Salinity Management Research Articles

Managing Water and Salt for Sustainable Agriculture in the Indus Basin of Pakistan

The Indus basin of Pakistan occupies about 16 million ha (Mha) of land. The Indus River and its tributaries are the primary sources of surface water. An estimated 122 km3 of surface water is diverted annually through an extensive canal system to irrigate this land. These surface water supplies are insufficient to meet the crop water requirements for the intensive cropping system practiced in the Indus basin. The shortfall in surface water is met by exploiting groundwater. Currently, about 62 km3 of groundwater is pumped annually by 1.36 million private and public tube wells. About 1.0 million tubewells are working only in the Punjab province. Small private tubewells account for about 80% of the pumped volume. Inadequate water allocation along the irrigation canals allows excessive water use by head-end farmers, resulting in waterlogging. In contrast, the less productive use of erratic supplies by tail-end farmers often results in soil salinity. The major issues faced by irrigated agriculture in Pakistan are low crop yields and water use efficiency, increasing soil salinization, water quality deterioration, and inefficient drainage effluent disposal. Currently, 4.5 Mha (about 30% of the total irrigated area) suffers from adverse salinity levels. Critical governance issues include inequitable water distribution, minimizing the extent to which salt is mobilized, controlling excessive groundwater pumping, and immediate repair and maintenance of the infrastructure. This paper suggests several options to improve governance, water and salt management to support sustainable irrigated agriculture in Pakistan. In saline groundwater areas, the rotational priorities should be reorganized to match the delivery schedules as closely as possible to crop demand, while emphasizing the reliability of irrigation schedules. Wherever possible, public tubewells should pump fresh groundwater into distributaries to increase water availability at the tail ends. Any substantial reform to make water delivery more flexible and responsive would require an amendment to the existing law and reconfiguration of the entire infrastructure, including thousands of kilometers of channels and almost 60,000 outlets to farmer groups. Within the existing political economy of Pakistan, changing the current water allocation and distribution laws without modernizing the infrastructure would be complicated. A realistic reform program should prioritize interventions that do not require amendment of the Acts or reconstruction of the entire system and are relatively inexpensive. If successful, such interventions may provide the basis for further, more substantial reforms. The present rotational water supply system should continue, with investments focusing on lining channels to ensure equitable water distribution and reduce waterlogging at the head ends. Besides that, the reuse of drainage water should be encouraged to minimize disposal volumes. The timely availability of farm inputs can improve individual farmers’ productivity. Farmers will need to have access to new information on improved irrigation management and soil reclamation approaches. Simultaneously, the government should focus more on the management of drainage and salinity.

Biogenic copper nanoparticles produced by using the Klebsiella pneumoniae strain NST2 curtailed salt stress effects in maize by modulating the cellular oxidative repair mechanisms

The negative effects of salinity on plant growth and physiology are well-established, which is one of the major threats to food security in semi-arid and arid regions of the world. The current research focuses on biosynthesis of copper nanoparticles (CuNPs) from a bacterial strain NST2, which was genetically identified as Klebsiella pneumoniae based on taxonomic identity of 16S rRNA gene. The strain was selected for bioprospecting of CuNPs owing to its Cu tolerance potential. The biologically-synthesized CuNPs were confirmed in culture by using ultraviolet visible spectroscopy. The material characteristics of green CuNPs were further investigated by using Fourier transform infrared spectroscopy, X-ray diffractometer, scanning electron microscopy and transmission electron microscopy, where crystallite size was ranged from 22.44 nm to 44.26 nm and particles were stabilized by various functional groups, such as carbonyl and amine groups. When 100 mg kg−1 of green CuNPs were mixed in saline soil in a pot experiment, the maize plants showed increased root and shoot length (43.52% and 44.06%, respectively), fresh weight (46.05% and 51.82%, respectively) and dry weight (47.69% and 30.63%, respectively) in comparison to control maize plants without CuNPs application. Moreover, green CuNPs at their highest treatment level (100 mg kg−1 of soil) counteracted the lipid peroxidation and oxidative damage in maize plants by promoting the activities of antioxidants and demoting the cellular levels of reactive oxygen species and ionic contents of Na+ and Cl-. Conclusively, biogenic CuNPs is an emerging and promising technique, which could replace traditional methods of salinity management in agricultural soils.

SALEACH: A new web-based soil salinity leaching model for improved irrigation management

Leaching is essential in irrigated croplands where natural precipitation is insufficient to control salinity buildup. Several useful models exist for salinity management; however, leaching requirement (LR) calculations are based on steady-state approaches that only consider salinity tolerance of crops and irrigation water salinity to estimate the LR. In this study, a web-based soil salinity leaching management model (SALEACH) was developed as an online tool to assist growers for better and easier management of soil salinity to sustain agricultural production in irrigated croplands. SALEACH employs the traditional steady-state approach to estimate LRs but improves outputs by not only considering irrigation water salinity (ECiw) and salinity tolerance of specific crops (ECt), but also root water uptake patterns to account for irrigation system differences, and soil types for differences in hydraulic characteristics, as well as water stress and rainfall input. The SALEACH model can calculate the required irrigation water depth by using the estimated LR or any user-specified leaching fraction (LF) values; it can predict the drainage water salinity and soil salinity in the rootzone based on the applied leaching; and it can estimate relative crop yield for a given LF. SALEACH-estimated LRs were assessed in different soil types and irrigation systems by comparing them with LRs, soil water and drainage water salinity values obtained from an existing steady-state model (WATSUIT) and a transient-state model (HYDRUS-1D). Statistical analyses showed that SALEACH-estimated LRs, soil salinity, and drainage water salinity were all in the acceptable ranges of the corresponding values derived from other models. Thus, we conclude SALEACH is reliable and can be employed by practitioners to produce satisfactory estimations of LRs and soil salinity by considering the soil, crop, water quality, and irrigation system. Adoption of the model can improve water use efficiency and reduce groundwater pollution.

Impact of lockdown due to COVID-19 pandemic on groundwater salinity in Punjab, India: some hydrogeoethics issues.

In the present study, a total of 48 groundwater samples (13 from shallow aquifers depth < 50 m and 35 samples from deep aquifers in the depth range 50–200 m) were collected from three industrial dominant districts (Ludhiana, Jalandhar and Moga) of Punjab after the lockdown period and before the start of southwest monsoon in the month of June, 2020 (pre-monsoon). The values for total dissolved solids (TDS) observed in Monsoon season (August, 2020) and November–December, 2019 (post-monsoon) were compared with the values taken in June, 2020 (pre-monsoon) to see the impact of lockdown due to COVID-19 pandemic on groundwater salinity. ~ 60% of samples were found to have TDS values more than acceptable limit (500 mg/l) before lockdown (post-monsoon season of 2019) period and after or during lockdown period (June, 2020) number of samples more than the acceptable limit (500 mg/l) reduced to 45%. Average TDS values reduced by 25% in shallow aquifers after lockdown and area under TDS values in acceptable limit (500 mg/l) increased by 23% of samples as compared to the TDS values found in monsoon season of year 2019. In deeper aquifers, increase of only 3% area under TDS values in acceptable limit of 500 mg/l was found. Reductions in TDS values in shallow aquifers clearly show that there is an urgent need for proper management of salinity causing elements and regulating these to check groundwater contaminations using the holistic and hydro-geoethical approach.

Monitoring land use and soil salinity changes in coastal landscape: a case study from Senegal

Soil salinity is a major issue causing land degradation in coastal areas. In this study, we assessed the land use and soil salinity changes in Djilor district (Senegal) using remote sensing and field data. We performed land use land cover changes for the years 1984, 1994, 2007, and 2017. Electrical conductivity was measured from 300 soil samples collected at the study area; this, together with elevation, distance to river, Normalized Difference Vegetation Index (NDVI), Salinity Index (SI), and Soil-Adjusted Vegetation Index (SAVI), was used to build the salinity model using a multiple regression analysis. Supervised classification and intensity analysis were applied to determine the annual change area and the variation of gains and losses. The results showed that croplands recorded the highest gain (17%) throughout the period 1984–2017, while forest recorded 3%. The fastest annual area of change occurred during the period 1984–1994. The salinity model showed a high potential for mapping saline areas (R2 = 0.73 and RMSE = 0.68). Regarding salinity change, the slightly saline areas (2 < EC < 4 dS/m) increased by 42% whereas highly saline (EC > 8 dS/m) and moderately saline (4 < EC < 8 dS/m) areas decreased by 23% and 26%, respectively, in 2017. Additionally, the increasing salt content is less dominant in vegetated areas compared with non-vegetated areas. Nonetheless, the highly concentrated salty areas can be restored using salt-resistant plants (e.g., Eucalyptus sp., Tamarix sp.). This study gives more insights on land use planning and salinity management for improving farmers’ resilience in coastal regions.

Salinity-affected threshold yield loss: A signal of adaptation tipping points for salinity management of dry season rice cultivation in the coastal areas of Bangladesh

The potential existence of threshold yield loss in dry season rice growing systems under coastal saline environment remains unexplored, a scenario that could have policy relevance in government planning of rice intensification in the coastal areas of Bangladesh. This study applied the adaptation tipping points (ATPs) approach to investigate threshold yield loss from multiple perspectives of farmers affected by salinity. Data were generated from 280 randomly-selected farmers (rice farmers, n = 109; shrimp farmers, n = 107; salt farmers, n = 64) from two coastal sub-districts using a semi-structured survey. Key informant interviews and focus group discussions were conducted to complement the survey results. Our study revealed that despite government actions to promote dry season rice cultivation, farmers have been growing less rice in this season, with salinity-affected yield loss being the prime reason. Most of the rice farmers have considered that they would discontinue rice cultivation in this season due to yield loss, while shrimp and salt farmers have already reduced rice cultivation for the same reason and shifted to shrimp and salt farming as they perceived these enterprises as highly profitable and require less labour than rice farming. Rice farmers would tolerate a greater rice yield loss (23%) under saline conditions compared with the shrimp (16%) and salt farmers (14%). The yield loss thresholds indicate the need for government actions to support and encourage integrated land management for rice, shrimp and salt farming, rather than research and extension efforts for dry season rice expansion alone. These actions could strengthen sustainable livelihood options to ensure food security, and contribute to the achievement of sustainable development goals, for instance no poverty (SDG-1), zero hunger (SDG-2), and good health and well-being (SDG-3).

Calcium in the mineral nutrition of yellow passion fruit cultivated in lined pits and with saline water

ABSTRACT Nutritional status is an important tool in salinity management, because salt stress interferes with both the absorption and the assimilation of mineral nutrients by plants. The objectives of this experiment were to evaluate the effects of water salinity, lateral protection of pits against water losses and calcium doses on the leaf concentration of macronutrients and sodium of yellow passion fruit cv. BRS GA1. The treatments were arranged in a randomized block design in split plots in a 2 × (2 × 5) factorial scheme, corresponding to water salinity (0.3 and 4.0 dS m-1) in the main plot, and the combinations between lateral protection of pits (without and with) and calcium doses (0, 30, 60, 90 and 120 kg ha-1) in the subplots. Leaf concentrations of macronutrients and sodium were determined at the phenological stage of full flowering. Irrigation of yellow passion fruit with 4.0 dS m-1 water decreased the leaf concentrations of macronutrients. The lining of the pits compromised macronutrient concentration in the plants. Calcium fertilization is recommended for yellow passion fruit cultivated in Entisol with low calcium concentration at the dose of 60 kg ha-1, because it raises nitrogen and calcium concentrations in plants irrigated with non-saline water and magnesium and sulfur concentrations in those irrigated with saline water. Calcium attenuates salt stress because it promotes the accumulation of macronutrients in yellow passion fruit under saline conditions.

Umbilical vein injection for management of retained placenta.

Umbilical vein injection for management of retained placenta.

Role of Ion Chemistry and Hydro-Geochemical Processes in Aquifer Salinization—A Case Study from a Semi-Arid Region of Haryana, India

In the present study, a total of sixty groundwater samples, twenty each for the pre-monsoon, monsoon and post monsoon seasons of 2018, were collected from selected locations in the Mewat district of Haryana, India. Electrical conductivity (EC) was measured at the site and total dissolved solids (TDS) were estimated. Samples were analysed for anions (chloride, sulphate, and bicarbonate) and cations (calcium, potassium, magnesium, and sodium). Multiple regression analysis was performed to analyse the data and report the dominant ions. Piper trilinear diagram and Gibbs plots were used to find out the water type and the factors controlling the chemistry of the groundwater, respectively. The saturation index of CaCO3, CaSO4 and NaCl was determined, using the PHREEQC MODEL. Sodium and calcium among cations, and chloride among the anions, had the highest degree of affinity and strong significance for all three seasons. The calcium–chloride water type dominated for all three seasons and Gibbs plot depicted that most of the Na+/Na+ + Ca2+ and Cl−/Cl− + HCO3− ratios show the weathering of rocks to form minerals as the major reason behind the ionic chemistry of the groundwater. The highest level of dissolution is encountered in the case of NaCl, followed by CaSO4, whereas CaCO3 depicts precipitation. The geochemical aspects of weathering, evaporation and ion exchange are the major processes responsible for high salinity, and anthropogenic activities are leading to its expansion. The findings from this study will be useful in management and remediation of groundwater salinity of the region.

Space-time modelling of groundwater level and salinity

Soil salinization resulting from shallow saline groundwater is a major global environmental issue causing land degradation, especially in semi-arid regions such as Australia. The adverse impact of shallow saline groundwater on soil salinization varies in space and time due to the variation in groundwater levels and salt concentration. Understanding the spatio-temporal variation is therefore vital to develop an effective salinity management strategy. In New South Wales, Australia, a hydrogeological landscape unit approach is generally applied, based on spatial information and expert operators, classifying the landscape in relation to landscape and climate. In this paper, a data science approach (random forest model) is introduced, based on historical groundwater quality and quantity data providing predictions in a 4-dimensional space. As a case study, we demonstrate the spatio-temporal factors impacting standing water levels (SWL) and associated salinity and predict the spatial and temporal variability in the Muttama catchment (1059 km2), in NSW, south eastern Australia. The random forest model explains 77% of the variance in the groundwater salinity (electrical conductivity) and 65% of the SWL. Spatial factors were the most significant variables determining the space-time variation in groundwater salinity and the occurrence of groundwater at the surface. Drilled piezometer depth and elevation are dominant factors controlling SWL, while salinity is mainly determined by underlying geology. The methodology in this study predicts salinity and SWL in the landscape at fine scales, through time, improving options for salinity management.

Socioeconomic, biophysical, and environmental impacts of raised beds in irrigated wheat: A case study from Egypt

Raised beds (RB) are hailed as means to mitigate the problem of excessive irrigation. However, their adoption and impacts in Egypt are not well-documented. This paper is based on survey data collected from a sample of 691 wheat fields drawn from three major wheat-producing provinces of Egypt. Using area-weights for upward aggregation, we estimated that 19.3% of total wheat area in the three provinces is cultivated with raised beds. We applied the endogenous switching regression model to analyze the socioeconomic, biophysical, and environmental impacts of RB. Model results showed that the adoption of RB led to a 937 kg/ha (12.79%) increase in yield, a US$77.60/ha (9.47%) increase in gross margins, an 824.63 m3/ha (15.05%) reduction in irrigation water application, 16.7% reduction in seeding rate, 5.56% increase in water productivity, and an 11.80% reduction in downside yield risk. Adoption of RB didn’t have significant effect on soil salinity and quantities of fertilizer and labor inputs. These results show that RB can provide panacea to several interrelated socioeconomic, biophysical, and environmental problems associated with irrigation. The policy implication of our findings is that Egypt and other similar countries can benefit from embracing RB as part of the technology packages promoted by their national agricultural extension systems. The benefits to these countries will increase if they invest more on research for adapting and perfecting the RB technology including its mechanization and its efficacy in soil salinity management.

IMPACT OF THE USE OF IRRIGATION WATER ON SOIL SALINIZATION CASE OF THE PALM GROVE OF BORDJ BEN AZOUZ BBA-BISKRA (ZIBAN OASIS, SOUTH-EASTERN ALGERIA)

This work deals with the physicochemical quality of water irrigation of agricultural land in the palm grove of Bordj ben Azouz. The aim is to evaluate their ability to irrigate palm groves and their effects on soil change under irrigation in the presence and / or absence of drainage. A hydro geochemical assessment of the groundwater, as well as drainage and. soil samples from irrigated and non-irrigated are performed. The electrical conductivity associated with the geochemical facies and SAR (Sodium adsorption Ratio) reflect a global salinity of the water irrigation, the drainage waters follow the same general trend as that the waters of the wells, the soils show a significant difference of the salinity between the irrigated / drained ones and the others not. The geochemical simulation was carried out using a thermodynamic model of the software Phreeqc Interactive 3.1.4-8929 indicates the supersaturation of the water with respect to the carbonate minerals and the under saturation for the evaporites where the gypsum is close to saturation even exceeds it so that it can precipitate itself by forming the gypso-limestone crust (Debdeb). To protect the environment from saline pollution, a sustainable water and salinity management plan must be installed as well as possible and continuous monitoring of the drainage system are required to remove salt water from irrigated soil.

Crop and Residue Management Improves Productivity and Profitability of Rice–Maize System in Salt-Affected Rainfed Lowlands of East India

This study was conducted over 3 years in a salt-affected coastal rainfed lowland ecosystem. Farmers most commonly grow tall rice varieties in the wet season to cope with flash and/or stagnant floods, leading to large amounts of rice residue production. Most of the land remains fallow during the dry season because of increased salinity and scarcity of freshwater for irrigation. The study aims to provide options for increasing cropping intensity through management of crop residues (CR) and soil salinity, conservation of soil moisture, and reduction in production cost. The rice–maize rotation was assessed with rice as the main plot as (1) puddled transplanted rice (PTR) with CR of both rice and maize removed, (2) PTR and 40% CR of both crops retained, (3) dry direct-seeded rice (DSR) with CR of both crops removed, and (4) DSR with 40% CR of both crops retained. Maize in the dry season was supplied with different N levels as sub-plots—control (0 kg N ha−1), 80, 120, and 160 kg N ha−1. DSR, when combined with CR retention (DSR + R), reduced soil salinity. The increase in rice grain yield with CR retention (observed in second and third years) and crop establishment (higher in DSR versus PTR in the third year) was 16 and 24%, respectively. The cost of production increased by 17% (USD 605 ha−1) in PTR compared with DSR (USD 518 ha−1). CR retention reduced irrigation water requirement by 37% and N requirement by 40 kg ha−1 for hybrid maize. When CR was removed (−R), the N requirement for hybrid maize increased to 160 kg N ha−1 compared to when it was partially (40%) retained, where the requirement was 120 kg ha−1 with similar yields. Available N was highest under DSR + R (314 kg ha−1) and lowest under PTR − R (169 kg ha−1), and it also increased with increasing N application up to 120 kg ha−1 (+R) and 160 kg ha−1 (−R). The results of the study hold promise for increasing cropping intensity and farmers’ incomes, with broader implications for increasing productivity on about 2.95 million hectares currently under a rice–fallow system in eastern India, and in coastal areas affected by similar conditions in South and Southeast Asia.

Irrigation efficiency, drain outflow and yield responses to drain depth in the Nile delta clay soil, Egypt

The conventional sub-surface drainage (FD) in the Nile delta clay soil, northern Egypt, results in excessive drainage and low irrigation efficiency (IE). However, a shallower placement of drain might reduce drain outflow and increase IE. The ultimate objective of the present study was to determine the optimum drain depth that minimizes drain outflow and maximizes IE and irrigation water use efficiency (IWUE), while maintaining crop yield and soil salinity. Compared to FD at 120 cm below the soil surface (BSS), the effect of four controlled drain depths (CD) at 40, 60, 80 and 100 cm BSS on drain outflow, IE, salinity buildup, yield and IWUE were investigated for two seasons (2017–18 and 2018–19; wheat-sunflower cropping system). Measurements were conducted for sunflower (as a summer crop). Irrigation was applied based on the soil water content of FD-treatment, thus irrigation depth varied for each treatment. The results showed that decreasing drain depth significantly reduced drain outflow and water input, while IE, seed yield and IWUE were increased. The maximum seed yield and IWUE were obtained at the shallowest drains. Compared with FD at 120 cm, drain depth at 40 cm decreased drain outflow (by 77.20%) and water input (by 29.3%), while increased seed yield and IWUE by 27% and 86%, respectively. Based on water balance, water-uptake from shallow groundwater was maximum for CD-40 cm treatment (31.05% of water-uptake) and was significantly higher than the other treatments. However, by the end of the second season, treatment with drain depth at 40 cm BSS recorded the highest soil salinity (3.6 dS m−1) due to the upward capillary rise of shallow groundwater. Increased soil salinity had no effect on seed yield because it was below the salinity threshold of sunflower. In terms of IE and IWUE, decreasing drain depth to 40 cm BSS is recommended, but with potential salinity buildup. Therefore, drain at 60 cm BSS (had similar seed yield to drain at 40 cm BSS) might lead to significant water-saving (21.8%), while maintaining seed yield and soil quality. In conclusion, modifying the drainage system by reducing drain depth and considering crop water-uptake from shallow groundwater might contribute to water saving. After all, careful water and soil management (e.g., periodic leaching), and suitable cropping systems should be considered for salinity management when decreasing drain depth.

Production and quality of watermelon fruits under salinity management strategies and nitrogen fertilization

The objective of this study was to evaluate the production and quality of ‘Sugar Baby’ watermelon fruits under different strategies of irrigation with saline water and nitrogen (N) fertilization in an experiment conducted in a protected environment in Campina Grande, Paraíba, Brazil. The experimental design adopted was in blocks with a 6 × 2 factorial scheme, corresponding to six strategies of irrigation with saline water applied at different phenological stages of the crop (SE irrigation with low-salinity water throughout the cycle; salt stress at the vegetative stage VE; vegetative and flowering VE/FL; flowering FL; fruiting FR; fruit maturation MAT) and two N doses (50 and 100% of the recommendation, equivalent to 50 and 100 mg of N kg-1 of soil) with five replicates. Two levels of irrigation water salinity were studied, one with low and the other with high electrical conductivity (ECw = 0.8 and 3.2 dS m-1). The salt stress applied at the vegetative and flowering stages reduced the contents of ascorbic acid and total soluble solids in ‘Sugar Baby’ watermelon fruits. The dose equivalent to 50% of the N recommendation promoted a greater fresh weight of watermelon fruits. Fertilization with 100% of N increased the hydrogen potential of watermelon fruits under salt stress at the vegetative and flowering stages. The anthocyanin content of watermelon fruits decreased under salt stress, regardless of the development stage; however, with 50% of recommendation of N, there was an increase in this variable.

Salinity management strategies and potassium fertilization in watermelon (Citrullus lanatus) cultivation

This study aimed to evaluate the gas exchanges and growth of ‘Sugar Baby’ watermelon under different strategies of irrigation with saline water and potassium fertilization, in an experiment conducted in a protected environment. The experiment was conducted in randomized blocks, in 8 x 3 factorial arrangement, corresponding to eight water salinity management strategies applied at the phenological stages of the crop (NS = no stress along the cycle; VE = salt stress during vegetative stage; VE/FL = salt stress during vegetative and flowering stages; FL = salt stress during flowering stage; FL/FR = salt stress during flowering and fruiting stages; FR = salt stress during fruiting stage; FR/MAT = salt stress during fruiting and maturation stages; MAT = salt stress during fruit maturation stage) and three potassium doses – KD (corresponding to 50, 100 and 150% of the recommendation), with three replicates. Two levels of water salinity were used, high and low values of electrical conductivity (ECw = 0.8 and 4.0 dS m-1). Watermelon growth and gas exchanges, especially transpiration, stomatal conductance, CO2 assimilation rate, instantaneous carboxylation efficiency, and absolute and relative growth rates of stem diameter were compromised by water salinity at the stages of flowering, fruiting and maturation. The potassium dose with 50% of K2O recommendation can be used in the cultivation of watermelon, without negatively affecting gas exchange and growth.

Soil salinization management for sustainable development: A review

The expansion of irrigated agriculture is of paramount importance to feed the burgeoning global population. However, without proper management, this expansion can result in environmental problems of irrigation-induced soil salinization. A recent FAO estimate reported that a large portion of total global soil resources are degraded and this problem is persistently expanding. Many irrigated areas of the world are facing the twin problems of soil salinization and waterlogging and presently over 20% of the total global irrigated area is negatively affected by these problems. And, if left unattended, this problem could expand to over 50% of the total global irrigated areas by 2050. The proper management of the aforementioned soil salinization is imperative for achieving most of the Sustainable Development Goals (SDGs) of the United Nations. For example, soil salinization management is vital for achieving the ‘Zero Hunger’ (SDG2) and ‘Life on Land’ (SDG15) among other SDGs. This paper provides a comprehensive review of different measures used for managing the environmental problems of soil salinization. All the possible sources of related and up to date literature have been accessed and over 250 publications were collected and thoroughly analyzed for this review. The centrality of the environmental problems is provided. The background of the problems, managing rising water table to control soil salinization, the role of drainage frameworks, the conjunctive use of diverse water sources, utilization of numerical models, and the use of remote sensing and GIS systems are described. And the application of the aforementioned techniques and methods in various case study regions across the globe are discussed which is followed by discussion and research gaps. Derived from the literature analysis and based on the identified research gaps, some key recommendations for future research have been made which could be useful for the stakeholders. The literature analysis revealed that an all-inclusive approach for dealing with the aforesaid environmental problems has been barely considered in the previous studies. Similarly, the continuing impacts of growing salt-tolerant plants on soil characteristics and the environment in total have not been widely considered in the previous investigations. Likewise, better irrigation practices and improved cropping systems along with the long-term environmental impacts of a particular approach has not been extensively covered in these studies. Also, previous studies have scarcely incorporated economic, social, and environmental aspects of the salinization problem altogether in their analysis. The analysis suggested that an inclusive feedback-supported simulation model for managing soil salinization should be considered in future research as the existing models scarcely considered some vital aspects of the problem. It is also suggested to enhance the sensing methods besides retrieval systems to facilitate direct detection of salinization and waterlogging parameters at large-scales. The existing time-lag between occurrence and recording of various data is also suggested to improve in the future scenario by the usage of information from multiple satellites that lessens the problems of spatial resolution by increasing the system efficiency.

Brackish water pond management strategies based on salinity and pyrite distribution in the Mahakam Delta, East Kalimantan

Brackish water ponds in the Mahakam delta are located in the area that has acidic soil and is affected by the distribution of salinity. This study aims to analyze brackish water pond management strategies based on salinity and pyrite distribution. The location of this research was in the local farmers’ brackish water ponds in the Mahakam delta, East Kalimantan. Sampling collection was carried out on several brackish water ponds with different salinity, namely salinity of 0 – 10 ppt, 11 – 20 ppt, and 21 – 30 ppt. Each type of salinity was represented by 10 brackish water ponds. Samples were selected using a purposive sampling technique in which respondents consisted of farmers, academics, and the government. Data were analyzed using the Analytic Hierarchy Process and qualitative descriptive methods. The results indicated that the alternative pond management strategies employed in the Mahakam delta were brackish water pond management with salinity and pyrite management approaches (0.312), brackish water pond management with pyrite management approach (0.222), and brackish water pond biophysical management (0.155).

Emulation of a Process-Based Salinity Generator for the Sacramento–San Joaquin Delta of California via Deep Learning

Salinity management is a subject of particular interest in estuarine environments because of the underlying biological significance of salinity and its variations in time and space. The foremost step in such management practices is understanding the spatial and temporal variations of salinity and the principal drivers of these variations. This has traditionally been achieved with the assistance of empirical or process-based models, but these can be computationally expensive for complex environmental systems. Model emulation based on data-driven methods offers a viable alternative to traditional modeling in terms of computational efficiency and improving accuracy by recognizing patterns and processes that are overlooked or underrepresented (or overrepresented) by traditional models. This paper presents a case study of emulating a process-based boundary salinity generator via deep learning for the Sacramento–San Joaquin Delta (Delta), an estuarine environment with significant economic, ecological, and social value on the Pacific coast of northern California, United States. Specifically, the study proposes a range of neural network models: (a) multilayer perceptron, (b) long short-term memory network, and (c) convolutional neural network-based models in estimating the downstream boundary salinity of the Delta on a daily time-step. These neural network models are trained and validated using half of the dataset from water year 1991 to 2002. They are then evaluated for performance in the remaining record period from water year 2003 to 2014 against the process-based boundary salinity generation model across different ranges of salinity in different types of water years. The results indicate that deep learning neural networks provide competitive or superior results compared with the process-based model, particularly when the output of the latter are incorporated as an input to the former. The improvements are generally more noticeable during extreme (i.e., wet, dry, and critical) years rather than in near-normal (i.e., above-normal and below-normal) years and during low and medium ranges of salinity rather than high range salinity. Overall, this study indicates that deep learning approaches have the potential to supplement the current practices in estimating salinity at the downstream boundary and other locations across the Delta, and thus guide real-time operations and long-term planning activities in the Delta.

Exogenous Application of Melatonin Induces Tolerance to Salt Stress by Improving the Photosynthetic Efficiency and Antioxidant Defense System of Maize Seedling

Melatonin is a ubiquitous signaling plant hormone that plays a crucial role in regulating the growth and development of plants under stress conditions. Since a few species have been investigated to unveil the effect of exogenous melatonin on salt stress, in the current research study, we investigated the effects of melatonin by measuring the photosynthetic characteristics and antioxidant defense system of maize seedling under salt stress (200 mM NaCl), along with different concentrations of melatonin (MT1—30, MT2–60, and MT3–90 µM) treatments. Salt stress reduced the plant growth characteristics and photosynthetic efficiency by increasing the ROS accumulation and reducing the antioxidant enzyme activities of maize seedling. However, pretreatment with melatonin on roots alleviated NaCl-induced decrease in photosynthetic rate and oxidative stress in a dose-dependent manner. Our results revealed that exogenous application of melatonin at an optimum concentration (60 µM) under salt stress conditions significantly increased the growth of plants, chlorophyll content, photosynthetic efficiency, antioxidant enzymes activities, i.e., superoxide dismutase (SOD), peroxide (POD), catalase (CAT) and ascorbate peroxidase (APX), and reduced the reactive oxygen species (ROS). This study unraveled the crucial role of melatonin in salt stress mitigation and thus can be implicated in the management of salinity in maize seedling.