACT FROM AUTHOR]

Soil provides essential nutrients for plant growth, but excess salts hinder development, making crops more vulnerable under climate change conditions. Soil microorganisms play a significant role in nutrient cycling. However, limited information is available on microbial behavior/community changes, and functional diversity in different soil types (normal, sodic, and highly sodic) and cropping systems [rice-wheat (RW); rice-wheat-mungbean (RWMb); maizewheat-mungbean (MWMb)] and management practices in the north-western Indo-Gangetic Plains of India. We investigated the influence of different soil types on physical and chemical properties at the surface level (0-15 cm) in relation to soil microbial population, activities, and functional diversity, focusing on community-level physiological profiling (CLPP) under different agriculture systems. Seven treatment combinations of soil types, cropping systems, and management practices were evaluated. Soil pHs were found to be lower in zerotill (ZT)-based sodic soil than in conventional-till (CT) sodic soil. Soil organic carbon (SOC) (0.91 and 0.90%) content and available N (154.46 and 132.74 kg ha-1) were higher with the ZT-based system under normal (N) soils (ZT-RWMb-N and ZT-MWMb-N) than in CT-based normal soil (0.67 and 121.04 kg ha-1). Similarly, higher SOC and N (0.85 and 76.11 kg ha-1) were found under ZT management in sodic soils (S) than under CT management (0.73% and 121.05 kg ha-1). Substrate utilization (amino acids, amines, carbohydrates, carboxylic acids, phenolic compounds, and polymers) increased with the incubation period. During 0-120 h of incubation, the highest utilization of amino acids, amines, carboxylic acids, phenolic compounds, and polymers was observed for ZT-MWMb-S soils, while the lowest was recorded for ZT-MWMb-N soils. Under high salt conditions, soil enzymatic activities (dehydrogenase, acid phosphatase, alkaline phosphatase, etc.) declined significantly compared to normal soils, affecting soil chemical and physical conditions. Microbial population and enzyme activities decreased with increasing salt stress across all cropping systems. These findings suggest that adopting efficient crop management practices can help mitigate the adverse effects of soil salinity on microbial diversity and soil health, thereby enhancing sustainable agricultural productivity in salt-affected regions. [ABSTRACT FROM AUTHOR]

Salinization and sodication present significant threats to crop productivity in many parts of the world including Pakistan. Cultivating halophytes like quinoa presents a viable solution for the profitable use of salt-affected lands. This study specifically examines the performance and salt tolerance mechanism of four quinoa accessions under varying salinity and sodicity levels. In addition to a control group, different combinations of electrical conductivity and sodium adsorption ratio (ECe dS m−1 SAR levels) were established: 10:20, 10:40, 20:20, and 20:40, achieved by using a mixture of salts. Most of the quinoa cultivars exhibited robust growth, with the exception of GLN-22, which proved unable to withstand high levels of salinity and sodicity, resulting in a 78% reduction in yield. GLN-29, on the other hand, demonstrated superior performance across all levels of salinity and sodicity. UAF-Q7 excelled under conditions of high salinity and low sodicity compared to equivalent salinity levels but elevated sodicity. Meanwhile, GLN-33 exhibited enhanced growth under elevated sodicity levels but struggled in the face of high salinity stress. In terms of nutrient uptake, GLN-29 displayed a higher accumulation of Na+ (32%) in older leaves compared to younger ones, alongside elevated levels of antioxidant activity at all salinity and sodicity levels. Notably, GLN-29 exhibited excellent adaptation to both high salinity and sodicity levels, resulting in the highest grain yield (14.75 g/pot) and the salt tolerance mechanism was associated with highly efficient K+ retention and transport of Na+ to older leaves. This underscores the necessity for further comprehensive field studies to ascertain its suitability for the sustainable utilization of salt-affected soils. [ABSTRACT FROM AUTHOR]

AbstractSalinity is one of the main factors that limit rice production globally. In Sub Saharan Africa, soil salinity has affected many countries. Understanding the available screening techniques and the mechanisms of salinity tolerance in rice is very important for dealing with soil salinity problem. This review summarizes the extent of soil salinity problems in some of the affected African countries and the available salt stress-tolerant rice genotypes. The problems, challenges and opportunities of salt-affected soils in Sub Saharan Africa are thoroughly described in this review, which also looks at breeding techniques which have been used for developing rice cultivars adapted to salt stress. Among the best option to deal with salinity-related problems is through the use of tolerant rice varieties, as many other available management approaches are not economically feasible for small-scale farmers. Also, the review discusses different approaches, both conventional and molecular breeding approaches that have greatly enhanced the current rice breeders’ toolboxes for developing salt-tolerant rice varieties. The review suggests that more efforts are required to leverage conventional breeding with molecular techniques for speedy identification of tolerant cultivars, useful markers and quantitative trait loci (QTLs). It is recommended that it is crucial to reinforce collaborative efforts and continuous investment in research, capacity building, and knowledge sharing for developing improved rice tolerant cultivars in order to fully address salinity problems in African.

In semi‐arid Mediterranean regions, particularly in some wetland soils, salinity is thought to be an indicator of low‐quality soils. In this study, a characterization is presented of the soils surrounding El Hito saline pond (Castilla La Mancha, Central Spain), an ecological halophyte niche within a natural semi‐arid steppe land. The main aim is to classify the salt‐affected soils and their morphology, genesis, and physico‐chemical properties. Four soil profiles were opened with a backhoe machine for sampling and subsequent description on the basis of their pedogenetic morphology. Systematic surface sampling was also performed. Standard methods were followed to measure the soil properties of 27 samples. Overall electrical conductivity (EC) and pH levels of the wetland were mapped (using ArcGIS 3.1.3). Soil salinity at elevated levels was detected, inhibiting plant uptake of water and nutrients. Distinct sub‐areas of extreme elevated surface salinity providing specialized plant habitats and poor soil structure were observed, as well as a mainly whitened‐yellowish‐greenish soil colour due to salt accumulation and poor drainage. The soils also showed alkaline pH values. In most samples, the pH was over 8.5, and EC was higher than 4 (dS m−1), and in several samples higher than 20 (dS m−1). A low sodium (Na) content was detected in the saturation extract where magnesium (Mg+) was the dominant soluble cation, followed by both calcium (Ca+) and sodium (Na+), and then potassium (K+), present in lower proportions. Sulphate (SO42−) and then chloride (Cl−) anions were dominant, although carbon trioxide, (CO3−) and carbonate (CO32−) anions were also present. The percentages of organic carbon (C) were very low, while total nitrogen (TN) and available phosphorus (P) were higher in the upper horizons, suggesting a degree of eutrophication. The present work will increase the existing knowledge about the role of El Hito saline pond, that play a vital ecological role in the broader biosphere, providing new suggestions to readers on how this knowledge can be used to improve these types of ecosystems. In particular, the agricultural pesticides and fertilizers continuously damage the soil fertility as evidenced by the high content of soluble phosphorus found in some points of the Hito saline pond. [ABSTRACT FROM AUTHOR]

Background. Salt-affected soils cause a significant portion of land to become unproductive yearly; its impact is severe in sub-Saharan African nations, especially the arid and semiarid lowlands, and the Rift Valley regions of Ethiopia are typically host to naturally salt-affected areas. Objective. To analyze the micronutrient content and map the micronutrient fertility status of agricultural salt-affected soils around Abaya and Chamo Lakes South Ethiopia Rift Valley. Methodology. A systematic sampling technique was employed to obtain 300 soil samples for the investigation from two depths (0-20 and 20-40cm), with a 600m sampling interval, of which 30 were used. The research data was analyzed using the application of standardized analytical procedures for soil data and descriptive and geostatistical techniques. Results. According to the study, there is low zinc available in the soil but an ample amount of iron, manganese, and copper. In addition, the study's findings revealed that, whereas the remaining micronutrient regional variability is found at long distances, available iron exhibited a regional variation in soil quality at small distances. Implications. The study suggests applying organic matter for better soil structure, water retention, and nutrient availability.Moreover, the results recommend that soils affected by salt might recover using various materials. Conclusions. In the study areas, zinc fertilizer may still be needed for an optimal yield even though the research area has low amounts of zinc fertilizer. The study concluded with management recommendations to minimize the adverse effects of very high micronutrient content on human health and plant growth.

Soil provides essential nutrients for plant growth, but excess salts hinder development, making crops more vulnerable under climate change conditions. Soil microorganisms play a significant role in nutrient cycling. However, limited information is available on microbial behavior/community changes, and functional diversity in different soil types (normal, sodic, and highly sodic) and cropping systems [rice-wheat (RW); rice-wheat-mungbean (RWMb); maize-wheat-mungbean (MWMb)] and management practices in the north-western Indo-Gangetic Plains of India. We investigated the influence of different soil types on physical and chemical properties at the surface level (0–15 cm) in relation to soil microbial population, activities, and functional diversity, focusing on community-level physiological profiling (CLPP) under different agriculture systems. Seven treatment combinations of soil types, cropping systems, and management practices were evaluated. Soil pHs were found to be lower in zero-till (ZT)-based sodic soil than in conventional-till (CT) sodic soil. Soil organic carbon (SOC) (0.91 and 0.90%) content and available N (154.46 and 132.74 kg ha−1) were higher with the ZT-based system under normal (N) soils (ZT-RWMb-N and ZT-MWMb-N) than in CT-based normal soil (0.67 and 121.04 kg ha−1). Similarly, higher SOC and N (0.85 and 76.11 kg ha−1) were found under ZT management in sodic soils (S) than under CT management (0.73% and 121.05 kg ha−1). Substrate utilization (amino acids, amines, carbohydrates, carboxylic acids, phenolic compounds, and polymers) increased with the incubation period. During 0–120 h of incubation, the highest utilization of amino acids, amines, carboxylic acids, phenolic compounds, and polymers was observed for ZT-MWMb-S soils, while the lowest was recorded for ZT-MWMb-N soils. Under high salt conditions, soil enzymatic activities (dehydrogenase, acid phosphatase, alkaline phosphatase, etc.) declined significantly compared to normal soils, affecting soil chemical and physical conditions. Microbial population and enzyme activities decreased with increasing salt stress across all cropping systems. These findings suggest that adopting efficient crop management practices can help mitigate the adverse effects of soil salinity on microbial diversity and soil health, thereby enhancing sustainable agricultural productivity in salt-affected regions.

Purpose: Salt-affected soils have significant enough salt concentrations to impact other land and soil resource uses, plant health, soil characteristics, and water quality. Consequently, a study was carried out in the South Ethiopian Rift Valley area around the lakes of Abaya and Chamo to determine the intensity and the types of salt-affected soil and map their spatial distributions. Methods: At 0–20 cm depths, a grid soil sampling scheme was employed to gather data from agricultural soils affected by salt. An adequately spaced grid cell of 200 m*200 m or seven transects, with seven samples collected every 200 m on each sampling site, was generated by the QGIS software's Fishnet tool, and an auger collected 226 soil samples from the proposed 245 soil sampling points. The analysis and interpretation of the data were done using both statistical and geostatistical methods. The un-sampled surface was predicted and mapped from laboratory point data using the standard Kriging algorithm in QGIS. Results: According to the results, the soil in the study area was rated as strongly alkaline and moderately alkaline in the reaction. The coefficient of variation (CV) was the lowest for soil pH. Except for the Ganta Kanchama site, low CV (100 % and showed significant variability among the samples. Out of 2274.65ha of the studied area, the type of salt 62.28 %, 26.09 %, 10.99 %, and 0.63 % were categorized as non-saline non-sodic, saline-sodic, sodic, and saline, respectively. Following saline-sodic, sodic, and saline soils, respectively, non-saline and non-sodic soils comprise most of the investigated areas. Conclusions: The result indicates almost all the salt-affected areas were situated in relatively lower slope areas exhibiting a flat to almost flat slope (0–2%). The study's findings are that the studied area needs specific soil management strategies to boost the salinity and sodicity problems around the study area and recommended reclamation techniques as the extent of the problems.

This article presents the results of soil and water analysis plus the plans —or “maps”— from the Report [1] issued 1974 on salt-affected soils in a new irrigation district located in the semi-arid Bardenas area of Aragón, northern Spain (Fig. 1). The survey was carried out by the now defunct Institute for Agrarian Reform and Development (i.e., IRYDA by its Spanish acronym). Work began in January 1972, with a preliminary reconnaissance survey on 53,000 ha using aerial photographs at a scale of 1:32,000 from the USAF photogrammetric flight of 1956-57 which covered almost the whole of Spain. Photographs from this flight are available on the Spanish aerial photograph viewer (https://fototeca.cnig.es/fototeca/). At that time, levelling for irrigation had not yet begun. This reconnaissance allowed the selection of an area of 32,300 ha (Fig. 1) with relevant salinity symptoms, like irrigated fields with irregular or no crop growth. A more detailed photo interpretation of the area was carried out at 1:12,000 scale from a flight in August 1971.The new irrigation district is fed by high quality water from the Pyrenees, but soon faced salinity problems that were well known to the farmers and echoed by the media [2, 3, 4] in an environment of great social concern about increasing agricultural production [5]. The Report, written in Spanish, is dated July 1974, but the soil profiles were described and sampled between April 1972 and March 1974. The Report [1] consists of two volumes, the first is a Memoria containing data from the surveys, laboratory analyses, pedological descriptions and some photographs of the soils and other land features of agricultural importance, as well as data and calculations for designing the drainage of selected plots. The second volume consists of five folded plans: a) location of the surveyed area at the scale of 1:200,000, and four plans at the scale of 1:25,000, b) soil-geomorphologic units, c) soil units describing their characteristics, d) land use, and e) locations of the described soil profiles and other field observations. Taken together, these data, improved by our orthorectification, gives a picture of the salinity and other soil properties in this area. The reuse of the data for comparisons with the evolution of agriculture in subsequent years —especially soil salinity and sodicity— will help to evaluate the agricultural practices over the last fifty years, particularly after intensive land levelling and irrigation.

Context: Given the global significance of wheat production and consumption, it is imperative to achieve high yields of nutritious wheat grains. However, the inadequate availability of zinc (Zn) in salt-affected soils can aggravate salt stress, decrease wheat grain yield, and grain Zn concentration. This study compared the effectiveness of soil Zn application and seed Zn priming in increasing Zn biofortification and grain yield of Zn-biofortified wheat grown in alkaline-calcareous soil affected by salts. Methods: Eighteen pots were filled with alkaline-calcareous soil containing elevated levels of soluble salts and exchangeable sodium (Na). The pots were subjected to soil Zn application (0 or 8 mg kg−1) and seed priming (control/non-, hydro-, or Zn-primed seeds) treatments, applied to a Zn-biofortified wheat (cv. Zincol-2016). Plant samples were collected at the heading and maturity stages to measure parameters related to plant growth and grain quality. Findings: Soil Zn application increased grain and straw yields across seed priming treatments by a maximum of 23 %, and seed Zn priming increased grain and straw yields across soil Zn rates by a maximum of 21 %. This yield response was accompanied by significant increases in grain potassium and Zn concentrations at maturity, as well as non-significant to significant increases in photosynthetic parameters (stomatal conductance, photosynthetic rate and transpiration rate) in flag leaves during heading. Additionally, compared to control, the combined treatment of soil Zn application and seed Zn priming decreased grain Na concentration by 14 %. Compared to control, both soil Zn application and seed Zn priming significantly increased grain Zn concentration. With the combined application treatment, the grain Zn concentration reached 27 mg kg−1, but it remained significantly below the desired level of >37 mg kg−1. Seed Zn priming decreased the phytate-to-Zn molar ratio in grains, while the treatments that received soil Zn application exhibited the lowest values of this ratio, potentially increasing Zn bioavailability to humans. Conclusions: The findings suggest that soil Zn application is more effective in enhancing grain yield and Zn concentration, while seed Zn priming remains crucial in low-Zn and high-salt soils. Future research should optimize Zn application strategies for Zn-biofortified wheat cultivated in salt-affected fields.

Salinization remains a major issue in soil degradation, for which biochar is a potential solution. In this meta-analysis, using 660 paired observations from 99 peer-reviewed articles, we evaluated biochar's effect on salt-affected soils and identified the initial soil properties, biochar properties and experimental factors influencing its efficacy. The results showed that the addition of biochar had a significant ameliorating effect on salt-affected soils. The soil electrical conductivity of saturated paste extract (ECe) was significantly reduced by 13.2%, and such effect was significant in severe salinization soil (rather than slight and moderate salinization). Meanwhile, the soil cation exchange capacity was significantly increased by 17.0%. However, the addition of biochar had no significant impact on soil pH. Model selection analyses further indicated that the level of initial salinity and the type of biochar feedstock were the most important factors regulating the response of soil ECe to biochar addition. In summary, while our study highlights the potential of biochar in ameliorating salt-affected soils, particularly in severely salinized soils, it also underscores the need for more comprehensive research in this field. Additional research is necessary to comprehensively address the significant heterogeneity of biochars, including their thorough characterization. In addition, more studies are required to explore the impact of biochar on both salt-tolerant and non-salt-tolerant plants in salt-affected soils.

Highlights Marginal lands such as salt-affected lands may supply adequate and cheap feedstock for biochar production. Biochar derived from halophytes can be befittingly used as a soil amendment, particularly for acidic soils. Halophyte biochar soil amendment can achieve all-wins in sustaining agriculture, ecology, and environment.

Soil degradation due to salts affects over 100 countries, especially in arid and semi-arid regions where salts migrate to the plant root zone via capillary action when evapotranspiration exceeds rainfall. Soil salinity reduces germination, growth, and root development, impacting crop yields, while excess sodium decreases water movement into the soil. Soil properties, namely, electrical conductivity (ECe), sodium adsorption ratio (SARe), and pH (pHe), affected by sparingly and soluble salts, are typically analyzed using soil saturated paste (SP). However, a simpler and cost-effective alternative is assessing soil salinity using soil:water solutions at ratio 1:5 (SW). This study developed empirical models between EC1:5-ECe, SAR1:5-SARe, and pH1:5-pHe to monitor soil salinity and sodicity in Lajas Valley, Puerto Rico, an agricultural reserve with 1,140 mm of mean annual rainfall and soils classified as saline and/or sodic. The ECe Sampling, Assessment, and Prediction software for Response Surface Sampling Design (ESAP-RSSD) optimized soil sampling with 48 points. Measurements of EC, pH, cations (Ca2+, Mg2+, Na+), and SAR were conducted using SP and 1:5 SW extracts. Simple linear regression models estimated ECe (R2 > 0.93, p < 0.0001) and SARe (R2 > 0.98, p < 0.0001) from 1:5 extracts. The pHe models varied with depth, showing a strong correlation (R2 > 0.62, p < 0.0001) from 0 to 30 cm and weakening (R2 > 0.27, p < 0.0022) from 90 to 120 cm. The simple linear regression models generally perform well for EC and pH variables, with better performance observed at shallower depths. SW proves to be a practical, cost-effective, and efficient method for assessing salt-affected soils in Lajas Valley. By enabling regular soil salinity analysis, the developed estimation models combined with SW extraction could improve soil management practices and agricultural productivity.

Traditional mapping of salt affected soils (SAS) is very costly and cannot precisely depict the space–time dynamics of soil salts over landscapes. Therefore, we tested the capacity of Landsat 8 Operational Land Imager (OLI) data to retrieve soil salinity and sodicity during the wet and dry seasons in an arid landscape. Seventy geo-referenced soil samples (0–30 cm) were collected during March (wet period) and September to be analyzed for pH, electrical conductivity (EC), and exchangeable sodium percentage (ESP). Using 70% of soil and band reflectance data, stepwise linear regression models were constructed to estimate soil pH, EC, and ESP. The models were validated using the remaining 30% in terms of the determination coefficient (R2) and residual prediction deviation (RPD). Results revealed the weak variability of soil pH, while EC and ESP had large variabilities. The three indicators (pH, EC, and ESP) increased from the wet to dry period. During the two seasons, the OLI bands had weak associations with soil pH, while the near-infrared (NIR) band could effectively discriminate soil salinity and sodicity levels. The EC and ESP predictive models in the wet period were developed with the NIR band, achieving adequate outcomes (an R2 of 0.65 and 0.61 and an RPD of 1.44 and 1.43, respectively). In the dry period, the best-fitted models were constructed with deep blue and NIR bands, yielding an R2 of 0.59 and 0.60 and an RPD of 1.49 and 1.50, respectively. The SAS covered 50% of the study area during the wet period, of which 14 and 36% were saline and saline-sodic soils, respectively. The extent increased up to 59% during the dry period, including saline soils (12%) and saline-sodic soils (47%). Our findings would facilitate precise, rapid, and cost-effective monitoring of soil salinity and sodicity over large areas. [ABSTRACT FROM AUTHOR]

Climate change is expected to affect the quality of soil and water, resulting in a significant impact on soil water balance in various regions around the world. Soil water potential plays a significant role in influencing evapotranspiration (ET), which is a crucial component of the soil water balance. The matric potential and the osmotic potential are the main components of the soil water potential. The osmotic potential is particularly important in dry soils, salt-affected soils, coastal lands, or when low-quality water is utilized for irrigation. Despite its importance, the impact of osmotic potential on ET has not been well-studied compared to other factors. Therefore, we conducted a study to investigate the impact of osmotic potential on ET from small-scale lab lysimeters planted with grass and equipped with scales and data loggers connected to computers. To create different osmotic potential levels, we irrigated the lysimeters with two different water qualities: distilled water and 4.79 dS.m−1 NaCl solution. The lysimeters were kept in well-watered conditions, and daily ET was monitored. Our results indicate a strong correlation between osmotic potential and ET. After three months of applying the treatments, the lysimeters with lower osmotic potential had a 39% reduction in cumulative ET compared to those irrigated with distilled water. Moreover, the osmotic stress affected plant health, leading to a notable decrease in the leaf area index and exerting a significant influence on evapotranspiration partitioning components, including transpiration and evaporation. [ABSTRACT FROM AUTHOR]

Halotolerant plant growth promoting rhizobacteria (PGPR) are beneficial microorganisms utilized to mitigate the biotic and abiotic stresses in plants. The areas of Sundarban mangroves of West Bengal, India have been reported to be rich in halotolerant microflora, yet major area remains unexplored. The present study, therefore, aims to map down the region-specific native microbial community potent of salt tolerance, plant growth promoting (PGP) activity and antagonistic activity against fungal pathogens. Bacterial samples were isolated from the saline soil of the Sundarban mangroves. A total of 156 bacterial samples were isolated and 20 were screened for their salt tolerance potential. These isolates were characterised using morphological, biochemical, and molecular approaches. Based on 16s rRNA sequencing, they were classified into 4 different genera, including Arthrobacter sp. (01 isolate), Pseudomonas plecoglossicida (01 isolate), Kocuria rosea (01 isolate), and Bacillus (17 isolates). The halotolerant isolates which possessed plant growth promoting traits including phosphate, and zinc solubilization, indole acetic acid production, siderophore, and ammonia generation were selected. Further, the effect of two halotolerant isolates GN-5 and JR-12 which showed most prominent PGP activities was evaluated in pea plant under high salinity conditions. The isolates improved survival by promoting germination (36 to 43%) and root-shoot growth and weight of pea plant in comparison to non-inoculated control plants. In a subsequent dual culture confrontation experiment, both these halo-tolerant isolates showed antagonistic activities against the aggressive root rot diseasecausing Macrophomina phaseolina (Tassi) Goid NAIMCC-F-02902. The identified isolates could be used as potential bioagents for saline soils, with potential antagonistic effect on root rot disease. However, further studies at the physiological and molecular level would help to delineate a detail mechanistic understanding of broad-spectrum defence against salinity and potential biotic pathogen. [ABSTRACT FROM AUTHOR]

The literature has shown that biochar can serve as potential amendment to achieve sustainable agriculture and environment. The accessibility and availability of cheap feedstock are considered as important constraint factors for the widespread application of biochar in agriculture. Marginal lands are widely distributed globally, several times larger than arable land, and hold little value for food production due to poor soil conditions. However, these lands are suitable for growing plants, which can be used as feedstock for biochar production. The salt-affected lands, as one of the main marginal lands, are particularly suitable for cultivating diverse varieties of halophytes that can be pyrolyzed into biochar, bio-gas, and bio-oil. The halophyte-derived biochar is useful to produce a desirable acid soil conditioner due to its high ash and rich bases, and improves soil characteristics under extreme saline conditions. Additionally, syngas and bio-oil hold potential benefits as fuels and industrial raw materials. This study introduces an innovative management technique for marginal lands such as salt-affected land, which can provide all-round benefits in food production, land management, vegetation coverage, carbon sequestration, and climate change mitigation. Highlights: Marginal lands such as salt-affected lands may supply adequate and cheap feedstock for biochar production. Biochar derived from halophytes can be befittingly used as a soil amendment, particularly for acidic soils. Halophyte biochar soil amendment can achieve all-wins in sustaining agriculture, ecology, and environment. [ABSTRACT FROM AUTHOR]

Biological invasions have modified the terrestrial biota worldwide, reducing biodiversity, and causing economic loss. Copernicia prunifera (Carnauba), a palm tree native to the semi-arid region of Brazil (Caatinga ecosystem), has high economic and social importance, but has been impacted by the invasive climbing shrub Cryptostegia madagascariensis (Madagascar rubber vine). We evaluated physiological, biochemical, and nutritional responses in mature plants of both species in two locations: Catuana (where there is an intense water-deficit during the dry season) and Minguaú (where there is high salinity and sodicity, and excess water throughout the year). Our results show that competitive interaction between the two species is mainly defined by their adaptability to abiotic soil constraints. C. prunifera is better adapted to severe water-deficit conditions, but its ecophysiological performance is not sufficient to withstand invasion by C. madagascariensis. The invader is more competitive in flooded, salt-affected soils, and is not severely impacted even with high sodium accumulation in its leaves. Our results also show that the negative impacts on C. prunifera intensify at the final stage of infestation, when the shading caused by C. madagascariensis restricts access to solar radiation and accelerates leaf senescence. However, the impact on C. prunifera precedes the permanent shading, as evidenced by the inhibition of net assimilation of CO2 under intermediate levels of infestation. These results reinforce the vulnerability of carnauba populations in the Caatinga ecosystem, which may be severely impacted without the development of technologies to mitigate the impact of invasion. [ABSTRACT FROM AUTHOR]

Salt-affected soils, which include both saline and sodic soils, are indeed found in various regions around the world. They can be found on all continents and are present under a wide range of climatic conditions. [...]

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Soil salinity and sodicity are the major environmental issues that lead to the deterioration of soil properties, nutrient cycling, and soil ecosystems around the globe. Nevertheless, the reciprocal effects of salinity and sodicity levels on depth-wise soil organic matter (SOM) and micronutrients remain elusive, particularly in Thailand. For a better understanding of such an issue, soil samples were collected from 38 sites at depths of 0–20, 30–50, 60–80, and 80–120 cm where they were affected by salts with variable levels of salinity and sodicity, having electrical conductivity (EC _e ), and exchangeable sodium percentage (ESP) from 0.20–74.70 dS m ^–1 , and 2.74%–113.23%, respectively. Soil physicochemical properties, including distribution of sand, silt, and clay, pH, soil organic carbon (SOC), and micronutrients (Fe, Zn, Mn, Cu, and B) were determined. The results exhibited that SOC content, ranging from 3.36–14.74 g kg ^–1 , was higher in topsoil (0–20 cm) compared to the other three soil depths and it correlated negatively with EC _e (0–20 and 80–120 cm) and ESP (80–120 cm), suggesting the declines in SOC amount due to high salinity and sodicity levels. Topsoil Mn concentration (0.06–182.06 mg kg ^–1 ) also tended to be greater than the other soil depths while Fe concentration in that soil depth (0.02–33.99 mg kg ^–1 ) tended to be smaller. The EC _e correlated negatively with the concentrations of Fe, Cu (all soil depths), and Zn (30–50 and 60–80 cm), and positively with Mn concentration (60–80 and 80–120 cm), suggesting that the availability of Fe Cu and Zn is vulnerable to high salinity and sodicity levels. Overall, our findings highlight that high salinity and sodicity levels brought about a reduction in SOC content and low concentrations of micronutrients in soils, irrespective of Mn concentration.

Biochar generated from the pyrolysis of organic materials reduces GHG emissions and impacts the soil's many other physical, chemical, and biological properties. This paper aims to show a systematic review of online databases about the progress and trends of knowledge in biochar, an important topic that contributes to the updating, synthesis, and dissemination of knowledge and allows classifying the growing flow of information and identifying accredited aspects from 2011 to 2022. From 2011 to 2022, 253 scientific articles were collected and 119 were selected. Cooccurrence networks were worked on, and the information was represented through graphs to visualize the total number of connections between entities, grouping (subdomains), and locating synonyms, among others. One of the selection criteria was the type of publication and the synopsis of the study of the effect of biochar on soil, environmental importance, and use in the agricultural sector, as well as the methodological approaches of the research process and implementation feasibility. The results showed a notable increase in research on the subject in recent years, with reports of effectiveness, as a soil conditioner and remediator, GHG mitigation, and a trend for water and soil decontamination with positive progress of new research. However, it is necessary to monitor the effects of the application of biochar in the medium and long term to originate cleaner production processes in the agricultural sector. [ABSTRACT FROM AUTHOR]

Afforestation, settled before 60-90 years and adjacent solonetzic grasslands, representing the natural vegetation cover were compared in this study based on their basic soil characteristics (pH, CaCO3 content, soil organic carbon (SOC), and exchangeable sodium percentage (ESP)) up to 2 m depth. The assumption was that the plantings of arbour vegetation can change soil characteristics of sodic soils not only in superficial layers but even in larger depths. Grasslands and forest soils were compared by standardised depths. Afforested soils showed lower pH in the depth at 0-100 cm, and slightly higher SOC content in subsoil (20-100 cm). CaCO3 content was significantly different (higher) only at the depth of 50-100 cm in afforested soils. Remarkable differences in ESP values were measured. Afforestation had in almost every layer (0-20, 20-50, 50-100 and 150-200 cm) a significant lower ESP value than grassland soil samples from the same depths. As the value of the ESP is relevant from soil classification purposes as well, the leaching of sodium also can change the taxonomic status of the soils from soils with natric horizon, to soils with Sodic or Bathysodic qualifiers.

This study was conducted in order to understand the effects of land use and soil types on microbial activity and community structure. Soil samples were collected from four different soil types (Solonetz, Solonchak, Chernozem and Gleysol) being used under different land use practices (arable, pasture and meadow). The soil chemical properties, moisture content, microbiological activity and community size were investigated. The principal component analysis results showed that different land uses and soil types are clearly separated based on the chemical properties of the soil. The canonical correspondence analysis results revealed that more than 78% of variation in the microbiological properties of the samples could be explained by environmental factors. Significant biological differences were observed among the different land use practices and soil types, and also soil cultivation affected the different groups of soil microbes. Sampling sites were separated into two main clusters (BrayCurtis) based on certain microbiological properties, salt-affected and non-salt-affected soils. The soil types were the main driving factor, with high soil taxonomic distances, however, low taxonomic distances indicated that land use had more pronounced effects on soil microbiological properties. [ABSTRACT FROM AUTHOR]

Salt-affected soils contain high levels of soluble salts (saline soil) and exchangeable sodium (alkali soil). Globally, about 932 million ha (Mha), including 831 Mha of agricultural land, is salt-affected. Salinity and sodicity adversely affect soil microbial diversity and enzymatic activities, and thereby carbon and nitrogen dynamics and greenhouse gas (GHG) emissions from soils. In this review article, we synthesize published information to understand the impact of salinity and sodicity on GHG production and emissions from salt-affected soils, and how various reclamation amendments (gypsum, phosphogypsum, organic manure, biochar, etc.) affect GHG emissions from reclaimed soils. Nitrous oxide (N2O) and methane (CH4) emissions are of greater concern due to their 298 and 28 times higher global warming potential, respectively, compared to carbon dioxide (CO2), on a 100-year time scale. Therefore, CO2 emissions are given negligible/smaller significance compared to the other two. Generally, nitrous oxide (N2O) emissions are higher at lower salinity and reduced at higher salinity mainly due to: (a) higher ammonification and lower nitrification resulting in a reduced substrate for denitrification; (b) reduced diversity of denitrifying bacteria lowered down microbial-mediated denitrification process; and (c) dissimilatory nitrate reduction to ammonium (DNRA), and denitrification processes compete with each other for common substrate/nitrate. Overall, methane (CH4) emissions from normal soils are higher than those of salt-affected soils. High salinity suppresses the activity of both methanogens (CH4 production) and methanotrophs (CH4 consumption). However, it imposes more inhibitory effects on methanogens than methanotrophs, resulting in lower CH4 production and subsequent emissions from these soils. Therefore, reclamation of these soils may enhance N2O and CH4 emissions. However, gypsum is the best reclamation agent, which significantly mitigates CH4 emissions from paddy cultivation in both sodic and non-sodic soils, and mitigation is higher at the higher rate of its application. Gypsum amendment increases sulfate ion concentrations and reduces CH4 emissions mainly due to the inhibition of the methanogenesis by the sulfate reductase bacteria and the enhancement of soil redox potential. Biochar is also good among the organic amendments mitigating both CH4 and N2O emission from salt-affected soils. The application of fresh organic matter and FYM enhance GHG emissions for these soils. This review suggests the need for systematic investigations for studying the impacts of various amendments and reclamation technologies on GHG emissions in order to develop low carbon emission technologies for salt-affected soil reclamation that can enhance the carbon sequestration potential of these soils. [ABSTRACT FROM AUTHOR]

India is facing economic losses of $US ~ 3.0 billion annually due to the existence of ~ 6.73 million ha of un‐reclaimed salt‐affected soils (SASs). The losses may go up significantly as future projections indicate an increase in the area of SASs to the extent of ~16 million ha by 2050, due to the impact of faulty irrigation practices and climate change. Managing the SASs is one of the major challenges in achieving land degradation neutrality, increasing crop productivity, and sustaining food security in India. Although the problem of SASs has been reduced to some extent through various technological interventions yet further efforts are needed for developing new avenues to further improve the productivity and restrict the expansion of salinity to new areas. The major interventions including application of various ameliorants, growing salt‐tolerant crops and cultivars, installation of sub‐surface drainage, adoption of alternate land‐use systems, and use of land shaping techniques have made significant impact nation‐wide in term of reclamation and productivity enhancement. Despite the achieved success in restoring the productivity of SASs, several constraints at the regional and national level have plagued the reclamation progress. The objective of this review is to compile relevant information available on the use and success of technological interventions to restore SASs. The emerging challenges, and the strategies that would be needed to address the problem of SASs in India are also discussed. This review may help India achieve the Sustainable Development Goals outlined by the UN for land degradation neutrality and food security. [ABSTRACT FROM AUTHOR]

Soil salinization is one of the main threats to soils worldwide, which has serious impacts on soil functions. Our objective was to map and assess salt-affectedness on arable land (0.85 km2) in Hungary, with high spatial resolution, using a combination of ensemble machine learning and multivariate geostatistics on three salt-affected soil indicators (i.e., alkalinity, electrical conductivity, and sodium adsorption ratio (n = 85 soil samples)). Ensemble modelling with five base learners (i.e., random forest, extreme gradient boosting, support vector machine, neural network, and generalized linear model) was carried out and the results showed that ensemble modelling outperformed the base learners for alkalinity and sodium adsorption ratio with R2 values of 0.43 and 0.96, respectively, while only the random forest prediction was acceptable for electrical conductivity. Multivariate geostatistics was conducted on the stochastic residuals derived from machine learning modelling, as we could reasonably assume that there is spatial interdependence between the selected salt-affected soil indicators. We used 10-fold cross-validation to check the performance of the spatial predictions and uncertainty quantifications, which provided acceptable results for each selected salt-affected soil indicator (for pH value, electrical conductivity, and sodium adsorption ratio, the root mean square error values were 0.11, 0.86, and 0.22, respectively). Our results showed that the methodology applied in this study is efficient in mapping and assessing salt-affectedness on arable lands with high spatial resolution. A probability map for sodium adsorption ratio represents sodic soils exceeding a threshold value of 13, where they are more likely to have soil structure deterioration and water infiltration problems. This map can help the land user to select the appropriate agrotechnical operation for improving soil quality and yield. [ABSTRACT FROM AUTHOR]

Phytoremediation is an efficient technique for the reclamation of salt-affected soils by growing plants. The present study aims to evaluate the intercropping of halophyte Atriplex nummularia Lindl. with naturally occurring species (Mimosa caesalpiniifolia Benth, Leucaena leucocephala (Lam.) de Wit and Azadirachta indica A. Juss.) adapted to semiarid regions as a management capable of enhancing the phytoremediation capacity of these species. A field experiment was conducted in a randomized block and contained four replicates. Species were cultivated alone and in association with A. nummularia to evaluate their potential uses in the reclamation of soils. Exchangeable Ca2+, Mg2+, Na+, and K+, as well as salinity and sodicity variables, were evaluated. The evaluations were performed at 9 and 18 months of plant growth. The results indicated that A. nummularia individualized was the treatment most efficient; with reductions of 80%, 63%, and 84% in electrical conductivity, sodium adsorption ratio, and exchangeable sodium percentage values, respectively at 18 months compared to starting of the experiment. However, the use of A. nummularia and species adapted to the semiarid in association, or even alone, promoted beneficial effects on the soil quality after the establishment of the plants. [ABSTRACT FROM AUTHOR]

Salt stress is the most pernicious of the abiotic stresses in arid and semiarid areas, having an adverse impact on crop growth and yields. Soil salinization decreases agricultural land by 1–2% every year and thus decreases crop yield, affecting ecological and socio-economic outcomes. Due to the increasing population and urbanization, it is the demand of the time to utilize every inch of land. In salt-affected soils, plant growth is destructively affected by the osmotic stress, ion toxicity, oxidative stress, and generation of ethylene. Salinity also affects microbiological processes and biological properties of soil and causes shifts in the microbial communities. Application of plant growth promoting microbes (PGPMs) is one of the significant strategies that can reduce the adverse effect of salt stress in crops and promote plant growth through several mechanisms such as secretion of growth hormones, increase in nutrient uptake, nitrogen fixation and protection from diseases. In this review, we have discussed salt affected soils and also addressed their impact on plant growth. We have highlighted the different mitigation strategies of salt-tolerant plant growth-promoting microbes which are beneficial for the growth of plants. [ABSTRACT FROM AUTHOR]

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Climate change is expected to affect the quality of soil and water, resulting in a significant impact on soil water balance in various regions around the world. Soil water potential plays a significant role in influencing evapotranspiration (ET), which is a crucial component of the soil water balance. The matric potential and the osmotic potential are the main components of the soil water potential. The osmotic potential is particularly important in dry soils, salt-affected soils, coastal lands, or when low-quality water is utilized for irrigation. Despite its importance, the impact of osmotic potential on ET has not been well-studied compared to other factors. Therefore, we conducted a study to investigate the impact of osmotic potential on ET from small-scale lab lysimeters planted with grass and equipped with scales and data loggers connected to computers. To create different osmotic potential levels, we irrigated the lysimeters with two different water qualities: distilled water and 4.79 dS.m−1 NaCl solution. The lysimeters were kept in well-watered conditions, and daily ET was monitored. Our results indicate a strong correlation between osmotic potential and ET. After three months of applying the treatments, the lysimeters with lower osmotic potential had a 39% reduction in cumulative ET compared to those irrigated with distilled water. Moreover, the osmotic stress affected plant health, leading to a notable decrease in the leaf area index and exerting a significant influence on evapotranspiration partitioning components, including transpiration and evaporation.

Salinization and sodification are types of degradation associated with the accumulation of salts and alkaline materials in the soil. They gradually advance unnoticed till severe degradation appears if not properly controlled. Relevant soil information is not routinely kept by many countries thus contributing to their advancement particularly in agricultural areas where their impacts have huge consequences on food security. We developed a 3‐step protocol to detect salinization and sodification advancement at different spatial scales and support soil information system development. The first step establishes an indicator database focusing on measured soil Electrical Conductivity (EC), pH, Exchangeable Sodium Percent (ESP), and a suit of environmental covariates. The second step outlines data harmonization strategies and classification of salinization and sodification problems. It also incorporates digital soil mapping for spatial information on salinization or sodification. The third step has time‐series modelling of salinization and sodification using mixed‐effects approach to improve hotspot detection in agricultural areas. The protocol was tested in Afghanistan, Sudan, and Lesotho using time‐series data between 2001 and 2018. It successfully identified salt and soda accumulation at different soil depths with more than 80% accuracy on holdout samples. In Sudan and Afghanistan, it identified topsoils as more prone to salinization than the subsoils and consequently depicted more salt accumulation in topsoils than subsoils in agricultural areas. In Lesotho, it identified emerging subsoil sodification. The protocol has potential for supporting the development of soil information on salinization and sodification which is currently lacking at many national and regional levels. [ABSTRACT FROM AUTHOR]

Afforestation, settled before 60-90 years and adjacent solonetzic grasslands, representing the natural vegetation cover were compared in this study based on their basic soil characteristics (pH, CaCO3 content, soil organic carbon (SOC), and exchangeable sodium percentage (ESP)) up to 2 m depth. The assumption was that the plantings of arbour vegetation can change soil characteristics of sodic soils not only in superficial layers but even in larger depths. Grasslands and forest soils were compared by standardised depths. Afforested soils showed lower pH in the depth at 0-100 cm, and slightly higher SOC content in subsoil (20-100 cm). CaCO3 content was significantly different (higher) only at the depth of 50-100 cm in afforested soils. Remarkable differences in ESP values were measured. Afforestation had in almost every layer (0-20, 20-50, 50-100 and 150-200 cm) a significant lower ESP value than grassland soil samples from the same depths. As the value of the ESP is relevant from soil classification purposes as well, the leaching of sodium also can change the taxonomic status of the soils from soils with natric horizon, to soils with Sodic or Bathysodic qualifiers. [ABSTRACT FROM AUTHOR]