Salt Accumulation In Soil Research Articles

Simulation of water-salt transport and balance in cultivated-wasteland system based on SWAP model in Hetao Irrigation District of China

Water and salt transport among different use type land is important to irrigation management in arid area. In this study, a typical irrigation unit including cultivated land and wasteland in Hetao Irrigation District of China was selected to explore water and salt transport between cultivated land and wasteland system. Soil water-salt dynamics, groundwater depth and salinity were observed within the period of crop growing and autumn irrigation period in 2018 and 2019. Calibrated SWAP model was used to simulate water and salt flux of cultivated land and wasteland during the crop growing period and autumn irrigation period. Furthermore, water-salt transport exchange capacity was calculated between cultivated land and wasteland system in study area. Groundwater was recharged by soil water and soil salt was leached in cultivated land during the crop growing period. Soil water was recharged by groundwater and soil salt was accumulated in saline wasteland during the crop growing period. During the crop growing period, the total leaching of soil salinity was 15.64 t·ha−1 in cultivated land. Soil salt accumulation was 2.03 t·ha−1 in saline wasteland. During the autumn irrigation period, the total leaching of soil salinity was 14.93 t·ha−1 in cultivated land. Total leaching of soil salinity was 1.56 t·ha−1 in saline wasteland. Overall, saline wasteland had an important role to receive salt from cultivated land and maintain salt dynamic balance in arid irrigation area with shallow groundwater.

Effects of long-term saline water irrigation on soil salinity and crop production of winter wheat-maize cropping system in the North China Plain: A case study

Fresh water shortage is a major problem for grain production in the low plain around Bohai Sea in the North China Plain. Relative abundance of shallow saline groundwater could serve as an alternative water resource for use during dry seasons. A continuous 8-year field study was conducted from 2015 to 2023 to assess the effects of salt content in irrigation water on soil salt accumulation and crop production. Fresh water (FW) with electrical conductivity (EC) at 1.6 dS/m and three levels of saline water (SW) with EC at 4.7 (SW1), 6.3 (SW2) and 7.8 dS/m (SW3) were used for irrigation. Results showed that a single irrigation event at the jointing stage of winter wheat increased grain production averagely by 18.6 %, 22.5 %, 12.9 % and 9.5 % compared with a rain-fed treatment (RF) under FW, SW1, SW2 and SW3, respectively. With an additional irrigation applied at flowering stage, both irrigations using FW increased the yield by 28.6 %, and both irrigations using SW2 increased the yield by 19.3 % compared with RF. Negative effects of salt on winter wheat overshadowed the positive effects of increased water supply under two irrigations both using SW. With an irrigation at maize sowing and the subsequent summer rainy season, the yield of maize following winter wheat was not affected by a one-time SW irrigation to the previous crop, but showed a 5.3 % yield reduction when two irrigations of SW were applied. There was no apparent salt accumulation in the top 1 m of the soil profile, but a slight increasing trend in the salt content in the 1–2 m layer of the soil profile under SW2 and SW3 irrigation. No apparent changes in soil physical properties were observed for continuous application of SW. It was suggested that SW with EC not exceeding 6.3 dS/m should be applied for a single irrigation during the winter wheat season. This practice could alleviate the fresh water shortage in this region and allow for the maintenance of a relatively stable yield of winter wheat and maize without the risk of salt accumulation in the soil.

Effects of Seasonal Freezing and Thawing on Soil Moisture and Salinity in the Farmland Shelterbelt System in the Hetao Irrigation District

Water resources are scarce, and secondary soil salinization is severe in the Hetao Irrigation District. Farmland shelterbelt systems (FSS) play a critical role in regulating soil water and salt dynamics within the irrigation district. However, the understanding of soil water and salt migration within FSS during the freeze–thaw period remains unclear due to the complex and multifaceted interactions between water and salt. This study focused on a typical FSS and conducted comprehensive monitoring of soil moisture, salinity, temperature, and meteorological parameters during the freeze–thaw period. The results revealed consistent trends in air temperature and soil temperature overall. Soil freezing durations exceeded thawing durations, and both decreased with an increasing soil depth. At the three critical freeze–thaw nodes, the soil moisture content at a 0–20 cm depth was significantly lower than at a 40–100 cm depth (p < 0.05). The soil water content increased with time and depth at varying distances from the shelterbelt, with an average increase of 7.63% after freezing and thawing. The surface water content at the forest edge (0.3H, 4H) was lower than inside the farmland (1H, 2H, 3H). Soil salt accumulation occurred during both freezing stable periods and melting–thawing periods in the 0–100 cm soil layer near the forest edge (0.3H, 4H), with the highest soil salinity reaching 0.62 g·kg−1. After the freeze–thaw period, the soil salt content in each layer increased by 11.41–47.26% compared to before the freeze–thaw period. Salt accumulation in farmland soil near the shelterbelt was stronger than in the far shelterbelt. The multivariate statistical model demonstrated goodness of fit for soil water and salt as 0.94 and 0.72, respectively, while the BP neural network model showed goodness of fit for soil water and salt as 0.82 and 0.85, respectively. Our results provide an efficient theoretical basis for FSS construction and agricultural water management practices.

Mineral accumulation, relative water content and gas exchange are the main physiological regulating mechanisms to cope with salt stress in barley

Salinity has become a major environmental concern for agricultural lands, leading to decreased crop yields. Hence, plant biology experts aim to genetically improve barley’s adaptation to salinity stress by deeply studying the effects of salt stress and the responses of barley to this stress. In this context, our study aims to explore the variation in physiological and biochemical responses of five Tunisian spring barley genotypes to salt stress during the heading phase. Two salinity treatments were induced by using 100 mM NaCl (T1) and 250 mM NaCl (T2) in the irrigation water. Significant phenotypic variations were detected among the genotypes in response to salt stress. Plants exposed to 250 mM of NaCl showed an important decline in all studied physiological parameters namely, gas exchange, ions concentration and relative water content RWC. The observed decreases in concentrations ranged from, approximately, 6.64% to 40.76% for K+, 5.91% to 43.67% for Na+, 14.12% to 52.38% for Ca2+, and 15.22% to 38.48% for Mg2+ across the different genotypes and salt stress levels. However, under salinity conditions, proline and soluble sugars increased for all genotypes with an average increase of 1.6 times in proline concentrations and 1.4 times in soluble sugars concentration. Furthermore, MDA levels rose also for all genotypes, with the biggest rise in Lemsi genotype (114.27% of increase compared to control). Ardhaoui and Rihane showed higher photosynthetic activity compared to the other genotypes across all treatments. The stepwise regression approach identified potassium content, K+/Na+ ratio, relative water content, stomatal conductance and SPAD measurement as predominant traits for thousand kernel weight (R2 = 84.06), suggesting their significant role in alleviating salt stress in barley. Overall, at heading stage, salt accumulation in irrigated soils with saline water significantly influences the growth of barley by influencing gas exchange parameters, mineral composition and water content, in a genotype-dependent manner. These results will serve on elucidating the genetic mechanisms underlying these variations to facilitate targeted improvements in barley's tolerance to salt stress.

Effects of Biochar and Straw Return on Soil Microbial Community Characteristics and Functional Differences in Saline Water Drip Irrigation Cotton Fields

In arid areas, fresh water resources are insufficient, and agricultural water mainly depends on shallow saline groundwater. However, long-term saline irrigation will cause soil salt accumulation and soil environment deterioration, which is not conducive to crop growth. In this study, based on the long-term irrigation of fresh water (0.35 dS·m-1, FW) and saline water (8.04 dS·m-1, SW), biochar (3.7 t·hm-2, BC) and straw (6 t·hm-2, ST) were added to the soil by an equal-carbon design. The aim was to clarify the effects of biochar and straw returning on the physical and chemical properties and microbial community structure of salinized soil. The results showed that saline irrigation significantly increased soil water content, electrical conductivity, available phosphorus, and total carbon content but significantly decreased pH value and available potassium content. The contents of available phosphorus, available potassium, and total carbon in soil were significantly increased by biochar and straw returning, but the conductivity value of soil irrigated with saline water was significantly decreased. The dominant bacteria in each treatment were Proteobacteria, Actinomycetes, Acidobacteria, Chloromycetes, and Blastomonas. Saline water irrigation significantly increased the relative abundance of Blastomonas and Proteobacteria but significantly decreased the relative abundance of Acidobacteria and Actinobacteria. Under the condition of fresh water irrigation, the relative abundance of Chlorocurvula was significantly reduced by the return of biochar. Straw returning significantly increased the relative abundance of Proteobacteria but significantly decreased the relative abundance of Acidobacteria, Actinomyces, Chloromyces, and Blastomonas. Under saline irrigation, the relative abundance of Chlorocurvula and Blastomonas were significantly reduced by biochar return to field. Straw returning significantly increased the relative abundance of Proteobacteria but significantly decreased the relative abundance of Acidobacteria, Actinomyces, Chloromyces, and Blastomonas. LEfSe analysis showed that saline irrigation decreased the potential markers and functional numbers of soil microorganisms.Under saline irrigation, biochar returning increased the number of potential markers and functions of soil microorganisms. Straw returning to field increases the number of potential markers of soil microorganisms. RDA results showed that soil microbial community and functional structure were significantly correlated with EC1:5, SWC, and pH. Saline water irrigation will deteriorate the soil environment, which is not conducive to agricultural production, among which EC1:5, SWC, and pH are important factors driving changes in soil microbial community and functional structure. Using biochar and straw to return to the field can reduce the harm of salt to soil and crops, laying a foundation for improving agricultural productivity.

Phytoremediation ability of Panicum maximum and Salicornia europaea irrigated with treated wastewater for salt elements in the soil

Soil salinity is one of the major problems that threaten the soils in Jordan, which led to a decrease in the percentage of arable land in Jordan. The phytoremediation process is concerned with the restoration of contaminated soils using tolerant plants, such as halophyte plants. In this context, the potential short-term phytoremediation ability of Panicum Mombasa and Salicornia Europaea was evaluated and measured. A field experiment was conducted over two consecutive years to study the ability of these previous two crops for the phytoremediation of saline soils induced by treated wastewater irrigation. Both crops with bare soil as a control were irrigated together from the effluent of the Ramtha Wastewater Treatment Plant at the same time. Soil electrical conductivity was identified as the main parameter for measuring the plant’s ability for salt absorption. The results for both seasons show a higher accumulation of salts in bare soil significantly as expected since no plants were present to absorb these salts and no leaching requirements were added with irrigation water. The absorption rate for each crop was measured at the 1st season for comparison. It is measured for each crop depending on the length of the growing season. Salicornia’s absorption rate was greater than Panicum, and it reached 36 ppm/day for salicornia, whereas it reached 33 ppm/day for panicum. In the 2nd season, both crops are planted and harvested together. Salt absorbed percentage from the soil under Salicornia was greater than Panicum and it reached 73 % as compared to bare soil. However, in the soils under Panicum, the amount of salts absorbed reached 37 % as compared to bare soil. Plant analysis for both crops shows higher salt ions accumulation in Salicornia tissues than Panicum, and this explains the higher absorption rate for Salicornia than Panicum. Microbiological analysis for Panicum shows some contamination, whereas no contamination occurs in Salicornia. This is explained by the high salinity environment in Salicornia which is not favorable for e-coil, total, and fecal coliform to grow. The obtained Results from this research state that both crops have the ability for phytoremediation, with greater ability for Salicornia.

Super absorbent polymer (SAP) on water‐salt transport in saline alkali soil: Effects of dosage, height and thickness

AbstractSoil salinisation is a pervasive form of land degradation posing a significant threat to the global environment. Saline soil, covering roughly 10% of the total land area, represents a crucial reserve of land resources. The use of super absorbent polymer (SAP) impacts capillary water movement through the soil because of its exceptional water absorption and retention capabilities. SAP is expected to influence the intricate water‐salt migration processes and their redistribution within soil. This study employed soil column experiments to investigate the impacts of varying SAP dosages (A), heights (B) and thicknesses (C) on soil water and salt transport in the Tianjin Binhai New Area, China. The main findings showed that: (1) average capillary water rise rate decreased with SAP dosage increase. The groundwater recharge trend in time was like that of capillary water rise height; (2) SAP usage increased water and salt content on the application layer and reduced surface soil salt accumulation; (3) the best SAP combination for application was 1.1% SAP at 17–18 cm from the groundwater level. This study provides basic effective SAP application strategies for preventing soil salinisation.

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.

Effect of GA3 and calcium on growth, biochemical, and fatty acid composition of linseed under chloride-dominated salinity.

The accumulation of salts in soil is an environmental threat affecting plant growth and crop yield. Linseed or flax is an ancient crop that has multifarious utilities in terms of industrial oil, textile fiber, and products. Salt susceptibility adversely affects linseed production, particularly to meet the growing demand for nutritional and nutraceutical products. In the present study, the ameliorative potential of gibberellic acid (GA3) and calcium (Ca2+) in mitigating the adverse effects of chloride-dominated salinity stress on the growth and physiological and biochemical processes in linseed was determined. Severe salinity treatment (10 dSm-1) resulted in stunted growth of tested linseed genotypes causing a significant reduction in biomass while proline content, phenol, H2O2, lipid peroxidation, and DPPH activity were increased in comparison to control. The exogenous application of 10-6M GA3 and/or 10mg CaCl2 kg-1 was found to mitigate the adverse effects of salinity stress. The mitigation was accomplished through the improvement of growth indicators, increased osmoprotectants such as proline and phenol content, stimulating DPPH activity, and reduction of H2O2 content and lipid peroxidation. The comparative evaluation of different saline treatments imposed individually and in combination with GA3 and Ca2+ revealed that combined GA3 and Ca2+ application exhibited synergistic effects and was most effective in mitigating the negative impacts of salt stress. The present study unravels the ameliorative role of GA3 and Ca2+ (individual or combined) in the physiologic-biochemical adaptive response of linseed plants grown under chloride-dominated salinity and thus aids in a better understanding of the underlying tolerance mechanisms of plants to withstand stress in saline environments.

THE SPATIAL DISTRIBUTION AND MOVEMENT OF SOLUBLE SALTS FROM ROMANIAN SOILS

The objective of this paper is to present a sketch map of the accumulation of soluble salts in soils from Romania, as a support for improving saline soils or preventing undesirable anthropogenic salinization phenomena.The map highlights the spatial distribution and movement of easily soluble salts in soil at the scale of the entire country, It is an overview on origin, sources and pathways of migration and accumulation of easily soluble salts in interdependence with natural factors and conditions.Taking into account the movement pathways of easily soluble salts in soil, two geochemical zones were separated on the map: the eluviation - transit zone and the transit - accumulation zone. In the last zone, areas where the accumulation of salts becomes dominant have been delimited, their transit being insignificant. The movement directions of easily soluble salts in soil are also highlighted on the map.From a naturalistic point of view, the map highlights the close connection between areas with accumulation of salts and areas where geological, geomorphological and hydrogeological conditions lead to a poor drainage. It also highlights the connection and importance of salt sources from geological deposits or salt masses in the hilly area in the formation, expansion and chemistry of saline soils in the plain or floodplain areas located in the neighbouring lowlands.

Quantifying the spatial water salinity threshold of saline water irrigation by applying distributed WAVES model

CONTEXTSaline water irrigation presents a viable solution to alleviate freshwater scarcity. However, it's crucial to consider the threshold of salinity, as excessive levels can adversely affect crop yield, crop productivity and soil sustainability. Additionally, due to varying surface conditions and management practices at the regional level, a distributed approach to saline water irrigation management is necessary. OBJECTIVEThe primary goal of this research was to develop a regional agro-hydrological crop model. The validated regional model was then employed to identify the spatial water salinity threshold for saline water irrigation. METHODSIn this research, we utilized the WAVES (WAter Vegetation Energy and Solute model), which was adapted for mulching environment and validated in severely arid and saline fields. To account for spatial variations, we applied a distributed method to upscale the WAVES to the regional level. Multisource and multiscale data were used for regional model validation. Different scenarios of salinity levels for saline water irrigation were simulated, and a comprehensive criterion to determine water salinity threshold was proposed considering cotton yield, water productivity and soil salt accumulation. RESULTS AND CONCLUSIONSModel evaluation indicated a high level of accuracy for the developed regional model. The comparison between simulated and measured values for soil salt content, soil water content, cotton leaf area index, measured lint yield, and statistical yield resulted in indices of agreement of 0.90, 0.71, 0.93, 0.58, and 0.70, respectively. The validated regional model was employed to simulate various saline water irrigation scenarios. The findings revealed that under identical irrigation water salinity, cotton cultivation on sandy loam soil is more productive but has a larger yield reduction percentage compared to silty loam soil. Moreover, the research indicates a groundwater depth of 1.5 m is associated with higher cotton production. Additionally, a spatial pattern of the irrigation water salinity threshold for saline water irrigation was determined, suggesting that the water salinity in most areas of the Tarim Irrigation District should not exceed 6 g L−1. Notably, in the current practice of pumping groundwater in situ for irrigation, approximately 46% of the areas are at risk, indicating that it's not suitable for saline water irrigation. SIGNIFICANCEThis study developed a distributed model under a typical irrigation district characterized by mulching, severe drought and salinization and defined the distributed spatial threshold for saline water irrigation. These research results hold significant implications for guiding regional-scale saline water irrigation and groundwater extraction.

Water and Salinity Variation along the Soil Profile and Groundwater Dynamics of a Fallow Cropland System in the Hetao Irrigation District, China

Managing soil salinity has always been a difficult problem for agriculture. Balancing water and salt while maintaining crop quality and yield is a key issue for agricultural sustainability. The Hetao lrrigation District in China has a complex mix of cultivated and uncultivated land which plays a crucial role in soil salinization processes. To investigate the dynamic properties of soil moisture and salinity, soil ions and groundwater, cultivated and fallow soils in the Hetao lrrigation District were analyzed, side by side, using a combination of field and laboratory tests, with data processed using univariate and multivariate statistical approaches. The results showed that soil moisture increased with increasing soil depth in both cultivated and fallow soils. Salinity showed an increasing trend in 2022 and 2023 from April to September. The soil ions were mainly sulfate in the cultivated soils and chloride in the fallow soils. The characteristic factors affecting salt accumulation in cultivated soils are Na++K+, Cl−, SSC, SO42−, HCO3−, and pH, and the characteristic factors affecting salt accumulation in fallow soils are Na++K+, Cl−, SSC, HCO3−, and pH. Water table depth varied with irrigation and precipitation and was strongly influenced by external environmental factors. Groundwater salinity remained stable throughout the study period. This study provides a theoretical basis for the prevention and control of soil salinization in arid and semiarid areas through the “dry drainage salt” measure.

IMPACT OF CHLORIDE AND LEAD ION CONTENT IN OPEN WATER SOURCES IN KYZYLORDA REGION ON POPULATION’S CANCER INCIDENCE

Relevance: In 2004-2013, the cumulative cancer incidence was about 200 cases per 100 thousand in Kazakhstan, while in the disaster area of Aral Sea – about 225 cases per 100 thousand. For comparison, cancer incidence in the prosperous region of Karaganda was 140 cases per 100,000 population. As of 2021, the incidence of colorectal cancer in Kyzylorda was 17.73 compared to 5.81 per 100,000 population in 2015.
 Factors of the surrounding macro- and microenvironment are trigger factors for tumor initiation. Salt deposits of the dried Aral Sea in the form of solonchaks spread to the territory of the entire Kyzylorda region. Pesticides and process water have been discharged into rivers for many years, which has led to the accumulation of heavy metal salts in water and soil on the banks of the rivers and in the place of the dried-up Aral Sea, which in turn can affect the increase in cancer incidence.
 The study aimed to study the dependence of cancer incidence on water pollution by ions of chlorine and lead in open water bodies in the Kyzylorda region.
 Methods: Analysis of cancer incidence in 2021 by localization: intestines, stomach, sarcomas, lungs, and melanomas in the Kyzylorda region. Determination of the content of chlorine ions by titration with silver nitrate, spectrophotometric determination of lead ions in the open water sources. Comparative correlation analysis of the concentration of chlorine ions and lead with cancer incidence in this region.
 Results: The maximum permissible chlorine and lead ions concentrations in all studied open water sources of the Kyzylorda region exceeded the norm by 1.024-20.26 times and 1.4-14.1 times, respectively. The presence of chlorides in the water increased intestine cancer incidence by 17% with an approximation certainty of 0.38. The presence of lead in water increased the incidence of melanomas by 22%, with an approximation certainty of 0.79. The correlation coefficient was r=0.618; p=0.07 for exceeding chlorides’ MPC and bowel cancer incidence.
 Conclusion: Heavy metals like lead in water samples in regions with increased cancer incidence indicate a co-dependent relationship of these factors. Pollutants such as chlorides and lead increase intestine cancer and melanoma incidence.

IMPACT OF CHLORIDE AND LEAD ION CONTENT IN OPEN WATER SOURCES
 IN KYZYLORDA REGION ON POPULATION’S CANCER INCIDENCE

Relevance: In 2004-2013, the cumulative cancer incidence was about 200 cases per 100 thousand in Kazakhstan, while in the disaster area
 of Aral Sea – about 225 cases per 100 thousand. For comparison, cancer incidence in the prosperous region of Karaganda was 140 cases per
 100,000 population. As of 2021, the incidence of colorectal cancer in Kyzylorda was 17.73 compared to 5.81 per 100,000 population in 2015.
 Factors of the surrounding macro- and microenvironment are trigger factors for tumor initiation. Salt deposits of the dried Aral Sea in the
 form of solonchaks spread to the territory of the entire Kyzylorda region. Pesticides and process water have been discharged into rivers for
 many years, which has led to the accumulation of heavy metal salts in water and soil on the banks of the rivers and in the place of the dried-up
 Aral Sea, which in turn can affect the increase in cancer incidence.
 The study aimed to study the dependence of cancer incidence on water pollution by ions of chlorine and lead in open water bodies in the
 Kyzylorda region.
 Methods: Analysis of cancer incidence in 2021 by localization: intestines, stomach, sarcomas, lungs, and melanomas in the Kyzylorda
 region. Determination of the content of chlorine ions by titration with silver nitrate, spectrophotometric determination of lead ions in the open
 water sources. Comparative correlation analysis of the concentration of chlorine ions and lead with cancer incidence in this region.
 Results: The maximum permissible chlorine and lead ions concentrations in all studied open water sources of the Kyzylorda region exceeded the norm by 1.024-20.26 times and 1.4-14.1 times, respectively. The presence of chlorides in the water increased intestine cancer incidence
 by 17% with an approximation certainty of 0.38. The presence of lead in water increased the incidence of melanomas by 22%, with an approximation certainty of 0.79. The correlation coefficient was r=0.618; p=0.07 for exceeding chlorides’ MPC and bowel cancer incidence.
 Conclusion: Heavy metals like lead in water samples in regions with increased cancer incidence indicate a co-dependent relationship of
 these factors. Pollutants such as chlorides and lead increase intestine cancer and melanoma incidence

Optimizing biochar application rates for improved soil chemical environments in cotton and sugarbeet fields under trickle irrigation with plastic mulch

Biochar can potentially change the soil physico-chemical environment significantly, but its impact on the soil chemical environment is poorly understood. To investigate this, a three-year field experiment with drip irrigation under plastic film mulch was conducted from 2018 to 2020 in a saline-alkali cotton and sugarbeet field in Xinjiang, China. The experiment examined the influences of different biochar application rates (BAR) on the distribution and variations of soil Na+ and K+ contents, soil nutrient contents (NO3–-N, NH4+-N, soil organic carbon, available phosphorus, and available potassium), soil salt content and accumulation. Four BAR treatments of 0, 10, 50, and 100 t ha–1, namely CK, B10, B50, and B100 were designed in 2018, with adjusted in 2019 and 2020 based on the former 2 year’s results, namely CK, B10, B25 (25 t ha–1), B50, and B100 in 2019, and CK, B10, B25, and B30 (30 t ha–1) in 2020. The results indicated that increasing BAR significantly increased Na+, K+, and soil nutrient contents in cotton and sugarbeet fields. Soil salinity were the highest in inter-rows, followed by narrow and wide rows, and salt accumulated at 0–60 cm depth the most. Weighted-average planar soil salt storage positively correlated with BAR, with lower soil salt contents for sugarbeet than cotton at the same depth. Based on the effects of different BAR on soil ion concents, soil nutrients, and soil salinity, we recommended 10 t ha−1 as an optimal BAR for improving the chemical environment of saline-alkali soil, and sugarbeet as an effective crop for reducing soil salinity. These findings provided valuable technique parameters for biochar application in saline-alkali land.

Effects of Drought Hardening and Saline Water Irrigation on the Growth, Yield, and Quality of Tomato

Drought hardening could promote the development of plant roots, potentially improving the resistance of crops to other adversities. To investigate the response and resistance of physiological and growth characteristics induced by drought hardening to salt stress in the later stages, a greenhouse experiment was carried out from 2021 to 2022 with one blank control treatment and twelve treatments that comprised combinations of four irrigation regimes (W1 = 85%, W2 = 70%, W3 = 55%, and W4 = 40% of the field capacity) and three irrigation water salinity levels (S2, S4, and S6, referring to 2 g, 4 g, and 6 g of sodium chloride added to 1000 mL of tap water, respectively). The results show that saline water irrigation introduced a large amount of salt into the soil, resulting in the deterioration of tomato growth, physiology, yield, and water use efficiency (WUE), but had a positive, significant effect on fruit quality. When the irrigation water salinity was 2 g L−1, the W2 treatment could reduce soil salt accumulation, even at the end of the maturation stage; consequently, enhancing the increments in plant height and leaf area index during the whole growing stage. The physiological activity of tomato plants under the W2 and W3 treatments showed a promoting effect. Correspondingly, the maximum values of the fruit quality of tomato plants irrigated with the same saline water were all obtained with the W2 or W3 treatment. However, the yield and WUE of the W3 treatment were lower than that of the W2 treatment, which was the highest among the same saline water irrigation treatments, consistent with the reflection of the changing trend of the ratio of fresh weight to dry weight. Overall, drought hardening can be considered an economically viable approach to mitigate the hazards of saline water irrigation, and the W2S2 combination is recommended for tomato production due to the maximum values of yield and WUE with a higher fruit quality among the twelve saline water irrigation treatments.

Salt-affected soils: field-scale strategies for prevention, mitigation, and adaptation to salt accumulation

The area of salt-affected soils is increasing globally, mainly due to land use and management malpractices, which can threaten soil health and the sustainability of farms. Climate change is likely to increase the prevalence of salt-affected soils in many agricultural areas due to increased aridity and, in coastal areas, due to the increase in sea water level. The causes and processes that develop salt-affected soils are diverse and can result in soil salinity, sodicity, alkalinity, or a combination of these conditions. There is a need to continuously update strategies to tackle salt-affected soils, finding solutions tailored at different scales. This work presents a review of the current knowledge related to salt-affected soils and identifies specific strategies and related case studies for the prevention, mitigation, and adaptation to salt accumulation in soils at the field scale while addressing their limitations, advantages, research needs, and innovation potential. The presented case studies show that adequate irrigation management and drainage can be used as a preventive measure to counter salt accumulation in soils. Phyto and bioremediation can be effective practices for the mitigation of soil sodicity. Leaching and drainage can be effective measures for mitigation of soil salinity. Crop rotation and management of soil organic matter can be used as adaptative measures that improve plant tolerance to salt-affected soils, while a newer approach, microbial management, shows innovation potential as an adaptative measure.

Optimizing brackish water and nitrogen application regimes for soil salinity, yield, fertilizer and water productivity of a mulched drip irrigated cotton cropping system

ContextBrackish water irrigation poses a threat to the sustainability of irrigated dryland crop systems, making it essential to identify effective water and nutrient management regimes to mitigate salt impact on agriculture. ObjectiveThis project is focused on determining the optimal combination of brackish irrigation water and nitrogen application in the mulched drip irrigation cultivation system for cotton crops in Xinjiang. MethodsThe combined effects of three brackish water irrigation amounts (I) (I1, 337 mm; I2, 412 mm; and I3, 562 mm) and three nitrogen application levels (N) (N1, 160 kg ha−1; N2, 315 kg ha−1; and N3, 395 kg ha−1) were investigated on soil salinity, cotton (Gossypium hirsutum L.) growth, nitrogen fertilizer and water productivity under mulched drip irrigation. The experiment was conducted over two growth cycles using a split-plot design with three replication treatments, with I arranged in the main plots and N in the subplots. ResultsResults indicated that irrigation amount, nitrogen application level, and their interaction significantly affected soil salt accumulation, cotton shoot biomass and yield, cotton nitrogen uptake (NU), nitrogen partial factor productivity (NPFP), and water productivity (WP). Additionally, the main effect year had a significant effect on all study variables, with higher values observed in 2017 compared to 2016, except for soil salt accumulation. The highest cotton shoot biomass, yield, NU, and WP as well as the lowest soil salt accumulation in mulched strips were both obtained in the I2N2 treatment. ConclusionThis treatment can be an optimal water and nitrogen management strategy for the cotton planting system under mulched drip irrigation and is crucial for achieving water and fertilizer savings in dryland conditions with brackish water irrigation.

Impact of Different Irrigation Methods on the Main Chemical Characteristics of Typical Mediterranean Fluvisols in Portugal

The sustainable management of Mediterranean agricultural soils, characterized by salinization and low organic matter content, requires a thorough understanding of their temporal and spatial evolution. The focal point of this investigation encompasses an area of 6769 ha within the Portuguese Mediterranean basin, from which as many as 686 topsoil specimens were acquired during the periods 2001/2002 and 2011/2012 for the purpose of scrutinizing soil organic matter (SOM) content, pH measured in water, and electrical conductivity (EC). The methodology employed both classical and geostatistical techniques, and the terrestrial samples were classified in accordance with the irrigation mechanisms in use (namely, drip and sprinkler systems), subsequently juxtaposed with their counterparts in rainfed systems. Predictive maps were generated using the Ordinary Kriging algorithm for spatial interpolation. The findings demonstrate that irrigated Fluvisols displayed lower SOM content compared to rainfed soils, with sprinkler-irrigated soils experiencing a 16.1% decrease and drip-irrigated soils showing a more pronounced 26.6% decrease. Moreover, drip-irrigated soils contained 12.5% less SOM compared to sprinkler-irrigated soils. The pH levels stabilized at around 6.6 in both rainfed and irrigated soils, with no significant differences observed between the irrigation methods. Furthermore, irrigated Fluvisols exhibited higher EC values compared to rainfed soils, with both sprinkler and drip-irrigated soils showing values that were 35.2% higher. These results underscore the impact of irrigation practices on soil properties, including elevated EC values due to increased soil salt accumulation. The study highlights the necessity of considering specific irrigation systems and associated practices to ensure sustainable soil health and productivity. Adopting management approaches that account for these factors is crucial for preserving optimal soil conditions in Mediterranean agricultural systems.

Effects of land use-land cover on soil water and salinity contents

Soil salinization due to inadequate land management is considered one of the main threats to the sustainable development of agroecosystems in arid and semiarid regions. Approximately 20% of irrigated areas in the word are threatened by secondary soil salinization. To explore the influence of land use-land cover (LULC) on soil water and salinity in those regions, farmland areas planted with spring-sown wheat (Triticum aestivum L.) or alfalfa (Medicago sativa L.), and bare land (CK) in the Qinwangchuan irrigated region of Gansu Province in China were selected as the research objects. The characteristics of surface vegetation (coverage, height, biomass), surface micro-environmental factors (light intensity, soil temperature) and soil physicochemical properties (moisture and salinity) were measured successively for four years, and their changes and quantitative relationships were analyzed. The results showed that the coverage, height, and biomass of surface vegetation (or stubble) under different LULCs in spring and autumn were significantly different (p < 0.05) and ranked as follows: alfalfa field > wheat field > bare land. With the increasing surface vegetation, the surface light intensity and topsoil temperature at a depth of 5 cm indicated decreasing trends; the water content in the 0–5-cm soil layer showed an increasing trend, while that in the 0–40-cm layers displayed the opposite trend; the salinity at depths of 0–5 and 0–40 cm indicated a decreasing trend. Correlation analysis showed that there was a significant negative correlation between the vegetation characteristics and the salinity in the 0–5- and 0–40-cm soil layers (p < 0.01), while opposite correlations were observed between the vegetation characteristics and the water content in the 0–5- and 0–40-cm soil layers. Regression analysis showed that a 1% increase in vegetation coverage would decrease the salinity at depths of 0–5 and 0–40 cm by 2.5 and 1.0 uS.cm−1, respectively. In summary, farmland planted with spring-sown crops with short growth periods or abandoned in semiarid and arid irrigated regions would gradually experience an increase in soil salinity, whereas the planting of perennial alfalfa could inhibit and lessen soil salt accumulation at depths of 0–5 and 0–40 cm, which is beneficial to improve the soil quality. In addition, this study also revealed the change rule of soil salts under different LULCs in semiarid regions, the fastest increasing stage of topsoil salts, and the importance of surface vegetation and stubble cover in controlling soil salinization.