Salinity Problems Research Articles

Comparative Transcriptomic Analyses Reveal Differences in the Responses of Diploid and Triploid Eastern Oysters to Environmental Stress.

Triploid oysters are commonly used as the basis for production in the aquaculture of eastern oysters along the USA East and Gulf of Mexico coasts. While they are valued for their rapid growth, incidents of triploid mortality during summer months have been well documented in eastern oysters, especially at low salinity sites. We compared global transcriptomic responses of diploid and triploid oysters bred from the same three maternal source populations at two different hatcheries and outplanted to a high (annual mean salinity = 19.4 ± 6.7) and low (annual mean salinity = 9.3 ± 5.0) salinity site. Oysters were sampled for gene expression at the onset of a mortality event in the summer of 2021 to identify triploid-specific gene expression patterns associated with low salinity sites, which ultimately experienced greater triploid mortality. We also examined chromosome-specific gene expression to test for instances of aneuploidy in experimental triploid oyster lines, another possible contributor to elevated mortality in triploids. We observed a strong effect of hatchery conditions (cohort) on triploid-specific mortality (field data) and a strong interactive effect of hatchery, ploidy, and outplant site on gene expression. At the low salinity site where triploid oysters experienced high mortality, we observed downregulation of transcripts related to calcium signaling, ciliary activity, and cell cycle checkpoints in triploids relative to diploids. These transcripts suggest dampening of the salinity stress response and problems during cell division as key cellular processes associated with elevated mortality risk in triploid oysters. No instances of aneuploidy were detected in our triploid oyster lines. Our results suggest that triploid oysters may be fundamentally less tolerant of rapid decreases in salinity, indicating that oyster farmers may need to limit the use of triploid oysters to sites with more stable salinity conditions.

Long-term potato response to different irrigation scheduling methods using saline water in an arid environment

Crops’ water requirement is generally higher than the annual average precipitation in arid environments characterized by scarce freshwater resources. While using saline water for irrigation can help sustain agriculture in water-stressed regions, several challenges arises concerning productivity and soil salinization. However, adoption of efficient irrigation techniques such as drip irrigation, irrigation scheduling, and deficit irrigation can help optimize water productivity and mitigate salinity problems in irrigated agriculture. In southern Tunisia, potato is considered among the main cultivated horticultural crops due to its high economic value while it is considered as a crop sensitive to salinity. This crop (cv. Spunta) was the subject of long-term studies (2002–2020) conducted during the fall period in the arid region of Médenine. The crop response to full and deficit irrigation with saline water was assessed for several seasons under contrasting climatic conditions. Scheduling using the soil water balance (SWB) method consisted of the total and/or partial replacement of accumulated crop evapotranspiration (ETc), as derived from climatic data and crop coefficients. The impact of decreasing amounts of irrigation waters on crop yield and soil salinity with waters having a salinity ranging between 3 and 7 dS m−1 was evaluated. Results showed improvements in yield (30% to 37%) obtained with the SWB strategy under actual farming conditions, supporting the use of this strategy for irrigation. Appropriate scheduling also seems to be a key element in saving water (15%–22%) and in reducing risks of soil salinization. In the dry environment of southern Tunisia, optimum supply seems to correspond to a replacement of 100% to approximately 70%–80% of ETc. Applying such irrigation levels resulted in a lower salinity buildup in the root zone and higher crop water productivity. Natural salt leaching seems to be more effective under a more humid soil profile. Yield decreases and soil salinity increases almost linearly (r2 = 0.60) with decreasing irrigation water amounts. Future work should focus on the integration of management practices when using saline water. Investigating the relationship and interaction between irrigation amounts, cultivar, fertilizer supply, and salt leaching will help in resolving productivity and environmental issues.

Assessment of microbial diversity in various saline soils driven by salt content

The Yellow River Delta, as an important reserve land resource area, faces soil salinization problems. Understanding the bacterial community composition in saline soils is an important foundation for control and utilization of saline soils. However, few studies have been conducted on the composition of bacterial communities in soils with different degrees of salinization. Thus, saline soils categorized into low-salinity (LS), medium-salinity (MS), and high-salinity (HS) based on electrical conductivity (EC) were collected. The 16S rRNA high-throughput sequencing analysis was performed to analyze the effects of salinities on soil bacterial community patterns, as well as the relationships between soil bacterial communities and environmental factors. The results showed that Actinobacteriota, Proteobacteria, Chloroflexi, Firmicutes, Acidobacteriota, Gemmatimonadota and Bacteroidota accounted for almost 90 % of all the bacterial community. The linear discriminant analysis effects (LDA > 3.7) showed that 6, 5 and 3 biomarkers were present in LS, MS and HS soils, respectively, which indicated EC was an important factor influencing the saline soil bacterial community patterns. Redundancy analysis further revealed that the primary environmental parameters impacting the bacterial community were pH, EC, nitrate nitrogen, available phosphorus, total phosphorus, and soil organic matter. According to network analysis, the microbial network complexity was increased steadily with increasing of soil salinity. These findings together revealed that bacterial communities could serve as a reliable way to assess and improve the quality of salinized soils.

RNA-Seq and WGCNA Analyses Reveal Key Regulatory Modules and Genes for Salt Tolerance in Cotton.

The problem of soil salinization has seriously hindered agricultural development. Cotton is a pioneering salinity-tolerant crop, so harvesting its key salinity-tolerant genes is important for improving crop salt tolerance. In this study, we analyzed changes in the transcriptome expression profiles of the salt-tolerant cultivar Lu Mian 28 (LM) and the salt-sensitive cultivar Zhong Mian Suo 12 (ZMS) after applying salt stress, and we constructed weighted gene co-expression networks (WGCNA). The results indicated that photosynthesis, amino acid biosynthesis, membrane lipid remodeling, autophagy, and ROS scavenging are key pathways in the salt stress response. Plant-pathogen interactions, plant hormone signal transduction, the mitogen-activated protein kinase (MAPK) signaling pathway, and carotenoid biosynthesis are the regulatory networks associated with these metabolic pathways that confer cotton salt tolerance. The gene-weighted co-expression network was used to screen four modules closely related to traits, identifying 114 transcription factors, including WRKYs, ERFs, NACs, bHLHs, bZIPs, and MYBs, and 11 hub genes. This study provides a reference for acquiring salt-tolerant cotton and abundant genetic resources for molecular breeding.

Assessing RO and NF Desalination Technologies for Irrigation-Grade Water

In this work, the performance of a Reverse Osmosis (RO) process using different types of reverse osmosis (RO) and nanofiltration (NF) membranes is evaluated for brackish water desalination for producing irrigation-grade water. The proposed desalination system is a single-stage system, where three types of RO and two NF membranes were examined. The different desalination systems were simulated using ROSA72 software. In order to validate the theoretical model, the results obtained from the simulation were compared to those obtained from the experiment conducted in this work. The El-Moghra aquifer of Egypt is considered the test bed due to a considerable amount of data being available for this aquifer. The El-Moghra aquifer has 79 wells, and the available water data, when checked against several quality parameters, show that none of the investigated wells are suitable for direct irrigation without treatment due to problems of salinity, the sodium adsorption ratio, and low water quality according to the irrigation water quality index values. The obtained results show that nanofiltration membranes exhibited superior energy efficiency compared to reverse osmosis membranes. However, what sets the nanofiltration membranes apart is their ability to elevate water quality in 89.9% of the total investigated wells to an acceptable level for agricultural purposes. This underscores the nanofiltration membranes as a highly effective alternative to reverse osmosis membranes, demonstrating the capability to produce water suitable for irrigation while concurrently reducing operational costs due to the lower energy consumption in nanofiltration-based systems.

The Formation Mechanism of Soil Interflow in Loess Hill Gully

To address the problems of salinization of the soil in gully control and land-making projects, the formation mechanism of soil interflow from a gully valley on the Loess Plateau was investigated, regarding its interface, water source, and spatial-temporal distribution characteristics, through field location monitoring and isotope tracer technique. The results showed the following: (1) there are two types of soil interflow in the Loess Plateau, namely soil interflow in slope and in gully, with interflow in gully being the main form; (2) adequate water supply, layered soil structure, and geographic disparity are conditions for the formation of soil interflow in the gully; (3) soil water is recharged by precipitation, surface water, and groundwater. Surface water is an important source of soil water recharge at the 0–100 cm depth, whereas groundwater is an important source of soil water recharge at the 100–200 cm depth. The results provide a basis for the regulation of the soil interflow, resource utilization, and land quality improvement in the Loess Plateau.

Optimal groundwater depth and irrigation amount can mitigate secondary salinization in water-saving irrigated areas in arid regions

Secondary salinization poses a significant threat to the sustainable development of water-saving irrigation districts. This study aims to explore the spatial and temporal variations in soil salinity and the factors influencing these changes in water-saving irrigation areas in the inland arid regions of Northwest China. The Manas River Irrigation District was selected as the study area. A grid measuring 10 km × 14 km grid was designed to determine the latitude and longitude coordinates of the grid centers, resulting in 66 sample points. Soil samples were collected from these points in 2013, 2014, 2020, and 2021 from the 0100 cm layer to obtain salinity data. Based on existing research and practical conditions in water-saving irrigation areas, 11 factors influencing soil salinity changes were identified, including irrigation area and irrigation amount. Classical statistical methods and interpretable machine learning techniques were employed to analyze the distribution characteristics of soil salinity and the influencing factors. This analysis proposes effective solutions to mitigate potential secondary salinization in irrigation areas. The results revealed that soil salinity in the irrigation area belonged to moderate variation (Cv = 46.74 %51.80 %). The horizontal direction of the irrigation area shows higher salt content in the upstream and downstream areas, and a gradual decrease in variability with increasing depth characterizes the vertical direction. From 2013–2021, soil salinization in the irrigation area gradually decreased. In 2013 and 2014, the area was predominantly covered by mild saline-alkali soil, accounting for 75.1 % and 76.6 % of the total area, respectively. However, in 2020 and 2021, non-saline soils became dominant, covering 60.9 % and 66.5 % of the total irrigation area, respectively. In order of importance, the factors affecting the spatial and temporal evolution of soil salinity are groundwater depth, annual water surface evaporation, water-saving irrigation area, underground water diversion amount, mineralization of groundwater, irrigation amount, surface water diversion amount, and annual rainfall. In the oasis irrigation area, maintaining a groundwater depth of 4.06.0 m and an irrigation amount of 55006000 m3 ha−1 can alleviate the problem of secondary salinization that may result from large-scale development of water-saving irrigation. The findings of this study provide a basis for the prevention and control of soil salinization in water-saving irrigation areas and the development and management of saline land in oasis areas.

Trends and Directions in Oats Research under Drought and Salt Stresses: A Bibliometric Analysis (1993-2023).

With global climate change leading to increasing intensity and frequency of droughts, as well as the growing problem of soil salinization, these factors significantly affect crop growth, yield, and resilience to adversity. Oats are a cereal widely grown in temperate regions and are rich in nutritive value; however, the scientific literature on the response of oat to drought and salt stress has not yet been analyzed in detail. This study comprehensively analyzed the response of oat to drought stress and salt stress using data from the Web of Science core database and bibliometric methods with R (version4.3.1), VOSviewer (version 1.6.19), and Citespace (version6.3.1.0) software. The number of publications shows an increasing trend in drought stress and salt stress in oat over the past 30 years. In the field of drought-stress research, China, the United States, and Canada lead in terms of literature publication, with the most academic achievements being from China Agricultural University and Canadian Agricultural Food University. The journal with the highest number of published papers is Field Crops Research. Oat research primarily focuses on growth, yield, physiological and biochemical responses, and strategies for improving drought resistance. Screening of drought-tolerant genotypes and transformation of drought-tolerant genes may be key directions for future oat drought research. In the field of salt-stress research, contributions from China, the United States, and India stand out, with the Chinese Academy of Agricultural Sciences and Inner Mongolia Agricultural University producing the most significant research results. The largest number of published articles has been found in the Physiologia Plantarum journal. Current oat salt-stress research primarily covers growth, physiological and biochemical responses, and salt-tolerance mechanisms. It is expected that future oat salt research will focus more on physiological and biochemical responses, as well as gene-editing techniques. Despite achievements under single-stress conditions, combined drought and salt-stress effects on oat remain understudied, necessitating future research on their interaction at various biological levels. The purpose of this study is to provide potential theoretical directions for oat research on drought and salt stress.

SALINE MAPS OF SOME SOILS OF MUTHANNA GOVERNORATE

performed based on data collected from 15 soil samples from 0 to 20 cm deep. We used salinity of the irrigated soils of Al-Muthana governorate in southern Iraq. These maps were 20% of the world's land. This study was made in order to map the spatial distribution of soil or anthropogenic processes, which is certainly an environmental problem that affects more than environment and agricultural production. The main causes of this salinization come from natural It is important to study the problem of salinization, soil salinity has adverse effects both on the ordinary kriging (OK) to analyze the spatial variability of soil salinity, The results confirmed that the use of saline maps was supportive in giving a clear vision of the of 12.11 dS m-1, for developing probability maps to determine the distribution of risk areas. showed the different classes of salinity with the highest value of 23.17 dS m-1 and lowest value map predicted by the electrical conductivity (EC) values using the ordinary kriging (OK) method while indicator kriging (IK) was used to analyze salinity versus threshold values . The salinity salinity of the soils for the study area

Spatial analysis and mapping of intensity and types of agricultural salt-affected soils around Abaya and Chamo Lakes, South Ethiopia Rift Valley

PurposeSalt-affected soils have significant enough salt concentrations to impact other land and soil resource uses, plant health, soil characteristics, and water quality. Consequently, a study was carried out in the South Ethiopian Rift Valley area around the lakes of Abaya and Chamo to determine the intensity and the types of salt-affected soil and map their spatial distributions. MethodsAt 0–20 cm depths, a grid soil sampling scheme was employed to gather data from agricultural soils affected by salt. An adequately spaced grid cell of 200 m*200 m or seven transects, with seven samples collected every 200 m on each sampling site, was generated by the QGIS software's Fishnet tool, and an auger collected 226 soil samples from the proposed 245 soil sampling points. The analysis and interpretation of the data were done using both statistical and geostatistical methods. The un-sampled surface was predicted and mapped from laboratory point data using the standard Kriging algorithm in QGIS. ResultsAccording to the results, the soil in the study area was rated as strongly alkaline and moderately alkaline in the reaction. The coefficient of variation (CV) was the lowest for soil pH. Except for the Ganta Kanchama site, low CV (<10 %) confirmed the similarity of pH values throughout all research areas. The EC values depicted that the study area is slightly saline except for the Ganta Kanchame site, which rated moderately saline to strongly saline. The variability of soil EC rated moderate to strong variation for the studied area. The exchangeable sodium percentage (ESP) values distribution between the study sites demonstrates considerable variability and difference. The area is dominated by low to high-risk rate soil sodicity, as evidenced by the soil ESP CV of the studied area, which was >100 % and showed significant variability among the samples. Out of 2274.65ha of the studied area, the type of salt 62.28 %, 26.09 %, 10.99 %, and 0.63 % were categorized as non-saline non-sodic, saline-sodic, sodic, and saline, respectively. Following saline-sodic, sodic, and saline soils, respectively, non-saline and non-sodic soils comprise most of the investigated areas. ConclusionsThe result indicates almost all the salt-affected areas were situated in relatively lower slope areas exhibiting a flat to almost flat slope (0–2%). The study's findings are that the studied area needs specific soil management strategies to boost the salinity and sodicity problems around the study area and recommended reclamation techniques as the extent of the problems.

Assessment of Soil and Water Salinity Status of Bitata Small Scale Irrigation Scheme of Guji Zone Oromia, Ethiopia

The Soil salinity, sodicity and water logging are becoming an emerging challenge for the irrigation development. So, assessments of irrigation schemes are very important to see the problems they have. The assessment of soil and water salinity status of Bitata small scale irrigation scheme of Guji Zone, Oromia region was done to identify, analyze and map salinity level using Geographic information System, the chemical properties of the soil was done at laboratory for samples analysis. After, spatial analyst and interpolation by Inverse distance Weight and Re-class the soil analyzed. Then the area of influence of the points was determined for the selected parameters and the results of investigation shows the majority of sample results are non-saline non sodic, even if, the samples were less, the sodicity problems occur at the study area on surface soil by considering three parameters at once and non-saline and non-sodic for profile soil. And when considering individual parameters of surface soil the results shows slightly saline depends on Electrical conductivity of saturation extracts, considering the exchangeable sodium percentage slightly to extremely sodic results was observed. And the results of irrigation water quality shows Very high Saline and Low Sodicity. The finding of the study recommends intervention of sodicity for surface soil and salinity and sodicity for water source used for irrigation is very important to control the expansions of it to the whole area of the scheme and to minimize the risk of salinity and sodicity problems of the water source used for irrigation. Management techniques that improve soil fertility such as crop rotations, manuring, fallow periods, proper management of crop residues, vermicomposting and leguminous cover crops and water-saving irrigation technologies suitable to the land of the area are the best options. And similar work is necessary to get additional information of the study areas because of the results of surface and profile soil and water source used for irrigation were far apart from each other.

Water Salinity Sensing with UAV-Mounted IR-UWB Radar

The quality of surface water is closely related to human’s production and livelihood. Water salinity is one of the key indicators of water quality assessment. Recently, there has been an increased salinization problem of surface water in many regions of the world, making it necessary to timely monitor the salinity of surface water. Water salinity sensing could be challenging when it comes to surface water with complicated basin and tributaries, where existing methods fail to satisfy both efficiency and accuracy requirements. To address this problem, we propose a novel water salinity sensing system USalt, which leverages the high mobility of UAV and the contactless sensing ability of IR-UWB radar, and realizes fast and accurate water salinity sensing for surface water. Specifically, we design novel methods to eliminate the contamination in raw received radar signals and extract salinity-related features from radar signals. Furthermore, we adopt a neural network model ssNet to precisely estimate water salinity using the extracted features. To efficiently adapt ssNet to different environments, we customize meta learning and design a meta-learning framework mssNet. Extensive real-world experiments carried out by our UAV-based system illustrate that USalt can accurately sense the salinity of water with an MAE of 0.39 g/100 mL.

Identification of Candidate Genes for Salt Tolerance at Seedling Stage in Rice Using QTL-Seq and Chromosome Segment Substitution Line-Derived Population

Rice is a staple food for more than half of the world’s population. However, the pervasive problem of salinity is severely undermining rice production, especially in coastal and low-lying areas where soil salinization is widespread. This stress, exacerbated by climate change, necessitates the development of salt-tolerant rice varieties to ensure food security. In this study, an F2:3 population (n = 454) from a cross of KDML105 and its chromosome segment substitution line (CSSL) was used to identify genomic regions associated with salt tolerance at the seedling stage. Using the QTL-seq approach, a QTL significantly associated with salt tolerance was identified on chromosome 1. Annotation of candidate genes in this region revealed the potential regulators of salt tolerance, including MIKC-type MADS domain proteins, calmodulin-binding transcription factors, and NB-ARC domain-containing proteins. These and other identified genes provide insights into the genetic basis of salt tolerance. This study underscores the importance of using advanced genomics tools and CSSL populations in the study of complex traits such as salt tolerance in rice. Several candidate genes identified in this study could be used in further studies on molecular or physiological mechanisms related to the salt response and tolerance mechanism in rice. Additionally, these genes could also be utilized in plant breeding programs for salt tolerance.

Eco-Physiological Studies of Some Halophytes Naturally Occurring in Tehsil Deedwana, District Deedwana-Kuchaman, Rajasthan, India

Abstract: Deedwana tehsil of State Rajasthan is facing a tragic problem of salinity. Almost 60% of total 160252.99 ha of land is under salt stress. This has created a deleterious impact on, not only the soils of these lands but also on the yield of the crops therein. Eco-physiological studies of some halophytes of these areas have shown that there are very characteristic structural features have been developed in these plants. Possible factor for this is soil which undergoing degradation due to increased ionic levels. This research paper presents an eco-physiological investigation of three halophytes, Salsola baryosma, Suaeda fruticosa, and Trianthema triquetra, in the arid region of Deedwana, Rajasthan, India. The study aims to understand the adaptive strategies and physiological responses of these plants to the extreme salinity conditions prevailing in their habitat. Field surveys were conducted to assess the distribution and abundance of the selected halophytes, followed by collection of plant samples for laboratory analysis.

Assessment of the Quality of Agricultural Soils in Manica Province (Mozambique)

Agriculture is the main economic activity of Mozambique and there is a lack of information about the quality of agricultural soils. In this paper, five soils from the Manica and Sussundenga districts (Manica province) sampled in the years 2021/2022 and 2022/2023 (before and after the rainy seasons) were subjected to an agronomical and environmental chemical analysis to assess their quality, from the fertility and environmental contamination points of view. Standard analytical methodologies from external certified laboratories and local X-ray fluorescence measurements were used. All the studied soils were acidic (pH ranging from 4.5 to 5.4), had no salinity problems (conductivity ranging from 4.2 to 11.8 mS/m), and had a low amount of soil organic matter (0.90% to 1.81%). Soils from the Sussundenga district had a very low cation exchange capacity (CEC) (average of 3.33 cmolc/kg), while that of those from the Manica district ranged from very low to average CEC (3.59 to 13.11 cmolc/kg). Sussundenga soils also had a phosphorous deficiency (values ranging from &lt;20 to 38.5 mg/kg) and there were deficiencies and/or excesses of some macro and micronutrients in all soil samples. Manica soils were contaminated, apparently from geogenic origin, with Cr (280 to 1400 mg/kg), Co (80 mg/kg), Ni (78 to 680 mg/kg) and V (86 mg/kg). Agricultural soil monitoring must be fostered in Mozambique in order to improve food quality and quantity to ensure economic and environmental sustainability.

Experimental evaluation of the protective properties of a humic preparation in relation to cultivated plants under salt stress

In connection with the widespread problem of soil salinity, the issue of increasing the salt tolerance of cultivated plants is becoming increasingly important. In this aspect, humic substances and preparations based on them are very promising. The aim of the study was to evaluate the effect of humic preparations on agricultural crops and lawn cereals under salt stress. Under laboratory conditions, the protective properties of the humic preparation «Ekorost» were evaluated in relation to the industrial crop Brassica rapa L. and to lawn grasses under the influence of salt stress induced by excessive concentrations of sodium chloride and anti-icing agent. It was revealed that the humic preparation «Ekorost» exhibits protective properties in relation to the indicated test cultures under conditions of artificially simulated salt stress, which is expressed in a noticeable stimulation of their germination and growth processes. In all the experiments, the most effective was a 0.1% aqueous solution of the drug «Ekorost», which allows us to recommend it in the indicated dosage to increase the salt tolerance of oil radish ( Brassica rapa L.) and lawn cereals.

Seed Priming for Mitigating Salinity Stress Effects in Plants: A General Review

Salinity is a significant abiotic stressor that inflicts considerable harm on agricultural fields and plants. Factors such as global warming, improper irrigation practices, excessive fertilization, drainage issues, inappropriate tillage and cultivation methods contribute significantly to the emergence of salinity problems in agricultural lands. When faced with stressors, plants employ various mechanisms to ensure their survival. Consequently, salinity stress adversely affects seed germination, leads to stunted plant growth, reduces yield, results in the accumulation of reactive oxygen species (ROS), diminishes chlorophyll content, elevates proline levels, promotes the production of malondialdehyde (MDA) and impacts osmoprotectants like glycine betaine. Salt stress not only induces osmotic stress and ion toxicity but also disrupts plant nutrient uptake. Today, numerous approaches are available to mitigate the detrimental impacts of stressful conditions and one such method is seed priming, which encompasses various techniques. This review delves into the adverse effects of salinity on plants and examines the role of seed priming processes in ameliorating these harmful consequences.

Determination of Seed Size Properties of Soybean Cultivars and Their Response under Salinity during Early Growth

Background: Seed sorting by seed size has been increasingly given importance in Türkiye but little is known about the impacts of seed size of soybean on germination and seedling growth, in regions suffering from salinity problems. Methods: The seeds classified as small (6-7 mm for Ataem, 4-6 mm for Kocatürk, 4-7 mm for Batem Erensoy and 4-5 mm for Göksoy) and large ( greater than 8 mm for Ataem and Batem Erensoy, greater than 7 mm for Kocatürk and greater than 6 mm for Göksoy. Seeds were exposed to 0, 10 and 20 dS m-1 of NaCl. Germination percentage, mean germination time and seedling growth parameters were investigated and compared. Result: Investigations revealed that, regardless of variety small seeds had a high content of chlorophyll pigments and slow and late mean germination time under NaCl stress. Emergence percentage differentiated in relation to seed size large seeds with 90.67% and small seeds with 73.67%. In conclusion, the large seeds produced significantly vigorous germination and seedling growth related to their high nutrient reserves and containing less chlorophyll pigmentation in their seeds. Therefore, care should be taken to select larger seeds, under saline conditions (10 dS m-1).

Impact of soil compaction and irrigation practices on salt dynamics in the presence of a saline shallow groundwater: An experimental and modelling study

AbstractSoil salt accumulation is a widespread problem leading to diminished crop yield and threatening food security in many regions of the world. The soil salinization problem is particularly acute in areas that lack adequate soil water drainage and where a saline shallow water table (WT) is present. In this study, we present laboratory‐scale column experiments, extending over a period of more than 400 days that focus on the processes contributing to soil salinization. We specifically examine the combined impact of soil compaction, surface water application model and water quality on salt dynamics in the presence of a saline shallow WT. The soil columns (60 cm height and 16 cm diameter) were packed with an agricultural soil with bulk densities of 1.15 and 1.34 g/cm−3 for uncompacted and compacted layers, respectively, and automatically monitored for water content, salinity and pressure. Two surface water compositions are considered: fresh (deionized, DI) and saline water (~3.4 mS/cm). To assess the sensitivity of compaction on salt dynamics, the experiments were numerically modelled with the HYDRUS‐1D computer program. The results show that the saline WT led to rapid salinization of the soil column due to capillarity, with the salinity reaching levels much higher than that at the WT. However, compaction layer provided a barrier that limited the downwards moisture percolation and solute transport. Furthermore, the numerical simulations showed that the application of freshwater can temporarily reverse the accumulation of salts in agricultural soils. This irrigation strategy can help, in the short‐term, alleviate soil salinization problem. The soil hydraulic properties, WT depth, water quality, evaporation demand and the availability of freshwater all play a role in the practicability of such short‐term solutions. The presence of a saline shallow WT would, however, rapidly reverse these temporary measures, leading to the recurrence of topsoil salinization.

The Threat of Saltwater Intrusion on Rice Farming in Katingan I Lowland Irrigation Area, Central Kalimantan

The Katingan I Lowlands Irrigation Area (LIA) is one of tidal lowlands irrigation area in Central Kalimantan, Indonesia. Because the Katingan I LIA utilizes water from the estuary, the occurence of saltwater intrusion is likely to occur. Assessing water salinity due to saltwater intrusion provides essential information for farmers to manage water appropriately. In addition, this information can also be used by the government to develop policies and management strategies for Katingan I LIA. Saltwater intrusion that occurs when sea water flows into irrigation canals and agricultural land can lead to increased salinity. High salinity levels can affect agricultural productivity, especially in rice crops. Therefore, a thorough salinity study is needed to support the development of rice farming. This study aims to evaluate salinity levels due to saltwater intrusion and understand the factors affecting them. The study measured tidal (water level elevation), electrical conductivity (EC), and salinity data of the Katingan River and several locations in the primary and secondary channels. Data collection methods included continuous and instantaneous measurements using portable data logger installations and handheld devices. The existing water salinity conditions at Katingan I LIA obtained the maximum water salinity value from the three locations of 14,536 ppm and the lowest water salinity value of 3.02 ppm. The maximum water salinity value that enters the primary canal is 5,547 ppm, higher than the thershold salinity value for rice farming (5,120 ppm). Therefore, anticipatory measuers must be conducted to reduce salinity intrusion, such as optitmizing water channels, making water gates, and managing the water use efficiently. It is also recommended that measurements be carried out during the dry season to see the comparison of results and the magnitude of the maximum water salinity value that occurs because salinity problems occur more during the dry season