Showing papers on "Soil salinity published in 2018"

Freshwater salinization syndrome on a continental scale.

Abstract: Salt pollution and human-accelerated weathering are shifting the chemical composition of major ions in fresh water and increasing salinization and alkalinization across North America. We propose a concept, the freshwater salinization syndrome, which links salinization and alkalinization processes. This syndrome manifests as concurrent trends in specific conductance, pH, alkalinity, and base cations. Although individual trends can vary in strength, changes in salinization and alkalinization have affected 37% and 90%, respectively, of the drainage area of the contiguous United States over the past century. Across 232 United States Geological Survey (USGS) monitoring sites, 66% of stream and river sites showed a statistical increase in pH, which often began decades before acid rain regulations. The syndrome is most prominent in the densely populated eastern and midwestern United States, where salinity and alkalinity have increased most rapidly. The syndrome is caused by salt pollution (e.g., road deicers, irrigation runoff, sewage, potash), accelerated weathering and soil cation exchange, mining and resource extraction, and the presence of easily weathered minerals used in agriculture (lime) and urbanization (concrete). Increasing salts with strong bases and carbonates elevate acid neutralizing capacity and pH, and increasing sodium from salt pollution eventually displaces base cations on soil exchange sites, which further increases pH and alkalinization. Symptoms of the syndrome can include: infrastructure corrosion, contaminant mobilization, and variations in coastal ocean acidification caused by increasingly alkaline river inputs. Unless regulated and managed, the freshwater salinization syndrome can have significant impacts on ecosystem services such as safe drinking water, contaminant retention, and biodiversity.

Soil Salinity: Historical Perspectives and a World Overview of the Problem

Abstract: Soil salinity is not a recent phenomenon, it has been reported since centuries where humanity and salinity have lived one aside the other. A good example is from Mesopotamia where the early civilizations first flourished and then failed due to human-induced salinization. A publication ‘Salt and silt in ancient Mesopotamian agriculture’ highlights the history of salinization in Mesopotamia where three episodes (earliest and most serious one affected Southern Iraq from 2400 BC until at least 1700 BC, a milder episode in Central Iraq occurred between 1200 and 900 BC, and the east of Baghdad, became salinized after 1200 AD) have been reported. There are reports clearly revealing that ‘many societies based on irrigated agriculture have failed’, e.g. Mesopotamia and the Viru valley of Peru. The flooding, over-irrigation, seepage, silting, and a rising water table have been reported the main causes of soil salinization. Recent statistics of global extent of soil salinization do not exist, however, various scientists reported extent differently based on different data sources, such as there have been reports like, 10% of the total arable land as being affected by salinity and sodicity, one billion hectares are covered with saline and/or sodic soils, and between 25% and 30% of irrigated lands are salt-affected and essentially commercially unproductive, global distribution of salt-affected soils are 954 million ha, FAO in 1988 presented 932 million ha salt-affected soils, of almost 1500 million ha of dryland agriculture, 32 million ha are salt-affected. Precise information on the recent estimates of global extent of salt-affected soils do not exist, many countries have assessed their soils and soil salinization at the national level, such as Kuwait, United Arab Emirates, Middle East, and Australia etc. Considering the current extent of salt-affected soils the cost of salt-induced land degradation in 2013 was $441 per hectare, a simple benefit transfer suggests the current annual economic losses could be $27 billion.

Effect of Different Levels of Humic Acids on the Nutrient Content, Plant Growth, and Soil Properties under Conditions of Salinity

Abstract: In this study, the effects were investigated of salinity, foliar and soil applications of humic substances on the growth and mineral nutrients uptake of Corn (Hagein, Fardy10), and the comparison was carried out of the soil and foliar applications of humic acid treatments at different NaCl levels. Soil organic contents are one of the most important parts that they directly affect the soil fertility and textures with their complex and heterogenous structures although they occupy a minor percentage of the soil weight. Humic acids are an important soil component that can improve nutrient availability and impact on other important chemical, biological, and physical properties of soils. The effects of foliar and soil applications of humic substances on the plant growth and some nutrient elements uptake of Corn (Hagein, Fardy10) grown at various salt concentrations were examined. Sodium chloride was added to the soil to obtain 20 and 60mM saline conditions. Solid humus was applied to the soil one month before planting and liquid humic acids were sprayed on the leaves twice on 20 th and 40 th day after seedling emergence. The application doses of solid humus were 0, 2 and 4 g/kg and those of liquid humic acids were 0, 0.1 and 0.2%. Salinity negatively affected the growth of corn; it also decreased the dry weight and the uptake of nutrient elements except for Na and Mn. Soil ap - plication of humus increased the N uptake of corn while foliar application of humic acids increased the uptake of P, K, Mg,Na,Cu and Zn. Although the effect of interaction between salt and soil humus application was found statistically significant, the interaction effect between salt and foliar humic acids treatment was not found significant. Under salt stress, the first doses of both soil and foliar application of humic substances increased the uptake of nutrients. Keyword: humic acids; nutrient content; plant growth; salinity, soil properties

Titanium Dioxide Nanoparticles Improve Growth and Enhance Tolerance of Broad Bean Plants under Saline Soil Conditions

Abstract: Soil salinity is established as one of the major environmental problems, decreasing crop productivity worldwide, thereby threatening sustainable agriculture. In the present study, we evaluated the effects of titanium dioxide nanoparticles (nTiO2) for ameliorating soil salinity in broad bean, an important leguminous crop. As nTiO2 is known to have pro-oxidant and antioxidant properties, the effects of three different nTiO2 concentrations (0·01%, 0·02% and 0·03%) were compared with respect to plant growth and stress responses. The 0·01% nTiO2 application significantly increased shoot length, leaf area and root dry weight of plants under normal conditions. These growth-promoting effects were simultaneous with increased levels of chlorophyll b, soluble sugars and proline and enhanced activities of antioxidant enzymes. Under saline soil conditions, although proline level and enzymatic antioxidant activities were increased, plant growth significantly reduced. The 0·01% nTiO2 supplementation significantly increased the activities of enzymatic antioxidants and levels of soluble sugars, amino acids and proline in salt-affected plants versus plants subjected to salinity alone. Thus, the increased antioxidant enzyme activities contributed to the observed reduction in hydrogen peroxide and malondialdehyde contents, while enhanced levels of proline and other metabolites contributed to osmoprotection, collectively resulting in significant plant growth improvement under salinity. Furthermore, nTiO2-mediated positive effects were concentration dependent with 0·01% nTiO2 being the most effective, whereas 0·02% showed an intermediate response and 0·03% was almost ineffective under both control and saline soil conditions. Our findings provide a foundation for nTiO2 application in improving growth of plants cultivated on naturally contaminated saline soils. Copyright © 2017 John Wiley & Sons, Ltd.

Coastal climate change, soil salinity and human migration in Bangladesh

Abstract: Climate change is not only altering weather patterns but also accelerating sea-level rise, leading to increased inundation and saline contamination of soils. Given projected sea-level rise, it is imperative to examine the extent to which farmers in coastal Bangladesh can adapt by diversifying economic activities before resorting to migration within and across borders. Here, to identify patterns in how households adapt to increased sea/freshwater flooding and soil salinity, we analyse nationally representative socioeconomic and migration data against a suite of environmental variables constructed at the sub-district level. Our results show that inundation alone has negligible effects on migration and agricultural production. However, gradual increases in soil salinity correspond to increasing diversification into aquaculture and internal migration of household members. Salinity is also found to have direct effects on internal and international migration even after controlling for income losses, with mobility restricted to certain locations within Bangladesh. Our study suggests that migration is driven, in part, by the adverse consequences of salinity on crop production. Projected sea-level rise and increased flooding threaten coastal agriculture. Gradual increases in soil salinity, but not inundation alone, are shown to correspond to increasing diversification into aquaculture and higher levels of internal migration.

Effect of biochar on alleviation of cadmium toxicity in wheat (Triticum aestivum L.) grown on Cd-contaminated saline soil

Abstract: Soil degradation by salinity and accumulation of trace elements such as cadmium (Cd) in the soils are expected to become one of the most critical issues hindering sustainable production and feeding the increasing population. Biochar (BC) has been known to protect the plants against soil salinity and heavy metal stress. A soil culture study was performed to evaluate the effect of BC on wheat (Triticum aestivum L.) growth, biomass, and reducing Cd and sodium (Na) uptake grown in Cd-contaminated saline soil under ambient conditions. Soil salinity decreased the plant growth, biomass, grain yield, chlorophyll contents, and gas exchange parameters and caused oxidative stress in plants compared with Cd stress alone. Salt stress increased Cd and Na uptake and reduced the potassium (K) and zinc (Zn) uptake by plants. AB-DTPA-extractable Cd and soil electrical conductivity (ECe) increased under salt stress compared to the soil without NaCl stress. Biochar application improved the plant growth and reduced the Cd and Na uptake except in plants treated with higher BC and salt stress (5.0% BC + 50 mM NaCl). Biochar application reduced the oxidative stress in plants and modified the antioxidant enzyme activities, and reduced the bioavailable Cd under salt stress. The positive effects of BC under lower salt stress while the negative effects of BC under higher BC and salt levels indicated that BC doses should be used with great care in higher soil salinity levels simultaneously contaminated with Cd to avoid the negative effects of BC on growth and metal uptake.

Conjunctive use of groundwater and surface water to reduce soil salinization in the Yinchuan Plain, North-West China

Abstract: Poor water resource management is an important factor in soil salinization in arid areas. In this study, the status of soil salinization and its controlling factors are summarized for the Yinchuan ...

How Human Activities Affect Heavy Metal Contamination of Soil and Sediment in a Long-Term Reclaimed Area of the Liaohe River Delta, North China

Abstract: Heavy metal pollution in soils and sediments is becoming a matter of wide concern, this study was carried out in Dawa County of the Liaohe River Delta, with the aim of exploring the impacts of land use levels on heavy metal contamination of soil and sediment A total of 129 soil samples were collected in different land use intensities (LUI) Soil metals (Fe, Mn, Cd, Cr, Cu, Ni, Pb and Zn) and soil salinity, pH, soil organic carbon (SOC), nitrate nitrogen (NO3−-N), available phosphorus (AP) and grain sizes were analyzed Correlation analysis indicated that SOC and grain size played important roles in affecting the heavy metal distribution The factor analysis results indicated that heavy metal contamination was most probably caused by industrial and agricultural wastewater discharges, domestic sewage discharge and atmospheric deposition Using ANOVA, it found that human activities significantly changed soil physic-chemical properties through soil erosion, leaching and fertilizer application, further affecting the behaviors of heavy metals in the soil and sediments The anthropogenic factors could lead to potential environmental risk, as indicated by the Geo-accumulation index (Igeo) results of heavy metals Overall, the heavy metals generally had approached or even exceeded moderately polluted (0 < Igeo < 1, 1 < Igeo < 2), but the Pb and Cu pollution level was low (Igeo < 0), and the Cd pollution level was moderately or strongly polluted (2 < Igeo < 3, 3 < Igeo < 4) in the five land use levels This study will provide valuable information for appropriately determining how land should be used in future reclamation areas, as well as for the sustainable management of estuarine areas around the world

Effects of arbuscular mycorrhizal fungi on growth and nitrogen uptake of Chrysanthemum morifolium under salt stress.

Abstract: Soil salinity is a common and serious environmental problem worldwide. Arbuscular mycorrhizal fungi (AMF) are considered as bio-ameliorators of soil salinity tolerance in plants. However, few studies have addressed the possible benefits of AMF inoculation for medicinal plants under saline conditions. In this study, we examined the effects of colonization with two AMF, Funneliformis mosseae and Diversispora versiformis, alone and in combination, on the growth and nutrient uptake of the medicinal plant Chrysanthemum morifolium (Hangbaiju) in a greenhouse salt stress experiment. After 6 weeks of a non-saline pretreatment, Hangbaiju plants with and without AMF were grown for five months under salinity levels that were achieved using 0, 50 and 200 mM NaCl. Root length, shoot and root dry weight, total dry weight, and root N concentration were higher in the mycorrhizal plants than in the non-mycorrhizal plants under conditions of moderate salinity, especially with D. versiformis colonization. As salinity increased, mycorrhizal colonization and mycorrhizal dependence decreased. The enhancement of root N uptake is probably the main mechanism underlying salt tolerance in mycorrhizal plants. These results suggest that the symbiotic associations between the fungus D. versiformis and C. morifolium plants may be useful in biotechnological practice.

Halophytes in biosaline agriculture: Mechanism, utilization, and value addition

Abstract: Land is considered as life-sustaining platform for food and water. However, there are contaminants like salt, heavy metal, industrial waste which decreases land fertility, posing serious threat to sustainable agriculture. In recent years, novel crop varieties with improved tolerance against environmental contaminants have been developed, but most of them faces severe yield penalty. Alternatively, naturally tolerant plants such as extremophiles can be screened for their potential as crops. The newly developed crop should be tolerant to different abiotic stresses, perform better under extreme conditions by producing higher biomass and yield. In view of this, the present review focuses on the effects of saline soil on plants and how a class of plants termed as “halophytes” can tolerate high levels of salt. The potential applications of halophytes in phyto-remediation, desalination, secondary metabolite production, medicine, food and saline agriculture have been discussed. A concept of saline agriculture has been proposed for rehabilitation of saline and degraded lands. In this context, a potential halophyte is cultivated in salt contaminated soil for desalination. The harvested halophyte can have industrial value and later on, rehabilitated soil can be utilized for agriculture purpose. Some success with halophyte cultivation has been demonstrated in environmentally degraded soils and it is imperative that large scale adoption of halophytes, as potential candidates, can be accorded as priority for rehabilitating contaminated soils, which can pave way for sustainable agriculture.

Cropland soil salinization and associated hydrology: trends, processes and examples.

Abstract: While global food demand and world population are rapidly growing, land potential for cropping is steadily declining due to various soil degradation processes, a major one of them being soil salinization. Currently, approximately 20% of total cropland and 33% of irrigated agricultural land are salinized as a result of poor agricultural practices and it is expected that by 2050, half of the croplands worldwide will become salinized. Thus, there is a real need to better understand soil salinization processes and to develop agricultural practices that will enable production of the needed amount of food to feed humanity, while minimizing soil salinization and other degradation processes. The major sources of solutes in agricultural environments are: (i) the soil itself, and the parent geological material; (ii) shallow and salt rich groundwater; and (iii) salt rich irrigation water. The salinization of soil is a combination of transport of solutes towards the root zone to replenish evaporation and transpiration and limited washing of the soil by rain or irrigation. Therefore, most salinized soils are present in arid and semi-arid environments where precipitation is low and evaporation is high. In this manuscript, examples of soil salinization processes from croplands around the world will be presented and discussed to bring attention to this important topic, to present the latest scientific insights and to highlight the gaps that should be filled, from both scientific and practical perspectives.

Rice in Saline Soils: Physiology, Biochemistry, Genetics, and Management

Abstract: Salt stress is an acute threat to plants, especially to field crops in irrigated and saline areas of the world. Rice is the second staple crop of the world after wheat, and its production is strongly affected by salinity. Therefore, to ensure food security, it is crucial to manage salt stress for sustainable rice production under saline conditions. Plant physiological, biochemical, and genetic characteristics play an important role in the adaptation of rice to saline environments. Further, the knowledge of the relationship among these characteristics is necessary to manage the salt stress and achieve optimal rice production. This review focuses on the response of rice to salinity stress; its physiological, biochemical, and genetic changes; its adaptation to saline soils through osmoregulation, ion homeostasis, apoplastic acidification, synthesis of antioxidants, genes, and hormonal regulations; and synthesis of stress-responsive proteins. Future research is needed on management strategies such as breeding for salt-tolerant cultivars, application of molecular markers to select salt-tolerant germplasm, potential of genetic transformation for salinity resistance, application of arbuscular mycorrhizal fungi, and plant growth-regulating rhizobacteria, nutrient management, and seed priming techniques for sustainable rice production in saline areas. In conclusion, salt stress affects metabolism and physiology of rice and reduces the agronomic yield. Therefore, development of salt-tolerant genotypes may be a prudent strategy to manage the salinity. Focused research on integration of different management options can lead to sustainable rice production in saline areas which may contribute significantly to global food security.

Strategies to Mitigate the Salt Stress Effects on Photosynthetic Apparatus and Productivity of Crop Plants

Abstract: Soil salinization represents one of the major limiting factors of future increase in crop production through the expansion or maintaining of cultivation area in the future. High salt levels in soils or irrigation water represent major environmental concerns for agriculture in semiarid and arid zones. Recent advances in research provide great opportunities to develop effective strategies to improve crop salt tolerance and yield in different environments affected by the soil salinity. It was clearly demonstrated that plants employ both the common adaptative responses and the specific reactions to salt stress. The review of research results presented here may be helpful to understand the physiological, metabolic, developmental, and other reactions of crop plants to salinity, resulting in the decrease of biomass production and yield. In addition, the chapter provides an overview of modern studies on how to mitigate salt stress effects on photosynthetic apparatus and productivity of crop plants with the help of phytohormones, glycine betaine, proline, polyamines, paclobutrazol, trace elements, and nanoparticles. To understand well these effects and to discover new ways to improve productivity in salinity stress conditions, it is necessary to utilize efficiently possibilities of promising techniques and approaches focused on improvement of photosynthetic traits and photosynthetic capacity, which determines yield under salt stress conditions.

Quantitative estimation of soil salinity by means of different modeling methods and visible-near infrared (VIS–NIR) spectroscopy, Ebinur Lake Wetland, Northwest China

Abstract: Soil salinization is one of the most common forms of land degradation. The detection and assessment of soil salinity is critical for the prevention of environmental deterioration especially in arid and semi-arid areas. This study introduced the fractional derivative in the pretreatment of visible and near infrared (VIS-NIR) spectroscopy. The soil samples (n = 400) collected from the Ebinur Lake Wetland, Xinjiang Uyghur Autonomous Region (XUAR), China, were used as the dataset. After measuring the spectral reflectance and salinity in the laboratory, the raw spectral reflectance was preprocessed by means of the absorbance and the fractional derivative order in the range of 0.0-2.0 order with an interval of 0.1. Two different modeling methods, namely, partial least squares regression (PLSR) and random forest (RF) with preprocessed reflectance were used for quantifying soil salinity. The results showed that more spectral characteristics were refined for the spectrum reflectance treated via fractional derivative. The validation accuracies showed that RF models performed better than those of PLSR. The most effective model was established based on RF with the 1.5 order derivative of absorbance with the optimal values of R2 (0.93), RMSE (4.57 dS m-1), and RPD (2.78 ≥ 2.50). The developed RF model was stable and accurate in the application of spectral reflectance for determining the soil salinity of the Ebinur Lake wetland. The pretreatment of fractional derivative could be useful for monitoring multiple soil parameters with higher accuracy, which could effectively help to analyze the soil salinity.

Salicylic acid alleviates salinity-caused damage to foliar functions, plant growth and antioxidant system in Ethiopian mustard ( Brassica carinata A. Br.)

Abstract: Soil salinity is considered as one of the major environmental factors that has reduced plant productivity worldwide This study investigates the impact of salinity on plant growth attributes, biochemical and physiological leaf characteristics in two cultivars (Adet and Merawi) of Brassica carinata and also explores the role of salicylic acid (SA) in mitigating the effect of salt stress Four-week-old cultivars were treated with NaCl (50, 100 and 150 mM) and SA (05 mM) and watered regularly with 100% field capacity Thus, they were grown under eight different treatments (T1 = no NaCl, no SA; T2 = 0 mM NaCl with 05 mM SA; T3 = 50 mM NaCl without SA; T4 = 50 mM NaCl with 05 mM SA; T5 = 100 mM NaCl without SA; T6 = 100 mM NaCl with 05 mM SA; T7 = 150 mM NaCl without SA; and T8 = 150 mM NaCl with 05 mM SA) Nine-week-old cultivars were sampled for analyzing the growth attributes, plant water status, nitrate reductase activity, proline accumulation, photosynthetic traits, lipid peroxidation level and activity of antioxidant enzymes Salinity treatments hampered the overall plant growth performance in a dose-dependent manner Salinity also reduced photosynthetic efficiency by inhibiting chlorophyll synthesis, nitrate reductase activity, chlorophyll fluorescence, stomatal conductance, net photosynthetic and transpiration rates and plant water status On the other hand, SA application alleviated the adverse effects of salinity and improved the performance of the studied parameters in both the cultivars Higher dose of salinity increased proline production, but SA application mitigates this impact in both the cultivars studied The activity of antioxidant enzymes increased under salt stress in a dose-dependent manner SA treatment to normal or salinity-stressed plants increased the enzymes activity, showing that SA has a crucial role in modulating the cell redox balance and protecting the plants from oxidative damage SA significantly reduced the salinity-caused effects on the overall performance of plants and their antioxidant systems in both the cultivars Of the two cultivars, Adet was more tolerant to salinity than Merawi Foliar application of SA improved the performance of Ethiopian mustard cultivars and mitigated the damage caused by salt stress

Large soil organic carbon increase due to improved agronomic management in the North China Plain from 1980s to 2010s

Abstract: Agricultural soils are widely recognized to be capable of carbon sequestration that contributes to mitigating CO2 emissions. To better understand soil organic carbon (SOC) stock dynamics and its driving and controlling factors corresponding with a period of rapid agronomic evolution from the 1980s to the 2010s in the North China Plain (NCP), we collected data from two region-wide soil sampling campaigns (in the 1980s and 2010s) and conducted an analysis of the controlling factors using the random forest model. Between the 1980s and 2010s, environmental (i.e. soil salinity/fertility) and societal (i.e. policy/techniques) factors both contributed to adoption of new management practices (i.e. chemical fertilizer application/mechanization). Results of our work indicate that SOC stocks in the NCP croplands increased significantly, which also closely related to soil total nitrogen changes. Samples collected near the surface (0-20 cm) and deeper (20-40 cm) both increased by an average of 9.4 and 5.1 Mg C ha-1 , respectively, which are equivalent to increases of 73% and 56% compared with initial SOC stocks in the 1980s. The annual carbon sequestration amount in surface soils reached 10.9 Tg C year-1 , which contributed an estimated 43% of total carbon sequestration in all of China's cropland on just 27% of its area. Successful desalinization and the subsequent increases in carbon (C) inputs, induced by agricultural projects and policies intended to support crop production (i.e. reconstruction of low yield farmland, and agricultural subsidies), combined with improved cultivation practices (i.e. fertilization and straw return) since the early 1980s were the main drivers for the SOC stock increase. This study suggests that rehabilitation of NCP soils to reduce salinity and increase crop yields have also served as a pathway for substantial soil C sequestration.

Soil salinity prediction and mapping by machine learning regression in Central Mesopotamia, Iraq

Abstract: Key Laboratory of Digital Land and Resources, East China University of Technology, Nanchang, Jiangxi, PR China 2 ICARDA (International Center for Agricultural Research in the Dry Areas), Rabat, Morocco College of Agriculture, University of Baghdad, Baghdad, Iraq GIS Division, Ministry of Agriculture, Baghdad, Iraq Earth Sciences Department, Faculty of Science, and Remote Sensing Center, University of Kufa, Kufa, Iraq Faculty of Science, East China University of Technology, Nanchang, Jiangxi, PR China Correspondence W. Wu, Key Laboratory of Digital Land and Resources, East ChinaUniversity of Technology, Nanchang, 330013 Jiangxi, PR China. Email: wuwc030903@sina.com; wuwch@ecit.cn Funding information East China University of Technology, Grant/ Award Number: DHTP2018001; Australian Agency for International Development, Grant/ Award Number: LWR/2009/034

Impacts of agricultural irrigation on groundwater salinity

Abstract: Agricultural irrigation represents the main use of global water resources. Irrigation has an impact on the environment, and scientific evidence suggests that it inevitably leads to salinization of both soil and aquifers. The effects are most pronounced under arid and semi-arid conditions. In considering the varied impacts of irrigation practices on groundwater quality, these can be classed as either direct—the direct result of applying water and accompanying agrochemicals to cropland—or indirect—the effects of irrigation abstractions on groundwater hydrogeochemistry. This paper summarizes and illustrates through paradigmatic case studies the main impacts of irrigation practices on groundwater salinity. Typically, a diverse range of groundwater salinization processes operating concomitantly at different time scales (from days to hundreds of years) is involved in agricultural irrigation. Case studies suggest that the existing paradigm for irrigated agriculture of focusing mainly on crop production increases has contributed to widespread salinization of groundwater resources.

Soil pH is equally important as salinity in shaping bacterial communities in saline soils under halophytic vegetation

Abstract: While saline soils account for 6.5% of the total land area globally, it comprises about 70% of the area in northwestern China. Microbiota in these saline soils are particularly important because they are critical to maintaining ecosystem services. However, little is known about the microbial diversity and community composition in saline soils. To investigate the distribution patterns and edaphic determinants of bacterial communities in saline soils, we collected soil samples across the hypersaline Ebinur Lake shoreline in northwestern China and assessed soil bacterial communities using bar-coded pyrosequencing. Bacterial communities were diverse, and the dominant phyla (>5% of all sequences) across all soil samples were Gammaproteobacteria, Actinobacteria, Firmicutes, Alphaproteobacteria, Bacteroidetes and Betaproteobacteria. These dominant phyla made a significant (P < 0.05) contribution to community structure variations between soils. Halomonas, Smithella, Pseudomonas and Comamonas were the indicator taxa across the salinity gradient. Bacterial community composition showed significant (P < 0.05) correlations with salt content and soil pH. Indeed, bacterial phylotype richness and phylogenetic diversity were also higher in soils with middle-level salt rates, and were significantly (P < 0.05) correlated with salt content and soil pH. Overall, our results show that both salinity and pH are the determinants of bacterial communities in saline soils in northwest China.

Introduction to Soil Salinity, Sodicity and Diagnostics Techniques

Abstract: It is widely recognized that soil salinity has increased over time. It is also triggered with the impact of climate change. For sustainable management of soil salinity, it is essential to diagnose it properly prior to take proper intervention measures. In this chapter soil salinity (dryland and secondary) and sodicity concepts have been introduced to make it easier for readers. A hypothetical soil salinity development cycle has been presented. Causes of soil salinization and its damages, socio-economic and environmental impacts, and visual indicators of soil salinization and sodicity have been reported. A new relationship between ECe (mS/cm) and total soluble salts (meq/l) established on UAE soils has been reported which is different to that established by US Salinity Laboratory Staff in the year 1954, suggesting the latter is specific to US soils, therefore, other countries should establish similar relationships based on their local conditions. Procedures for field assessment of soil salinity and sodicity are described and factors to convert EC of different soil:water (1:1, 1:2.5 & 1:5) suspensions to ECe from different regions are tabulated and hence providing useful information to those adopting such procedures. Diversified salinity assessment, mapping and monitoring methods, such as conventional (field and laboratory) and modern (electromagnetic-EM38, optical-thin section and electron microscopy, geostatistics-kriging, remote sensing and GIS, automatic dynamics salinity logging system) have been used and results are reported providing comprehensive information for selection of suitable methods by potential users. Globally accepted soil salinity classification systems such as US Salinity Lab Staff and FAO-UNESCO have been included.

Salt-tolerant and plant-growth-promoting bacteria isolated from high-yield paddy soil.

Abstract: Growth and productivity of rice is negatively affected by soil salinity However, some salt-tolerant bacteria improve the health of plants under saline stress In this study, 305 bacteria were isol