Effectiveness of compost use in salt-affected soil

Bridging gaps and seeding futures: A synthesis of soil salinization and the role of plant-soil interactions under climate change

Soil salinization, exacerbated by climate change, poses significant threats to agricultural productivity, land restoration, and ecosystem resilience. This study reviews current knowledge on plant-soil interactions as a strategy to mitigate soil salinization induced by climate change, focusing on their role in soil salinity dynamics and tolerance mechanisms. The review examines how alterations in hydrological and temperature regimes impact soil salinity and how plant-soil mechanisms-such as salt exclusion, compartmentalization, and plant-microbe interactions-contribute to salinity mitigation. This, in turn, enhances soil quality, fertility, microbial diversity, and ecosystem services. The analysis identifies a growing body of research and highlights key themes and emerging trends, including drought, microbial communities, and salt tolerance strategies. This study underscores the critical role of plant-soil interactions in sustainable salinity management and identifies knowledge gaps and future research priorities, advocating for plant-soil interactions as a crucial pathway for improving ecosystem resilience to salinity stress amid climate change.

Enhancing salt tolerance and crop growth in agricultural systems: the impact of magnetized-ionized water irrigation on soil properties, microbial communities, and cotton growth

BACKGROUND

The development of agricultural practices requires an understanding of the improvement of salt tolerance and crop growth in agricultural systems through magnetized-ionized water irrigation.

METHOD

This study examined the impacts of fresh water (F), brackish water (B), magnetized-ionized fresh water (MIF), and magnetized-ionized brackish water (MIB) on soil properties and the growth of cotton seedlings through microbial analysis during the cotton seedling period.

RESULTS

The results revealed that magnetized-ionized water irrigation improved soil water retention and promoted salt leaching. In comparison with F irrigation, plant height, leaf area index (LAI), dry matter accumulation (DM), and chlorophyll content (SPAD) levels increased by 3.61%, 4.07%, 5.76%, and 1.33%, respectively, under MIF irrigation. Similarly, when compared with B irrigation, LAI, DM, and SPAD increased by 5.13%, 6.12%, and 3.12% under MIB irrigation. Magnetized-ionized water irrigation also led to a notable rise in the relative abundance of beneficial soil bacterial communities, particularly Pseudomonas and Azoarcus, as well as fungal communities like Trichoderma, while reducing the prevalence of pathogenic fungi, such as Lasionectria, Gibberella, and Alternaria. Notably, this irrigation approach induced alterations in soil properties, and partial least squares path modeling revealed significant links between soil properties and both cotton growth and fungal community structure (with path coefficients of -0.884 and 0.693, respectively).

CONCLUSION

This study elucidated the distinct effects of soil properties and growth indices on cotton yield during the seedling period, providing a crucial scientific foundation for enhancing future agricultural production through the use of magnetized-ionized water irrigation. © 2024 Society of Chemical Industry.

Survival and plasticity in Acacia saligna growth across Contrasting management practices and growing niches

Reforestation and afforestation either through natural regeneration, tree planting or both methods have been globally promoted to motivate ecological restoration of degraded lands and to improve livelihoods. However, moisture stress and infertile soils limit the survival and growth of trees planted for restoration in drier areas. Hence, understanding the factors that determine the restoration success of drylands through tree planting is critical. We conducted a factorial experiment in Tigray, Ethiopia to evaluate the survival, growth performance and biomass of planted seedlings of the multipurpose agroforestry tree species Acacia saligna over 24 months. The treatments were application of watering (W), mulching (M) and compost (C) separately and in combinations (WM, WMC). We established experimental plots on farmland and on a nearby hillside-exclosure to examine the role of planting niches on seedling performance. Seedlings treated with watering, mulching, and compost (WMC) revealed significantly greater height, root collar diameter (RCD), and dry biomass compared to the other treatments. Seedlings planted in farmland showed significantly greater height, RCD, and total dry biomass compared to those planted at the hillside-exclosure. Although the survival rate was slightly higher in farmland, we also found sufficient survival rates in the hillside-exclosures. Therefore, post-planting care and activities including mulching, watering and fertilization are crucial to enhance the survival and growth performance of A. saligna or other tree species so that efforts in reversing land degradation and restoration of drylands will be successful.

The mechanism of using magnetized-ionized water in combination with organic fertilizer to enhance soil health and cotton yield

Addressing critical challenges in sustainable agriculture, notably water scarcity and soil degradation, necessitates innovative irrigation and fertilization methods. This investigation thoroughly assessed the effects of combining inorganic and organic fertilizers under brackish water irrigation, particularly focusing on magnetized-ionized brackish water-a promising solution for these challenges. The study shows that the integration of inorganic and organic fertilizers notably enhances soil water retention and salt leaching when applied with magnetized-ionized brackish water irrigation (MIBIO treatment), with water storage rate and salt accumulation rate observed at -0.454 and -0.075, respectively. Additionally, soil microbial diversity and uniformity witnessed significant improvement, positively influencing cotton growth rates, particularly noting a dry matter accumulation rate of 9.3262 kg·(ha·°C)-1. Transcriptomic analysis revealed that the MIBIO treatment elevated gene expression during the boll period, with notable enrichment in pathways such as the MAPK signaling pathway-plant and amino sugar and nucleotide sugar metabolism. Furthermore, the partial least squares path modeling indicated that soil alkali-hydrolyzed nitrogen (AN) and available potassium (AK) positively impact cotton leaf transcription and yield, with path coefficients of 0.613 and 0.428, respectively. Specifically, AN and AK contribute to enhancing cotton growth and affect the expression of metabolism genes in cotton leaves, thereby increasing cotton yield. Our study highlights the crucial role of irrigation and fertilization in influencing the soil environment and cotton growth. We recommend the use of magnetized-ionized water irrigation in combination with organic fertilizers as a strategy to boost agricultural productivity. Through the development of these strategies, our goal is to offer farmers practical guidance that can be readily implemented to enhance crop production efficiency, reduce environmental impact, and adhere to the principles of sustainable agriculture.

Understanding Salinity-Driven Modulation of Microbial Interactions: Rhizosphere versus Edaphic Microbiome Dynamics

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

Applications of humic and fulvic acid under saline soil conditions to improve growth and yield in barley

BACKGROUND

Enriching the soil with organic matter such as humic and fulvic acid to increase its content available nutrients, improves the chemical properties of the soil and increases plant growth as well as grain yield. In this study, we conducted a field experiment using humic acid (HA), fulvic acid (FA) and recommended dose (RDP) of phosphorus fertilizer to treat Hordeum vulgare seedling, in which four concentrations from HA, FA and RDP (0.0 %, 50 %, 75 % and 100%) under saline soil conditions . Moreover, some agronomic traits (e.g. grain yield, straw yield, spikes weight, plant height, spike length and spike weight) in barley seedling after treated with different concentrations from HA, FA and RDP were determined. As such the beneficial effects of these combinations to improve plant growth, N, P, and K uptake, grain yield, and its components under salinity stress were assessed.

RESULTS

The findings showed that the treatments HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6), improved number of spikes/plant, 1000-grain weight, grain yield/ha, harvest index, the amount of uptake of nitrogen (N), phosphorous (P) and potassium (K) in straw and grain. The increase for grain yield over the control was 64.69, 56.77, 49.83, 49.17, and 44.22% in the first season, and 64.08, 56.63, 49.19, 48.87, and 43.69% in the second season,. Meanwhile, the increase for grain yield when compared to the recommended dose was 22.30, 16.42, 11.27, 10.78, and 7.11% in the first season, and 22.17, 16.63, 11.08, 10.84, and 6.99% in the second season. Therefore, under salinity conditions the best results were obtained when, in addition to phosphate fertilizer, the soil was treated with humic acid or foliar application the plants with fulvic acid under one of the following treatments: HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6).

CONCLUSIONS

The result of the use of organic amendments was an increase in the tolerance of barley plant to salinity stress, which was evident from the improvement in the different traits that occurred after the treatment using treatments that included organic amendments (humic acid or fulvic acid).

The potential and prospects of modified biochar for comprehensive management of salt-affected soils and plants: A critical review

Soil salinization has become a global problem that threatens farmland health and restricts crop production. Salt-affected soils seriously restrict the development of agricultural, mainly because of sodium ion (Na+) toxicity, nutrient deficiency, and structural changes in the soil. Biochar is a carbon (C)-based substance produced by heating typical biomass waste at high temperatures in anaerobic circumstances. It has high cation exchange capacity (CEC), adsorption capacity, and C content, which is often used as a soil amendment. Biochar generally reduces the concentration of Na+ in soil colloids through its strong adsorption, or uses the calcium (Ca) or magnesium (Mg) rich on its surface to exchange sodium ions (Ex-Na) from soil colloids through cation exchange to accelerate salt leaching during irrigation. Nowadays, biochar is widely used for acidic soils improvement due to its alkaline properties. Although the fact that biochar has gained increasing attention for its significant role in saline alkali soil remediation, there is currently a lack of systematic research on biochar improvers and their potential mechanisms for identifying physical, chemical, and biological indicators of soil eco-environment assessment and plant growth conditions affected by salt stress. This paper reviews the preparation, modification, and activation of biochar, the effects of biochar and its combination with beneficial salt-tolerant strains on salt-affected soils and plant growth. Finally, the limitations, benefits, and future needs of biochar-based soil health assessment technology in salt-affected soils and plant were discussed. This article elaborates on the future opportunities and challenges of biochar in the treatment of saline land, and a green method was provided for the integrate control to salt-affected soils.

Multi-scale failure mechanisms of hydraulic engineering exposed to seasonally frozen salinization environment: Integrating SBAS-InSAR and mechanical experiments

Constructing hydraulic engineering ensures agricultural development and improves salinization environments. However, in seasonally frozen salinization regions, hydraulic engineering is prone to deformation failure. Leakage from canal raises the regional groundwater level, triggering secondary salinization environmental issues. Exploring the instability mechanisms is thus necessary for hydraulic engineering. Traditional deformation monitoring techniques and soil experiments are constrained by observation scale and timeliness. In this study, Sentinel-1B data from November 2017 to August 2019 were acquired. The small baseline subset (SBAS) InSAR approach was employed to interpret the seasonal deformation characteristics in both the vertical and slope directions of a damaged canal segment in Songyuan, Northeast China. The mechanical properties of saline-alkali soil under varying water contents were quantified by integrating unconfined compression experiment (UCE). In May, as the soil thawed downward, a frozen lenses with poor permeability formed at a depth of approximately 100 cm, causing the accumulation of meltwater and infiltrated precipitation between the frozen layer and the melting layer in the canal. The soil water content at a depth of 80 to 140 cm exceeded 22 %, reaching a threshold for rapid reduction in unconfined compression strength (UCS). Consequently, in spring, the low soil strength between the frozen layer and the melting layer resulted in interface sliding, with a displacement of -133.88 mm in the canal slope direction. Furthermore, the differential projection of freeze-thaw deformation in the slope direction caused continuous creep of the canal towards the free face, with a value of -23.27 mm, exacerbating the formation of the late spring landslide. Integrating InSAR and engineering geological analysis is beneficial for addressing deformation issues in hydraulic engineering. Ensuring the sustainable operation of hydraulic engineering holds important implications for mitigating the salinization process.

Alterations in the composition and metabolite profiles of the saline-alkali soil microbial community through biochar application

Saline-alkali soil poses significant chanllenges to sustainable development of agriculture. Although biochar is commonly used as a soil organic amendment, its microbial remediation mechanism on saline-alkali soil requires further confirmation. To address this, we conducted a pot experiment using cotton seedlings to explore the potential remediation mechanism of rice straw biochar (BC) at three different levels on saline-alkaline soil. The results showed that adding of 2% biochar greatly improved the quality of saline-alkaline soil by reducing pH levels, electrical conductivity (EC), and water-soluble ions. Moreover, biochar increased the soil organic matter (SOM), nutrient availability and extracellular enzyme activity. Interestingly, it also reduced soil salinity and salt content in various cotton plant tissues. Additionally, biochar had a notable impact on the composition of the microbial community, causing changes in soil metabolic pathways. Notably, the addition of biochar promoted the growth and metabolism of dominant salt-tolerant bacteria, such as Proteobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota. By enhancing the positive correlation between microorganisms and metabolites, biochar alleviated the inhibitory effect of salt ions on microorganisms. In conclusion, the incorporation of biochar significantly improves the soil microenvironment, reduces soil salinity, and shows promise in ameliorating saline-alkaline soil conditions.

Biochar and Chlorella increase rice yield by improving saline-alkali soil physicochemical properties and regulating bacteria under aquaculture wastewater irrigation

The combined effects of biochar and Chlorella under aquaculture wastewater irrigation in improving saline-alkali soil physicochemical properties, microbial communities, and rice yield, is not yet clear. This study utilized soil physicochemical indicators and gene sequencing to examine the effect of salinity stress, biochar and Chlorella under aquaculture wastewater irrigation on soil properties, bacterial community compositions, and rice production. Treatments included three factors in a randomized complete block design with three replications: (i) Biochar - 40 tons ha -1 (BW) versus no-biochar (BN); (ii) Salinity - 3‰ salinity (SH) versus 1‰ salinity (SL); and (iii) Chlorella - with 107 cells mL -1 Chlorella (CW) versus no-Chlorella (CN). The results revealed that increased salinity adversely affected the soil nutrients (TOC, NO3⁻-N, NH4+-N, Olsen-P), and enzyme activity (urease, sucrase, catalase), resulting in a 9.67% reduction in rice yield compared to SL treatment. However, the close correlation between alterations in soil bacterial communities, functions, and soil physicochemical properties, as well as rice yield, indicated that biochar and Chlorella promoted rice yield by enhancing the physicochemical properties of saline-alkali soil and bacterial community when irrigated with aquaculture wastewater: (1) addition of biochar increased the146.05% rice yield by increasing TOC content, the complexity of bacterial co-occurrence patterns, nitrogen fixation potential, and nitrification potential, (2) addition of Chlorella increased TOC, NO3⁻-N, NH4+-N, enhanced urease, sucrase, catalase activity, and nitrification potential to increased rice yield by 60.29%, and (3) compared with the treatment T3 (SHBNCN), the treatments with biochar (BW) and Chlorella (CW) increased the yield by 561.30% and 445.03% under 1‰ and 3‰ salinity, respectively. These findings provide novel perspectives on the capacity of biochar and Chlorella to improve saline-alkali soil properties and increase rice yield irrigated with aquaculture wastewater.

Municipal solid waste compost: a comprehensive bibliometric data-driven review of 50 years of research and identification of future research themes

This paper offers a thorough bibliometric review of the literature on municipal solid waste compost (MSWC), focusing on the past two decades. Using an extensive dataset of 827 documents, the research patterns are analyzed via the R-based Bibliometrix package, merging metadata from Web of Science and Scopus. The analysis reveals substantial global growth in MSWC research, with a particular surge in the last 20 years. Discipline-specific journals are the main publishers, while multidisciplinary environmental outlets gained more citations. The study identifies five major collaborative author clusters that dominate productivity and citation frequency. The thematic evolution over the past five decades shows a transition from waste disposal towards topics such as heavy metals, soil properties, and plant nutrition, with emerging themes like carbon sequestration, biochar, and microplastics signaling future research directions. Specifically, the field has experienced a 7.86% annual growth rate, with an average citation rate of 26.88 per article. The 827 publications emerged from 317 sources and 1910 authors, with an international co-authorship rate of 14.75%, reflecting the field's interdisciplinary character. Thirteen primary sources and twenty-two key authors were identified as major contributors. On the geographical front, Spain and Italy led with the most contributions and highest citation count, respectively. In terms of keywords, "heavy metals" and "sewage sludge" were the most recurrent, indicating the prevailing topics in MSWC research. This analysis hence provides key insights into the evolution and future trajectory of MSWC studies.

Effects of different fertilization methods on Lolium multiflorum Lam. growth and bacterial community in waste slag

Waste slag has low nutrient content, so it has insufficient nutrient cycling and transformation in the soil ecosystem. There are few studies on the application of oligotrophic phosphate-solubilizing bacteria and phosphate (P) fertilizer to improve the properties of waste slags. In this study, three oligotrophic bacterial strains with P solubilizing activity, namely, Bacillus subtilis 2C (7.23 μg/mL), Bacillus subtilis 6C (4.07 μg/mL), and Bacillus safensis 2N (5.05 μg/mL), were isolated from waste slags. In the pot experiment, compared with no application of P fertilizer, inoculation of Bacillus subtilis 2C with a 50% recommended dose of P fertilizer significantly increased the available phosphorus (AP), total phosphorus (TP), and total nitrogen (TN) in slag by 33.16%, 76.70%, and 233.33%, respectively. The N, P uptake and fresh weight of Lolium multiflorum Lam. were significantly improved by 114.15%, 139.02%, and 100%, respectively. The analysis of the bacterial community showed that the application of P fertilizer decreased the diversity and richness of the bacterial community, and with the addition of phosphorus fertilizer and Bacillus subtilis 2C, the bacterial community in the slag developed towards eutrophication. Redundancy analysis (RDA) showed that the TP content in the slag was significantly correlated with the bacterial community (P = 0.001, < 0.01), followed by the TN content. This study on different P fertilizer application methods can provide some basic ideas for improving the performance of waste slag.

Integrated microbiological and metabolomics analyses to understand the mechanism that allows modified biochar to affect the alkalinity of saline soil and winter wheat growth

In order to understand the mechanism that allows modified biochar (BC) to enhance the salt tolerance and growth of crops in saline-alkali soil, we tested the effects of ordinary BC, nanoparticle-size BC, acidified BC (HBC), and acidified nanoparticle-size BC on winter wheat growth and the soil properties by combining microbiological and metabolomics analyses. The results showed that compared with the control with no BC, the plant height increased by 17.33 % under HBC and the proportion of large soil aggregates increased by 1.25-2.83 times. HBC increased the relative abundances of some dominant genera of bacteria (e.g., Streptococcus) and fungi (e.g., Mycothermus), as well as functions such as bacterial metabolic genetic information processing and cellular processes, and reduced the abundance of pathotrophic fungi. Metabolomics analysis showed that HBC upregulated various metabolites (including amino acids and their derivatives, lipids, flavonoids, and organic acids) and five main metabolic pathways. Among the KEGG pathways, the pyrimidine metabolism pathway was significantly upregulated, as well as crop leaf metabolism, β-alanine metabolism, and valine, leucine, and isoleucine metabolism, and the antioxidant levels and resistance to salt-alkali stress were enhanced in winter wheat leaves. Partial least squares-path modeling suggested that HBC affected the growth of winter wheat by significantly changing the soil physicochemical properties and microbial structure (path coefficients of 0.566 and 0.512, respectively).

Application of Potassium Humate and Salicylic Acid to Mitigate Salinity Stress of Common Bean

In the current study, we investigated the effect of potassium humate (Kh) and salicylic acid (SA) in mitigating the salinity stress of common bean plants. Common bean seedlings were treated with 0.2 g/L SA as a foliar application and 0.3 g/L Kh as a soil application individually or in combination. After 7 days of germination, plants were treated with 50 mM NaCl and normal water as a control. Our results indicate that salt treatment reduced the plant growth (fresh and dry shoots and roots), leaf pigments (total chlorophyll and carotenoids), ascorbic acid (AA), glutathione (GSH), and potassium (K) contents. On the contrary, proline content; sodium (Na); hydrogen peroxide (H₂O₂); superoxide anion (O₂^•-); and antioxidant enzymes, including catalase (CAT), peroxidase (POX), and superoxide dismutase (SOD), were increased by saline stress. However, applying either individual Kh and SA or their combination stimulated seedling growth under salinity stress by increasing growth parameters, leaf pigment contents, AA, GSH, proline content, K content, and antioxidant enzymes compared with the control. Additionally, Na content, H₂O₂, and O₂^•- were reduced by all applications. The application of the Kh (0.3 g/L) + SA (0.2 g/L) combination was more effective than using the individual compounds. In conclusion, applications of Kh + SA can mitigate salt stress and improve the seedling growth of common bean.

Effect of surface water and underground water drip irrigation on cotton growth and yield under two different irrigation schemes

To investigate the effect of surface water and underground water drip irrigation on cotton yield, dry matter accumulation and nutrients uptake, two consecutive field experiments were conducted. The first experiment (different mixing ratio irrigation) comprised of five ratios of underground water to surface water including; 1:0 (U), 0:1 (S), 1:1 (U:S = 1:1), 1:2 (U:S = 1:2) and 1:3 (U:S = 1:3). Whereas, the second experiment (round irrigation) comprised of eight treatments including: 1:3 (T₁), 2:2 (T₂), 3:1 (T₃), {S:U 3:1 (T₄)}, 2:2 {S:U (T₅)}, 1:3 {S:U (T₆)}, 4:0 (T₇) and 0:4 (T₈). The average concentration of leaves dry matter after 8^th irrigation in different mixing ratio experiment was significantly increased by 131.2% (S), 34.4% (U: S = 1:1), 59.3% (U: S = 1:2), and 93.7% (U: S = 1:3), respectively, relative to U treatment. Likewise, the stem dry matter increased from 48.5 g (U), to 122.2 g (S) and 101.6 g (U:S = 1:3). The soil available N at 0–20 cm after 8^th irrigation recorded an average increase rate of 40.1%, 6.6%, 13.5%, and 29.5%, respectively. However, at 20-40cm an average increase rate of 37.4% (S), 7.1% (U: S = 1:1), 20.0% (U: S = 1:2), and 21.9% (U: S = 1:3) were noted (p < 0.05). The highest cotton yield of 6571 kg h^-1 was recorded in S treatment compared with the U treatment (5492 kg h^-1), U: S = 1:1 (5502 kg h^-1), U: S = 1:2 (5873 kg h^-1) and U: S = 1:3 (6111 kg h^-1). Contrastingly, in round irrigation experiment the highest leaves dry matter at various growth stages were recorded in T8 treatment. For instance, compared with T7 treatment an average increase rate of 50.6% (growth), 100.9% (boll) and 93.3% (boll opening), in stem dry matter were recorded in T8 treatment. Moreover, the concentration of N in round irrigation at 0–20 cm at different growth stages were 83.3±2.8 (growth stage), 79.01±1.84 (boll stage), and 96.16±3.83 (boll opening stage) in T8. Whereas, in T7 the concentration of N was 36.1±5.9 (growth), 54.51±2.81 (boll), and 53.9±3.83 (boll opening) (p < 0.05). Similarly, cotton yield were substantially higher in T8 applied treatment and follows the sequence of T8 > T1 > T4 > T2 > T5 > T3 > T6 > T7. Overall, our findings provide meaningful information to current irrigation practices in water scarce regions. Improving water use efficiency is a viable solution to the water scarcity. Therefore, surface water irrigation is recommended as an effective irrigation strategies to improve cotton yield and growth.

Muz Atıkları Kompostunun Toprağın Azot ve Fosfor ile İlişkili Enzimatik Aktiviteleri Üzerine Kısa Süreli Etkisinin İzlenmesi

A large amount of plant pruning waste occurs after annual care in banana production areas. This waste material contains significant amounts of organic substances and nutrients. In this study, banana waste compost (BWC) was applied to the soil both alone and in mixture with leonardite (LT) and vinasse compost (VC). Treatments include: control (CL), banana waste compost alone (BWC-2: 2 t da-1; BWC-4: 4 t da-1; BWC-8: 8 t da-1), leonardite alone (LT: the recommended application rate), leonardite with banana waste compost (BWC-2+LT; BWC-4+LT; BWC-8+LT), vinasse compost alone (VC: the recommended application rate), vinasse compost with banana waste compost (BWC-2+VC; BWC-4+VC; BWC-8+VC). Afterwards, the changes in the activities of nitrogen (NH4+NO3) and phosphorus (available P) related enzymes (urease and alkaline phosphatase) were monitored through analyzes made on soil samples taken on certain days (0th, 10th, 20th, 40th, 80th). During this period, the pH and EC values of the soil were also measured. According to the results obtained; it was determined that banana waste compost combined with leonardite generally positively affects the pH, EC, exchangeable NH4-NO3 and, available P of the soil, as well as the activity of urease and alkaline phosphatase compared to other treatments. In this regard, according to the control, the urease activity of the soil increased by 875%, the alkaline phosphatase activity by 149%, the exchangeable NH4+NO3 by 188%, available P by 83%, and the EC value by 100%. However, the pH value decreased by about 5%. As a result, it can be stated that the application of banana waste compost combined with leonardite as a soil conditioner at least 4 t da-1 will be economical and 10 to 20 days after this application, nitrogen and phosphorus availability will increase in the soil.

Liquid Organic Fertilizer Amendment Alters Rhizosphere Microbial Community Structure and Co-occurrence Patterns and Improves Sunflower Yield Under Salinity-Alkalinity Stress

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.

Biochar/vermicompost promotes Hybrid Pennisetum plant growth and soil enzyme activity in saline soils

Soil salinity has become a major threat to land degradation worldwide. The application of organic amendments is a promising alternative to restore salt-degraded soils and alleviate the deleterious effects of soil salt ions on crop growth and productivity. The aim of present study was to explore the potential impact of biochar and vermicompost, applied individually or in combination, on soil enzyme activity and the growth, yield and quality of Hybrid Pennisetum plants suffered moderate salt stress (5.0 g kg^-1 NaCl in the soil). Our results showed that biochar and/or vermicompost promoted Na⁺ exclusion and K⁺ accumulation, relieved stomatal limitation, increased leaf pigment contents, enhanced electron transport efficiency and net photosynthesis, improved root activity, and minimized the oxidative damage in Hybrid Pennisetum caused by soil salinity stress. In addition, soil enzymes were also activated by biochar and vermicompost. These amendments increased the biomass and crude protein content, and decreased the acid detergent fiber and neutral detergent fiber contents in salt-stressed Hybrid Pennisetum. Biochar and vermicompost addition increased the biomass and quality of Hybrid Pennisetum due to the direct effects related to plant growth parameters and the indirect effects via soil enzyme activity. Finally, among the different treatments, the use of vermicompost showed better results than biochar alone or the biochar-compost combination did, suggesting that the addition of vermicompost to the soil is an effective and valuable method for reclamation of salt-affected soils.

Synergistic action of Trichoderma koningiopsis and T. asperellum mitigates salt stress in paddy

Intensive cultivation increases the salinity and alkalinity of soil leading to its degradation. Such soil lead to abiotic stress conditions in plants causing ROS-mediated cellular damage. Microbes constitute an important group of bio-stimulants, which are promising alternatives to reduce ROS-mediated abiotic stresses and improve plant growth. In the present study synergistic activity of stress-tolerant Trichoderma koningiopsis NBRI-PR5 (MTCC 25372) and T. asperellum NBRI-K14 (MTCC 25373) (TrichoMix) was assessed in paddy crop under salt stress conditions. Improved soil microbial biomass carbon (MBC), total organic carbon (TOC), and available nutrients N/P/K by 2-3 folds was observed in the pot experiment using the TrichoMix. It restored the heterogeneous microbial population of the paddy rhizosphere during salt stress and modulated the soil enzyme activities. The anatomical distortions in rice roots due to salt stress were stabilized in presence of the TrichoMix. Different stress marker genes (OsMAPK5, OsAPX, OsGST, OsUSP, OsBADH, OsLYSO, OsNRAMP6, and OsBz8) were differentially modulated by the TrichoMix in presence of salt stress as compared to the control. The TrichoMix increased the yield by 10% in marginally stressed fields; however, it enhanced the yield by approximately 60% when used with the 50% recommended dose of NPK. In the integrated treatment, Fe and Zn were fortified by approximately 40% and 29% respectively in the grains. From the present study, it was concluded that the TrichoMix stimulated the rice plants to accumulate osmoprotectants, improved the anatomical features, modulated the plant defense system, and improved the grain yield and quality. Therefore, the NBRI-PR5 and NBRI-K14 mixture may be used as a bio-stimulant to increase productivity in the rapidly deteriorating soil and reduce the NPK inputs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01192-6.

Plant growth promoting bacteria (PGPR) induce antioxidant tolerance against salinity stress through biochemical and physiological mechanisms

Salinity is one of the most severe abiotic stress in the world. Also, the irrigated lands have been treated with second salinity. Canola is one of the most important industrial crops for oil production all over the world which is affected by salinity. Salt stress causes imbalanced ion hemostasis (Na⁺ and K⁺) and interrupted mineral absorption in canola. Also, salinity stress leads to oxidative stress (production and accumulation of reactive oxygen species (ROS). Accumulation of ROS is extremely dangerous and lethal for plants. As a consequence, canola production is reduced under salinity stress. So, a suitable approach should be found to deal with salinity stress and prevent the loss of production oilseed. Plant growth-promoting rhizobacteria (PGPR) can colonize on the plant root surface and alleviate the salt stress effect by providing minerals like nitrogen, phosphate, and potassium. Also, they alleviate salt stress by phytohormones like auxin (IAA), cytokinin (CK), and abscisic acid (ABA). This study focus on physiological parameters like leaf area (LA), root length (RL), shoot length (SL), chlorophyll fluorescence indexes (F_v/F_m and F_v/F₀), relative water content (RWC), electrolyte leakage index (ELI), photosynthesis pigments (chlorophyll a, b, and carotenoids), Na⁺, and K⁺; and biochemical parameters like malondialdehyde (MDA) content, hydrogen peroxide content (H₂O₂), total protein content, proline, antioxidant capacity, and antioxidant enzyme activities in canola through the inoculation with Enterobacter sp. S16-3 and Pseudomonas sp. C16-2O. This study showed that LA, RL, SL, chlorophyll fluorescence indexes, RWC were significantly increased and ELI was significantly decreased in bacteria inoculated treatments. Also, MDA, H₂O₂ were decreased, and antioxidant capacity, proline, and antioxidant enzymes were increased due to inoculation with these bacteria. Besides, the amount of K⁺ as an index of salinity tolerance significantly increased, and leaf Na⁺ content was significantly decreased.

Takakura composting method for food wastes from small and medium industries with indigenous compost

The current work aimed to study the physical, chemical and biological properties of food wastes generated from small and medium industries by using Takakura composting methods. Composting method was referred as indigenous compost (IC) and commercial compost (CC) reactors. The reactors were operated at 44 °C, pH (6 to 8.5) and 40 to 55 % of moisture for 22 weeks in closed environment using a carpet around the basket to avoid external disturbance. The results revealed that the total Kjeldahl nitrogen (TKN), total phosphorus (TP) and potassium (K) in the IC reactors were 6300, 10.57 and 726.07 ppm, respectively, while 8400, 15.45 and 727.81 ppm, respectively, in the CC reactors. Moreover, both IC and CC has Cd2+, Cr2+, Cu2+, Pb2+, Ni2+ and Zn2+ concentrations within the compost legislation standard (CLS). The findings of this study indicated that the composting method could be used as an alternative food waste management in small and medium industry and the Takakura composting method is suitable for food waste composting.

Co-Application of Biochar and Arbuscular mycorrhizal Fungi Improves Salinity Tolerance, Growth and Lipid Metabolism of Maize (Zea mays L.) in an Alkaline Soil

This study reports the mitigating strategy against salinity by exploring the potential effects of biochar (5%), Arbuscular mycorrhizal fungi (20 g/pot, AMF), and biochar + AMF on maize (Zea mays L.) plants grown under saline stress in a greenhouse. The maize was grown on alkaline soil and subjected to four different saline levels; 0, 50, 100, and 150 mM NaCl. After 90 d for 100 mM NaCl treatment, the plant's height and fresh weight were reduced by 17.84% and 39.28%, respectively, compared to the control. When the saline-treated soil (100 mM NaCl) was amended with AMF, biochar, and biochar + AMF, the growth parameters were increased by 22.04%, 26.97%, 30.92% (height) and 24.79%, 62.36%, and 107.7% (fresh weight), respectively. Compared to the control and single AMF/biochar treatments, the combined application of biochar and AMF showed the most significant effect in improving maize growth under saline stress. The superior mitigating effect of biochar + AMF was attributed to its effective ability in (i) improving soil nutrient content, (ii) enhancing plant nutrient uptake, (iii) increasing the activities of antioxidant enzymes, and (iv improving the contents of palmitoleic acid (C16:1), oleic acid (C18:1), linoleic acid (C18:2), and linolenic acid (C18:3). Thus, our study shows that amending alkaline and saline soils with a combination of biochar-AMF can effectively mitigate abiotic stress and improve plant growth. Therefore, it can serve as a reference for managing salinity stress in agricultural soils.

Additions of optimum water, spent mushroom compost and wood biochar to improve the growth performance of Althaea rosea in drought-prone coal-mined spoils

Ecosystem degradation as a result of coal mining is a common phenomenon in various regions of the world, especially in arid and semi-arid zones. The implementation of appropriate revegetation techniques can be considered crucial to restore these degraded areas. In this regard, the additions of spent mushroom compost (SMC) and wood biochar (WB) to infertile and degraded soils have been reported to enhance soil fertility and plant growth under water (W) deficit conditions. However, the combined application of W, SMC and WB to coal mine degraded soils, to promote Althaea rosea growth and facilitate subsequent restoration, has not been explored yet. Hence, in the current study a pot experiment was carried out by growing A. rosea on coal mine spoils to assess the influence of different doses of W, SMC and WB on its morpho-physiological and biochemical growth responses. The results indicated that several plant growth traits like plant height, root length and dry biomass significantly improved with moderate W-SMC-WB doses. In addition, the simultaneous application of W-SMC-WB caused a significant decrease in hydrogen peroxide (H₂O₂) (by 7-56%), superoxide anion (O₂^●‒) (by 14-51%), malondialdehyde (MDA) (by 23-46%) and proline (Pro) contents (by 23-66%), as well as an increase in relative water content (by 10-27%), membrane stability index (by 2-24%), net photosynthesis rate (by 40-99%), total chlorophylls (by 43-113%) and carotenoids (by 31-115%), as compared to the control treatment. The addition of SMC and WB under low-W regime enhanced leaf water use efficiency, and soluble sugar content, also boosting the activity of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase in leaf tissues, thus reducing the oxidative stress, as proved by low levels of H₂O₂, O₂^●‒, MDA and Pro contents. Finest growth performance under optimum doses of W (60% field capacity), SMC (1.4%) and WB (0.8%) suggest that revegetation of A. rosea with the recommended W-SMC-WB doses would be a suitable and eco-friendly approach for ecological restoration in arid degraded areas.

Growth Responses, Physiological Alterations and Alleviation of Salinity Stress in Sunflower (Helianthus annuus L.) Amended with Gypsum and Composted Cow Dung

Salt accumulation in soils poses severe challenges for crop production in arid and semi-arid regions. Scarcity of rainfall and a high evaporation rate in these regions are considered major reasons for salt accumulation. It drastically reduces the leaching of excessive salts below the root zone of crops. The toxic effects of salts on plants can be greatly reduced with the use of biological and inorganic amendments. The present study was conducted to investigate the positive influence of gypsum (GP), composted cow dung (CCD) and the combined use of gypsum and composted cow dung (GP+CCD) on the growth, seed yield, and physiological and chemical attributes of sunflowers (Helianthus annuus) in salty soil conditions. Saline-sodic soil was prepared using salts that include NaCl, Na2SO4, MgSO4, and CaCl2. It contained three levels of electrical conductivity (EC), i.e., 1.8, 6, and 12 dS m−1, and had a sodium adsorption ratio (SAR) of 15. We noted significant deleterious effects of excessive salt stress on multiple attributes of the growth, produce, physiology, and chemical factors of sunflowers. However, treatment with GP+CCD improved all these attributes in all these conditions over the control treatment. Treatment with GP+CCD also significantly increased N, P and K contents over the control in the absence of salt stress, i.e., normal conditions. Conversely, treatment with GP+CCD caused an extreme decline in antioxidant enzyme activity (APX, GPX, CAT and SOD) and Na+/K+ ratio in seeds of up to 90, 75, and 71% over control at an EC level of 1.8, 6, and 12 dS m−1, respectively. This study suggests the combined application of gypsum and composted cow dung for better production of sunflowers in salt-affected soils, and augmented growth, yield, physiology, biochemistry and nutritional value in the sunflower seeds.

Bacterial Communities in Alkaline Saline Soils Amended with Young Maize Plants or Its (Hemi)Cellulose Fraction

We studied three soils of the former lake Texcoco with different electrolytic conductivity (1.9 dS m-1, 17.3 dS m-1, and 33.4 dS m-1) and pH (9.3, 10.4, and 10.3) amended with young maize plants and their neutral detergent fibre (NDF) fraction and aerobically incubated in the laboratory for 14 days while the soil bacterial community structure was monitored by means of 454-pyrosequencing of their 16S rRNA marker gene. We identified specific bacterial groups that showed adaptability to soil salinity, i.e., Prauseria in soil amended with young maize plants and Marinobacter in soil amended with NDF. An increase in soil salinity (17.3 dS m-1, 33.4 dS m-1) showed more bacterial genera enriched than soil with low salinity (1.9 dS m-1). Functional prediction showed that members of Alfa-, Gamma-, and Deltaproteobacteria, which are known to adapt to extreme conditions, such as salinity and low nutrient soil content, were involved in the lignocellulose degradation, e.g., Marinimicrobium and Pseudomonas as cellulose degraders, and Halomonas and Methylobacterium as lignin degraders. This research showed that the taxonomic annotation and their functional prediction both highlighted keystone bacterial groups with the ability to degrade complex C-compounds, such as lignin and (hemi)cellulose, in the extreme saline-alkaline soil of the former Lake of Texcoco.

Climate Change and Salinity Effects on Crops and Chemical Communication Between Plants and Plant Growth-Promoting Microorganisms Under Stress

During the last two decades the world has experienced an abrupt change in climate. Both natural and artificial factors are climate change drivers, although the effect of natural factors are lesser than the anthropogenic drivers. These factors have changed the pattern of precipitation resulting in a rise in sea levels, changes in evapotranspiration, occurrence of flood overwintering of pathogens, increased resistance of pests and parasites, and reduced productivity of plants. Although excess CO2 promotes growth of C3 plants, high temperatures reduce the yield of important agricultural crops due to high evapotranspiration. These two factors have an impact on soil salinization and agriculture production, leading to the issue of water and food security. Farmers have adopted different strategies to cope with agriculture production in saline and saline sodic soil. Recently the inoculation of halotolerant plant growth promoting rhizobacteria (PGPR) in saline fields is an environmentally friendly and sustainable approach to overcome salinity and promote crop growth and yield in saline and saline sodic soil. These halotolerant bacteria synthesize certain metabolites which help crops in adopting a saline condition and promote their growth without any negative effects. There is a complex interkingdom signaling between host and microbes for mutual interaction, which is also influenced by environmental factors. For mutual survival, nature induces a strong positive relationship between host and microbes in the rhizosphere. Commercialization of such PGPR in the form of biofertilizers, biostimulants, and biopower are needed to build climate resilience in agriculture. The production of phytohormones, particularly auxins, have been demonstrated by PGPR, even the pathogenic bacteria and fungi which also modulate the endogenous level of auxins in plants, subsequently enhancing plant resistance to various stresses. The present review focuses on plant-microbe communication and elaborates on their role in plant tolerance under changing climatic conditions.

How the surfactants mixed with emulsion can enhance the sand-fixation ability in the high salt-affected sandy land

In order to control the impacts of salt crystallization damage, in this article, the surfactant Pluronic L35 (L35, a nonionic surfactant), for the first time, was added into P(VAc-DBM-AA-SSS) emulsion to improve the ecological sand-fixing capability in high salt-affected sandy land. This study started from the analysis of salt tolerance of P(VAc-DBM-AA-SSS) film by scanning electron microscope (SEM) and mechanical property. Then, the surfactant L35 has been selected to study the effect on salt crystal behaviour before reaction with emulsion. The performance and morphology of adding varied L35 and 3% NaCl into P(VAc-DBM-AA-SSS) emulsion have been considered. In addition, sand-fixing properties (e.g. compressive strength and water retaining) of the emulsion mixed with L35 were evaluated. Finally, the influence of the emulsion mixed with L35 on the growth of plant was investigated for understanding its ecological effect. The experimental results showed that the L35 could change the morphology of salt in sand; moreover, adding L35 into P(VAc-DBM-AA-SSS) emulsion can visibly enhance the sand-fixing ability in high salt-affected sandy land. The investigation into the influence of the emulsion mixed with L35 on the growth of plant also showed a dependable ecological effect.

Potential risk assessment of soil salinity to agroecosystem sustainability: Current status and management strategies

Soil salinization has become a major global agricultural issue that threatens sustainable development goals related to food security, agriculture, resource conservation, and nutrition. The higher levels of salinity have detrimental effects on soil physico-chemical and biological characteristics and plant metabolism. Also, salinity poses a negative impact on the abundance and distribution of soil microbes and soil-dwelling organisms. Research has always been trying to overcome the salinity issue, but it does not fit well in conventional approaches. This review unravels traditional and modern salinity management techniques. Out of the available salinity management techniques, some are focused on enhancing soil properties (chemical amendments, biochar, earthworms, and their vermicompost, compost, microbial inoculants, electro remediation), some focus on improving plant properties (seed priming, afforestation, crop selection, genetic improvements, agroforestry) and some techniques augment both soil as well as plant properties in a synergic manner. Therefore, it is imperative to find a conclusive solution by integrating traditional and modern methods to find the most effective response to regionally-specific salinity related problems. This review aimed at critical analysis of the salinity problems, its impact on agroecosystem, and different management approaches available to date with a balanced viewpoint that would help to draw a possible roadmap towards the future investigation in this domain for sustainable management of salinity issues around the globe.

Agricultural Production in Qatar’s Hot Arid Climate

Agriculture has played an essential role in the provision of food and has been a major factor in overall economic development for societies around the world for millennia. In the past, agriculture in hot, arid countries like Qatar faced many challenges, the primary one being a dearth of water for irrigation. Historically this severely limited Qatar’s economic development, which was based largely on resource exploitation, pearl fishing, and only more recently, on the exploitation of its oil and gas reserves which subsequently has led to Qatar’s great wealth. This paper gives an overview of the recent evolution of Qatar’s agricultural sector and investigates future trends that tackle the challenges of its hot arid climate and the limited availability of agricultural resources. Specifically, the review analyses Qatar’s potential to develop a national food security strategy based on a significant expansion of food production in the country. We review recent policy actions implemented to address challenges in the food supply chain caused by a 3.5-year blockade imposed by the adjacent Arab Gulf States, discussing the renewed interest in the potential that an enhanced agricultural sector must provide some aspects of food security and the implications for policymakers that would logically ensue.

Environmental salinization processes: Detection, implications & solutions

A great portion of Earth's freshwater and land resources are salt-affected and thus have restricted use or may become unsuitable for most human activities. Some of the recent scenarios warn that environmental salinization processes will continue to be exacerbated due to global climate change. The most relevant implications and side-effects in ecosystems under excessive salinity are destructive and long lasting (e.g. soil dispersion, water/soil hypersalinity, desertification, ruined biodiversity), often with non-feasible on site remediation, especially at larger scales. Agro-ecosystems are very sensitive to salinization; after a certain threshold is reached, yields and food quality start to deteriorate sharply. Additionally, salinity often coincides with numerous other environmental constrains (drought, waterlogging, pollution, acidity, nutrient deficiency, etc.) that progressively aggravate the threat to food security and general ecosystem resilience. Some well-proven, widely-used and cost-effective traditional ameliorative strategies (e.g. conservation agriculture, application of natural conditioners) help against salinity and other constraints, especially in developing countries. Remotely-sensed and integrated data of salt-affected areas combined with in situ and lab-based observations have never been so easy and rapid to acquire, precise and applicable on huge scales, representing a valuable tool for policy-makers and other stakeholders in implementing targeted measures to control and prevent ecosystem degradation (top-to-bottom approach). Continued progress in biotechnology and ecoengineering offers some of the most advanced and effective solutions against salinity (e.g. nanomaterials, marker-assisted breeding, genome editing, plant-microbial associations), albeit many knowledge gaps and ethical frontiers remain to be overcome before a successful transfer of these potential solutions to the industrial-scale food production can be effective.

Plant survival under drought stress: Implications, adaptive responses, and integrated rhizosphere management strategy for stress mitigation

In many regions of the world, the incidence and extent of drought spells are predicted to increase which will create considerable pressure on global agricultural yields. Most likely among all the abiotic stresses, drought has the strongest effect on soil biota and plants along with complex environmental effects on other ecological systems. Plants being sessile appears the least resilient where drought creates osmotic stress, limits nutrient mobility due to soil heterogeneity, and reduces nutrient access to plant roots. Drought tolerance is a complex quantitative trait controlled by many genes and is one of the difficult traits to study and characterize. Nevertheless, existing studies on drought have indicated the mechanisms of drought resistance in plants on the morphological, physiological, and molecular basis and strategies have been devised to cope with the drought stress such as mass screening, breeding, marker-assisted selection, exogenous application of hormones or osmoprotectants and or engineering for drought resistance. These strategies have largely ignored the role of the rhizosphere in the plant's drought response. Studies have shown that soil microbes have a substantial role in modulation of plant response towards biotic and abiotic stress including drought. This response is complex and involves alteration in host root system architecture through hormones, osmoregulation, signaling through reactive oxygen species (ROS), induction of systemic tolerance (IST), production of large chain extracellular polysaccharides (EPS), and transcriptional regulation of host stress response genes. This review focuses on the integrated rhizosphere management strategy for drought stress mitigation in plants with a special focus on rhizosphere management. This combinatorial approach may include rhizosphere engineering by addition of drought-tolerant bacteria, nanoparticles, liquid nano clay (LNC), nutrients, organic matter, along with plant-modification with next-generation genome editing tool (e.g., CRISPR/Cas9) for quickly addressing emerging challenges in agriculture. Furthermore, large volumes of rainwater and wastewater generated daily can be smartly recycled and reused for agriculture. Farmers and other stakeholders will get a proper knowledge-exchange and an ideal road map to utilize available technologies effectively and to translate the measures into successful plant-water stress management. The proposed approach is cost-effective, eco-friendly, user-friendly, and will impart long-lasting benefits on agriculture and ecosystem and reduce vulnerability to climate change.

Apply biochar to ameliorate soda saline-alkali land, improve soil function and increase corn nutrient availability in the Songnen Plain

Soda saline-alkali soils are characterized by high concentration of sodium cations on the exchange complex or in soil-water resulting in soils which are physically as well as nutritionally challenging for crop production. Biochar application has received growing interest as a sustainable technology to improve physicochemical properties in non-saline and non-alkali soils. However, information is inadequate regarding potential of using corn straw derived biochar as an organic material to reduce soda saline-alkali stress. Based on the established model of corn straw biochar-soda saline alkali soil-corn system, soil and plant samples were collected from long-term field experiment in soda saline-alkali land with different addition rates of corn straw biochar (CK: control, T5: 5 ton ha^-1, T10: 10 ton ha^-1, T15: 15 ton ha^-1, T20: 20 ton ha^-1, T25: 25 ton ha^-1, T30: 30 ton ha^-1). In the seedling and harvest period, addition of corn straw biochar enhanced the contents of cation exchange capacity (CEC), organic matter, and nutrients of 0-20 cm and 20-40 cm saline-alkali soil layers and the above ground and underground parts of corn. However, the results were contrary as far as pH, salt, and Na⁺ were concerned, and the effect of T20 was the most significant. Principal component analysis showed that CEC, pH, salinity, and organic matter could be used as indicators to evaluate the improvement effect of biochar on soda saline-alkali soil. Irrespective of the application of biochar, pH, salt content, Na⁺, and nutrients concentrations at seedling stage were higher than those at harvest stage, indicating that planting corn could improve soda saline-alkali soil. It may be concluded that corn straw biochar can be used as an organic amendment for reducing adverse effects of salinity and alkalinity on soil functions governed by their rates of addition.

Effects of Garden Waste Compost and Bentonite on Muddy Coastal Saline Soil

In order to effectively utilize resources and improve the amelioration effect of coastal saline soil, we studied the effects of applying garden waste compost and bentonite on highly saline coastal soil. Four treatments were established: a nonamended control; application of 68 kg·m−3 of garden waste compost; application of 15 kg·m−3 of bentonite; and mixed application of 68 kg·m−3 of garden waste compost and 15 kg·m−3 of bentonite. The results showed that the soil salinity of the three treatments was significantly lower than that of the nonamended control. The desalination effect of the mixed application was the best, and the salinity in the 0–20 and 20–40 cm soil layers decreased to 3.95 g·kg−1 and 3.82 g·kg−1, respectively. Application of both the garden waste compost alone and the mixed application significantly improved the physical and chemical properties of the soil. However, the mixed application had the best effect because of its ability to increase the total porosity, saturated hydraulic conductivity, and soil nutrient levels. The growth of Robinia pseudoacacia cv. Idaho in the mixed application treatment was also better than other treatments. Principal component analysis and comprehensive scores indicated that the addition of 68 kg·m−3 of garden waste compost and 15 kg·m−3 of bentonite was the optimal application.

Synergistic Effect of Rhamnolipid and Saponin Biosurfactants on Removal of Heavy Metals from Oil Contaminated Soils

In this study synergistic effect of the biosurfactants saponin and rhamnolipid on the removal of the heavy metals such as vanadium, nickel and chromium from contaminated soil was investigated. Washing solutions were prepared by using different concentrations of two biosurfactants. In this work, the optimum HLB value of the extraction process of about 10.5 was obtained for the mixture of 62.5 % rhamnolipid and 37.5 % saponin. According to our results, at the optimal HLB value, a maximum removal was obtained for Ni of 87 %, Cr of 71 % and Va of 70 %. Our results also showed that the efficiency of heavy metals decreased with increasing the pH value of system. The optimum pH value of heavy metals removal was 5. According to the results of this research saponin and rhamnolipid have the synergistic effect on the heavy metals removal and it seems to be a good alternative to chemical surfactants for environmental applications.

Improving yield-related physiological characteristics of spring rapeseed by integrated fertilizer management under water deficit conditions

Two separate field experiments were conducted in 2018 and 2019 as split-plot based on randomized complete block design with three replications to evaluate physiological responses of rapeseed to fertilization treatments (control, chemical fertilizer, inoculation of seeds with PGPR, vermicompost and combined fertilizers) under different irrigation levels (irrigation after 70,100, 130, and 160 mm evaporation). Water stress increased the activities of catalase, polyphenol oxidase, peroxidase and superoxide dismutase and the contents of proline, soluble sugars and malondialdehyde and also leaf temperature, but decreased membrane stability index, chlorophyll content, leaf water content, stomatal conductance and grain yield. Application of fertilizers particularly combined fertilizers decreased proline content and leaf temperature, but increased the antioxidant enzymes activities, soluble sugars, chlorophyll content, leaf water content, membrane stability index, and stomatal conductance under different irrigation intervals. These superiorities of fertilization treatments were led to considerable improvement in grain yield. The results revealed that the combined fertilizer application improved most of the physiological parameters. It was deducted that the application of combined fertilizers reduced chemical fertilizer by about 67% and alleviated the deleterious effects of water limitation on field performance of rapeseed.

Alleviation of Salinity-Induced Oxidative Stress, Improvement in Growth, Physiology and Mineral Nutrition of Canola (Brassica napus L.) through Calcium-Fortified Composted Animal Manure

Salinity stress is one of the serious restrictive issues for optimum crop production in arid to semi-arid areas. Application of organic amendments have shown positive effects on crop growth and yield under such scenario. The present study was conducted to estimate the potential of calcium-fortified composted animal manure (Ca-FCM) to enhance growth and yield of canola under saline soil conditions. Salt affected soils with various electrical conductivity (EC) levels (original 1.5, 5, and 10 dS m−1) were developed via spiking the soil with sodium chloride (NaCl) salt. The results reveal that soil salinity reduced the growth, physiological, yield, and nutritional parameters of canola. However, application of 3% calcium-fortified composted manure significantly enhanced the growth and yield parameters at all EC levels as compared to control. Plant physiological parameters such as photosynthetic rate, relative chlorophyll contents (SPAD value), and relative water content were also increased with the application of 3% Ca-FCM at all EC levels in comparison to control. Application of 3% Ca-FCM also mediated the antioxidant enzymes activities at all EC levels in comparison to control. Moreover, application of 3% Ca-FCM caused maximum increase in nitrogen, phosphorus, and potassium concentrations in shoot at all EC levels. Conversely, application of 3% Ca-FCM showed maximum decrease in Na+/K+ ratio in leaf up to 83.33%, 77.78%, and 71.43% at EC levels 1.5, 5, and 10 dS m−1, respectively, as compared to control. It was concluded that application of calcium-fortified composted animal manure (Ca-FCM) could be an efficient method for improving growth, yield, physiological, and nutritional parameters of canola through mediation of antioxidant defense machinery under saline soil conditions.

Effects of Alternating Irrigation with Fresh and Saline Water on the Soil Salt, Soil Nutrients, and Yield of Tomatoes

Saline water irrigation has become extremely important in arid and semi-arid areas in northwestern China. To study the effect of alternating irrigation models on the soil nutrients, soil salts, and yield of tomatoes with fresh water (total dissolved solids of 0.50 g·L−1) and saline water (total dissolved solids of 3.01 g·L−1), a two-year field experiment was carried out for tomatoes in the Hetao Irrigation District (HID), containing six drip irrigation models: T1 (all freshwater irrigation), T2 (saline water used in the seedling and flowering stages; fresh water in the fruit-set and breaker stages), T3 (saline water in the flowering and fruit-set stages; fresh water in the seedling and breaker stages), T4 (saline water in the fruit-set and breaker stages; fresh water in the seedling and flowering stages), T5 (saline water in the flowering and breaker stages; fresh water in the seedling and fruit-set stages), T6 (saline water in the seedling and fruit-set stages; fresh water in the flowering and breaker stages). The study found that saline water irrigation tends to have a positive effect on soil total nitrogen and a negative influence on soil total phosphorus at each growth stage of the tomato. Soil Na+, Mg2+, Ca2+, K+, and Cl− increased over the growth period, soil HCO3− decreased gradually by growth stage, and the salt ions increased with the amount of saline water applied in alternating irrigation. Though the soil salt accumulated in all experimentally designed alternating irrigation models, soil alkalization did not occur in the tomato root zone under the soil matric potential threshold of −25 kPa. The utilization of saline water resulted in about a 1.9–18.2% decline in fruit yield, but the total soluble solids, lycopene, and sugar in the tomato fruits increased. Ultimately, drip irrigation with fresh water at the seedling to flowering stages and saline water at the fruit-set to breaker stages was suggested for tomato cultivation in HID.

Municipal solid waste (MSW): Strategies to improve salt affected soil sustainability: A review

Salt-induced soil degradation is a serious threat to global agriculture which is responsible for diminished productivity of agro-ecosystems. Irrigation with poor quality water and indiscriminate use of chemical fertilizers to increase crop productivity creates salt accumulation in soil profile thereby reducing crop sustainability. High concentration of salts in soil inhibits plant growth due to low osmotic potential of the soil solution, ion toxicity and imbalance reduces nutrient uptake, crop yields. Low productivity of saline soils is not only due to salt toxicity or excess amounts of soluble salts but also lack of available mineral nutrients especially nitrogen, phosphorus, potassium and soil organic matter. Hence, sustainable management of salt-affected soils are paramount importance to meet the demands of food grain production for an ever-rising population in the world. Recently, municipal solid waste has gained importance as an organic amendment for restoring soil fertility and finally contributing to productivity of salt-affected soils. This paper compares extant waste generation, their properties and standards pertinent to municipal solid waste in different countries and explores the unique recent history in some countries that shows high environmental regard and rapid changes and also suggests policy experiencing from high environmental regard and rapid changes from other countries, so that policy makers can propose new or revise current municipal solid waste standards for salt affected soils. Municipal solid waste compost improves soil biological, physical and chemical properties because of high soil organic matter and lower concentration of pollutants. Therefore, the use of municipal solid waste in salt-affected soils could be an alternative to costly chemical amendments as well as reduce the reliance on chemical fertilizers for increasing productivity of salt-affected soil. The municipal solid wastes significantly improve crop yields. However, further long-term experimental investigations are needed to re-validate the application of municipal solid waste compost in improving physical, chemical and biological properties and to step up organic fertilization use in a wide range of both saline and sodic soils. In future, research should be directed to address these issues globally to minimise ecological disturbances and to set environmental standards, and evaluate the feasibility of the policies in different countries and their impact on socio-economic conditions of local people.

Biochar application for the remediation of salt-affected soils: Challenges and opportunities

Soil salinization and sodification are two commonly occurring major threats to soil productivity in arable croplands. Salt-affected soils are found in >100 countries, and their distribution is extensive and widespread in arid and semi-arid regions of the world. In order to meet the challenges of global food security, it is imperative to bring barren salt-affected soils under cultivation. Various inorganic and organic amendments are used to reclaim the salt-affected lands. The selection of a sustainable ameliorant is largely determined by the site-specific geographical and soil physicochemical parameters. Recently, biochar (solid carbonaceous residue, produced under oxygen-free or oxygen-limited conditions at temperatures ranging from 300 to 1000°C) has attracted considerable attention as a soil amendment. An emerging pool of knowledge shows that biochar addition is effective in improving physical, chemical and biological properties of salt-affected soils. However, some studies have also found an increase in soil salinity and sodicity with biochar application at high rates. Further, the high cost associated with production of biochar and high application rates remains a significant challenge to its widespread use in areas affected by salinity and sodicity. Moreover, there is relatively limited information on the long-term behavior of salt-affected soils subjected to biochar applications. The main objective of the present paper was to review, analyze and discuss the recent studies investigating a role of biochar in improving soil properties and plant growth in salt-affected soils. This review emphasizes that using biochar as an organic amendment for sustainable and profitable use of salt-affected soils would not be practicable as long as low-cost methods for the production of biochar are not devised.

Land-Sparing Opportunities for Solar Energy Development in Agricultural Landscapes: A Case Study of the Great Central Valley, CA, United States

Land-cover change from energy development, including solar energy, presents trade-offs for land used for the production of food and the conservation of ecosystems. Solar energy plays a critical role in contributing to the alternative energy mix to mitigate climate change and meet policy milestones; however, the extent that solar energy development on nonconventional surfaces can mitigate land scarcity is understudied. Here, we evaluate the land sparing potential of solar energy development across four nonconventional land-cover types: the built environment, salt-affected land, contaminated land, and water reservoirs (as floatovoltaics), within the Great Central Valley (CV, CA), a globally significant agricultural region where land for food production, urban development, and conservation collide. Furthermore, we calculate the technical potential (TWh year^-1) of these land sparing sites and test the degree to which projected electricity needs for the state of California can be met therein. In total, the CV encompasses 15% of CA, 8415 km² of which was identified as potentially land-sparing for solar energy development. These areas comprise a capacity-based energy potential of at least 17 348 TWh year^-1 for photovoltaic (PV) and 2213 TWh year^-1 for concentrating solar power (CSP). Accounting for technology efficiencies, this exceeds California's 2025 projected electricity demands up to 13 and 2 times for PV and CSP, respectively. Our study underscores the potential of strategic renewable energy siting to mitigate environmental trade-offs typically coupled with energy sprawl in agricultural landscapes.

Spatial and halophyte-associated microbial communities in intertidal coastal region of India

Microbial communities in intertidal coastal soils respond to a variety of environmental factors related to resources availability, habitat characteristics, and vegetation. These intertidal soils of India are dominated with Salicornia brachiata, Aeluropus lagopoides, and Suaeda maritima halophytes, which play a significant role in carbon sequestration, nutrient cycling, and improving microenvironment. However, the relative contribution of edaphic factors, halophytes, rhizosphere, and bulk sediments on microbial community composition is poorly understood in the intertidal sediments. Here, we sampled rhizosphere and bulk sediments of three dominant halophytes (Salicornia, Aeluropus, and Suaeda) from five geographical locations of intertidal region of Gujarat, India. Sediment microbial community structure was characterized using phospholipid fatty acid (PLFA) profiling. Microbial biomass was significantly influenced by the pH, electrical conductivity, organic carbon, nitrogen, and sodium and potassium concentrations. Multivariate analysis of PLFA profiles had significantly separated the sediment microbial community composition of regional sampling sites, halophytes, rhizosphere, and bulk sediments. Sediments from Suaeda plants were characterized by higher abundance of PLFA biomarkers of Gram-negative, total bacteria, and actinomycetes than other halophytes. Significantly highest abundance of Gram-positive and fungal PLFAs was observed in sediments of Aeluropus and Salicornia, respectively than in those of Suaeda. The rhizospheric sediment had significantly higher abundance of Gram-negative and fungal PLFAs biomarkers compared to bulk sediment. The results of the present study contribute to our understanding of the relative importance of different edaphic and spatial factors and halophyte vegetation on sediment microbial community of intertidal sediments of coastal ecosystem.

Enhanced Salt Tolerance under Nitrate Nutrition is Associated with Apoplast Na+ Content in Canola (Brassica. napus L.) and Rice (Oryza sativa L.) Plants

To analyze the effect of nitrogen form on salt stress, we studied the response of two different plant species, canola (Brassica napus L.), a dicotyledon which prefers NO₃^- nutrition, and rice (Oryza sativa L.), a monocotyledon which prefers NH₄⁺ nutrition, to salt stress under NO₃^- (NN) and NH₄⁺ (AN) nutrition. Salt stress was simulated by the addition of 150 and 100 mM NaCl to NN (NNS) and AN (ANS) in canola and rice seedlings, respectively. Salt stress induced reductions of shoot and root biomass that were more drastic under ANS. A higher Na⁺ content was obtained in NNS than in ANS. The impact of Na⁺ on the reduction of biomass (Δbiomass/Na⁺) was 162, 181, 230 and 245% higher in canola root, canola shoot, rice root and rice shoot in ANS than in NNS, respectively. In both canola and rice seedlings, the ratio of leaf Na⁺ content in apoplasts to symplasts ([Na⁺]_apo/[Na⁺]_sym) was higher in NNS than in ANS. Also, in canola seedlings, the ratio of apoplast Na⁺ in the leaf edge to the leaf center ([Na⁺]_LE/[Na⁺]_LC) was 18 times higher in NNS than in ANS. Our results illustrate that the confinement of Na⁺ in the canola leaf edge, as well as the restriction of Na⁺ in leaf apoplasts of canola and rice seedlings, protect cells from suffering Na⁺ stress and contribute to the higher tolerance of NO₃^--fed plants.

Bioavailability of Sodium and Trace Metals under Direct and Indirect Effects of Compost in Urban Soils

The contamination of urban soil with sodium (Na) and trace metals can be one of the major concerns for groundwater contamination and street tree health. The bioavailability of Na, copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in urban soil amended with 0, 5, and 10% w/w compost was evaluated at none, medium, and high contamination levels of soil mixtures. The relationship between soil properties, compost addition, contamination level and metal uptake by barley ( L.) was determined using multivariate linear regression and path analysis. The results indicated the direct negative effect of compost on metal absorption possibly through specific complexation for Cu, Zn, Cd, and Pb. Compost can also affect the absorption of Na and Cd indirectly by means of cation exchange capacity (CEC) and pH. The degree of soil contamination with metals can affect the competition of cations for the complexing sites of the soil mixtures and, therefore, can induce changes in metal availability for plants. Compost addition to the soil also increased nutrient availability, except for ammonium (NH) and nitrate (NO). We concluded that in the short term, the addition of compost significantly reduced metal bioavailability and improved nutrient availability. However, more studies are required to monitor the long-term ability of the compost to reduce Na and trace metal bioavailability in urban soil.

Biological response of using municipal solid waste compost in agriculture as fertilizer supplement

Waste management and declining soil fertility are the two main issues experienced by all developing nations, like India. Nowadays, agricultural utilization of Municipal Solid Waste (MSW) is one of the most promising and cost effective options for managing solid waste. It is helpful in solving two current burning issues viz. soil fertility and MSW management. However, there is always a potential threat because MSW may contain pathogens and toxic pollutants. Therefore, much emphasis has been paid to composting of MSW in recent years. Application of compost from MSW in agricultural land helps in ameliorating the soil's physico-chemical properties. Apart from that it also assists in improving biological response of cultivated land. Keeping the present situation in mind, this review critially discusses the current scenario, agricultural utilization of MSW compost, role of soil microbes and soil microbial response on municipal solid waste compost application.

Properties of surfactants on high salt-affected sandy land in enhanced sand fixation: salt tolerance, adsorption isotherms and ecological effect

The water solubilization method was used to study the phase behavior of microemulsion. The adsorption of surfactants on sand particles was investigated at different salinities. The effects of surfactants on soils microbial growth were evaluated.

Effects of 24-epibrassinolide on plant growth, osmotic regulation and ion homeostasis of salt-stressed canola

This study evaluated effects of foliar spraying 24-epibrassinoide (24-EBL) on the growth of salt-stressed canola. Seedlings at the four-leaf stage were treated with 150 mM NaCl and different concentrations of 24-EBL (10(-6), 10(-8), 10(-10), 10(-12) M) for 15 days. A concentration of 10(-10) M 24-EBL was chosen as optimal and used in a subsequent experiment on plant biomass and leaf water potential parameters. The results showed that 24-EBL mainly promoted shoot growth of salt-stressed plants and also ameliorated leaf water status. Foliar spraying of salt-stressed canola with 24-EBL increased osmotic adjustment ability in all organs, especially in younger leaves and roots. This was mainly due to an increase of free amino acid content in upper leaves, soluble sugars in middle leaves, organic acids and proline in lower leaves, all of these compounds in roots, as well as essential inorganic ions. Na(+) and Cl(-) sharply increased in different organs under salt stress, and 24-EBL reduced their accumulation. 24-EBL improved the uptake of K(+), Ca(2+), Mg(2+) and NO3(-) in roots, which were mainly transported to upper leaves, while NO3(-) was mainly transported to middle leaves. Thus, 24-EBL improvements in ion homeostasis of K(+)/Na(+), Ca(2+)/Na(+), Mg(2+)/Na(+) and NO3(-)/Cl(-), especially in younger leaves and roots, could be explained. As most important parts, younger leaves and roots were the main organs protected by 24-EBL via improvement in osmotic adjustment ability and ion homeostasis. Further, physiological status of growth of salt-stressed canola was ameliorated after 24-EBL treatment.

Selection of a halophytic plant for assessing the phytotoxicity of dredged seaport sediment stored on land

The filling of dry quarries in coastal areas with sediments dredged in seaports represents a potentially interesting method of recycling of these materials. However, this recycling requires the prior carrying out of an Environmental Risk Assessment of the scenario concerned. For this, the question arose as to the type of plants capable of developing on the surface of such a deposit and the method to implement for assessing the possible phytotoxicity of dredged sediments. To answer this question, we chose to work with halophytic plants to be free from the salt-related effect and to assess only the effect related to the toxic compounds present. Based on the objectives set, these works led to the use of common plants of the French coast, with direct seeding, and with pollution-sensitive plants. Three species of angiosperms, Armeria maritima, Anthemis maritima and Plantago coronopus, were finally tested. As a result of this work, Armeria maritima was retained as the most suitable plant for testing the possible phytotoxic effect of dredged marine sediments stored on land. The results obtained with this plant are as follows: germination of 40 % of the seeds in 31 days, produced biomass of 493 mg FW in 6 months and a capacity to bioaccumulate metal pollutants in roots with 350 and 720 mg/kg DW for Zn and Cu, respectively.