Saturation Extract Research Articles

Spatio-temporal assessment of soil salinization utilizing remote sensing derivatives, and prediction modeling: Implications for sustainable development

This study aims to investigate the combined use of multi-sensor datasets (Landsat 4–5 &8 OLI satellite imagery, spatial resolution = 30 m) coupled with field studies to evaluate spatio-temporal dynamics of soil salinization along the coastal belt in West Bengal, India. This study assesses soil salinization by mapping the salinity and electrical conductivity of saturation extract (ECe) and utilizing spectral signatures for estimating soil salinity. The SI change (%) was analyzed (2021–1995), categorizing increases in salinity levels into 5%, 10%, and 50% changes possibly due to salt encrustation on the soil layers. The land use land cover (LULC) change map (2021–1995) demonstrates that the study area is continuously evolving in terms of urbanization. Moreover, in the study area, soil salinity ranges from 0.03 ppt to 3.87 ppt, and ECe varies from 0.35 dSm−1 to 52.85 dSm−1. Additionally, vulnerable saline soil locations were further identified. Classification of soil salinity based on ECe reveals that 26% of samples fall into the non-saline category, while the rest belong to the saline category. The Spectral signatures of the soil samples (n = 19) acquired from FieldSpec hand spectrometer show significant absorption features around 1400, 1900, and 2250 nm and indicate salt minerals. The results of reflectance spectroscopy were cross-validated using X-ray fluorescence and scanning electron microscopy. This study also employed partial least square regression (PLSR) approach to predict ECe (r2 = 0.79, RMSE = 3.29) and salinity parameters (r2 = 0.75, RMSE = 0.51), suggesting PLSR applicability in monitoring salt-affected soils globally. This study’s conclusion emphasizes that remote sensing data and multivariate analysis can be crucial tools for mapping spatial variations and predicting soil salinity. It has also been concluded that saline groundwater used for irrigation and aqua-cultural activities exacerbates soil salinization. The studywill help policymakers/farmers identify the salt degradation problem more effectively and adopt immediate mitigation measures.

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.

Survey and Characterization of Ground Water Quality and its Effect on Soil Properties in Malpura Block of Tonk District Rajasthan, India

In Malpura block of Tonk district, a survey was conducted to evaluate the quality of the groundwater and determine how it affected the soil qualities. Using a handheld GPS, 60 groundwater samples and 60 soil samples overall were taken at six sites include Lawa(V1), Borkhandi(V2), Kadila(V3), Jankipura(V4), Diggi(V5) and Nukkad(V6) in the Malpura block of the Tonk district. The pH, EC, SAR and RSC of ground water ranged from 6.95-8.40, 2.18-3.15(dsm-1), 2.73-10.45 (m mol/L), 1.64-22.3 (meq/L), respectively. The anion contents followed the pattern Cl>SO42> HCO3>NO3>CO32 whereas the cations were found to be in the following order: Na+> Mg2+> Ca2+> K+. The village of Lawa had the lowest saturation rate (22.84%) and Diggi had the highest saturation percentage (38.34%). The correlation coefficient revealed that electrical conductivity (EC) of soil saturation extract was significantly and positively correlated with EC (0.625), Cl- (0.200) and Na+ (0.242) of Groundwater used for irrigation.

Pedological features of a sustainable halophyte wetland: El Hito saline pond (Central Spain)

AbstractIn semi‐arid Mediterranean regions, particularly in some wetland soils, salinity is thought to be an indicator of low‐quality soils. In this study, a characterization is presented of the soils surrounding El Hito saline pond (Castilla La Mancha, Central Spain), an ecological halophyte niche within a natural semi‐arid steppe land. The main aim is to classify the salt‐affected soils and their morphology, genesis, and physico‐chemical properties. Four soil profiles were opened with a backhoe machine for sampling and subsequent description on the basis of their pedogenetic morphology. Systematic surface sampling was also performed. Standard methods were followed to measure the soil properties of 27 samples. Overall electrical conductivity (EC) and pH levels of the wetland were mapped (using ArcGIS 3.1.3). Soil salinity at elevated levels was detected, inhibiting plant uptake of water and nutrients. Distinct sub‐areas of extreme elevated surface salinity providing specialized plant habitats and poor soil structure were observed, as well as a mainly whitened‐yellowish‐greenish soil colour due to salt accumulation and poor drainage. The soils also showed alkaline pH values. In most samples, the pH was over 8.5, and EC was higher than 4 (dS m−1), and in several samples higher than 20 (dS m−1). A low sodium (Na) content was detected in the saturation extract where magnesium (Mg+) was the dominant soluble cation, followed by both calcium (Ca+) and sodium (Na+), and then potassium (K+), present in lower proportions. Sulphate (SO42−) and then chloride (Cl−) anions were dominant, although carbon trioxide, (CO3−) and carbonate (CO32−) anions were also present. The percentages of organic carbon (C) were very low, while total nitrogen (TN) and available phosphorus (P) were higher in the upper horizons, suggesting a degree of eutrophication. The present work will increase the existing knowledge about the role of El Hito saline pond, that play a vital ecological role in the broader biosphere, providing new suggestions to readers on how this knowledge can be used to improve these types of ecosystems. In particular, the agricultural pesticides and fertilizers continuously damage the soil fertility as evidenced by the high content of soluble phosphorus found in some points of the Hito saline pond.

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.

Comparison of Saturated Hydraulic Conductivity under the Reclaimed Conditions of Salt Affected Soil

Solving the soil problems that affect negatively on growth of plants and reduce the soil permeability is necessary for the study site, Thein Gone Village in Yamethin Township, Myanmar. The objectives of this study were; to identify the soil whether it is salt-affected or not and to investigate the proper reclamation method with different rates of amendments by comparing the saturated conductivity (Ks). Both composite (disturbed) and core (undisturbed) soil samplings were collected at three profiles (0 - 60 cm soil depth) during March, 2023. Some soil properties such as texture, bulk density (g cm-3), moisture content (%), ECe (electrical conductivity, saturated extract; mS cm-1), pH (1:5 water), SAR (sodium absorption ratio) and pH and EC of leaching water were also measured. Firstly, the study site was problematic with high pH due to Na+ distribution of underground water although there was some application of gypsum for a decade. Also, low permeability (Ks < 1x10-8 cm s-1) was another problem there. To leach the salt (EC < 1 mS cm-1 in leachate), 1500 cm3 of water was necessary for one core (98.21 cm3 soil volume). It was relatively high amount for using the quality-water. For reclamation methods, gypsum 5 t ha-1, sulphur 1 t ha-1, and cow-dung manure 20 t ha-1 gave the minimum (- log Ks) value among different rates of each amendment. The less the - log Ks, the more permeable the soil becomes. Among different amendments, gypsum 5 t ha-1 showed the fastest saturated hydraulic conductivity. Moreover, it is necessary to drain out the leachate to prevent the formation of saline -sodic soil.

Crescimento e aspectos fisiológicos da rúcula submetida a salinidade do solo e doses de adubação

ABSTRACT Arugula is a vegetable with considerable prominence in the commercial sector, so knowing the ideal dose of fertigation and the effects of soil salinity on its agronomic characteristics is essential for good production. The aim of the study was to evaluate the morphological and physiological aspects of arugula, cultivar Broadleaf, at different levels of soil salinity and doses of fertilization via fertigation. The experiment was conducted in a greenhouse during two consecutive growing cycles, from May to June and from July to August 2021. The experimental design used was randomized blocks, arranged in a 4 x 3 factorial scheme, with four replicates. Treatments consisted of four levels of electrical conductivity of the saturated extract (ECse = 0.57, 1.3, 2.3, and 3.3 dS m-1) and three doses of fertilization via fertigation (F1= 100%, F2= 50%, and F3= 25% of the recommended NPK doses). The variables analyzed were: plant height (cm), number of leaves, leaf area (m2 plant-1), shoot fresh mass and shoot dry mass (g plant-1), leaf water percentage, SPAD, and gas exchange (photosynthesis, transpiration, stomatal conductance, and internal CO2 concentration). There was a reduction in arugula growth in soil with ECse above 2.1 dS m-1. Fertigation using the full dose of fertilizer recommended for arugula cultivation proved to be an effective strategy for increasing both biomass production and physiological activity.

Long-term Effects of Irrigation with Treated Municipal Wastewater on Soil Chemical and Physical Responses in Commercial Vineyards in the Coastal Region of South Africa

The prolonged drought in the Western Cape province of South Africa in recent years has been particularly detrimental to the wine industry. Water restrictions imposed by authorities and the limited supply of fresh water that can be stored, have emphasisedthe need for alternative water sources for vineyard irrigation. Treated municipal wastewater has been used successfully as an alternative source of irrigation water in other countries. A long-term trial was conducted in commercial vineyards in the Coastal region of South Africa to assess the impact of treated municipal wastewater irrigation on vineyards. Cabernet Sauvignon and Sauvignon blanc grapevines were irrigated using treated municipal wastewater from the Potsdam wastewater treatment works for 11 years. Grapevines were either rainfed (RF), irrigated with treated municipal wastewater via a single dripper line (SLD), or received twice the volume of wastewater via a double dripper line (DLD). Irrigation using treated municipal wastewater increased soil pH(KCl), the electrical conductivity of the saturated extract (ECe) and Cl-. Substantial amounts of Na+ and K+ accumulated in the topsoil due to irrigation with treated municipal wastewater. These soil K+ increases could have a negative effect on wine colour stability should the levels of soil K+ be such that they are absorbed excessively by grapevines. The near-saturation hydraulic conductivity (Kns) at the surface of the soil could be related to the ECe in the topsoil. The results represent specific in-field situations in three commercial vineyards under one set of climatic conditions.

Effects of Applying Sewage Sludge Treated with Amendments on Soil Chemical Properties

ABSTRACT Soil application of treated sewage sludge is considered a beneficial management option for agriculture and environment. Sludge treated with clay minerals or biochar was evaluated as soil amendment, in comparison with limed or untreated sludge. Bentonite, vermiculite, biochar or lime was added to dewatered sewage sludge at 0 and 15% rates, in three replications and air-dried. Then, the treated and untreated sludge were added to two soils, one acid and one alkaline, at 0 (control), 1 and 3% rates, in three replications. The results showed that the pH of acid soil significantly increased compared to control upon addition of treated and untreated sludge at both rates, but remained acidic (<6.0) in all cases except for limed sludge. Upon addition of 3% treated or untreated sludge to both soils, organic carbon (OC) significantly increased compared to control. The same stands for soil available ammonium nitrogen (NH4-N), phosphorus (P), potassium (K), copper (Cu), zinc (Zn) and boron (B) for both soils and rates. Soil total heavy metals, which regulate sludge’s agronomic use, were below the legislative limits. However, the 3% addition rate of all kinds of sludge, especially of untreated, to both soils increased the electrical conductivity of saturation extract (ECse >2 dS m−1) at unacceptable levels for sensitive crops and available P, B and Zn 2–3, 2–4 and 6–12 times above the initial, respectively. Consequently, sewage sludge treated with bentonite, vermiculite or biochar could be used as a soil amendment but at rates lower than 3% (≈120 Mg ha−1).

Comparing Two Saline-Gypseous Wetland Soils in NE Spain

Small (&lt;1 km2) saline wetlands scattered across the landscape often go unnoticed or are threatened by urbanization or other interventions, despite their role as biodiversity shelters. This study is needed to show methods for monitoring this specific kind of wetland, and to guide the selection of analytical techniques. We provide data and comparisons for salient soil traits of two quasi-pristine gypsiferous and saline wetlands named Farrachuela (FA) and Agustín (AG). The soil characteristics presented in this article are a more sensitive indicator of their ecological status than some of the most used indicators, such as birds and plants. We found significant differences between the two saladas in percent water saturation, equivalent calcium carbonate, gypsum content, and soil salinity expressed as electrical conductivity both of 1:5 soil-to-water ratio and of saturation extracts. The differences were also significant in the concentrations of Mg2+, Na+, and Cl−, while they were non-significant for Ca2+, HCO32−, and SO42−. The mean contents of the six ions were lower in FA than in AG. Both pH and sodium adsorption ratios were significantly different between the two wetlands. The data are mainly examined and plotted by displaying their non-parametric statistics, a synoptic approach that will allow us to monitor the evolution of the wetlands against both traditional agricultural pressures and emerging green energy infrastructures. Last but not least, we discuss the shortcomings of some standard laboratory methods when applied to gypsum-rich soils.

Characterization and Classification of Soils in Agroecosystems in a Moist Enclave in Northeastern Brazil

Modern times have required studies that take into account the main soil features, aligning the use of land with the protection of more sensitive environments. From this perspective, this study aimed to perform a morphological description and determine the physical and chemical attributes for soil classification in the community of Poção, located in the municipality of Martins/RN, by highlighting the more sensitive attributes in the differentiation of environments through multivariate analysis. Nine soil profiles were identified to perform the morphological description and collect samples for physical and chemical analyses. The study updates the soil classes found in the study area: Acrisols, Planosols, and Cambisols, with the relief being the main factor responsible for the difference between soil attributes. The influence of organic matter on the soil attributes highlights the importance of its maintenance. Aluminum and the clay fraction are responsible for the distinction of the Acrisol class, whereas silt, potassium sodium, total organic carbon, the electrical conductivity of the saturation extract, and the cation exchange capacity allow the differentiation of Fluvisols.

A new approach to develop nitrogen fertilizer recommendation: a case study for Washington Navel orange cultivar

The quantitative recommendation of nutrients is one of the most important problems in plant nutrition and soil fertility. In this study, we explored a recommendation based on the correlation between N in soil saturation extract (NSSE) and that in plant organs (NPO). For this purpose, 39 Washington Navel Orange (WNO) orchards were selected in Jahrom (Iran), and from each orchard three WNO were chosen. For two consecutive years, in March and late May samples were taken from root, leaves, stem, fruit, and soil, and their nitrogen concentration determined. Orchards were divided into two categories, the first group was high-yield orchards and the second group included other orchards. A correlation matrix was run between NPO and NSSE; variables with significant correlation with NSSE were chosen and a multivariate regression was established between them. The results showed a significant positive correlation between plant organs with each other. Also, there was a significant correlation between NSSE and NPO, and the highest correlation was observed between nitrogen in young leaves and soil. A formula for estimating the amount of nitrogen fertilizer required for each orchard group was developed.

Lixiviação de sais e produção de maracujazeiro irrigado com água de baixa e alta salinidade

ABSTRACT The objective of this study was to evaluate the effect of irrigation with low- and high-salinity water on the increment of salts in the soil, the production components of sour passion fruit and the leaching of salts by rainfall and by leaching fraction of 10%. The treatments were arranged in randomized blocks, in a split-plot scheme, corresponding to three irrigation management practices [evaluation of soil chemical attributes before irrigation; and after irrigation with water of low electrical conductivity (0.35 dS m-1), and high electrical conductivity (4.00 dS m-1) in the main plot], and in the subplot two soil depths of evaluation (0-20 and 20-40 cm) and three soil sampling times (at 115 days after transplanting of seedlings (DAT) - beginning of flowering; at 199 DAT - end of the dry season; and at 379 DAT - end of the rainy season). Irrigation increased the electrical conductivity of the soil saturation extract, with higher values in the surface layer and at the end of the dry season. Rainfall during the rainy season reduced the saline character of soil from moderately saline and strongly saline, in treatments irrigated with water of low and high electrical conductivity, to non-saline and slightly saline, respectively. Irrigation with high-electrical conductivity water negatively affected the production components and yield of sour passion fruit.

Medium-Term Effect of Organic Amendments on the Chemical Properties of a Soil Used for Vegetable Cultivation with Cereal and Legume Rotation in a Semiarid Climate

The response of a Petrocalcic Palexeroll dedicated to the cultivation of vegetables (Apium graveolens L.) with a rotation of a mixture of cereals and legumes when organic amendments are added has been studied; specifically, three fertilization treatments were experimented with: two organic (LSM and COA) and one with chemical fertilizers (I). The LSM and COA plots were managed according to the regulations governing organic production, while in I, conventional agricultural production practices were used. Over a three-year period, monthly samples were taken from the topsoil and analyzed for organic carbon (OC), total nitrogen (TN), C/N ratio, total P (P), electrical conductivity of the saturation extract (ECext) and extract ions, pH in water (pHw) and 1 M KCl (pHKCl), cation exchange capacity (CEC), exchangeable bases (Mg2+, K+, Na+), and assimilable elements (Fe, Cu, Mn, Zn). The results obtained indicated significant differences between the treatments for the OC, TN, C/N, and P; specifically, in the case of OC the mean concentrations were 22.2 &gt; 20.1 &gt; 17.5 g kg−1 for the LSM, COA, and I, respectively. The addition of organic amendments also improved the soil function for food production, evidenced by the higher concentrations of K, Mg, and micronutrients. The ECext and extracted ions were also sensitive to the treatments such that the sequence of ECext in the third year was COA = LSM &gt; I, with values of 5.0, 4.8, and 3.3 dSm−1, which forced a rethink of the doses of the amendments applied. These results suggest that the LSM-based agronomic model had a beneficial effect on the soil properties and contributed to its function as a C sink.

Salinity-specific stomatal conductance model parameters are reduced by stomatal saturation conductance and area via leaf nitrogen

Modeling stomatal behavior is necessary for accurate stomatal simulation and predicting the terrestrial water‑carbon cycle. Although the Ball-Berry and Medlyn stomatal conductance (gs) models have been widely used, variations and the drivers of their key slope parameters (m and g1) remain poorly understood under salinity stress. We measured leaf gas exchange, physiological and biochemical traits, soil water content and electrical conductivity of saturation extract (ECe), and fitted slope parameters of two genotypes of maize growing in two water and two salinity levels. We found m was different between the genotypes, but no difference in g1. Salinity stress reduced m and g1, saturated stomatal conductance (gsat), the fraction of leaf epidermis area allocation to stomata (fs), and leaf nitrogen (N) content, and increased ECe, but no marked decrease in slope parameters under drought. Both m and g1 were positively correlated with gsat, fs, and leaf N content, and negatively correlated with ECe in the same fashion among the two genotypes. Salinity stress altered m and g1 by modulating gsat and fs via leaf N content. The prediction accuracy of gs was improved using salinity-specific slope parameters, with root mean square error (RMSE) being decreased from 0.056 to 0.046 and 0.066 to 0.025 mol m−2 s−1 for the Ball-Berry and Medlyn models, respectively. This study provides a modeling approach to improving the simulation of stomatal conductance under salinity.

Chemical processes and sustainability of rice-shrimp farming on saline acid sulfate soils in mekong delta

In the history of rice-shrimp farming (RSF) in the Mekong Delta, in saline acid sulfate soils (ASS), RSF has proved its sustainability as there is no long-term accumulation of acidity and salinity that adversely affect RSF production. However, the soil processes involved in this phenomenon are not well understood. This study aimed to determine the significant changes in soil and water chemical indicators associated with soil processes during different stages of RSF. Sampling was conducted in six stages to determine the pH and electrical conductivity (EC) of canal and field water, and the pHe, ECe, and sodium-soluble saturated extract (Na-sol) of surface soil (surS) and subsurface soil (subS) in the low-salinity area (LSA) and high salinity area (HSA) of Bac Lieu province. Putative exchange (exch.) Na+ hydrolysis occurs at the beginning of the rainy season when excess salts are leached. This drastically increases the pH of the field water by 0.6 pH units, from 8.2 to 8.8 in stages 1 to 2, respectively. Putative sulfurization has been shown to occur in subS in both LSAs and HSAs, with a significant decrease of 0.5 pH units from stages 4 to 5, leading to a decrease in the Na-sol of subS through exch. Na+ transformation. Simultaneously, with active soil preparation and liming for RSF, chemical processes such as exch. Na+ hydrolysis, sulfurization, and Na+ transformation are the main factors promoting exch. Na+ desorption, which help to reduce the long-term build-up of salinity and acidity that adversely affect RSF production. Although gypsum is considered an effective material in improving saline soils, in Vietnam, gypsum is the liming material of CaSO4; however, it is not commonly used in agriculture because of its high cost. By using CaCO3 or dolomite as a liming material in saline ASS, the dissolution of lime by sulfuric acid can provide a good opportunity for soil improvement and rice growth in RSF.

Atributos químicos do solo sob combinações de adubação orgânica e salinidade da água

ABSTRACT The use of brackish water causes chemical changes in cultivated soils. It is therefore necessary to apply strategies that can minimize its negative impacts, such as the use of organic fertilizers. This study aimed to evaluate in the field the chemical attributes of a Red Yellow Argisol under irrigation with saline water and organic fertilizing in an area cultivated with corn. The design was randomized blocks, in a split-plot scheme, with the plots comprising salinity levels for the irrigation water (0.8 and 3.0 dS m-1) and the subplots combinations of organic fertilizers (cattle manure + poultry biofertilizer + goat biofertilizer; cattle manure + goat biofertilizer; cattle manure + poultry biofertilizer; control), with four replications. The 3.0 dS m-1 irrigation has a negative effect on the soil chemical attributes, particularly reducing the pH and increasing the sodium, exchangeable sodium percentage and electrical conductivity of the soil saturation extract. The combination of cattle manure + poultry biofertilizer + goat biofertilizer mitigates the salt stress by favouring the accumulation of nitrogen and organic matter, while the cattle manure + poultry biofertilizer favours the potassium accumulation in the soil. The combination of cattle manure + poultry biofertilizer + goat biofertilizer increases the contents of phosphorus and potassium when using the 0.8 dS m-1 irrigation.

Matéria orgânica e sombreamento no acúmulo de íons em solo cultivado com noni sob salinidade

ABSTRACT This study aimed to evaluate the influence of organic matter on the salt accumulation in three layers of soil cultivated with noni plants irrigated with brackish water, in open field and under partial shading conditions. The experimental design was in randomized blocks, arranged in a split-split-plot scheme with five replicates. The plots were constituted by the cultivation environments (open and shaded field), the subplots by the electrical conductivity of the irrigation water (0.3, 1.5, 3.0, 4.5, and 6.0 dS m-1), and the sub-subplots by the absence and presence of organic matter. At 110 days after application of the treatments, the electrical conductivity of the saturation extract and the potassium, sodium, calcium, and magnesium concentrations were determined in three soil layers (0-10, 10-20, and 20-30 cm). Partial shading reduced the total accumulation of salts and sodium in the soil compared to the open field. Increasing the electrical conductivity of irrigation water reduced potassium concentrations in the soil, but this effect is offset by the addition of organic matter, which releases potassium, calcium, and magnesium for plant nutrition. However, cattle manure increases sodium accumulation in the soil in treatments with the highest water salinity.

Peanut shell biochar’s effect on soil physicochemical properties and salt concentration in highly saline-sodic paddy fields in northeast China

Soil salinization is a major ecological threat to crop growth and production. Biochar addition can alleviate the negative impacts of saline-sodic stress in crops. Here, a two-year field experiment was conducted in a highly saline-sodic paddy field to evaluate the response of soil physico-chemical properties, ionic concentration, and rice yield to biochar applications. The soil was amended with peanut shell biochar as follows: zero biochar (B0), 33.75 t ha−1 (B1), 67.5 t ha−1 (B2), and 101.25 t ha−1 (B3). Biochar significantly reduced soil bulk density (BD), while it markedly increased total porosity (TP) and saturated hydraulic conductivity (Ks). Furthermore, biochar markedly decreased the Na+ concentration, Na+/K+ ratio, Na+/Ca2+ ratio, HCO3-, and CO32- while it increased the concentrations of K+, Ca2+, and Mg2+. Biochar significantly decreased the electrical conductivity of soil saturation extract (ECe). The exchangeable sodium percentage (ESP) of B1, B2, and B3 were 53.6%, 62.3%, and 71.0% lower, respectively, than that of B0, and the corresponding decrease in sodium adsorption ratio (SARe) was 51.2%, 58.1%, and 60.5%. Biochar had no effect on the soil pH but significantly increased the soil cation exchange capacity (CEC). The rice biomass yield, grain yield, and harvest index significantly increased after biochar application.

Salt stress and leaching fraction in cowpea culture

Salt stress negatively affects the agronomic performance of agricultural crops. In this sense, the objective of this work was to evaluate growth and soil saturation extract parameters (EC and pH) in cowpea crop irrigated with saline water under different leaching fractions. The experiment was conducted in the experimental area of the Auroras Seedling Production Unit, which belongs to the Universidade da Integração Internacional da Lusofonia Afro-Brasileira. The design used was entirely randomized, in a 5x2 factorial scheme, referring to five leaching fractions (0; 5; 10; 15 and 20%) and two electrical conductivities of the irrigation water (0.3 and 4.0 dS m -1 ), with five repetitions. The leaf area, aboveground and root dry mass were negatively affected with the increase of the leaching fraction, however, with less intensity with water of lower salinity. Increasing the leaching fraction increased the number of leaves, stem diameter, and pH, but more efficiently with the lower salinity water. The increase of the leaching fraction associated with water of higher salinity increased the electrical conductivity of the saturation extract of the soil.