Levels Of Electrical Conductivity Research Articles

Physico-chemical and correlation study of ground drinking water of Tonk district of Rajasthan (India)

This study investigates the qualitative analysis of groundwater obtained from the Tonk district of Rajasthan to determine its suitability as potable water. Around 321 ground drinking water samples were collected and analysed for various physico-chemical characteristics including pH, electrical conductivity (EC), total dissolved solid (TDS), HCO3−, F−, Cl−, SO42−, NO3−, Ca2+, Mg2+, total hardness (TH) and total alkalinity (TA) in Tonk district of Rajasthan (India). The groundwater in the region is a little alkaline and hard. The EC during the pre-monsoon period varies from 434 to 7271 µS/cm, while in the post-monsoon period, it ranges from 356 to 8871 µS/cm. TDS of samples ranged between 285 to 5090 mg/L in the pre-monsoon and 247 to 6140 mg/L post-monsoon seasons. Few samples have EC, TDS, and TH levels higher than the permissible limit, restricts its usage as drinking water. The water quality in the study area varies from soft-fresh to hard-brackish in both pre- and post-monsoon seasons. Anion concentrations in analysed samples followed the order: HCO3− > Cl− > SO42− > NO3− > F−. Notably, the Water quality index (WQI) results for all collected samples fall within the range of 4.55–96.83, indicating they are considered safe and suitable for drinking purposes. Water quality data was analysed by correlation study and geochemical processes. A strong correlation between the Water Quality Index (WQI) and fluoride levels is found in both seasons. The geochemical analysis shows that most of the samples are in the rock water interaction zone, with some in the evaporation zone due to the high content of chloride ions. The groundwater chemistry appears to be influenced by rock-water interaction and evaporation sedimentation. The molar ratio of Ca2+/Mg2+ denotes calcite dissolution and silicate weathering revealing enrichment of Ca2+ and HCO3− ions in aquifer.

Morphological and Physiological Responses of Two Penstemon Species to Saline Water Irrigation

Penstemon, with more than 250 species native to North America, holds significant aesthetic and ecological value in Utah, supporting diverse pollinators. Despite their significance, the survival of penstemon is threatened by challenges such as habitat loss, climate change, and Utah’s naturally high soil salinity. To address these challenges and understand their adaptability, this study evaluated the salt tolerance of two penstemon species [Penstemon davidsonii (Davidson’s penstemon) and Penstemon heterophyllus (foothill penstemon)] under controlled greenhouse conditions. The aim was to develop baseline information for nursery production and landscape use that utilize reclaimed water for irrigation. Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 1.0 dS·m−1 as control or a saline solution at an EC of 2.5, 5.0, 7.5, or 10.0 dS·m−1 for 8 weeks. Half of the plants were harvested after four irrigation events, and the remaining plants were harvested after eight irrigation events. At harvest, visual rating (0 = dead and 5 = excellent without foliage salt damage), plant width, number of shoots, leaf area, shoot dry weight, leaf greenness [Soil Plant Analysis Development (SPAD)], stomatal conductance, and canopy temperature were collected to assess the impact of salinity stress. In both species, salt damage was dependent on the salinity levels and length of exposure. After four irrigation events, both species exhibited foliage damage that increased in severity with rising EC. The most severe damage was observed in plants receiving saline solution at an EC of 10.0 dS·m−1. After eight irrigation events, P. davidsonii exposed to a saline solution with an EC of 10.0 dS·m−1 received a visual rating of 0, whereas P. heterophyllus had a visual rating of 0.4. Both species exhibited salinity-induced effects, with variations observed in the specific parameters and the degree of response. Penstemon davidsonii exhibited significant salinity stress, as indicated by reduced leaf area, shoot dry weight, SPAD reading, and stomatal conductance with increasing EC of the saline solution. In addition, in both species, at both harvests, canopy temperatures increased either linearly or quadratically by 8% to 36% as the EC levels of the saline solution increased. These results indicate that P. davidsonii was more sensitive to salinity stress than P. heterophyllus.

Modification of Hilhorst model for saturated extract electrical conductivity estimation of coir using frequency domain reflectometry sensors – A laboratory study

Frequency domain reflectometry (FDR) sensors can measure moisture content and electrical conductivity (EC) of growing media, thus providing information for effective water and nutrient management of crops. FDR sensors generally provide the bulk EC (σb) value, which is different from the saturated extract EC (σe) values that most growers and practical studies generally use. To properly estimate σe of media, we modified the previous Hilhorst model that calculates pore water EC (σp) from FDR sensor readings. The 16 coir samples with four moisture and four EC levels were prepared, and their changes in the dielectric constant of bulk medium (εb), σb, and medium temperature from the FDR sensors were recorded and used for analysis. As a result, the εσb=0 (εb when σb is 0) of the coir used in this experiment was 1.64, which was much lower than the εσb=0 suggested for mineral soil (4.1), indicating that the medium-specific εσb=0 should be adjusted. Although σe value estimation through the Hilhorst model with adjusted εσb=0 improved, the values were still unreliable to represent the actual σe values (root mean square error, RMSE = 2.280, R2 = 0.30). To convert the σp derived from the Hilhorst model with adjusted εσb=0 to actual σe, the regression equation was applied as σe = 0.5381 × σp + 1.6493. The adjusted Hilhorst model could provide a more reliable σe estimation (RMSE = 0.929, R2 = 0.62). These results indicate that proper adjustment of εσb=0 for the specific medium is necessary, and adjusting the equation for converting σp into σe would be helpful to properly interpret the σb to practically utilize the FDR sensors for effective water and nutrient management.

Assessment of tube well water quality in selected residential areas in Khulna

Clean water is vital for sustainable development, fostering socio-economic growth, ecological stability, and human survival. The study aimed to evaluate the quality of tube well water in specific residential areas of Khulna for drinking purposes, comparing it with the standards of World Health Organization (WHO) and Bangladesh (BD). Twenty tube well water samples were collected from residential areas at depths of 700-1500 ft. The samples were tasted with about 20 parameters, including physical: color, taste, odor, total dissolved solids (TDS) and total suspended solids (TSS); chemical: acidity/alkalinity (pH), arsenic (As), electrical conductivity (EC), dissolved oxygen (DO), bicarbonate (HCO3–), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), chloride (Cl–), iron (Fe), phosphate (PO43–), sulfate (SO42–), potassium (K+); and bacteriological parameters: total coliforms and E. coli bacteria. Most of the samples were found to have higher TDS (avg. 1380 mg/L), TSS (avg. 620 mg/L), Fe (avg. 20.2 mg/L), K+ (avg. 194.1 mg/L), and Na+ (avg. 439 mg/L) concentrations compared to the WHO and BD Standards. 90 to 95% of samples exhibited acceptable levels of EC, pH, DO, Mg2+, Ca2+, Cl–, and SO43–. The salinity levels in most of the samples were excessive to be used for drinking, and the levels were especially very high in samples S-01(Na+ 820 and Cl- 3195 mg/L) and S-04 (Na+ 660 and Cl- 2946 mg/L). The arsenic levels were found to be higher than acceptable limit in S-01 (0.086 mg/L) and S-04 (0.091 mg/L) as well. E. coli and other bacteria in a few samples (S-01, 04, 13, 16, 17, 19) were detected.

Variations in macrofaunal communities along sand physico-chemical gradient across the intertidal zones on island beaches

Island beaches, once mistakenly considered as 'ecological deserts', are actually unique ecosystems that support abundant macrofaunal communities. However, limited studies have examined the variations and determinants of macrofaunal communities across the intertidal zones on island beaches, which is crucial for shedding light on the underlying ecological processes and enhancing biodiversity conservation efforts. Here, we explored the variations in macrofaunal communities along sand physico-chemical gradient across four intertidal zones on nine representative beaches, within the largest land-bridge archipelago in eastern China. Our findings revealed that species richness, density, and Shannon-Wiener diversity of macrofaunal communities were notably higher in the lower intertidal zones, exhibiting a positive correlation with elevated levels of sand moisture (M), electrical conductivity (EC), available potassium (AK), and grain size (GS). Conversely, macrofaunal Simpson diversity displayed an inverse pattern, with heightened values observed in the vegetation zone. The Saprophagous, Predaceous, and Omnivorous groups of macrofaunal communities demonstrated an increase with higher levels of EC, AK, and M in the lower intertidal zones. Furthermore, Phytophagous group of macrofaunal communities tended to inhabit the vegetation zones characterized by elevated levels of sand total phosphorus (TP), total nitrogen (TN), and organic carbon (OC). Primarily, our findings indicate that sand nutrition, moisture, and salinity play pivotal roles in shaping the variations of macrofaunal communities on island beaches. These insights offer valuable perspectives into the holistic responses of macrofauna on island beaches to changes in sand physico-chemical properties, serving as a crucial theoretical foundation for the assessment, conservation, and restoration of island beaches.

Effects of Variable Electrical Conductivity Levels in Hydroponic Nutrient Solutions on Morphological and Physiochemical Characteristics of Cucumber Plants in Advanced Greenhouse Cultivation

Cucumber (Cucumus sativus L.) is a fruit of the Cucurbitaceae family that is refreshing, low in calories, and offers various health benefits due to its rich nutritional profile. However, high-tech hydroponic greenhouse production of cucumber is nutrient-intensive and requires efficient management of electrical conductivity (EC) in the growing medium. In this study, three different EC levels (1.3, 2.6, and 3.6 dS/m) were applied to the nutrient medium of hydroponically grown Lebanese and Continental varieties of cucumber. The experiment did not have a significant impact on the number of fruits (p=0.744, p=0.163) or leaves per plant (p=0.252, p=0.377) at varying EC levels. However, in the Continental variety, pH (0.001***) and osmolality (0.005**) were significantly different among the three varied EC levels. High EC levels in the nutrient medium resulted in reduced TSS, pH, and osmolality of the fruit juice. Although the plants grown in low EC conditions produced almost the same number of fruits and leaves per plant as those grown in optimal EC conditions (2.6 dS/m), the physio-chemical attributes of the cucumbers were of inferior quality.

Hydrogeological structures of karst features using hydrographs in an underground river basin formed in a peak cluster depression, southwest China

Understanding of the hydrological behaviors in different karst features is crucial for evaluating the hydrological storage and transfer functions of a karst system. In this study, the Maocun karst underground river system, characterized by typical karst features, was selected as the research area in the southwest region of China. The main objectives of this research are to analyze the hydrogeological structure characteristics of each karst feature and assess water storage capacity in different aquifer media. Frequency distribution curve (FDC) of electrical conductivity (EC) values revealed that recharge sources in the five karst features differed and varied according to the amount of precipitation. All hydrographs of water levels in five karst features were divided into three periods due to the presence of triple aquifer media in the basin. The spatial structure of each feature was interpreted by analyzing the variation characteristics of recession exponential coefficients (λ). Additionally, the ratios of fissure water, fracture water, and conduit water sources were calculated based on the recession curves of water levels. Results showed that fast water flow had the highest proportion in the relatively open subsystem located upstream, while fracture water flow had the lowest proportion. The slow water flow was the main pattern of water storage in the basin. Values of EC in water decreased with a well-connected spatial structure and high hydraulic conductivity. There were significant differences in the values of EC among conduit water, fracture water, and matrix water. These values were calculated using mathematical relationships between EC and water level hydrographs. The results indicated that the EC values in matrix water exceeded 200 μS/cm, while EC values in conduit water/channel water were below 100 μS/cm. Finally, hydrogeological conceptual models were constructed for five karst features based on the depletion characteristics of the aquifer media during each recession period. These characteristics were interpreted using variation curves of EC and hydrographs of water levels. These findings not only elucidated the characteristics of hydrogeological structures in multiple karst features, but also had significant implications for the assessment of karst water sources.

Reduced fertigation input sustains yield and physiological performance for improved economic returns and cleaner production of greenhouse eggplant

Greenhouse horticulture, a sustainable alternative to conventional horticulture, maximises resource use and return for vegetable production. This study evaluated the impact of varying nutrient solution electrical conductivity (EC) levels (EC 1.8, 2.8, and 3.8) on eggplant cultivars (Solanum melongena L. cv. Lydia, and Tracey) performance and economic viability in high-tech glasshouses. We found that morphological traits such as plant height and leaf number were consistent across EC levels, while fruit weight, length, and width are significantly higher at the lowest EC (1.8). Photosynthetic rates increased significantly with rising EC levels, while other gas exchange parameters such as stomatal conductance, intrinsic water use efficiency, and vapour pressure deficit were similar for all EC levels tested. Yield analysis revealed a negative correlation between eggplant yield and increasing EC levels, with optimal yields in both eggplant varieties (0.81 and 1.14 kg m−2 week−1 in Lydia and Tracey, respectively) achieved at the lowest EC. Economic analysis highlighted that lower EC levels lead to lower operational costs and higher net profit values (NPV). Sensitivity analysis underscored the importance of wholesale price and crop yield in determining NPV, with lower EC levels offering a shorter payback period of approximately 6 years in Australia and China and higher economic returns. The study highlights the significance of optimizing EC levels for achieving more resource-sustainable and profitable eggplant production in greenhouses.

Pathogen-specific patterns of milking traits in automatic milking systems

Early detection of intramammary infection (IMI) can improve animal health and welfare in dairy herds. The implementation of sensors and automatic milking systems (AMS) in dairy production inherently increases the amount of available data and hence also the potential for new approaches to mastitis management. To utilize the full potential of data from AMS and auxiliary sensors, a better understanding of physiological and pathological changes in milking traits associated with different udder pathogens may be imperative. This observational study aimed to investigate pathogen-specific patterns in milking traits recorded in AMS. The milking traits included; online somatic cell count (OCC), electrical conductivity (EC), milk yield (MY), and average milk flow rate (AMF). Data were collected for a study period of 2 years and included 101 492 milkings from 237 lactations in 169 cows from one farm. Measurements of OCC were recorded at cow-level and data on EC, MY, and AMF were obtained at quarter-level. In addition to the data obtained from the AMS, altogether 5756 quarter milk samples (QMS) were collected. Milk samples were obtained monthly for bacteriological culturing. We included findings of 13 known mastitis pathogens to study pathogen-specific patterns in milking traits. These patterns were compared with those in a baseline group consisting of cows that did not have any positive milk culture results throughout the lactation period. Patterns of the milking traits are described for all positive samples both across 305 d in milk (DIM), and in the 15-d period before a positive bacteriological sample. The association between a positive sample and the milking traits (ln(OCC), EC-IQR; the ratio between the quarter with the highest and the quarter with the lowest level of EC, and MY) for the 15 d before the detection of a pathogen was assessed using mixed effects linear regression models. All pathogens were associated with alterations in the level and variability of ln(OCC) relative to lactations with no positive bacteriological samples. A positive sample for Staph. aureus was associated with increased values for MY during the 15 d before a positive diagnosis. It is biologically plausible to interpret changes in OCC and EC-IQR as consequences of an intramammary infection (IMI), while higher MY in bacteriologically-positive cows is most likely linked to the increased risk of infection in high-yielding cows. In this study, the most notable changes in the traits (OCC and EC-IQR) were observed for Staph. aureus and Strep. dysgalactiae, followed by Strep. simulans, Strep. uberis, and Lactococcus lactis. Even if we did not detect significant associations between positive bacteriology and EC-IQR, visual assessment and descriptive statistics indicated that there might be differences suggesting that it could be an informative trait for detecting infection when combined with OCC and possibly other relevant traits using machine learning algorithms.

Contrasting salinity effects of artificial seawater and sodium chloride on Carica papaya L. cultivar Red Lady physiology and growth

BackgroundMany coastal areas of the world will be impacted by seawater intrusion inland exposing crops to increasing levels of soil salinity. Studies of salinity stress in horticultural crops, including papaya, invariably use NaCl as the salt source, which may not be indicative of seawater.MethodsThis study compared plant growth, physiological, and nutritional responses, including leaf gas exchange, maximal potential quantum efficiency of photosystem II (the ratio of variable to maximum chlorophyll fluorescence; Fv/Fm), the leaf chlorophyll index (LCI), electrolyte leakage (EL), leaf relative water content (RWC), leaf water potential (Ψw), leaf osmotic potential (Ψo), leaf and root N, P, K, Ca, Mg, Na and Cl contents, and growth of potted ‘Red Lady’ papaya plants, in a calcined clay substrate, irrigated with NaCl or artificial seawater (Instant Ocean®) at six soil electrical conductivity (EC) levels (0, 1, 2, 3, 4 or 6 dS m−1).ResultsThere were slight significant reductions in Ψw, Ψo, net CO2 assimilation (A), stomatal conductance (gs), and transpiration (Tr) with increasing EC regardless of the salt source. Leaf Ca, Mg, Na and Cl contents and root Mg, Na, and Cl increased significantly with increasing EC levels. For both salt sources, there was an indication of osmotic adjustment and tolerance of papaya up to an EC level of 6 dS m−1. A significant difference between the response to NaCl and artificial seawater was observed for plant height, leaf Mg and Cl contents, and root Mg and Na contents.ConclusionThe use artificial seawater may be a better source than NaCl for studying papaya responses to increasing soil salinity.

Evaluating the Enzyme Activities and Soil Physicochemical Properties of Four Typical Halophytic Communities in Saline-Sodic Soil

Four typical halophytic communities found in saline-sodic soil, including Phragmites australis, Suaeda glauca, Leymus chinensis, and Puccinellia parl, were investigated in this study. A comparison was made among the electrical conductivity (EC) value, pH value, soil organic carbon (SOC), and soil enzyme activity across various soil depths. The findings of this study indicate that the EC and pH levels of the soil at the 0–40 cm depth vary among the four communities, with Suaeda glauca having the highest values, followed by Puccinellia parl, Phragmites australis, and Leymus chinensis. The highest value of SOC among the four communities was observed in the Leymus chinensis community (0.85–0.94 g/kg), followed by the Phragmites australis community (0.50–0.77 g/kg), and the lowest levels were observed in the Puccinellia parl community (0.37–0.78 g/kg). As the soil depth increases, there is a decline in the amount of SOC. With an increase in soil depth, the content of SOC in the soil decreased, and the content of total nitrogen (TN) and the activity of six enzymes in the soil of each community increased. Furthermore, at the soil layer of 0–20 cm, the TN content in the soils was negatively correlated with pH and EC (p < 0.01), and so was the total phosphorus (TP). Additionally, the TP content is considerably positively connected with alkaline phosphatase (ALP) activity, whereas the TN content is significantly positively correlated with Soil Urease (S-UE) activity. Within the soil depth of 20–40 cm, the levels of TN, TP, and SOC exhibit a negative association with pH and EC. However, this link is weaker compared to that observed in the surface soil. A strong inverse correlation (p < 0.05) exists between the TP concentration and the ALP activity. The objective of this study was to investigate the use of halophytes in various saline-sodic soils for diverse avenues of restoration, and to establish a database on the role and efficacy of plant roots in enhancing saline-sodic soil.

Rice Husks and Leaf Mold Used as Peat Substitutes to Improve the Morphological, Photosynthetic, and Biochemical Properties of Chrysanthemum (Chrysanthemum × morifolium)

Chrysanthemums (Chrysanthemum × morifolium) are highly valued for their ornamental and economic benefits. However, the commonly used growing medium for chrysanthemums, peat, is not renewable, and peatlands are facing depletion. Therefore, it is important to find sustainable alternatives to peat. This study aims to evaluate the potential of rice husks and leaf mold mixed with peat and perlite in different ratios (10–20–30–40–80% v/v/v/v) as substitute materials for peat in chrysanthemum production. The study examines the physical and chemical properties of the different growing media ratios, as well as their effects on plant growth, development, and physiological indicators. The results of the experiment demonstrate that the different ratios of the cultivation substrate significantly influence the physical and chemical properties of the growing medium, as well as the growth and physiological indicators of chrysanthemums. A 20–30% proportion of rice husks and leaf mold promotes the growth and photosynthetic activity of chrysanthemum cuttings, resulting in increased plant height, leaf area, total chlorophyll content, and net photosynthetic rate. The mixed substrates (10–40%) maintain suitable pH levels, electrical conductivity (EC), and nutrient content (nitrogen, phosphorus, and potassium). However, an 80% ratio of rice husks negatively affects plant survival and growth due to elevated EC and potassium levels. In conclusion, a peat medium containing 20% rice husks and leaf mold provides a more favorable cultivation substrate for producing high-quality chrysanthemums while promoting sustainable horticultural practices.

Distribution of Soil Organic Carbon Density Fractions in Aggregates as Influenced by Salts and Microbial Community

Understanding soil organic carbon (SOC) at the aggregate level is crucial for soil health in secondary-salinized greenhouse development. Nevertheless, the specific patterns and contributions of ion content and microbial communities on SOC density fractions at the aggregate level remain unclear in secondary-salinized soil. We investigated variations in salts [electrical conductivity (EC) and ions] and microbial communities across various aggregate classes in both a 16-year-use greenhouse and open-field soils. We also examined SOC density fractions, including the light fraction (LF), the heavy fraction of particulate organic matter (POM), and mineral-associated organic matter (MOM) across different aggregates. The findings revealed that a lower Ca2+/K+ along with elevated EC levels (average 2.49 mS cm−1) reduced the macroaggregate percentage in greenhouse compared to open-field conditions, with a lower EC of 0.58 mS cm−1. Bacterial diversity and community composition exhibited no variation across different aggregate sizes at both sites. Conversely, fungal diversity and relative abundance (primarily dominated by Ascomycota of 78.50%) substantially increased in microaggregates (<0.25 mm) compared to macroaggregates (>0.25 mm). Macroaggregates exhibited a higher proportion of LF and MOM (3.3–18.2%, 24.9–34.5%, and 2.9–4.0% for LF, MOM, and POM, respectively) than microaggregates. Correlation and redundancy analyses revealed that fungal diversity, particularly the relative abundance of Ascomycota in aggregates < 0.25 mm, significantly and positively influenced (p < 0.05) the proportion of MOM carbon in terms of the overall SOC (J-type). This study provides valuable insights into the distribution patterns of SOC within the secondary salt-affected soils.

Exploring the sources of variation of electrical conductivity and total and differential somatic cell count in Italian Mediterranean buffaloes

In the buffalo dairy sector, a huge effort is still needed to improve mastitis prevention, detection, and management. Electrical conductivity (EC) and total somatic cell count (SCC) are well-known indirect indicators of mastitis. Differential somatic cell count (DSCC), which represents the proportion of neutrophils and lymphocytes on the total SCC, is instead a novel phenotype collected in the dairy cattle sector in the last lustrum. As little is known about this novel trait in dairy buffalo, in the present study we explored the nongenetic factors affecting DSCC, as well as EC and total somatic cell score (SCS), in the Italian Mediterranean buffalo. The data set used for the analysis included 14,571 test-day (TD) records of 1,501 animals from 6 herds, and climatic information of the sampling locations. The original data were filtered to exclude animals with less than 3 TD per lactation and, for the investigated traits, outliers beyond 4 standard deviations. In the statistical model we included the fixed effects of herd (6 classes), days in milk (DIM; 10 classes of 30 d, with the last being an open class until 360 d), parity (6 classes, from 1 to 6+), year-season of calving (11 classes, from summer 2019 to winter 2021/2022), year-season of sampling (9 classes, from spring 2020 to spring 2022), production level (4 classes based on quartiles of average milk yield by herd), and temperature-humidity index (THI; 4 classes based on quartiles, calculated using the average temperature and relative humidity of the 5 d before sampling). Average EC, SCS, and DSCC vary across herds. Considering DIM, greater EC values were observed at the beginning and the end of lactation; SCS was slightly lower, but DSCC was greater around the lactation peak. Increased EC, SCS, and DSCC levels with increasing parity were reported. Year-season calving and year-season sampling only slightly affected the variation of the investigated traits. Milk of high-producing buffaloes was characterized by lower EC and SCS mean values, nevertheless it had slightly greater DSCC percentages. Buffaloes grouped in the highest THI classes (classes 3 and 4) showed, on average, greater EC, SCS, and DSCC in comparison to the lower classes, especially to class 2. Results of the present study represent a preliminary as well as necessary step for the possible future inclusion of EC, SCS, or DSCC in breeding programs aimed to improve mastitis resistance in dairy buffaloes.

Road salt intrusion dynamics in an ex-urban native wetland complex

Inland freshwater wetlands throughout the northern U.S. and Canada are experiencing an increase in salinity due to road salt runoff during winter months. Salinization affects soil texture, contaminant transport, microbial activity, and plant growth in wetlands. Therefore, there is a pressing need to understand the dynamics of road salt intrusion in urbanized freshwater ecosystems. We used distributed high-resolution sensors to evaluate the dynamics of road salt intrusion into a wetland complex, Gensburg Markham Prairie (GMP), located in the ex-urban area outside Chicago, Illinois (USA). The in situ sensors measure electrical conductivity (EC), surface and groundwater level, precipitation, water temperature, and air temperature at 30-minute intervals. Water samples were collected monthly from 13 shallow groundwater wells and eight surface water locations and analyzed for Cl-, Mg2+, Na+, Ca2+, and K+. Two-years of continuous data show periodic spikes in EC during winter months, generally by an order-of-magnitude, due to intrusion of road salt applied on nearby roads. However, this behavior was not evident from monthly water samples, indicating that traditional water quality sampling methods likely miss such abrupt salt intrusion dynamics caused by rapid snowmelt runoff events. Higher levels of EC and Cl- occurred at the periphery of GMP near roadways, as well as in a preferential flow path to the interior of the wetland. Spectral analysis of EC time-series in ditches suggests that there is no correlation between salinity dynamics at super-annual timescales. This indicates that the salinity dynamics at GMP are event-driven, and the introduced solutes are rapidly exported from the site. This research supports development of improved de-icing strategies by local agencies and informs site-specific management of wetland ecosystems under anthropogenic stressors.

Interaction of climate, topography and soil properties with cropland and cropping pattern using remote sensing data and machine learning methods

Precision agriculture which facilitates and enables crop management through site-specific recommendations, is essential to optimize agricultural inputs in space and time. In this study, we used Landsat and MODIS-NDVI product data with climatic, topographic data and laboratory-analyzed soil samples to map the spatial distribution of seven soil properties; soil texture (T), electrical conductivity (EC), potential hydrogen (pH), nitrogen (N), phosphorus (P), potassium (K), and organic matter (OM) in the Punjab, Pakistan from 2000 to 2020. We examined and compared three statistical prediction models: the support vector machine (SVM), the random forest regression (RFR), and the multiple linear regression (MLR). The predictions were validated against a separate set of soil samples while considering the modeling region and an extrapolation area. Model performance statistics showed that the RFR often provided the highest accuracy, with the machine learning algorithms performing slightly better than the MLR. It was discovered that one obstacle to accurately forecasting soil parameters at unsampled areas with MLR was its inability to handle non-linear connections between independent and dependent variables. The results indicate that the cultivated area decreased from 43.16 % in 2000 to 38.24% in 2020. The soil has a high level of EC due to salinity. In general, the soils contained < 1% OM with lower N. However, the K and P contents were considered medium and adequate. Free remote sensing data has made it possible to improve soil knowledge at local and regional scales in data like Punjab with little outlays of time and money.

Effect of EC Levels of Nutrient Solution on Glasswort (Salicornia perennis Mill.) Production in Floating System

Halophytes have evolved to tolerate high salinity environments. The halophyte glasswort (Salicornia and Sarcocornia species) grows by the sea or in salty soils and can be consumed with pleasure. In this study, the cultivation of glasswort was studied by testing the effects of different electrical conductivity (EC) levels (10, 15, 20, 25, 30 and 35 mS cm−1) of a nutrient solution. Salicornia perennis Mill. was grown on floating systems in unheated greenhouse conditions. To adjust the different EC levels, sodium chloride was added to the Hoagland nutrient solution (EC: 2 mS cm−1). Plant growth and yield parameters, shoot color, evapotranspiration, and shoot nutrient content were determined. Among the tested EC levels, the highest plant height (33.56 cm), shoot (172.75 g) and root fresh weights (41.74 g), stem diameter (7.85 mm), and fresh biomass (2864.06 g m−2) were obtained from an EC level of 25 mS cm−1. There were no significant differences in shoot color excluding b* and chroma values. It was concluded that glasswort could be grown in hydroponic systems as a new crop and that an EC value of 25 mS cm−1 is the most appropriate for the cultivation of Salicornia perennis Mill. on floating systems.

The effects of two different biochars on the characteristics of saline acid sulfate soil

AbstractBiochar can be a potential bio‐amendment for remediating saline acid sulfate soil and its effects may be dependent on its properties. The current study sought to assess the effects of two different biochars on the properties and quality of saline acid sulfate soil. The experiment was implemented by mixing soil with biochars made from longan branches (LBs) and coconut coir biochar (CB) at five rates of 0%, 0.7%, 1.5%, 3%, and 6% (w/w). After 100 days of incubation in a greenhouse, soil samples from experimental pots were taken and analyzed for 11 parameters. The results showed that biochar significantly enhanced pH while declining the concentration of SO42− and exchangeable Al and Fe. Mechanisms responsible for these effects could be due to the high alkaline properties of the added biochar. Coconut biochar raised the concentration of exchangeable Na, K, and Mg more strongly than LB. Consequently, coconut biochar greatly increased the soil electrical conductivity (EC) value, while longan biochar exhibited no significant effect. The soil quality index of the 6%‐LB‐added soil increased by 64% and that of the 6%‐CB‐added soil increased by 45%, compared with the zero‐biochar‐added soil. Lower soil quality induced by CB compared with LB may be attributed to CB's initial properties, which had higher EC, Cl−, and Na levels than LB. The findings suggested that biochar addition can improve overall quality but alter individual properties of saline acid sulfate soil in different directions, depending on the properties of the added biochar, which requires more studies to clarify its ameliorative effects.

Surface water electrical conductivity and bicarbonate ion determination using a smart hybridization of optimal Boruta package with Elman recurrent neural network

Water quality (WQ) monitoring in the surface water resources is a crucial concern as it has an impact on human health and ecosystem equilibrium. An accurate simulation of river WQ indicators as a function of available variables with data mining techniques is not much explored by the researchers. In this study, two smart dual-preprocessing hybridized with Elman recurrent neural network (ERNN) were developed for an accurate simulation of two surface WQ indices including electrical conductivity (EC) and bicarbonate (HCO3-) in the Northern zones of Karun River, Iran. Nine input features including sodium adsorption ratio (SAR), magnesium (Mg2+), Ca+2 (calcium) sum of the anions (Sum.A), SO42-(sulphate) Cl-(chloride), pH, discharge (Q), and Na+ (sodium) were employed to simulate the EC and HCO3- in surface water Two Boruta-data filtering strategies including Boruta-XGBoost (BXGB) and Boruta-Extra Tree (BET) were utilized to extract the most important WQ indicators in available features. The best subset regression (BSR) scheme was utilized to optimize the input combinations of available features to predict EC and HCO3-. Three superior scenarios (C1, C2, and C3) were considered for each target variable to feed the machine learning (ML) models. The dual pre-processing was hybridized with ERNN to compare the results of advanced ML approaches i.e., long short-term memory (LSTM), Kernel ridge repression (KRR), and Elastic net regression (ELNET). Eight hybrid modeling paradigms (BXGB-ERNN, BET-ERNN, BXGB-KRR, BET-KRR, BXGB-ELNET, BET-ELNET, BXGB-LSTM, and BET-LSTM) were evaluated in terms of performance using statistical criterions such as correlation coefficient (R), root mean square error (RMSE), and Kling-Gupta efficiency (KGE). Results revealed that the BET-ERNN-C1 hybrid model outperformed the other models for HCO3- (R = 0.9847, RMSE = 0.0793 mEq/L, and KGE = 0.9782) and EC simulation (R = 0.9543, RMSE = 51.0260 μS/cm, and KGE = 0.9406) in terms of performance efficiency. Results indicated that the BET-ERNN-C1 model resulted in minimum values of IQR for EC (0. 7.455) and HCO3- (0.1819). Overall, the result of modeling showed that the ERNN-C1 model had a superior performance in simulating the WQ indices followed by BXGB-ERNN-C3 and BXGB-KRR approaches. Results of this study suggested that the predictions of WQ indicators using hybrid models can be used to assess the acceptable levels of EC and HCO3- in surface water using appropriate input variables efficiently and reliably.

Effects of NaCl and CaCl2 as Eustress Factors on Growth, Yield, and Mineral Composition of Hydroponically Grown Valerianella locusta

Corn salad (Valerianella locusta) is a popular winter salad, cultivated as an ingredient for ready-to-eat salads. The application of mild salinity stress (eustress) can increase the flavor and reduce the nitrate content of certain crops but, at the same time, a wrong choice of the eustress type and dose can negatively affect the overall productivity. In this research, the effects of different isosmotic salt solutions, corresponding to two different electrical conductivity (EC) levels, were investigated on the yield and mineral composition of hydroponically grown Valerianella locusta "Elixir". Five nutrient solutions (NS) were compared, including a basic NS used as the control, and four saline NS were obtained by adding to the basic NS either NaCl or CaCl2 at two rates each, corresponding to two isosmotic salt levels at a low and high EC level. Corn salad proved moderately susceptible to long-term salinity stress, suffering growth losses at both low and high EC levels of saline solution, except from the low NaCl treatment. Hence, it appears that mild salinity stress induced by NaCl could be employed as an eustress solution and corn salad could be cultivated with low-quality irrigation water (20 mM NaCl) in hydroponic systems.