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A field experiment was conducted to investigate suitable irrigation methods for cultivating four types of vegetable crops in sodic soil with alkaline irrigation water. The experiment employed a split-plot design, with drip, sprinkler, and furrow irrigation methods applied to main plots, while the cultivation of cluster beans, bhendi, vegetable cowpeas, and onions took place in subplots. Both drip and sprinkler irrigations proved more efficient than furrow irrigation, resulting in significant yield increases. Specifically, drip irrigation led to yields of 4120, 5160, 9264, and 4019 kg ha−1 for cluster beans, bhendi, vegetable cowpeas, and onions, respectively, in sodic soil with alkaline irrigation water. This represented a yield increase of 43%, 34%, 71%, and 49%, respectively, compared to furrow irrigation. Post-harvest soil samples were collected and analyzed to assess the impact of irrigation methods on soil sodicity, revealing substantial reductions in electrical conductivity and exchangeable sodium percentage with drip irrigation. Additionally, drip irrigation was found to be effective in mitigating soil sodicity compared to sprinkler and furrow irrigation methods. The study also identified sodicity build-up as a critical factor influencing soil microbial populations and enzyme activities in sodic soil and alkaline irrigation water environments. Consequently, based on these findings, drip irrigation is recommended as the preferred method for cultivating vegetable crops in such environments. [ABSTRACT FROM AUTHOR]

Background: Sodic soils are harmful to agricultural and natural environments in Ethiopia's semi-arid and arid regions, leading to soil degradation and reduced productivity. This study investigated how amendment resources could help improve the chemical properties of sodic soils around the Abaya and Chamo Lakes in the South Ethiopia Rift Valley. Methods: A factorial experiment was conducted to study the effects of gypsum (GYP) and farmyard manure (FYM) on sodic soil reclamation. The experiment had four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha−1), with three replications. The pots were incubated for three months and leached for one month, after which soil samples were collected and analyzed for chemical properties. ANOVA was performed to determine the optimal amendment level for sodic soil reclamation. Results: The study found that applying 10 ton FYM ha−1 and gypsum at 100% gypsum required (GR) rate resulted in a 99.8% decrease in exchangeable sodium percentages (ESP) compared to untreated composite sodic soil and a 1.31% reduction over the control (GYP 0% + FYM 0 ton ha−1). As a result, this leads to a decrease in soil electrical conductivity, exchangeable sodium (Ex. Na), and ESP values. The results were confirmed by the LSD test at 0.05. It is fascinating to see how different treatments can have such a significant impact on soil properties. The prediction models indicate that ESP's sodic soil treatment effect (R2 = 0.95) determines the optimal amendment level for displacing Ex. Na from the exchange site. The best estimator models for ESP using sodic soil treatment levels were ESP = 1.65–0.33 GYP for sole gypsum application and ESP = 1.65–0.33 GYP + 0.28 FYM for combined GYP and FYM application, respectively. Conclusion: The study found that combined GYP and FYM applications reduced ESP to less than 10% in agriculture, but further research is needed to determine their effectiveness at the field level. [ABSTRACT FROM AUTHOR]

Soil sodification is a soil degradation process that commonly occurs in the irrigated soils of arid and semi-arid lands, resulting in a significant decrease in productivity. Assessing the impacts of different types of water (irrigation water, groundwater, and rainfall) on soil drainage is important for achieving sustainable land management of irrigated areas. We investigated the changes in soil saturated hydraulic conductivity (HC) under different salt treatments by separating the effects of swelling and dispersion. The salt treatments were conducted at different salt compositions (SAR∞, SAR10, SARO; SAR=Na/(Ca/2)1/2 (cations: mol, L-1)) and concentrations (0.05, 0.01, 0.001 N) on Indian soil (sandy clay loam). The soil columns were continuously leached with each treatment solution and changes in the HC were plotted against the cumulative amount of leaching solution. Furthermore, the effects of swelling and dispersion by Na on the drainage properties were observed separately. Our results support the existing findings that dispersion is triggered at concentrations below the critical coagulation concentration (CCC), which further varies with the degree of sodification in a single mineralogy. The distinct manner of HC reduction between SAR10- and SAR∞-treated soils could imply different behaviors of the dispersed particles, which form a soil crust or cause soil erosion. Finally, we present the preliminary results of our experiments and discuss future research on the CCC reset mechanisms. [ABSTRACT FROM AUTHOR]

Sodic soil formation, following irrigation with saline-sodic water has become a major concern due to its negative impact on soil structure, crop growth and yield. However, specifically in orchards, little knowledge exists regarding the reclamation of sodic soils. Our objective was to examine the effects of different amendments on soil reclamation and crop performance of olive grove. The study was conducted in a 14 years old olive grove, grown in a clayey soil, in which irrigation started in 2008 using saline-sodic water resulting in sodium adsorption ratio (SAR) ranging from 22 to 40 (mmolc L−1)0.5. Six treatments were studied: control (no amendments applied), CaCl2, MgCl2 and H2SO4 that were added to the irrigation water, and gypsiferous material (GM) that was added to the soil surface prior to the rainy season and either left spread or tilled into the upper soil layer. Soil samples were analyzed for selected saturated extract properties and for aggregate stability. Additionally, plant parameters including yield, trunk expansion, fruit oil content, and tree nutritional status were measured. The results showed that the lowest SARs were observed in the GM and GM till treatments at 0–30 cm [5.0 and 3.3 (mmolc L−1)0.5, respectively], while CaCl2 and MgCl2 treatments had the lowest SARs at 30–90 cm [16.2 and 17.1 (mmolc L−1)0.5, respectively]. GM and CaCl2 application raised the electrical conductivity (EC) levels to 6.9 and 7.6 dS m−1 respectively. GM addition resulted in the most stable aggregates which was associated with a significant improvement in average tree productivity of 33 kg/tree. Conversely, MgCl2 had the lowest average yield, of 21.3 kg/tree, which was attributed to the high concentration of Mg that led to some nutrient imbalances. In conclusion, the current study showed the efficacy of different amendments based on Ca for remediating sodic soil in drip-irrigated orchards.

Land degradation is one of the most pressing environmental problems of the 21st century particularly due to its impact on global food security and environmental quality through the loss of biodiversity and ecosystem services. Land degradation happens at an accelerated rate and affects regions inhabited by more than one‐third population of the world. This phenomenon resulted in a dramatic reduction in the productivity of cropland and rangeland of world thus threatening the environmental quality and food security. It manifests in various forms such as desertification, soil erosion, sodicity, salinity, heavy metal contamination, pesticide contamination, declining soil fertility, and fate of polycyclic aromatic hydrocarbons. The world now has a real chance for the next generation to grow sustainably and eliminate acute food scarcity. Microbes, as vital elements of soil, play an important role in maintaining soil biological properties and fertility. Due to their multifarious biological functions and metabolic uniqueness, microorganisms can fix or solubilize nutrients, add organic matters to the soil to improve its quality. Many of the microorganisms can produce biological compounds or enzymes, which can degrade or scavenge toxic substances from the soils. In this review, we have discussed in detail how diverse microorganisms can help to restore different types of degraded lands. The limitations in application of microorganisms in restoration of soil health and possible scopes to improve the applicability have also been discussed here. [ABSTRACT FROM AUTHOR]

Amelioration of salt affected soils aims to reduce exchangeable sodium percentage (ESP), improve crop growth and yield. A field study was conducted with soybean-mustard cropping system for four consecutive years (2016–2019) to study the effect of soil amendments on crop yield, nutrient use efficiency and soil properties in degraded vertisol of North Western India. Treatments consist of various combinations of gypsum, farm yard manure (FYM) and crop residue (CR) with recommended fertilizer doses (RNPK), were laid in random block design with three replications. Application of gypsum alone and combined with organic amendments, showed pronounced decrease in ESP, slight reduction in pH, increased bioavailability of nutrients, as reflected by higher nutrient uptake and crop yields. Grain yield improvement in soybean (37–41%) and mustard (58–63%) was recorded in plots receiving RNPK + Gypsum + CR + FYM, RNPK + Gypsum + CR or FYM over only chemical fertilizer treatments. Combined application of gypsum with organic amendments increased N, P, K and S uptake by 75, 76, 84 and 114%, respectively over RNPK alone in soybean-mustard system. Highest values of apparent recovery efficiency and agronomic efficiency of N, P, K, S was registered under RNPK + Gypsum and RNPK + Gypsum + CR/FYM. Highest physiological and internal efficiency of nutrients was registered under RNPK and decreased with amendment application. This study revealed the combined use of FYM (10 t ha−1), CR (3 and 1.5 t ha−1), gypsum (2.5 t ha−1) with fertilizers as a sustainable technology for reclaiming soil sodicity, improving nutrient use efficiency and crop productivity under soybean-mustard system. [ABSTRACT FROM AUTHOR]

Background: Sodic soils are harmful to agricultural and natural environments in Ethiopia’s semi-arid and arid regions, leading to soil degradation and reduced productivity. This study investigated how amendment resources could help improve the chemical properties of sodic soils around the Abaya and Chamo Lakes in the South Ethiopia Rift Valley. Methods: A factorial experiment was conducted to study the effects of gypsum (GYP) and farmyard manure (FYM) on sodic soil reclamation. The experiment had four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha−1), with three replications. The pots were incubated for three months and leached for one month, after which soil samples were collected and analyzed for chemical properties. ANOVA was performed to determine the optimal amendment level for sodic soil reclamation. Results: The study found that applying 10 ton FYM ha−1 and gypsum at 100% gypsum required (GR) rate resulted in a 99.8% decrease in exchangeable sodium percentages (ESP) compared to untreated composite sodic soil and a 1.31% reduction over the control (GYP 0% + FYM 0 ton ha−1). As a result, this leads to a decrease in soil electrical conductivity, exchangeable sodium (Ex. Na), and ESP values. The results were confirmed by the LSD test at 0.05. It is fascinating to see how different treatments can have such a significant impact on soil properties. The prediction models indicate that ESP’s sodic soil treatment effect (R2 = 0.95) determines the optimal amendment level for displacing Ex. Na from the exchange site. The best estimator models for ESP using sodic soil treatment levels were ESP = 1.65–0.33 GYP for sole gypsum application and ESP = 1.65–0.33 GYP + 0.28 FYM for combined GYP and FYM application, respectively. Conclusion: The study found that combined GYP and FYM applications reduced ESP to less than 10% in agriculture, but further research is needed to determine their effectiveness at the field level.

The reclamation potential of Halimeda microloba in sodic soil was studied. The soil sample was collected and soil quality parameters were studied before and after reclamation. The seaweed was collected from the southeast coast of India and it was identified as Halimeda microloba. In addition, various commercial fertilizers including Rhizobium, Azotobacter, Azospirillum, Trichoderma, Pseudomonas, and gypsum were purchased, isolated, and identified for their influential reclamation. A pot experiment was carried out and after 1 month of treatment, the soil parameters were accomplished. The Vigna radiata (green gram) seeds were sought, monitored, and examined periodically. After reclamation treatment, the pH was greatly reduced from 9.8 to 8.0 in Halimeda microloba treatment. Meanwhile, electrical conductivity and exchangeable sodium percentage levels were diminished from 713.8 to 234.3 µs/cm and 62 to 21% respectively in gypsum treatment. Furthermore, the calcium content in gypsum was found to be 5010 mg/100 kg, and in Halimeda microloba of about 3772 mg/100 kg. Similarly, microbial biomass carbon was found to be a notable increase (P < 0.05) in gypsum and seaweed treatment as compared to control. There is a substantial growth of bacterial and fungal populations in seaweed and gypsum-treated soil. However, the individual use of different microorganisms has shown limited outcomes on the sodic soil. Indeed, the treatment with gypsum/seaweed, and seaweed shows promising in plant growth, soil enzyme activity (dehydrogenase), and enhanced nutrient uptake in the soil gypsum treatment. Finally, this study is the first attempt as proved as Halimeda microloba is an efficient biological candidate for ameliorate sodic soil transformation with a wide range of agricultural benefits. [ABSTRACT FROM AUTHOR]

The effect of the Fertilizer Industry Waste Gypsum Material (FIWGM) on the rehabilitation of barren soils has been investigated with this research. The soil improvement tests were carried out in randomized blocks with three replications and 0, 20, 40 and 60 tons ha-1 of FIWGM have been applied. By the intermittent ponding method, a total of 360 cm of water has been given, including 30 cm at each time. At the end of the trial, the application of FIWGM has showed positive effect on the physical and chemical properties of the soil. As the dose of FIWGM increased, soil infiltration rates increased, and soil sodium and boron concentrations decreased significantly. 360 cm of leaching water provided the removal of exchangeable sodium equivalent to 33.7 and 42.9 tons of gypsum for 100 cm of soil depth, with 20 and 40 tons per hectare of FWIGM applied to the test plots. The statistically significant correlation coefficient (R2=0.921**) has been determined between the leaching water depth (Dlw)/soil depth (Ds) and the boron/initial boron remaining (B/Bo) in the soil (B/Bo = 0.622-0.168Ln Dlw/Ds).

The management of municipal solid waste (MSW) and the reclamation of degraded sodic soils are two serious environmental and socio-economic problems experienced by the developing nations. To overcome these problems, a technology has been developed for the composting of MSW using earthworm and ligno-cellulolytic microbial consortia and its utilization for the sustainable reclamation of degraded sodic soils, as well as for harnessing their productivity potential. To standardize on-farm composting under aerobic conditions, the field experiment consisted of seven treatment combinations, replicated thrice with municipal solid waste (MSW) sole and in combination with agricultural wastes (AW) treated with earthworms (Eisenia foetida) and consortia of lingo-cellulolytic microbes such as Aspergillus spp., Trichoderma spp. and Bacillus spp. It was conducted at ICAR-CSSRI, Research farm, Shivri, Lucknow, India. The results revealed that the thermophilic phase was achieved at 60 days of composting and thereafter the temperature decreased. Marked changes in pH and EC were found and they changed from acidic to neutral. The reduction in total C, from initial to maturity, varied from 4.45 to 14.14% and the increase in total P and total K from 4.88 to 88.10% and 12.00 to 35.71%, respectively. The nutrient-rich quality compost based on the lowest C: N ratio, highest nutrient contents, microbial population (bacteria and fungi) and enzymatic activities was obtained from a mix of MSW and AW, enriched with earthworms and consortia of lingo-cellulolytic microbes. The efficacy of this enriched compost was evaluated for the reclamation of sodic soils and their potential for sustaining productivity of the rice-wheat cropping system was harnessed through combined application with a reduced dose of gypsum. The results indicated that the application of on-farm compost @10 t ha−1 in conjunction with a reduced quantity of gypsum (25% GR) significantly (p < 0.05) improved the physico-chemical and microbial soil properties, and enhanced productivity of the rice-wheat cropping system over the use of only gypsum. This study proved that on-farm compost of MSW and its utilization for the reclamation of degraded sodic soils can be an alternate solution for useful disposal and management of MSW, thereby improving the health and productivity of sodic soils. [ABSTRACT FROM AUTHOR]

In the present study, the salinization trends of different soil types from a small hydrographic basin situated in NE Romania (Roșior basin) are investigated. The climatic conditions are favorable for long dry summers and intensive evaporation. The soils are developed on immature evolved clay sediments, as revealed by geochemical analysis. The salinity varies among soil types, attaining maximum values for Solonetz with total dissolved salts (TDS) between 1165.75 to 1881.25 mg/L. The aqueous solutions are represented by natural water and soil solution. The hydrogeochemical facies of the natural waters change from HCO3−—Mg2+ in the upper basin to SO42−—Na+ in the middle or lower basin. The soil solution is moderately or strongly salinized and shows anionic variations from HCO3− to SO42− in the studied profiles, whereas Na+ is always the main cation. The concentrations of Na+ and SO42− evolve simultaneously. Raman spectroscopic exploration of the white efflorescences, which occur on topsoil, reveals the presence of thenardite as the dominant phase. The composition of soil solution results from both the ionic exchange and evaporation processes. The nature of soil solution mineralization and summer temperatures are two main factors that interact and promote the thenardite precipitation. The soil salinization induces negative effects on crop nutrition, impacting further the crop yields. The results of this study can be extrapolated to larger areas formed on Sarmatian sedimentary deposits affected by salinization processes. [ABSTRACT FROM AUTHOR]

Currently more than 20 per cent of the world's irrigated land is salt affected. Of that about 60 per cent are sodic soils, warranting greater attention for efficient and eco-friendly environmentally amelioration techniques. Transformation and availability of several plant nutrient elements are affected by soil sodicity. Alkali/sodic soils are to be reclaimed so as tomake nutrients available to plants optimally. A laboratory incubation study was examined to analyse the impact of various amendments, either alone or in combination with nitrogen (N) @75 kg/ha, on the physico-chemical characteristics and nitrogen dynamics in sodic soil of Kumulur village Trichy District, Tamil Nadu (pH-10.4, EC-0.40 dS, m-1, ESP-31.8). The investigation was conducted at ADAC&RI in Trichy with three replications and eight treatments in a completely randomized design. The treatments used for sodic soil reclamation utilizing a standardized procedure were Gypsum (GYP) + Green manure (GM) @ 6.5 t ha-1 (T2), Distillery spent wash (DSW) @ 5 lakhs liter-1(T4), and Green leaf manure (GLM) @ 12.5 t ha-1(T3). Soil samples were taken at 15-day intervals from the 15th to the 60th day and tested for NH4-N, NO3-N, and accessible nitrogen. Using DSW, GYP + GM, and GLM, the pH of the water was decreased from 10.2 to 8.37, 8.42, and 9.21, respectively. The soil pH dropped the most in the DSWcontrolled treatments. The application of nitrogen alone without any amendments (T5) recorded a higher value (135 kg ha-1) during an initial period (15 days) only and thereafter declined sharply due to various losses, i.e., volatilization, denitrification or fixation. When nitrogen was applied along with amendments, a significant (CD-0.05%) buildup in available N contents was observed over the application of N alone. Available nitrogen (325 kg ha-1), nitrate nitrogen (102 kg ha-1) and ammonical nitrogen (205 kg ha-1) were significantly increased due to the addition of amendments. However, the decline in available N with incubation period was only marginal when nitrogen was applied along with amendments. An increase in NH4-N at 30 DAI might be due to the release of nutrients. A slight increase in the nitrate-N content of the soil was observed at the end of the incubation period due to microbial oxidation of NH4-N to NO3-N. The application of amendments could save a quantity of N dose besides reclaiming the sodicity. [ABSTRACT FROM AUTHOR]

Within a 300 x 600 m complex heterogeneous sodic grassland two techniques were compared for assessing soil salinity. The standard technique is based on repeated field instrumental measurements at 420 points. The alternative technique was performed with the use of numerical simulation of salt accumulation carried out on 3 profiles. These profiles have been selected as representatives of the distinct classes, or map strata of salt accumulation, distinguished with preliminary statistical clustering of the instrumental measuring points. Simulated values were extrapolated for the 3 strata distinguished. The maps obtained with the two techniques were statistically correlated. The use of numerical simulation is cost-effective. Further improvements are expected from a combination of improved numerical simulation and utilization of more strata. Research and publication was supported by the EU Program No. PL970598, (Contract No. ENV4-CT97-0681) and the Hungarian Scientific Research Fund (OTKA) (Project Nos. T 023271, T025623, T 030738, T 037731). [ABSTRACT FROM AUTHOR]

Purpose: Poor hydro-physical properties associated with sodic soil despite intervention of reclamation technologies have become emerging issues for sustainable crop production. Coal combustion fly ash (FA), from thermal power stations, is also posing environmental hazards. The objective of the study was to resolve hydro-physical problems of reclaimed sodic soil using FA and green manure (GM) with wider impact on least limiting water range (LLWR), plant-available water capacity (PAWC), and crop productivity with safe FA disposal. Materials and methods: A field experiment was conducted with seven treatments on sodic soils which had been reclaimed 15 years back, but crop productivity was low due to its poor hydro-physical properties. The treatments were as follows: control (reclaimed sodic soil); 1% v/v FA; 1% v/v FA + sesbania as GM; 2%v/v FA; 2% v/v FA + GM; 3% v/v FA; and 3% v/v FA + GM. Soil hydro-physico-chemical analysis was carried out to study changes in soil properties under the treatments. Results: The results indicated a decreased bulk density, exchangeable sodium percentage, and dispersion ratio with increasing dose of FA alone and with GM. Saturated hydraulic conductivity was found maximum (0.258 cm h−1) in 2%v/v FA + GM. The wider differences of least limiting water range between control and treated plots (7.45–18.12% v/v) in comparison to plant-available water capacity (PAWC; 20.24–26.48%v/v) indicated sensitiveness of LLWR towards small changes in soil physical properties. The maximum grain yield of rice (5.2 t ha−1) and wheat (3.6 t ha−1) was harvested in 3% v/v FA + GM, which was on par with 2% v/v FA and 3%v/v FA. Toxic elements like Cr, Cd, and Pb in soil were found within the permissible limits as a result of FA application. Conclusion: The results of the study suggested that addition of FA alone or in combination with GM may help in the improvement of hydro-physical environment of reclaimed sodic soil, with respect to hydraulic conductivity, infiltration rate, dispersion ratio, percentage of soil aggregate size, LLWR, and PAWC. Thus, 2% v/v FA could safely be used to improve hydro-physico-chemical properties of soil and provide a sustainable and effective strategic approach for FA disposal and crop productivity enhancement. [ABSTRACT FROM AUTHOR]

Natural and anthropogenic processes are primary drivers for soil degradations in the Gangetic plain of India. Indian Remote Sensing (IRS) data was used to assess soil degradations and study spatial changes comparing with the legacy datasets. Based on the nature, extent, and degrees of limitations, these soils were evaluated to suggest suitable reclamation and management options. Typical strong signature (white tones) from a barren highly salinized soil (P3, P6, P9, P11, and P15) and higher energy absorption (blue-black tones) from a permanent waterlogged surface (P13, P14, P10) in the irrigated areas have favored delineation of salt-affected, strong, and permanent waterlogged areas. Moderate and slightly salt-affected soils (P1, P2, P4, P5, P7, P8, and P12) and the areas with high water table depths (P13 and P14) have shown mixed spectral signatures for associations of soil, water, and crops and were mapped using ground truth and soil chemical analysis data. Irrigation with poor quality ground water (RSC: 1.2 to 12.3 me L−1) has prompted developing salinity and sodicity in P2, P5, and P11, while irrigation in poorly drained areas caused appearance of waterlogging (WTD < 1.5 m) and salinization (P3, P5, P7, P9, P13, P14). The gypsum application and sub-surface drainage (SSD) techniques have enhanced soil reclamation by (i) neutralizing CO32 − and HCO3 − in P12 (pH 9.2, ESP 24) and (ii) controlling soil salinity (EC 3.0 dS m−1) and waterlogging (WTD > 1.5 m) in P14. Soils with CaCO3 layers at shallow depth in P3 (0.7–4.2%), P6 (1.2–7.1%), P9 (8–16%), P11 (4–15%), and P13 (0.9–9.4%) were managed using forest plantations. Ground water with high SAR in T1 to T7 can be applied for agriculture using mixing or cyclic mode. Water with high RSC in T4, T5, T7, T8, T9, and T10 needs treatment with gypsum. A significant area (~ 24.87%) of salt-affected soils was reclaimed since 1971. Prominent changes (3.27 to 17.71%) were shown in Panipat and Karnal districts. Small areas of brick kiln (P11), industrial effluent (P10), riverine sand, partially stabilized dunes, and mining have appeared due to anthropogenic activities. [ABSTRACT FROM AUTHOR]

Municipal solid waste management and poor fertility status of sodic soils are two important issues experienced by all developing nations including India. Disposal of municipal solid waste (MSW) being produced in huge amounts is a challenging task for researchers and policy makers. Reclamation of salt affected soils with chemical amendments is a costly affair for resource-poor farmers. Composting of MSW and its enrichment with microbes is one of the options for its recycling and utilization for the reclamation of salt-affected soils. A field experiment was conducted in sodic soil to study the performance of microbial enriched municipal solid waste compost (EMSWC) alone and in combination with a reduced dose of gypsum on growth, yield, nutrient uptake, and grain quality of rice and wheat. The experiment was conducted for three consecutive years from 2018 to 2019 and 2020 to 2021 at ICAR Central Soil Salinity Research Institute, Research farm, Shivri, Lucknow, India, in sodic soil having pH 9.2, electrical conductivity (EC) 1.14 dSm−1, exchangeable sodium percentage (ESP) 48, and organic carbon 0.30%. There were six treatments consisting of control, recommended dose of gypsum (50% GR), and enriched and un-enriched MSW compost with reduced dose of gypsum (25% GR). Based on the results pertaining to plant growth, yield-attributing characters, and yields, the treatment T6 (application of microbial enriched MSW compost @ 10 t ha−1 in conjunction with gypsum @25% GR) performed the best. Grain yield of rice and wheat (5.45 and 3.92 t ha−1) with treatment T6 was 29.45% and 110.75% higher over control (T1) and 29.45% and 110.06% over the recommended dose of gypsum (T2). Maximum nutrient content and N, P, and K uptake in rice-wheat grain and straw was observed with the treatment T6 (MSW compost plus gypsum @ 25 GR). However, the highest Na content and Na: K ratio in plant parts were recorded in treatment T2. The highest positive net return and benefit to cost (B/C) ratio were observed in treatment T6 followed by T5 and the lowest in treatment T1 (control), whereas negative return was calculated in treatment of gypsum alone (T2). This shows that the cost of sodic soil reclamation with application of gypsum was not recovered until the second year of cultivation. The results of this study showed significant impacts in MSW management for regaining the productivity potential of sodic soils. [ABSTRACT FROM AUTHOR]

Soil physicochemical properties are the main driving factors affecting the stability and diversity of the soil microbial community. The impacts of the saline–alkali situation and associated soil degradation need to be understood and reversed as soil diversity and communities are increasingly affected by saline–alkaline soil. However, the differences between salinization and alkalization soil and their impact on microbiota have been overlooked. The object of this study is to demonstrate the differences in salinization and alkalization soil and the driving factors affecting microbiota. In this study, 12 soil samples collected from saline–alkaline spots were used to detect the differences in soil physicochemical properties. The soil microbial community was sequenced by high-throughput sequencing. The results of ESP and EC in the soil samples indicated that the soil samples were categorized as saline soil and sodic soil. Venn diagrams indicated that unique OTUs in saline soil showed higher adaptation and environmental tolerance. Partial Mantel tests showed that the differences in pH, exchangeable sodium percentage (ESP), C/N, Na, and K between saline and sodic soil were the primary determinants affecting the relative abundance of bacterial and fungal communities, besides electrical conductivity (EC). In the KEGG analysis, ESP mainly affected the cellular processes in the archaea. Metabolism in the bacterial function was positively correlated with K only in sodic soil. These results indicated that the proportions in sodic soil were more strongly affecting soil microbiota. [ABSTRACT FROM AUTHOR]

Sodic soil formation, following irrigation with saline-sodic water has become a major concern due to its negative impact on soil structure, crop growth and yield. However, specifically in orchards, little knowledge exists regarding the reclamation of sodic soils. Our objective was to examine the effects of different amendments on soil reclamation and crop performance of olive grove. The study was conducted in a 14 years old olive grove, grown in a clayey soil, in which irrigation started in 2008 using saline-sodic water resulting in sodium adsorption ratio (SAR) ranging from 22 to 40 (mmol c L−1)0.5. Six treatments were studied: control (no amendments applied), CaCl 2 , MgCl 2 and H 2 SO 4 that were added to the irrigation water, and gypsiferous material (GM) that was added to the soil surface prior to the rainy season and either left spread or tilled into the upper soil layer. Soil samples were analyzed for selected saturated extract properties and for aggregate stability. Additionally, plant parameters including yield, trunk expansion, fruit oil content, and tree nutritional status were measured. The results showed that the lowest SARs were observed in the GM and GM till treatments at 0–30 cm [5.0 and 3.3 (mmol c L−1)0.5, respectively], while CaCl 2 and MgCl 2 treatments had the lowest SARs at 30–90 cm [16.2 and 17.1 (mmol c L−1)0.5, respectively]. GM and CaCl 2 application raised the electrical conductivity (EC) levels to 6.9 and 7.6 dS m−1 respectively. GM addition resulted in the most stable aggregates which was associated with a significant improvement in average tree productivity of 33 kg/tree. Conversely, MgCl 2 had the lowest average yield, of 21.3 kg/tree, which was attributed to the high concentration of Mg that led to some nutrient imbalances. In conclusion, the current study showed the efficacy of different amendments based on Ca for remediating sodic soil in drip-irrigated orchards. • Soils irrigated with sodic water require reclamation. • Gypsiferous material addition yielded stable aggregates and improved crop productivity. • Adding CaCl 2 and MgCl 2 effectively decreased SAR to a depth of 90 cm. • Amending with MgCl 2 caused nutrient imbalances. • Addition of sulferic acid was ineffective in sodic soil remediation. [ABSTRACT FROM AUTHOR]

Identifying drought-tolerant crops/genotypes may provide a sustainable solution to improve productivity on rain-fed sodic soils. However, the identification of genotypes tolerant to sodicity has been impeded by a lack of suitable, high-throughput techniques. Here, we propose an unmanned aerial vehicle remote sensing coupled with field experimental approach to evaluate drought tolerance and/or water use of contrasting wheat genotypes by quantifying Genotype × Environment interactions on rain-fed moderately sodic and highly sodic soil sites in Australia. Significant differences (p < 0.05) between the sites and some between genotypes were observed based on remote sensing-based vegetative drought indices, while in-season agro-climatic and soil moisture conditions were similar (p > 0.10) between the sites. This suggests that genotypes at both sites would have grown with similar access to moisture if differences in soil constraints had not been present. Further, as a useful indicator of drought, a crop health index was computed by integrating drought vegetative and temperature response variables that significantly correlated with wheat yield (coefficient of determination R2 = 0.67; root mean square error RMSE = 28.4 g m−2 and R2 = 0.41; RMSE = 33.6 g m−2 for the moderately sodic and highly sodic site, respectively). Further, a drought stress tolerance index was developed using estimates of yield anomaly between the sites to differentiate genotypes tolerant to drought on sodic soils. Genotypic ranking to drought tolerance was further compared and validated with actual field measured crop water use efficiency data. Wheat genotypes Bremer and Gladius were identified as the most and least tolerant to drought on sodic soils. The research improves our understanding of genotypic response in drought stress and can assist farmers in the selection of drought-tolerant wheat genotypes in sodic soil environments. • UAV multispectral and thermal imagery were integrated for drought tolerance of wheat genotypes on sodic soils. • Drought vegetative and temperature response indices were used to quantify genotypic variations. • A new DSTI metric was developed on G×E interactions to quantify genotypic tolerance to drought. • Estimates of yield anomaly between sites using crop health index data was used to develop DSTI. • The study can be useful to improve crop productivity on rain-fed sodic soils. [ABSTRACT FROM AUTHOR]

The processes of sodication and desodication in soil influences agricultural productivity. We explored sodication and desodication processes in montmorillonite and illite with varying ratios of clay contents in 5% and 25 % on sodium adsorption ratios (SAR) of 7, 13, and 20 of equilibrated solution with 10 mmolc L-1. The sodication and desodication processes were observed to vary considerably, depending on the type of clay, clay content, and equilibrated solution. Sodication and desodication processes were different even for the same clay under similar conditions. The differences in clay sodication based on SAR of equilibrated solution were observed, and it was found that sodication progressed comparatively more rapid in illite than in montmorillonite. The desodication processes varied according to the type of clay and clay content. In montmorillonite, desodication progressed comparatively better at low clay content than at high clay content. In contrast, it progressed more rapid at high clay content than at low clay content in illite. However, desodication processes in illite with low clay content had similar tendencies as SAR of an equilibrated solution. As a result, the Gapon equilibrium constant was different for clay sodication and desodication processes even in the same clay mineral and clay content. The clay sodication and desodication processes as well as final exchangeable sodium percentage values were affected not only by SAR of the equilibrated solution but by the type of clay minerals and clay contents as well. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the efficacy of gypsum and sulphuric acid amendments to reclaim a sodic soil. A sodic soil filled in PVC columns was utilised for leaching studies. At a rate of 50% of the water holding capacity, 1% diluted sulphuric acid and 50% of gypsum were added. The soil column was subjected to leaching with four levels of water (5, 10, 15 and 20 cm). Continuous leaching was achieved when water application was repeated four times at a 24-hour interval. Leachate was collected from each soil column separately and characterised for pH, EC, cations, and anions. The characteristics of leachate varied significantly depending on the chemical amendments and the water level used. Sulphuric acid reclaimed the sodic soil more efficiently than gypsum amendment with water applications in the order of 20 > 15 > 10 > 5 cm. [ABSTRACT FROM AUTHOR]

Napier grass (Pennisetum purpureum) is a fast-growing forage crop cultivated throughout the year in tropical and subtropical regions. A phytoremediation study was undertaken at the Agricultural College and Research Institute (AC & RI), Killikulam, Thoothukudi District, Tamil Nadu, India, during 2020-2021 to evaluate the performance of cumbu napier varieties on sodic and neutral soil. Four cumbu napier varieties, CO (BN) 6, CO (BN) 5, KKM 1 and CO (CN) 4, were tested in both soils. Pots were filled with 10 kg of soil. Three cuttings of cumbu napiers per pot were planted as per the treatment schedule. Germination and growth parameters were observed up to three harvests. The results of the present study revealed that the germination percentage of variety CO (BN) 6 was highest (100%) among the varieties under sodic conditions. Growth parameters such as plant height, leaf length, number of leaves, and number of clumps of this variety showed better efficiency under high sodic levels than other varieties. This variety CO (BN) 6 could tolerate and be established well under alkaline soil and produced amaximum plant height (134 cm) and a higher number of clumps (10) during the third harvest. The growth pattern of cumbu napier varieties was in the order of CO (BN) 6> CO (BN) 5 > KKM 1 > CO (CN) 4. Furthermore, the experimental results revealed that cumbu napier could be recommended as a suitable crop for sodic soil. [ABSTRACT FROM AUTHOR]

The aim of the research is the dissipation of Phenanthrene in sodic soil in the presence of PGPR by two mucilagenous plant species (Trigonella foenum-graceum and Brassica juncea). To evaluate of affectivity of bioremediation in the presence of local sodic soil was artificially contaminated with the known different concentration of Phenanthrene separately to analyze the dissipation of Phenanthrene. Soil samples were taken after the 30 days of incubation in the presence of plant species and PGPR. Gas Chromatography result clearly indicate that Trigonella foenum-graceum (99%) is more efficient plant over the Brassica juncea (96%) is further indicate that PGPR having synergistic effect on phytoremediation of Phenanthrene. Trigonella foenum-graceum is more efficient plant species over the Brassica juncea to dissipate Phenanthrene contaminated sodic soil. PGPR play synergistic effect on phytoremediation. [ABSTRACT FROM AUTHOR]

Sodification is a major soil problem that limits plant productivity in arid and semi-arid regions. For ameliorating sodic soils, the application of chemical amendments that can release calcium (Ca), which expels soil exchangeable sodium (Na), is the most widely accepted approach for solving this problem. However, an alternative more economical method would be desired in developing countries that have large areas of sodic soils. The goal of the present study was to examine the effectiveness of using compost to expel soil exchangeable Na. Composts made from cattle manure, rice straw, and rapeseed pomace were added to a sodic soil (Tongliao, Inner Mongolia, China) at mass ratios of 0 − 10%, and the soil was leached with water. Soil exchangeable cations in the forms of outer sphere and inner sphere complexes were then extracted successively and their concentrations determined. Changes in the soil dispersibility resulting from the addition of compost was also examined. The concentration of Na in both the outer sphere and inner sphere complexes decreased when rice straw or rapeseed pomace compost added, but this was not observed when cattle manure compost, which is abundant in water-soluble Na, was used. The amount of K in both forms increased with increasing rate of addition of each compost, suggesting that the K in the compost replaced both the Na that is adsorbed to soil by electrostatic attraction and by chemical interactions. The largest removal of Na, 73% for outer sphere complex and 93% for inner sphere complex, was attained in the case of rapeseed pomace compost, which had the largest water-soluble K/water-soluble Na ratio, at a mass ratio of 5%. The addition of compost also neutralized soil pH and reduced soil dispersion, the latter being effective in improving the physical properties of the soil. [ABSTRACT FROM AUTHOR]

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Sodic soils account for nearly one third of Australia's land mass and pose several challenges such as dispersion and erosion, thus destabilizing vast eco-systems. Chemical stabilizers such as lime, cement, fly ash etc., improve the mechanical performance of such soils and reduce their dispersivity. This study presents the results of a novel triple blend stabilization method for strongly sodic soil with Exchangeable Sodium Percentage (ESP) in 15-25%. Lime, cement and fly ash (LCF) were adopted in four different blend proportions to achieve at least 1.5MPa Unconfined Compressive Strength (UCS) as per Transport and Main Roads (TMR) specification. The results indicate that B4-4% with 20/50/30 LCF yielded the best performance with lowest shrinkage of 2.9% and higher dry density 2126.4 kg/m3. Regression analysis of UCS results projected that an additional 2.53% soil-stabilizer replacement is required to improve the performance of B4 from 0.86MPa to reach 1.5 MPa. Scanning Electron Microscopy (SEM) analysis showed needle-like ettringite crystals and Calcium-Silicate- Hydrates (CSH) net-like structures over 28-day curing. X-Ray diffractometry (XRD) indicated a drop of 20.8% in Na+ and 20.3% increase in Ca++. The triple blend stabilization technique enhances UCS performance by 167% with a less than 5% of the total volume of the additives when compared to the single and double blends. [ABSTRACT FROM AUTHOR]

Drying shrinkage of soil contaminated by alkaline solutions in ecologically fragile areas is a key issue that affects the strength, stability, and permeability of contaminated soil. Reinforcement with polypropylene fibers is a common physical treatment method. This paper presents experimental investigations of the shear strength, permeability, formation, and development of desiccation cracks in sodic soil with four different contents of polypropylene fibers: 0%, 2%, 4%, and 8%. The shear strength and permeability coefficient were tested by the SLB-1 triaxial shear permeability tester. Meanwhile, a series of crack images and water content evolution were obtained during free desiccation tests with self-designed monitoring equipment. The dynamic changes in the cracks are then quantitatively analyzed by using digital image processing and geographic information system (GIS) analysis. The experimental results show that shear strength increases and permeability coefficient decreases with the increase of fiber content. The evaporation process with different polypropylene fiber contents has three stages, namely, Stages I, II, and III that are in accordance with the slope of the evaporation curve. However, the polypropylene fiber content has little effect on the total duration of crack development. The crack development process has three stages. The crack ratio, fractal dimension, and average width decrease as the polypropylene fiber content increases. The fractal dimension gradually and linearly increases with time. The fractal dimensions of the cracks are reduced with increased polypropylene fiber content, which indicates that polypropylene fibers can inhibit the development of soil cracking. Because the elastic modulus of the fibers is very high, it is difficult for the fibers to be pulled out from the soil during cracking. Therefore, friction is produced at the interface between the fibers and soil particles, which can inevitably inhibit the relative sliding of the fibers and share the tensile stress caused by the structural shrinkage in the soil. Therefore, polypropylene fibers can dramatically improve the stability and integrity of soil, similar to a "bridge." In conclusion, these research results provide an important explanation for dealing with alkali-contaminated foundations and soils. [ABSTRACT FROM AUTHOR]

Sodicity is a major soil constraint in many arid and semi-arid regions worldwide, including Australia, which adversely affects the ability of crops to take up water and nutrients from the soil, reducing yield. Reliable methods and tools are required for appropriate selection of traits, may provide a better understanding of crop responses to multiple stresses, especially in sodic soil. A novel strategy was developed using unmanned aerial vehicle (UAV)-thermal imaging and agglomerative hierarchical clustering-based techniques to evaluate and rank the physiological performance of 18 contrasting wheat genotypes grown on a moderately sodic and a highly sodic soil in north-eastern Australia. We obtained UAV-thermal imaging data at different times of the day (9:30, 12:00, and 15:00 hrs) close to flowering stage. Crop biophysical parameters (Leaf potassium concentration, normalized difference vegetation index, crop water uptake, stomatal conductance, plant moisture content, and aboveground biomass) were measured at close to flowering by destructive plant sampling and ground-based proximal sensing and yield was machine harvested at maturity. Canopy temperatures derived from thermal imagery between 28.9 and 35.4 °C were observed at the moderately sodic site, and between 36.2 and 41.0 °C at the highly sodic site from 9:30 to 15:00 hrs. Canopy temperature was consistently higher than corresponding ambient air temperatures indicating plant water stress at both sites. While the air temperature was not significantly different (p > 0.05) between the two sites, canopy temperature was significantly higher (p < 0.01) on highly sodic soil compared to moderately sodic soil, indicating greater water stress at the highly sodic site. This difference was most likely due to the adverse impacts of sodic soil constraints and not primarily due to environmental variations. Hence, our study revealed that sodic soil constraints can intensify plant water stress. Statistical analysis between canopy temperature (9:30, 12:00, and 15:00 hrs) and crop biophysical parameters showed close negative correlations at both moderately sodic (R2 = 0.54 to 0.83) and highly sodic (R2 = 0.30 to 0.89) sites. A closer correlation was observed at 15:00 hrs for both sites. Thus, high-resolution UAV-thermal imaging has potential to detect water-stressed plants on sodic soil. Agglomerative hierarchical clustering was used as an unsupervised machine learning tool for ranking of physiological performance of wheat genotypes. Results suggest that UAV-thermal imaging and AHC techniques can discriminate cultivars tolerant to sodicity. The study improves our understanding of crop physiological behaviour and can assist farmers in selection of water stress tolerant genotypes to sustain food security in sodic soil under water-limited environments. [ABSTRACT FROM AUTHOR]

Soil physicochemical properties are the main driving factors affecting the stability and diversity of the soil microbial community. The impacts of the saline–alkali situation and associated soil degradation need to be understood and reversed as soil diversity and communities are increasingly affected by saline–alkaline soil. However, the differences between salinization and alkalization soil and their impact on microbiota have been overlooked. The object of this study is to demonstrate the differences in salinization and alkalization soil and the driving factors affecting microbiota. In this study, 12 soil samples collected from saline–alkaline spots were used to detect the differences in soil physicochemical properties. The soil microbial community was sequenced by high-throughput sequencing. The results of ESP and EC in the soil samples indicated that the soil samples were categorized as saline soil and sodic soil. Venn diagrams indicated that unique OTUs in saline soil showed higher adaptation and environmental tolerance. Partial Mantel tests showed that the differences in pH, exchangeable sodium percentage (ESP), C/N, Na, and K between saline and sodic soil were the primary determinants affecting the relative abundance of bacterial and fungal communities, besides electrical conductivity (EC). In the KEGG analysis, ESP mainly affected the cellular processes in the archaea. Metabolism in the bacterial function was positively correlated with K only in sodic soil. These results indicated that the proportions in sodic soil were more strongly affecting soil microbiota.

Soil salinization and alkalization is an acute problem in Western Siberia because of the rise of saline groundwater above the critical level. We studied modern hydromorphism of solonetzes in the forest-steppe zone of Western Siberia. The dynamics of the groundwater level were studied in the years with different moistening and during the growing seasons. The chemical composition of the groundwater was compared with the composition of salts in the soil water extracts to identify negative processes of soil salinization and solonetzization under the impact of groundwater. Field studies were performed on the plots of the long-term experiment on the effect of different gypsum rates on the properties of crusty solonetzes in Novosibirsk oblast. During the study, a sharp rise in the groundwater level took place in 2013; it resulted in an increase in the groundwater salinity and the amount of soluble salts in the solonetz profile in 2015–2016. An increase in the content of hypothetical soda in the profile of the solonetz was recorded. The results of this study may be used to monitor the state of soils in Western Siberia and to plan land reclamation measures during the development of virgin land and the return of abandoned fields into agricultural use. [ABSTRACT FROM AUTHOR]

Exogenous applications of plant bio-regulators (PBRs) were evaluated during kharif of 2017 and 2018 for their efficiency to facilitate growth and production processes in paddy (Oryza sativa L.) grown in loam soils undergoing sodification (pHs 8.5 & 8.3; ESP 37 & 13) with alkali groundwater irrigation (RSC 3.4 meq L-1 at site-I during both the years and RSC 4.4 & 3.7 meq l-1 at site-II during 2017 and 2018, respectively). The PBRs included gibberellic acid (GA, 25 ppm), potassium nitrate (PN, 15 g l-1), salicylic acid (SA, 10uM), sodium benzoate (SB, 150 mg l-1; 2017 only) and thio-urea (TU, 500 ppm). These were sprayed at three stages, i.e. seedling establishment and tillering (30-40 days after transplanting), booting and maximum growth (50-60 DAT) and flowering and grain formation (80-90 DAT). PBRs promoted growth and improved yields and contributing attributes like tillers, panicle length and filled grains. The increase in grain yield equaled 20, 16, 2, 16 and 24% with application of GA, PN, SA, SB and TU, respectively at Site-I during 2017 and the counter values at Site-II were 4, 24, 2, 17 and 21%. Similarly, during 2018, the improvements in yield equaled 3, 15, 4 and 20% with GA, PN, SA and TU at Site-I and nil, 14, 8 and 7% at Site- II, respectively. The Na:K ratio was lower especially with PN while grain quality monitored in terms of protein and gluten contents remained unaffected. On the basis of consistency, it emerges that the use of thio-urea and potassium nitrate is a viable option for alleviating sodicity stress in paddy under alkali groundwater irrigated conditions.

Fungi colonise various substrates such as organic matter (dead or alive) from plants or animals. These fungi can be specialists (i.e. belonging to a substrate) or generalists (i.e. surviving on different types of organisms). Fungi fulfil various functions in specialised niches, for example, acting as plant pathogens, helping in plant growth from the root systems or decomposing organic matter and fertilising soil. Species are specialised to occur in only one niche, or others can utilise or occur in various niches. For example, certain species occur only within certain plant tissues (endophytes), on the exterior surface of the plants growing above the ground (epiphytes) or below the ground in the sphere surrounding the roots (rhizosphere). Different soil types or conditions can favour certain species. This study used environmental sequencing to characterise the fungal communities associated with the root exterior and interior of Sida cordifolia, a plant growing across the varying soil conditions of the catena system. Fungal rhizosphere communities between three commonly occurring plant species – S. cordifolia, Melhania acuminata (both Malvaceae) and Kyphocarpa angustifolia (Amaranthaceae) – in one of the soil types were also studied to compare and contrast the fungal rhizosphere communities of these herbs. Molecular Operational Taxonomic Units co-occurred between niches, soil conditions and the rhizospheres of three plants at the same location, whilst others were restricted to only one niche or plant species. Results showed that soil conditions in a catena can influence the associations of fungal species between different catena zones, on the outside and inside of the roots, and that these communities also differ between plant species. Conservation implications: This study showed that complex and sensitive fungal communities are associated with plant roots in different zones of the catena. This is most likely also true between different habitats and soil types on a larger scale. This study emphasises the need to also manage a catena system on the micro-ecological scale whilst framing conservation and management plans of the Kruger National Park.

Fungi colonise various substrates such as organic matter (dead or alive) from plants or animals. These fungi can be specialists (i.e. belonging to a substrate) or generalists (i.e. surviving on different types of organisms). Fungi fulfil various functions in specialised niches, for example, acting as plant pathogens, helping in plant growth from the root systems or decomposing organic matter and fertilising soil. Species are specialised to occur in only one niche, or others can utilise or occur in various niches. For example, certain species occur only within certain plant tissues (endophytes), on the exterior surface of the plants growing above the ground (epiphytes) or below the ground in the sphere surrounding the roots (rhizosphere). Different soil types or conditions can favour certain species. This study used environmental sequencing to characterise the fungal communities associated with the root exterior and interior of Sida cordifolia , a plant growing across the varying soil conditions of the catena system. Fungal rhizosphere communities between three commonly occurring plant species – S. cordifolia, Melhania acuminata (both Malvaceae) and Kyphocarpa angustifolia (Amaranthaceae) – in one of the soil types were also studied to compare and contrast the fungal rhizosphere communities of these herbs. Molecular Operational Taxonomic Units co-occurred between niches, soil conditions and the rhizospheres of three plants at the same location, whilst others were restricted to only one niche or plant species. Results showed that soil conditions in a catena can influence the associations of fungal species between different catena zones, on the outside and inside of the roots, and that these communities also differ between plant species. Conservation implications: This study showed that complex and sensitive fungal communities are associated with plant roots in different zones of the catena. This is most likely also true between different habitats and soil types on a larger scale. This study emphasises the need to also manage a catena system on the micro-ecological scale whilst framing conservation and management plans of the Kruger National Park. [ABSTRACT FROM AUTHOR]