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We characterize here the saline‐alkaline soils composed of Na2CO3 and NaHCO3 in the Ganga floodplain and the peninsular basin using various chemical proxies and the isotopic composition of Sr. Abundance of saline‐alkaline soils in the Ganga floodplain and their higher solubility make them an important source of non‐chloride Na and other dissolved ions including Sr to the river waters. Inverse model based source apportionment of dissolved ions indicates ∼26%–71% of Na at the Ganga outflow is influenced by the saline‐alkaline soils; however, in some of the tributaries of the Ganga in the floodplain, for example, in the Gomti, this contribution exceeds 85%. The estimated silicate erosion rate by correcting for the saline‐alkaline soil contribution in the Ganga floodplain (∼5 tons km−2 yr−1) is less than one third of that of the Himalayan headwaters (16 tons km−2 yr−1) emphasizing the important role of physical erosion in controlling the chemical erosion in the mountain catchments compared to higher temperature and residence time in the floodplain. The silicate sourced dissolved fluxes from the floodplains are comparable to those from the Himalaya because of the vast drainage area of the floodplains and peninsular catchment. The findings of this study have direct relevance to studies on the determination of silicate weathering rates of not only the Ganga system, but also of other basins infested by saline‐alkaline soils such as the Columbia, the Colorado, the upper Rio Grande, the Missouri‐Mississippi river system, the Parana river, the Niger, the Nile, and the Orange. Plain Language Summary The saline‐alkaline soils containing Na2CO3 and NaHCO3 are present abundantly in the plain and peninsular drainages of the Ganga. Their higher solubility contribute significantly to the dissolved ions budget of the river waters which was earlier considered as the part of silicate weathering resulting in overestimation of silicate weathering and hence the CO2 consumption in the Ganga System. Chemical and isotopic characterisation of these salts in the Ganga system allowed us to estimate actual silicate weathering of the system and associated CO2 consumption impacting the carbon cycle. This study estimates three times higher silicate erosion rate in the mountainous catchment of the Ganga, 16 tons km−2 yr−1 compared to its plain catchment, ∼5 tons km−2 yr−1. This study puts the hotly debated topic of importance of mountain versus plain erosion of the Ganga on rest and emphasizes the role of higher physical erosion in contributing to the higher chemical erosion in the hilly terrain compared to higher temperature and residence times in the plain catchment. Key Points The Ganga Plain is infested by saline‐alkaline soils, Na2CO3 and NaHCO3 minerals If not corrected, they overestimate the silicate erosion rates (SERs) in the Ganga Basin SER in the Ganga Plain is one third of that in the Himalaya

Artificial sulfur (S) and nitrogen (N) addition experiments often fail to accurately simulate acid deposition in terms of type, composition, intensity, frequency, and duration, potentially leading to biased estimates of deposition impact on plant diversity. Consequently, studying plant diversity patterns around acid emission sources provides a more reliable alternative. Yet, this approach remains understudied in field research, particularly in saline‐alkaline regions where high soil buffering capacity may attenuate plant sensitivity to acid deposition. Therefore, we investigated plant functional diversity (PFD) and analyzed its influencing factors in a desert coal‐mining region in northwestern China characterized by high pH, abundant CaCO3 content in soils, and increasing acid deposition. The plant communities were characterized by high leaf thickness, low specific leaf area, and limited leaf total carbon (C) and N concentrations, indicating the preference of the plant communities for a slow investment‐returning ecological strategy in the study region. In this context, leaf traits (e.g., thickness and total C and N concentrations), rather than PFD, played a major role in stabilizing plant communities. The intensity of S and N deposition had no effect on PFD. In contrast, exchangeable cation (BC) deposition directly reduced the functional richness, functional dispersion, and the Rao's indices, possibly by exacerbating soil salinity and alkalinity in the study region. Our findings indicate that PFD is mainly influenced by BC deposition in saline‐alkaline coal‐mining regions. Therefore, the potential risk of BC deposition, which accompanies acid deposition, posed on plant diversity should not be overlooked in these regions. Although sulfur and nitrogen deposition had limited effects on plant functional diversity, the study found that leaf traits played a key role in maintaining plant community stability under acid deposition conditions.

【Objective】Soil salinity and alkalinity is an abiotic factor affecting crop growth in the Yellow River Delta, and various methods have been developed to improve its fertility. This paper experimentally investigates the influence of combination of organic and mineral nitrogen fertilizations on water and salt dynamics, as well as the yield of winter wheat in this type of soil.【Method】The experiment was conducted in a wheat field. It consisted of two organic fertilization treatments: 0 kg/hm2 (F0) and 75 kg/hm2 (F1); each treatment had three mineral nitrogen applications: 180 kg/hm2 (N1), 225 kg/hm2 (N2) and 270 kg/hm2 (N3). During the experiment, we measured soil water and salt distribution along the soil profiles, as well as grain yield of the wheat. 【Result】① During wheat growth period, average soil water content in the 0-40 cm soil layer in the F1 treatment was higher than that in the F0 treatment, and soil water content in both F treatments increased as nitrogen application increased. Over the whole wheat growth period, soil salinity, especially in the 0-40m soil layer, in the F1 treatment was lower than that in the F0 treatment. At harvest stage, F1N3 reduced soil salinity in the 0-40 cm layer and the 0-100 cm layer by 45.65% and 29.16%, respectively, compared F0N3. ② Compared to F0, F1 increased maximum plant height, leaf area, dry matter accumulation, and contribution of post-anthesis dry matter accumulation to grains by 15.42%, 3.80%, 19.54% and 17.70%, respectively. F1N3 increased grain yield and its components significantly, compared to other treatments; its harvest index was 45.07% and partial factor productivity of nitrogen fertilizer was 34.11 kg/kg, lower only than that in F1N2. ③ Correlation analysis showed that soil salinity was negatively correlated with plant height and grain yield, while grain yield was positively correlated with dry matter accumulation and spike numbers per unit area, both at significantly levels. Comprehensive evaluation analysis indicated that F1N3 was optimal among all treatments.【Conclusion】Applying 75 kg/hm2 of organic fertilizer as base fertilization combined with topdressing 270 kg/hm2 of nitrogen fertilizer can effectively reduce soil salinity and increase yield of winter wheat in the saline and alkaline soil in the Yellow River Delta, despite its partial factor productivity of nitrogen fertilizer tending to decrease. These results provide guidance for improving winter wheat production in this region.

There is evidence of increased soil organic carbon (SOC) and inorganic carbon (SIC) under fertilization in dry croplands of arid and semi-arid areas. However, not much is known about the responses of SOC and SIC in coastal saline − alkaline paddy soils that undergo flooding − draining cycles. Here, we assess the impacts of various combinations of organic and phosphorus fertilization on SOC and SIC and other soil properties in a saline − alkaline paddy field of the Yellow River Delta. Our study showed that organic fertilization resulted in an increase of SOC by 11.9% over 0 − 20 cm and 13.3% over 20 − 100 cm (i.e., 140 − 250 g C m−2y−1 over 0 − 100 cm) whereas phosphorus fertilization only led to a significant increase of SOC in subsoils (or ~ 75 g C m−2y−1 over 0 − 100 cm). There were little differences in SIC over 0 − 20 cm among the treatments; but SIC showed a significant decrease over 20 − 100 cm under organic fertilization combined with lower rate of phosphorus fertilization. However, high rate of phosphorus fertilization combined with organic amendment led to an increase in SIC stock, but a decrease in SOC stock in the subsoil. There was a significant negative relationship between SIC and SOC stocks in this paddy soil. This study demonstrated that fertilization practices could have complex influences on SOC and SIC in saline − alkaline paddy fields due to the flooding − draining cycles that lead to changes in soil conditions.

PurposeThis study investigated the chemical and physical mechanisms associated with the movement of water and salt in saline-alkali soil amended with different types of biochar.Materials and methodsFour types of biochar were selected: ordinary laboratory-prepared biochar (BC), acidified biochar (HBC), particle size modified biochar (NBC), and composite modified biochar (HNBC). The physical and chemical properties of the biochar treatments were characterized. Vertical infiltration simulation tests were conducted to analyze the effects of modification on the adsorption and distribution of salt ions on biochar, and the soil water-stable macro-aggregates in saline-alkali soil.Results and discussionThe porous structure, specific surface area (SSA), micropore volume (VMIC), and H/C value were increased by acidification, particle size modification, and composite modification. Compared with BC, HBC and HNBC enhanced the O/C and (O+N)/C values, thereby increasing the hydrophilicity. The vertical infiltration tests showed that the depth of the soil wetting peak and cumulative infiltration were both higher than in the control (CK) after adding biochar, where HBC had the greatest water retention capacity. The modified biochar reduced the salt content and water-soluble Na+ content of the soil profile by increasing the soil water content and adsorbing Na+. The modified biochar promoted the formation and stabilization of soil water-stable macro-aggregates. Amending soil with HBC showed the greatest reduction in salt content and increased water-stable macro-aggregation.ConclusionsHBC improved the water retention and Na+ adsorption capacity of biochar. This enhanced the formation of soil water-stable macro-aggregates and improved the effects of biochar on saline-alkali soil by altering soil physical and chemical properties.

Response of rhizosphere microbial community structure and co-occurrence patterns to liquid organic fertilizer in sunflower cropland was investigated. Moderate and severe saline-alkaline soils were treated with liquid organic fertilizer containing mainly small molecular organic compounds (450 g L–1) at a rate of 4500 L ha–1 year−1 over 2 years. Compared with the untreated soils, organic fertilizer treatment increased soil nutrient concentrations by 13.8–137.1% while reducing soil pH and salinity by 5.6% and 54.7%, respectively. Organic fertilizer treatment also improved sunflower yield, plant number, and plant height by 28.6–67.3%. Following organic fertilizer treatment, fungal α-diversity was increased, and the effects of salinity-alkalinity stress on rhizosphere microbial communities were alleviated. The relative abundances of some halotolerant microbes and phytopathogenic fungi were reduced in organic fertilizer-treated soils, in contrast to increases in the relative abundances of plant growth-promoting microbes and organic matter decomposers, such as Nocardioides, Rhizophagus, and Stachybotrys. Network analysis revealed that severe salinity-alkalinity stress stimulated cooperation among bacteria, while organic fertilizer treatment tended to stimulate the ecosystem functions of fungi with higher proportions of fungi-bacteria and fungi-fungi links. More keystone taxa (e.g., Amycolatopsis, Variovorax, and Gemmatimonas) were positively correlated with soil nutrient concentrations and crop yield-related traits in organic fertilizer-treated soils. Overall, liquid organic fertilizer amendment could attenuate the adverse effects of salinity-alkalinity stress on sunflower yield by improving soil quality and optimizing rhizosphere microbial community structure and co-occurrence patterns.

BackgroundAlkaline-saline (AS) stress threats crop development and productivity. Understanding the genetic control of AS tolerance in wheat is important to produce wheat cultivars that outstand such a severe stress condition.MethodsA set of 48 cultivars were tested under controlled and AS stress conditions at seedling and maturity stages. The effect of AS on seedlings and kernel traits was measured to select tolerant and high-yielding genotypes. Single-marker-analysis (SMA) and gene enrichment were conducted to understand the genetic control of AS tolerance in both growth stages.ResultsAS stress decreased all kernel traits and most of the seedling traits. High correlations were found between the studied traits in each growth stage. The correlation between the traits related to both stages was non-significant. SMA identified a total of 292 and 52 markers significantly associated with the studied traits under controlled and AS stress conditions. Seven and 20 gene models were identified to control AS tolerance in each stage. Gene enrichment analysis identified one and six networks that control AS tolerance. Four genotypes were selected as superior genotypes.ConclusionThe genetic control of the studied traits differs under control and AS conditions. Two genetic systems control AS tolerance in each growth stage. This study is the first one that unlocked the genetic control of AS tolerance in seedling and mature growth stages and identified the biological process that lead to this tolerance. Four genotypes were selected for crossing in future breeding programs to improve AS tolerance in spring wheat.

Background and aims Phosphorus (P) addition is considered key factor in soil organic carbon (SOC) cycle. The potential impact mechanisms of P addition on SOC stability and sequestration were explored in saline-alkali soil. Methods A 9-year field experiment was arranged in the Yellow River Delta, which included (i) CK, no fertilization; (ii) NK, N and K fertilizer application; (iii) NP1K and (iv) NP2K, NK plus 28 and 56 kg P ha −1  year −1 application, respectively. Results Compared with NK, the content of particulate OC (POC) was significantly increased by 29.9% and 26.8% in NP1K and NP2K treatments, respectively. The variation trend of aromatic-C and microbial biomass C (MBC) was similar to that of POC, which were positively corelated with SOC sequestration. Meanwhile, C and specific C mineralization rate (CMR, SCMR) were increased with P addition, which might be due to the decrease of carboxyl or amidogen-C. Moreover, owing to the increase in root biomass, SOC sequestration was significantly increased by more than 9.3% with P addition. Redundancy analysis further indicated that root biomass was the main factor in regulating SOC. While the CMR and SCMR were higher of NP2K treatment than those of NP1K treatment, this might result in SOC sequestration was no significant change between the two treatments. Conclusion Long-term low-level P fertilization is a preferable practice to increase POC, stable chemical composition and MBC, and then SOC sequestration. These findings provide important insights into how long-term different levels of P application regulate soil C cycling in saline-alkali paddy soil. Graphical abstract

PurposeAlkaline salinity constrains crop yield. Previously, we observed local adaptation of Arabidopsis thaliana to saline-siliceous soils (pH ≤ 7) and to non-saline carbonate soils. However, no natural population of A. thaliana was localized on saline-alkaline soils. This suggests that salinity tolerance evolved on saline-siliceous soils may not confer tolerance to alkaline salinity. This hypothesis was explored by addressing physiological and molecular responses to alkaline salinity of A. thaliana that differ in tolerance to either non-alkaline salinity or carbonate.MethodsA. thaliana native to saline-siliceous soils (high salinity, HS), non-saline carbonate soils (high alkalinity, HA), or soils with intermediate levels of these factors (medium saline-alkalinity, MSA) were cultivated in common gardens on saline-siliceous or saline-calcareous substrates. Hydroponics and irrigation experiments confirmed the phenotypes. The growth, mineral concentrations, proline content, osmotic potential, genetic variation distribution, and expression levels of selected genes involved in salinity and alkalinity tolerance were assessed.ResultsHS performed best on saline-siliceous soil and in hydroponics with salinity (pH 5.9). However, HS was more sensitive to saline-alkaline conditions than HA and MSA. The fitness under saline-alkaline conditions was ranked according to MSA > HA > HS. Under alkaline salinity, MSA best maintained ion homeostasis, osmotic balance, and higher expression levels of key genes involved in saline or alkaline tolerance (AHA1, root HKT1 and FRO2, and shoot NHX1 and IRT1).ConclusionIn A. thaliana, salinity tolerance evolved on saline-siliceous soils does not provide tolerance to alkaline salinity. Plants native to intermediate conditions (MSA) have more plasticity to adapt to alkaline salinity than those locally adapted to these individual stress factors.

Cotton ( Gossypium spp .) is a key crop in Kazakhstan, yet its productivity is constrained by saline-alkaline soils, which affect approximately 41% of the nation’s arable land. Conventional soil remediation methods are often unsustainable and economically impractical. This study investigates the potential of Bacillus megaterium PEF-1, a plant growth-promoting rhizobacterium (PGPR) isolated from cotton rhizospheres in the Turkestan region, as a biofertilizer for saline-alkaline conditions. The strain demonstrated high tolerance to salinity (up to 10% NaCl), alkalinity (pH 9.0), and heavy metals, and produced significant levels of indole-3-acetic acid (IAA; 895 mg/L in vitro). Field trials with seed inoculation (10⁹ CFU/mL) showed marked improvements in cotton growth, including increases in plant height (18%), boll number (22%), and yield (25%) relative to controls. Soil analyses revealed enhanced nutrient availability in treated plots: nitrogen (+ 4.3%), phosphorus (+ 15.1%), potassium (+ 26.8%), and humus content (+ 29.3%). Stress mitigation was achieved through ACC deaminase-mediated ethylene reduction and superoxide dismutase (SOD)-driven reactive oxygen species (ROS) scavenging. Acute toxicity tests, conducted in accordance with OECD guidelines, confirmed the strain’s biosafety with no adverse effects in mammalian models. Bacillus megaterium PEF-1 exhibits strong potential as a sustainable biofertilizer for improving cotton yields and soil fertility under saline-alkaline stress. Its capacity for nutrient mobilization, phytohormone synthesis, and abiotic stress alleviation aligns with the United Nations Sustainable Development Goals (SDGs) 2 (Zero Hunger) and 15 (Life on Land), offering a scalable, eco-friendly alternative to chemical fertilizers for arid and degraded agroecosystems.