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The properties of a large number of concrete infrastructures in China are deteriorating year by year, raising the need for repairing and strengthening these infrastructures. By introducing waterborne polymers into a cement concrete system, brittle cracks and easy bonding performance defects of concrete can be compensated for to form a long-life, semi rigid, waterborne polymer-modified cementitious repair material with a promising development prospect. This paper investigates the modification effect of polymer emulsions on ordinary cement mortar. Our research mainly focused on the physical and mechanical properties, durability, microstructure and application status of waterborne polymer-modified cementitious composites. Literature studies show that with the increase in waterborne polymer content (0 wt%~20 wt%), the performance of cement mortar significantly improves, which in turn expands its application range. Compared with ordinary cement mortar, the introduction of waterborne polymers blocks some of the pores in the cement to a certain extent, thus improving its permeability, freeze–thaw resistance and durability. Finally, this paper describes the application of waterborne polymer–cementitious composites in western saline soil environments, as well as discusses the prospects of their development. [ABSTRACT FROM AUTHOR]

The salinity of the salt lake is an important factor to evaluate whether it contains some mineral resources or not, the fault buried in the salt lake could control the abundance of the salinity. Therefore, it is of great geological importance to identify the fault buried in the salt lake. Taking the Gasikule Salt Lake in China for example, the paper established a new method to identify the fault buried in the salt lake based on the multi‐source remote sensing data including Landsat TM, SPOT‐5 and ASTER data. It includes the acquisition and selection of the multi‐source remote sensing data, data preprocessing, lake waterfront extraction, spectrum extraction of brine with different salinity, salinity index construction, salinity separation, analysis of the abnormal salinity and identification of the fault buried in salt lake, temperature inversion of brine and the fault verification. As a result, the study identified an important fault buried in the east of the Gasikule Salt Lake that controls the highest salinity abnormal. Because the level of the salinity is positively correlated to the mineral abundance, the result provides the important reference to identify the water body rich in mineral resources in the salt lake. [ABSTRACT FROM AUTHOR]

Soil salinization is a critical and global environmental problem. Effectively mapping and monitoring the spatial distribution of soil salinity is essential. The main aim of this work was to map soil salinity in Shandong Province located on the Yellow River Delta of China using Sentinel-1/2 remote sensing data and digital elevation model (DEM) data, coupled with soil sampling data, and combined with four regression models: support vector regression (SVR), stepwise multi-regression (SMR), partial least squares regression (PLSR) and random forest regression (RFR). For these purposes, 60 soil samples were collected during the field survey conducted from 9 to 14 October 2019, corresponding to the Sentinel-1/2 and DEM data. Then we established a soil salinity and feature dataset based on the sampled data and the features extracted from Sentinel-1/2 and DEM data. This study adopted the feature importance of the RF model to screen all features. The results showed that the CRSI index made the greatest contribution in retrieving soil salinity in this region. In this paper, 18 sampling points were used to validate and compare the performance of the four models. The results reveal that, compared with the other regression models, the PLSR model has the best performance (R2 = 0.66, and RMSE = 1.30). Finally, the PLSR method was used to predict the spatial distribution of soil salinity in the Yellow River Delta. We concluded that the model can be used effectively for the quantitative estimation of soil salinity and provides a useful tool for ecological construction. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study conducted a nationwide specific assessment of soil chromium (Cr) contamination status in 506 of China's industrial regions. The overall soil Cr concentrations were 0.74–37,967.33 mg/kg, and the soil Cr content in 4.15% of the regions exceeded the reference screening value (2500 mg/kg). Geochemical accumulation index (Igeo) and monomial potential ecological risk index (E) revealed Cr salt production and tanning were the primary control industries. The non-carcinogenic risks posed by Cr salt production and tanning industries were higher than the national average values, and children were the most vulnerable groups. The heavily polluted regions were mainly located at the Yangtze River Delta, the Bohai Rim, the Pearl River Delta, the Yangtze River Basin, and the Yellow River Basin. The Yangtze River Delta was further identified as the high priority control area based on the class distribution of Igeo and E. Regression analysis showed the soil Cr concentrations in industrial regions increased during 2002–2009 and then turned into a declining trend in 2009–2021. This paper gives detailed insights into soil Cr pollution status in industrial regions across China and the results may serve as references for formulating tailored control measures for different industries and areas. [ABSTRACT FROM AUTHOR]

Plastic shed vegetable (PSV) cultivation has become an important vegetable production system in China, which accounts for about 1/4 of the total vegetable production of China. Shandong is the largest facility vegetable growing area in China. Continued years of high-input, high-output planting methods have brought some problems to the surrounding environment. Salinization has not only affected the soil and groundwater environment, but also the growth of vegetables. A comprehensive understanding of soil salinization in plastic shed vegetable fields is important for the sustainable development of the vegetable farming industry. In this paper, random survey sampling was used to collect soil samples from representative PSV production areas in Shandong Province, and the soil salinization status, acidification status, salt ion composition, and the main causes of soil salinity were studied in the survey area. Our study found that the salinized soils (mild, moderate, and severe levels) in the surveyed areas accounted for 40% of the total samples, and the total soluble salt (TSS) increased with the increase of the planting years. After continuous planting for 10 years, the soil pH showed a downward trend, indicating that salinization and acidification occurred simultaneously. A significant positive correlation was observed between TSS and soil organic matter (SOM) (r = 0.4773**). Principal component analysis found that , , , , Ca2+, K+, Mg2+, and Na+ had higher positive loads on principal component 1, the factor loads were 0.557–0.927, and the contribution rate reached 34.928%. Correlation analysis also showed that TSS was positively correlated with the concentrations of these ions (P < 0.01). The soil salinization status should be closely monitored and regulated by regulatory authorities to improve environment and soil health through balanced fertilization, thereby improving the yield and quality of vegetables. [ABSTRACT FROM AUTHOR]

Red clay is widely distributed globally and is closely related to human production and life. The middle reaches of the Yellow River basin in China are characterized by complex geological structures, concentrated rainfall periods. The soluble salts such as sodium sulfate enter the red clay particles along with the infiltrating water, forming a red clay-like saline soil. In order to study the effects of water and salt on red clay soils, this paper uses red clay in the Heyang of Weinan with different ratios of distilled water (10–20%) and Na2SO4 (0–4%), and obtains the resistivity of red clay soils at different frequencies (100 Hz–100 kHz) using an inductance, capacitance and resistance digital bridge tester. The results show that the resistivity of red clay is negatively correlated with water and salt content. With the increase of water content, the increase of conductive paths in the pore water improved the electrical conductivity of the red clay; while when the concentration of Na2SO4 increased, the free moving anions and cations in the pore water increased, the electrical conduction efficiency increased and the resistivity decreased. The high frequency increased the conductivity of red clay by contributing to electrical double layer deformation, whereas the electrode polarization led to inhibition of conductivity under low frequency. A negative power exponential relationship exists between the resistivity of red clay and the test frequency. This study may provide a valuable reference for the rapid identification of the physical properties of red clay and its internal structure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil salinization has become one of the major environmental problems threatening food security. The identification and knowledge of the spatial distributions of soil salinization are key in addressing this problem. This study assumes that a good saline land identification effect can be obtained with the help of deep learning methods. Therefore, this study used the OLI sensor data from the Landsat-8, based on the U2-Network, and proposes a method to extract saline land from remote sensing images. The study also adds different salinity indices (SI, SI1, and SI2) to explore its impact on classification accuracy. Through our method, accurate saline soil distribution information were obtained, and several verification indicators (the Intersection-over-Union (IoU), recall, precision, and F1-score) were all measured above 0.8. In addition, compared with the multi-spectral training results, the classification accuracy increased after adding a specific salinity index, and most of the accuracy indices increased by about 2% (the IoU increased by 3.70%, recall increased by 1.50%, precision increased by 2.81%, and F1-score increased by 2.13%). In addition, we also included a case study based on our methodology to analyze the distribution characteristics and changes of saline soil in the Zhenlai area of Northeast China from 2016 to 2020. We found that the area of saline land in the Zhenlai area has reduced, which shows that the extraction method proposed in this study is feasible. Overall, this paper indicates that deep learning-based methods can efficiently extract the salinity of soil and enhance the mapping of its spatial distribution. The study has the broad impact of supplementing satellite imagery for salinity modeling and helping to guide agricultural land management practices for northeastern China and other salinized regions. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the important role of vegetation in the integrity of structures and functions of coastal wetland ecosystems, the restoration of degraded coastal wetland vegetation has attracted increased attention. In this paper, the newborn coastal wetland in the Yellow River Delta (YRD) of China was selected to research the effect of salinity and oil exploitation on the germination of soil seed banks of three dominant vegetation communities. The germination experiment with three concentration gradients of NaCl and three concentration gradients of diesel treatments showed that there were 14 species present in the soil seed bank of the multi-species community: three species in the Phragmites australis community, and five species in the P. australis—Suaeda glauca community. The species in the seed bank of the three communities were much richer than the above-ground vegetation in this study. Soil salinity had a significant inhibitory effect on the seedling numbers of germinated species, the seedling density, and the species diversity of the soil seed banks, while the inhibitory effect of diesel was indistinctive under the designed concentrations. There existed significant interactions between the vegetation community type and soil salinity on the number of germinated species, the seedling density, and the Margalef index. Soil salinity is considered an important factor for wetland vegetation restoration in the YRD, but its effect had species-specific differences. Soil seed banks of the present three communities could be used to promote the restoration of degraded wetlands within certain soil salinity and oil concentration ranges. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil desertification affects the service functions of the ecosystem. In severe cases, it even causes a decline in agricultural productivity and shrinkage of animal husbandry, posing a threat to regional eco-environment and economic sustainability. The previous research on soil remediation research mainly concentrates on heavy metal degradation, saline soil improvement, and eroded and degraded soil improvement. There is little report on the biomass improvement and restoration of sandy soil. Therefore, this paper explores the remediation effect of biomass amendment on the physical-chemical performance and sustainable utilization of sandy soil in Huangyangtan, the largest sandy land in northern China's Hebei Province. Specifically, the authors detailed the strategies to measure the physical-chemical indices and microbial diversity of Huangyangtan sandy soil, and introduced the materials and mode of the biomass amendment test on Huangyangtan sandy soil, followed by an elaboration on the test results. The influence of different test fertilizers on the soil was analyzed in four dimensions, namely, physical performance, chemical performance, biological performance, and crop yield. The results show that biomass amendment can effectively remediate sandy soil, and promote its sustainable utilization. [ABSTRACT FROM AUTHOR]

The development of agriculture in the arid and semiarid regions of China mainly depends on agricultural irrigation. Until 2016, water required for agricultural irrigation has accounted for more than 90% of the total water consumption. But traditionally extensive broad irrigation causes frequent loess geological hazards in irrigation area and it threatens security of local life and property. In this paper, we selected the Heifangtai irrigation district in Yongjing County, Gansu Province, where frequent instabilities occur, as the study area. We used laboratory tests and numerical simulation to examine the mechanism of loess landslides owing to the irrigation hydrological cycle. Irrigation changes the local natural hydrogeological conditions because of the loose and macroporous structure of loess. The numerous pores and fissures constitute preferential migration pathways of irrigation water; thus, irrigation can increase the groundwater level and hydraulic gradient. Broad irrigation is the main inducing factor of geological hazards (including landslides, collapses, and soil salinization) in arid and semiarid regions, and the development of fissures and sinkholes increases the risk of landslides. New water-saving irrigation methods need to replace the traditional irrigation methods and improve the utilization of water resources. A monitoring and warning system in susceptible areas should be established to ensure the sustainability of local agriculture. [ABSTRACT FROM AUTHOR]

Optimum management of irrigated crops in regions with shallow saline groundwater requires a careful balance between application of irrigation water and upward movement of salinity from the groundwater. Few field-validated surrogate models are available to aid in the management of irrigation water under shallow groundwater conditions. The objective of this research is to develop a model that can aid in the management using a minimum of input data that are field validated. In this paper a 2-year field experiment was carried out in the Hetao irrigation district in Inner Mongolia, China, and a physically based integrated surrogate model for arid irrigated areas with shallow groundwater was developed and validated with the collected field data. The integrated model that links crop growth with available water and salinity in the vadose zone is called Evaluation of the Performance of Irrigated Crops and Soils (EPICS). EPICS recognizes that field capacity is reached when the matric potential is equal to the height above the groundwater table and thus not by a limiting hydraulic conductivity. In the field experiment, soil moisture contents and soil salt conductivity at five depths in the top 100 cm, groundwater depth, crop height, and leaf area index were measured in 2017 and 2018. The field results were used for calibration and validation of EPICS. Simulated and observed data fitted generally well during both calibration and validation. The EPICS model that can predict crop growth, soil water, groundwater depth, and soil salinity can aid in optimizing water management in irrigation districts with shallow aquifers. [ABSTRACT FROM AUTHOR]

Based on the discovery of the "natural orange soil layer" in the wall foundation of the Ming Great Wall in Huangzhong County, Xining City, northwest China, this paper reveals the mechanism behind the barrier effect of this layer on the salinity deterioration through the combination of qualitative judgment and quantitative testing. Based on this mechanism, the conventional lime soil was improved by adding modified polyvinyl alcohol as the cementing agent and fly ash, thereby generating a modified cushion material. Indoor tests of freeze-thaw and temperature-humidity cycles for the modified cushion material were then conducted alongside field tests of rammed restorations in the basal sapping zone with and without the modified cushion. The test results show that the modified cushion materials have excellent durability and act as a substantial barrier to salinity deterioration. The research results provide a new approach to repairing the basal sapping of earthen sites. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In seasonally frozen areas, physical and mechanical soil properties change dynamically under the effect of the freeze-thaw cycles (FTCs), which is a problem that cannot be ignored in geotechnical engineering. In order to study the effect of the FTC on the strength and the mechanism of deformation and failure of saline soil, this paper took Nong'an saline soil as the research object. In total, 105 groups of remolded samples with different salt contents (S) after FTCs were examined in unconsolidated-undrained tests. On the basis of the experiment results, the influence of FTCs on the mechanical properties of Nong'an saline soil was analyzed. The failure principal stress difference (σ1 − σ3)f and cohesion (c) were both decreased with FTC. This occurred especially rapidly after the first cycle and became stable between 30 and 60 cycles. The internal friction angle φ increased at first and then decreased. According to experimental data, a modified Duncan-Chang model was established. Compared with the experiment results, this model was reasonable to simulate the stress-strain relationship of Nong'an saline soil. Furthermore, the empirical formulas of Duncan-Chang model parameters were obtained by regression analysis. This provides a theoretical basis for saline–soil foundation and subgrade engineering in seasonal frozen areas. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

(1) Monitoring salinized soil in saline–alkali land is essential, requiring regional-scale soil salinity inversion. This study aims to identify sensitive variables for predicting electrical conductivity (EC) in soil, focusing on effective feature selection methods. (2) The study systematically selects a feature subset from Sentinel-1 C SAR, Sentinel-2 MSI, and SRTM DEM data. Various feature selection methods (correlation analysis, LASSO, RFE, and GRA) are employed on 79 variables. Regression models using random forest regression (RF) and partial least squares regression (PLSR) algorithms are constructed and compared. (3) The results highlight the effectiveness of the RFE algorithm in reducing model complexity. The model incorporates significant environmental factors like soil moisture, topography, and soil texture, which play an important role in modeling. Combining the method with RF improved soil salinity prediction (R2 = 0.71, RMSE = 1.47, RPD = 1.84). Overall, salinization in Minqin oasis soils was evident, especially in the unutilized land at the edge of the oasis. (4) Integrating data from different sources to construct characterization variables overcomes the limitations of a single data source. Variable selection is an effective means to address the redundancy of variable information, providing insights into feature engineering and variable selection for soil salinity estimation in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Research for changes of soil water and salt is an important content of land sciences and agriculture sciences in arid and semi arid regions. In this paper, sampling in actual agricultural fields, laboratory analysis of soil samples and statistical analysis methods are used to quantitatively analyze soil salinity changes under different irrigation methods throughout the cotton growing season in Shihezi reclamation area. The results show that irrigation methods play an important role in soil salt content in the surface soil (0-20 cm) and sub-deep soil (40-60 cm), followed by deep soil layer (60-100 cm) and root soil layer (20-40 cm). Furrow irrigation yields the maximum soil salt content in deep layer (60-100 cm) or sub-deep layer (40-60 cm) and the maximum salinity occurs in the first half of the cotton growing season (June or earlier). In contrast, drip irrigation yields the maximum soil salinity in the root layer (20-40 cm) or sub-deep (40-60 cm), and this usually appears in the second half growing season (July or after). The ratio of chloride ion to sulfate ion (Cl-/) and its change in the soil are on the rise under furrow irrigation, while the value first increased and then decreased with a peak point in June under drip irrigation. This suggests that furrow irrigation may shift the type of soil salinization to chloride ion type moreso than drip irrigation. Potassium and sodium ion contents of the soil show that soil sodium+potassium content will drop after the first rise under furrow irrigation and the value is manifested by fluctuations under drip irrigation. Potassium+sodium content change is relatively more stable in the whole cotton growth period under irrigation methods. The maximum of sodium and potassium content of the soil usually occur in deep soil layer (60-100 cm) or sub-deep soil layer (40-60 cm) in most sample points under furrow irrigation while it is inconsistent in different sample points under drip irrigation. A nonparametric test for paired samples is used to analyze differences of soil salt content under different irrigation methods. This analysis shows that the impact of irrigation on soil salinity is most significant in July, followed by August, June, May, and April in most sample points. The most significant impact of irrigation methods occurs in the surface soil layer (0-20 cm), followed by deep layer (60-100 cm), root layer (20-40 cm) and sub-deep (40-60 cm). These conclusions will be benefitial for mitigation of soil salinization, irrigation and fertilization and sustainable land use. [ABSTRACT FROM AUTHOR]

Agriculture is the highest consumer of water resources in China. Soil water models play a vital role in agriculture in terms of estimating water use, water allocation and current water status at a given scale. In this paper, transport models widely used for water and salinity in soils are introduced. The advantages and drawbacks of the modelling, the applicability and the application situation are also analysed. Recent development and applications of these modelling are pointed out. Finally, prospect of these modelling was predicted. [ABSTRACT FROM AUTHOR]

A continuous long-term field experiment (2008-2018) was conducted in Xinjiang, north-western China, to assess the impact of farmyard manure (FYM) and inorganic fertilisers on the sustainable biomass yield of sweet sorghum cultivar (Xingaoliang No. 3) and soil chemical properties. Seven treatments, associated with nitrogen (N), phosphorus (P), potassium (K), FYM, and their different combination, were compared with the control plot (CK). As a result, the treatments NP, PK, NK, NPK and NPKM significantly increased the average biomass yields by 30-48% over CK. The 12 t/ha FYM per year with NPK (NPKM) increased both the yield and total soluble solids (TSS) by 48% and 7.9%, respectively, while the 18 t/ha/year application rate of FYM had an adverse effect on yield. Stem TSS, soil available N and K for all treatments decreased while soil organic carbon, soil total salt and the available P for FYM applied treatments increased over the years. The soil pH stabilised at 7.8-8.2 at the end. In conclusion, the 12 t/ha/year of FYM is the most efficient rate for a single application or incorporation with inorganic fertilisers. A more reasonable application rate of N and K fertiliser to increase the yield and irrigation rate to reduce soil salt needs for further investigation. [ABSTRACT FROM AUTHOR]

The Songnen Plain is an important agricultural base in China and one of the important areas of distribution of saline-alkaline soils in the cold region. Saline-alkaline soils severely restrict maize growth. This study was to potentially promote the soil nutrient in the maize rhizosphere, microbes diversity, and maize yield by Trichoderma asperellum in saline-alkaline soil of the cold region. In the present study, we applied different amounts of T. asperellum in field experiments for three consecutive years. High-throughput sequencing was used to analyse the impact of Trichoderma on microbes diversity in maize rhizosphere soils. Changes in crop yield and soil nutrients were also monitored. T. asperellum treatment significantly increased the relative abundance of beneficial microbes genera. In the control treatment, the pathogenic microbes were the dominant genera. Pearson's correlation analysis revealed that changes in the soil microbial community composition were closely related to soil nutrients and were highly correlated with T. asperellum treatment concentration. Further, T. asperellum treatment increased crop yield by 4.87-20.26%. These findings suggest that T. asperellum treatment optimised the microenvironment of the maize rhizosphere soil, alleviated microbial community degeneration in cold region saline-alkaline soil, and promoted maize growth. [ABSTRACT FROM AUTHOR]

Cultivation and growing salt-tolerant (halophytes) plants in coastal saline-alkali soils has been regarded as an effective way to reduce soil salinization and restore degraded vegetation. Planting halophytic plants generally alters soil properties and indirectly influences soil respiration. The aim of this paper is to evaluate the seasonal variation in soil respiration under different vegetation types in coastal saline-alkali land in northern China, and to identify how tree species, stand age, and soil properties (soil temperature, moisture, and salinity) explained the temporal and spatial variation in soil respiration. Soil respiration from halophytic plants (Tamarix chinensis and Lycium chinense) and salinealkali bare land were measured using an LI-COR 6400XT portable photosynthesis system equipped with a portable soil CO2 flux chamber from May to October 2016. The results indicated that T. chinensis and L. chinense shrub communities significantly reduced soil salinity, slightly reduced soil bulk density, improved soil organic carbon, and promoted the microbial community. Soil respiration from T. chinensis and L. chinense plantations were significantly higher than that from bare land. Coastal salinized bare land is a weak carbon source for global carbon. Soil respiration was generally restrained by soi salinity and reduced with increasing soil salinity. Soil respiration showed a positive and negative correlation ith soil temperature, moisture, and salinity. Incorporating salinity, together with soil temperature and other abiotic factors, may improve predictions for soil CO2 respiration. [ABSTRACT FROM AUTHOR]

Land salinization is one of the most common land degradation processes. Tongyu county exemplifies all the forms of land degradation in Northeast China and is prone to land salinization due to its fragile physical conditions. In this study, Landsat remote sensing images are adopted to invert surface albedo, MSAVI (modified soil adjusted vegetation index), and salinity index (SI) data. The feature space models of albedo-SI and MSAVI-SI, considering the bare soil and vegetation information respectively, are constructed and compared. Land salinization changes for the period of 1998–2017 are investigated using the salinization monitoring index (SMI) and salinization detection index (SDI) extracted from the feature space models. Our results show that the land salinization situation in Tongyu county have tended to improve, associated with the biological, ecological and engineering means for the degraded land rehabilitation. The feature space models is applicable for the extraction of salinization information, and albedo-SI may evaluate land salinization levels with higher accuracy. [ABSTRACT FROM AUTHOR]

The variation in paleosalinity and paleoredox affect the production and preservation of organic matter. The study of ancient salinity and redox conditions of source rocks is of great significance for the enrichment of organic matter and the exploration of petroleum resources. In this paper, the commonly proxies for paleosalinity and paleoredox are distinguished and discussed. The paleosalinity and paleoredox of the Lucaogou Formation in the Jimsar Sag of the Junggar Basin are reconstructed by combining the minerals, corrected elements, biomarkers and isotope indicators. Research suggests that the gammacerane index, carbon and oxygen isotopes, corrected Sr/Ba, and Mg/Al can be used to evaluate the paleosalinity of the Lucaogou Formation. Among the commonly used redox proxies, only V/Cr, U/Th, and V EF can be used to evaluate the redox conditions of the Lucaogou Formation, and their thresholds have been corrected. The paleo-sedimentary environment of the Lucaogou Formation has undergone frequent changes and is generally in a brackish and reductive environment. The paleo-sedimentary environment is an important influencing factor for the enrichment of organic matter of the study area. A relative higher salinity and reduction environment is conducive to the organic matter enrichment and high-quality source rocks formation in the Lucaogou Formation. • The impact of volcanic ash on element evaluation indicators was conducted. • The evaluation indicators of salinity have been corrected. • The evaluation indicators for redox conditions were corrected based on Re-U-Mo method. • The paleosalinity and redox conditions of the Lucaogou Formation were reconstructed with corrected indicators and thresholds. [ABSTRACT FROM AUTHOR]

The control of irrigation volume is of significant importance in arid regions of northwest China. Particularly, it has a crucial impact on the salinization of shallow groundwater areas. In 2022 and 2023, field experiments were conducted to test three distinct under-membrane irrigation treatments. These treatments were assigned water quotas of HW (27 mm), MW (22.5 mm), and LW (18 mm). The HYDRUS-2D model was integrated with a field experiment to accurately simulate the dynamic fluctuations of soil water and salt in the sunflower root zone. The model's performance was assessed and verified using real-field data from 2022 and 2023, and the simulation results closely matched the measured values. This research also used stable hydroxide isotopes to assess the water supply from various soil layers at different time intervals in sunflower plants. The results indicated that the three different levels of irrigation applied under the membrane had a significant impact on soil water content. Specifically, there was a significant difference in soil water content at a depth of 0–40 cm (p < 0.05), while there was little effect on the water content at a depth of 40–60 cm (p > 0.05). After irrigation, the average salt content in the top 0–20 cm of soil decreased by 7.0% compared to the medium and low irrigation levels, and by 10.8% compared to the medium irrigation level. Additionally, the medium irrigation level resulted in a 10.8% decrease in salt content compared to the low irrigation level, and a 4.1% decrease compared to the medium irrigation level. During the same period, the soil salinity levels at depths of 0–20 cm, 20–40 cm, 40–60 cm, and 60–100 cm in the area outside the membrane were measured to be 2.7~4.8 g·kg−1, 2.8~4.0 g·kg−1, 2.7~3.4 g·kg−1, and 1.7~2.6 g·kg−1, respectively. These levels decreased by 13.1~55.5%, 0.7~42.8%, −0.4~16.2%, and −72.7~7.5%, respectively. Following irrigation, the HW treatment mostly absorbed water in the 0–40 cm soil layer, while the MW and LW treatments absorbed water in both the 0–40 cm and 60–80 cm soil levels. The results indicated that the most optimal drip irrigation method beneath the membrane in this location was achieved when the amount of water applied was between 25–30 mm. This method demonstrated a combination of water conservation, high crop yield, and effective salt suppression. [ABSTRACT FROM AUTHOR]

Organic amendment is an effective method to reclaim salt-affected soil. However, in coastal land with shallow saline groundwater, it is limited known about the mechanism of organic amendment on soil desalinization. Thus, to examine the effect of topsoil organic matter content on soil water/salt transport and distribution, two-year field observations in Bohai coastal land, North China, and soil column experiments simulating salt accumulation and salt leaching were conducted, respectively. There were different organic fertilizer amendment rates in 0–20 cm topsoil, 0% (CK), 50% (OA 0.5), and 100% (OA 1.0) (w/w) for soil column experiments. Field observation showed that after organic amendment (OA), the soil's physical structure was improved, and less of the increase in topsoil salt content was observed, with more salt accumulated in deep soil layers during the dry season. In addition, OA greatly promoted salt leaching during the rainy seasons. The results of the soil column tests further indicated that OA treatments significantly inhibited soil evaporation, with less salt accumulated in the topsoil. Although there was no difference in soil water distribution between the CK and OA 0.5 treatment, the topsoil EC for the OA 0.5 treatment was significantly lower than that for CK. During soil water infiltration, the OA 0.5 and OA 1.0 treatments significantly increased the infiltration rates, enhanced the wetting front, and promoted salt leaching to deeper soil layers, compared with CK. The improvement of soil organic amounts could make the soil more self-resistant to the coastal salinization. The findings of this study provide some insights into soil water/salt regulation in heterogeneous soil masses and on the permanent management of coastal saline farmland. [ABSTRACT FROM AUTHOR]

Freeze–thaw cycles (FTCs) occur during the nongrowing season, and residual nitrogen (N) increases the risk of N loss with melting water. To study the effect of FTCs on soil N, rice fields in improved irrigated saline soil in northeast China were selected as the research subjects. Water content (10%, 20%, and 30%), different N fertilizer levels (180 and 220 kg/ha), and multiple FTCs of soil samples were used to clarify the effects of N fertilizer application and water content on N efficiency. The results indicate that, after the third FTC, the soil ammonium nitrogen (NH4+-N) level increased significantly. NH4+-N increased with an increase in the initial soil moisture content and decreased with fertilizer levels. Nitrate nitrogen (NO3−-N) decreases with increasing initial soil moisture. The inorganic N increased significantly compared with that in the unfrozen stage, indicating that FTCs promote soil N mineralization. However, high fertilization rates inhibit mineralization. Analysis of variance showed that NO3−-N is sensitive to the N application rate, water content, and salinity (p < 0.05). FTCs and artificial fertilization are the factors that affect N mineralization (p < 0.05). The research results are significant for preventing nitrate leaching and soil acidification during spring plowing and providing a scientific basis for fertilization systems and water environment pollution in improved saline soils. [ABSTRACT FROM AUTHOR]

Grasshoppers have profound effects on both grassland ecosystems and livestock production. Despite commendable efforts made by China in grasshopper control, completely eradicating or preventing them still remains a distant prospect. This study aims to analyze the ecological distribution and patterns of grasshopper occurrences in order to provide more accurate monitoring techniques and preventive measures. By considering four types of environmental determinants—meteorology, vegetation, soil, and topography—we systematically identified 18 key influencing factors. These factors encompass various developmental stages of grasshoppers, including variables such as temperature, precipitation, vegetation coverage, vegetation type, soil moisture, soil salinity, soil type, and terrain characteristics. The MaxEnt model is employed in this study to comprehensively capture complex ecological interactions. Omission curves, Receiver Operating Characteristic curves (ROC curves), and the Area Under the Curve (AUC values) demonstrate the robustness and high accuracy of the MaxEnt model. Our research results indicate that meteorological factors are the primary influencing factors for the distribution of grasshoppers, surpassing the effects of vegetation, soil, and terrain. Precipitation and vegetation type emerge as key factors shaping their distributional patterns. Integrating the Sen-MK trend method, our findings identify the epicenter of damage primarily within the central, southern, and northeastern regions, notably affecting locales such as New Barag East County and the Ewenki Autonomous Banner. While their impact in 2012 was particularly severe, temporal trends indicate a decreasing risk of grasshoppers in specific regions, with escalated activity observed in other areas. The empirical insights from this study lay a solid foundation for the development of monitoring and control strategies concerning grasshoppers. Furthermore, the derived theoretical framework serves as a valuable foundation for future research endeavors addressing grasshopper infestations. [ABSTRACT FROM AUTHOR]

To alleviate the contradiction between the shortage of freshwater resources and the rapid development of industries and agriculture in China, field experiments were conducted to study the response of tomatoes to different water salinity (ECi) levels under drip irrigation in coastal semi-humid areas and arid areas. The effects of water salinity on salt accumulation in the root zone, tomato growth, yield, yield components, and quality response were investigated. The results indicated that the electrical conductivity of the soil saturation extract (ECe) increased with the irrigation water salinity. In semi-humid area, the maximum ECe was not higher than 5 dS/m, and the value was lower in wet year, at approximately 2 dS/m. In arid area, the ECe increased in the first year and then tended to balance. The ECe exceeded 4 dS/m when the ECi is higher than 6.6 dS/m. Salinity hindered the yield of tomatoes, which was mainly manifested by a reduced fruit diameter, fruit number, and single fruit weight. The salinity thresholds that tomato can endure without yield reduction 1.8 dS/m in semi-humid area and 2.1 dS/m in arid area, when ECe of root zone exceeded the threshold, for every 1 dS/m increase in ECe, the relative yield decreased by 14% and 12%, respectively. Nevertheless, tomato fruit quality is improved under saline water irrigation. Vitamin C (VC) content shows a significant quadratic curve relationship with ECe, and the maximum appeared at 4.0 dS/m in semi-humid area and 5.9 dS/m in arid area. Total sugar (TS) and total acid (TA) contents were significantly improved in arid area, for every 1 dS/m increase in ECe, the relative TS and TA increased by 12.8% and 20.3%, respectively. From the comprehensive point of saving water, avoiding yield reduction, and improving tomato fruit quality, saline water of about 6.3 dS/m and 4.9 dS/m is suggested for drip irrigation of tomatoes in semi-humid areas and arid areas in China. [ABSTRACT FROM AUTHOR]

Soil degradation due to salinity and sodicity is one of the most important impediments to agricultural production in China. In addition, the need for the development of new, clean coal-refining technologies has risen in China. As a background of this re- search, salt-affected soils were ameliorated with coal bio-briquette ash, and the positive effects and the increase in carbon due to the soil amelioration have been confirmed. Moreover, the effect of salts leaching into coal bio-briquette ash has been investigated by using a soil column equipped with tensiometers and four-electrode sensors. Combustion ashes from coal bio-briquettes made from low-quality coal, biomass (corn stem), and a desulfurization agent (Ca(OH)2) were examined to two types of salt-affected soil of higher EC and exchangeable sodium percentage (ESP) by the column equipment. Consequently, initial Na leaching was confirmed from the results of the leachate EC and Na content of the leachate at 3.0 wt% and 6.0 wt% application rates. Amelioration in the soil of higher EC and ESP with the coal bio-briquette ash was effective at a higher application rate. These results also indicate that ash has the possibility of ameliorating high-EC and high-ESP soils. Finally, we could predict the necessary water volume for Na leaching by using the experimental results and the meteorological data and could estimate the quantity of irrigation water necessary. These results indicated the effectiveness of using low-quality coal bio-briquette ash as a soil amendment to salt-affected soil of higher EC and ESP. [ABSTRACT FROM AUTHOR]

Soil salinization is a worldwide environmental problem with severe economic and social consequences. In this paper, estimating the soil salinity of Pingluo County, China by a partial least squares regression (PLSR) predictive model was carried out using QuickBird data and soil reflectance spectra. At first, a relationship between the sensitive bands of soil salinity acquired from measured reflectance spectra and the spectral coverage of seven commonly used optical sensors was analyzed. Secondly, the potentiality of QuickBird data in estimating soil salinity by analyzing the correlations between the measured reflectance spectra and reflectance spectra derived from QuickBird data and analyzing the contributions of each band of QuickBird data to soil salinity estimation Finally, a PLSR predictive model of soil salinity was developed using reflectance spectra from QuickBird data and eight spectral indices derived from QuickBird data. The results indicated that the sensitive bands covered several bands of each optical sensor and these sensors can be used for soil salinity estimation. The result of estimation model showed that an accurate prediction of soil salinity can be made based on the PLSR method ( R 2 = 0.992, RMSE = 0.195). The PLSR model's performance was better than that of the stepwise multiple regression (SMR) method. The results also indicated that using spectral indices such as intensity within spectral bands (Int1, Int2), soil salinity indices (SI1, SI2, SI3), the brightness index (BI), the normalized difference vegetation index (NDVI) and the ratio vegetation index (RVI) as independent model variables can help to increase the accuracy of soil salinity mapping. The NDVI and RVI can help to reduce the influences of vegetation cover and soil moisture on prediction accuracy. The method developed in this paper can be applied in other arid and semi-arid areas, such as western China. [ABSTRACT FROM AUTHOR]

Soil salinity has been known to be problematic to land productivity and environment in the lower Yellow River Delta due to the presence of a shallow, saline water table and marine sediments. Spatial information on soil salinity has gained increasing importance for the demand of management and sustainable utilization of arable land in this area. Apparent electrical conductivity, as measured by electromagnetic induction instrument in a fairly quick manner, has succeeded in mapping soil salinity and many other soil physical and chemical properties from field to regional scales. This was done based on the correlation that existed between apparent electrical conductivity and many other soil properties. In this paper, four spatial prediction methods, i.e., local polynomial, inverse distance weighed, ordinary kriging and universal kriging, were employed to estimate field-scale apparent electrical conductivity with the aid of an electromagnetic induction instrument (type EM38). The spatial patterns estimated by the four methods using EM38 survey datasets of various sample sizes were compared with those generated by each method using the entire sample size. Spatial similarity was evaluated using difference index (DI) between the maps created using various sample sizes (i.e., target maps) and the maps generated with the entire sample size (i.e., the reference map). The results indicated that universal kriging had the best performance owing to the inclusion of residuals and spatial detrending in the kriging system. DI showed that spatial similarity between the target and reference maps of apparent electrical conductivity decreased with the reduction in sample size for each prediction method. Under the same reduction in sample size, the method retaining the most spatial similarity was universal kriging, followed by ordinary kriging, inverse distance weighed, and local polynomial. Approximately, 70 % of total survey data essentially met the need for retaining 90 % details of the reference map for universal kriging and ordinary kriging methods. This conclusion was that OK and UK were two most appropriate methods for spatial estimation of apparent electrical conductivity as they were robust with the reduction in sample size. [ABSTRACT FROM AUTHOR]

This paper is based on long-term monitoring data for soil water, salt content, and groundwater characteristics taken from shelterbelts where there has been no irrigation for at least 5 years. This study investigated the distribution characteristics of soil water and salt content in soils with different textures. The relationships between soil moisture, soil salinity, and groundwater level were analyzed using 3 years of monitoring data from a typical oasis located in an extremely arid area in northwest China. The results showed that (1) the variation trend in soil moisture with soil depth in the shelterbelts varied depending on soil texture. The soil moisture was lower in sandy and loamy shelterbelts and higher in clay shelterbelts. (2) Salinity was higher (about 3.0 mS cm) in clay shelterbelts and lower (about 0.8 mS cm) in sandy shelterbelts. (3) There was a negative correlation between soil moisture in the shelterbelts and groundwater level. Soil moisture decreased gradually as the depth of groundwater table declined. (4) There was a positive correlation between soil salinity in the shelterbelts and the depth of groundwater table. Salinity increased gradually as groundwater levels declined. [ABSTRACT FROM AUTHOR]

• Impacts of agricultural water management on hydrology and environment were studied. • Sixty year's data on irrigation, drainage, soil salinity, groundwater etc., were analyzed. • Uncontrolled irrigation and the lack of effective drainage had several negative effects. • Water-saving practices benefit salinity control but do harm to wetland protection. • A balance between several factors is required for effective water management. Irrigation projects often result in many far-reaching environmental changes. This paper considers the case of the Hetao Irrigation District, the largest irrigation project along the Yellow River in China, and studies the impacts of agricultural water management on the hydrology and the environment. Long-term data (1954–2013) concerning irrigation, drainage, soil salinity, groundwater, and the environment of Wuliangsuhai Wetland, the lake that receives the drainage water, were collected and analyzed. The findings show that uncontrolled irrigation and the absence of effective drainage initially resulted in a rising groundwater table, worsening soil salinization, and the expansion of the lake, which is an important internationally recognized wetland. The completion of an artificial drainage system and the implementation of water-saving practices have had promising effects on lowering the groundwater table and controlling soil salinity. However, the risk of soil salinity is still threatening the irrigation system because salt is continuously accumulating within it and the total dissolved salts (TDS) in the groundwater are increasing. For better soil salinity control, more effective drainage is necessary to drain more salt and lower the water table, but this may harm the natural vegetation and the eco-environment of the Wuliangsuhai Lake because the non-point-source pollution from agricultural drainage has resulted in a serious eco-crisis in the Wuliangsuhai Lake. The results show that it is important to ensure there is a certain amount of low-TDS drainage water to protect the Wuliangsuhai Lake environment. Therefore, a balance must be achieved among soil salinity control, groundwater quality, favorable conditions for natural vegetation, and wetland protection. Further research is needed to develop optimal agricultural water management strategies, especially in the context of the ongoing water-saving renovation program. [ABSTRACT FROM AUTHOR]

The aim of this paper was to assess the influence of tamarisk shrubs on soil fertility, salinity and nematode communities in various habitats located in an arid desert-oasis region in northwest China. Three habitats were studied: sand dune, riparian zone and saline meadow, where tamarisk shrubs have been established in recent decades in order to vegetation restoration used as desertification control and saline land rehabilitation projects and become the dominant plant community. The parameters measured include soil organic carbon (SOC), total nitrogen, available phosphorus (P) and potassium (K), pH, salt component, and nematode community characteristics. Enrichment ratios (a comparison of the soil measurements between soils under canopy and in the open interspaces) for soil nutrients and salinity were used to evaluate fertility and salinity islands underneath the tamarisk shrubs. The soil nematode community was used as a biological indicator of soil condition. SOC and available P and K were higher beneath the plant canopy than in the open interspaces outside that canopy. The enrichment ratios for SOC and nutrients were highest for the sand dune habitat and tamarisk shrubs clearly created islands of greater salinity under the canopies. Nematode abundance per 100 g dry soil varied considerably between the locations and habitats, with the highest abundance found in sand dune and the lowest in saline meadow. A significantly higher nematode abundance and a lower trophic diversity were found in soils under the canopy compared to the soils in the open interspaces. With the exception of saline meadow, the abundance of bacterivores increased and fungivores decreased under the canopy relative to the open interspaces, and bacterivores dominated under the canopies in the sand dune and riparian habitats. The enrichment ratios for salinity were higher than for fertility, suggesting that improved soil fertility can not limit the impact of salinization beneath tamarisk shrubs. The adverse effect of salt accumulation on the soil environment should be taken into account when using tamarisk as restoration plant species, especially in saline meadow and controlling of tamarisk density should be considered when undertaking re-vegetation projects in the arid desert oasis regions. [ABSTRACT FROM AUTHOR]

• Dilatant crystals caused the internal structure of the concrete to undergo the process of loose damage after densification. • The corroded concrete specimens were divided into three parts from the outside to the inside. • The formula for calculate the internal expansion stress were given. • A constitutive model based on ion diffusion, chemical reaction and mechanical analysis was established. Stress-strain constitutive relationship is one of the basic mechanical properties of concrete materials, and the stress-strain relationship of concrete subjected to salt corrosion has changed significantly. Saline soil in Western China has the characteristics of many kinds of salt and high concentration, which makes the damage to concrete more serious. In this paper, the uniaxial compressive stress-strain constitutive relation of corroded concrete in saline soil area of Western China is studied, and the constitutive model based on ion diffusion, chemical reaction and mechanical analysis was also given. Firstly, the causes and mechanisms of the change of stress-strain curve of corroded concrete were analyzed via the stress-strain curve, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and porosity. Then, the corroded concrete specimens were divided into three parts from the outside to the inside, namely, the corrosive damage part, the corrosive enhancement part and the non-corrosive part. Combined Fick's diffusion law and chemical reaction, the formulas for calculate the critical failure depth and the internal expansion stress were given. The corrosion effects of the corrosive damage part and the corrosive enhancement part were expressed by the critical failure depth and the internal expansion stress respectively. Finally, based on the meso-statistical parallel bar constitutive model of non-corroded concrete, a stress-strain constitutive model of corroded concrete in saline soil region of Western China was established considered the corrosion effect. [ABSTRACT FROM AUTHOR]

• Data-driven sub-robust optimization method is used. • Consideration of soil salinization control systemic risk issues. • Comparison of simulated and measured values in 5 years. • Simulation-Optimization approach is used to solve the problem. • Sustainable water-resources management measures are suggested. How to rationally optimize the allocation of surface water and groundwater resources in saline-alkali areas is a difficult problem in current model optimization. Based on an interval two-stage stochastic programming (ITSP) method, this paper considers the system risk involved in saline-alkali land treatment, follows a robust optimization method, and constructs an interval two-stage data-driven subrobust optimization (ITDRO) model, which can optimize the distribution of groundwater and surface water for different crops and realize the combination of wells and canals through the joint dispatch of surface water and groundwater. This paper takes the Urad Irrigation Area as the research object, and the obtained results provide water distribution objectives under situations of multiple sources of water, multiple crops, and different robust coefficients. After the successful calibration and verification of the SaltMod model, the water distribution target is taken as the main input parameter and substituted into the simulation model based on the principle of water and salt balance. The output includes soil salinity, drainage salinity, groundwater salinity (GWS), groundwater table (GWT) depth, and drainage. The results show that the integrated ITDRO and SaltMod model can control the groundwater level below the critical depth under the premise of satisfying crop irrigation, reducing the groundwater level by approximately 0.75 m and the GWS in the irrigation area by approximately 0.68 g/L, which can provide a reference for the prevention and control of soil salinization and waterlogging. This approach is suitable for arid and semiarid regions that face similar problems. [ABSTRACT FROM AUTHOR]

In the Songnen Plain, China, salinization has become increasingly serious and desertification has increased rapidly since the middle of the twentieth century, restricting the economic growth of the area and threatening the environment. Many factors can cause the formation of saline–alkali soil, but none of them explain the origin of the substantial amount of soda that exists in the basin and its distribution pattern. This paper focuses attention on the relationship between the formation of saline–alkali soil and neotectonic movement, and the climate–tectonic cycle over the geological history of the region. Data interpreted by Thematic Mapper for two periods of time have been used to analyze changes in the saline–alkali soil. The results provide a useful tool for demonstrating the relationship between the saline–alkali soil and neotectonic movement, and for improving the technology and methods used to protect, manage, exploit and utilize the saline–alkali soil. [ABSTRACT FROM AUTHOR]

Drought and fresh water shortage are in the way of sustainable agriculture development in the North China Plain. The scarcity of fresh water forces farmers to use shallow saline ground water, which helps to overcome drought and increase crop yields but also increases the risk of soil salinization. This paper describes salt regimes and crop responses to saline irrigation water based on field experiments conducted from October 1997 to September 2005. It was found that use of saline water causes the ECe of the topsoil (0–100 cm, Cv: 0.196∼0.330) to be higher and more variable than the subsoil (100–180 cm, Cv: 0.133∼0.219). The salt load rapidly increased, notably in the upper 80 cm and especially during the season of October 1999 to June 2000. It was concluded that the maximum soil depth to which the soil was leached during the wet season was about 150 cm. The relative yields of winter wheat could be ranked Fresh Sufficient (FS, 100%) > Fresh Limited (FL, 91.80%) > Saline Sufficient (SS, 91.63%) > Saline Limited (SL, 88.28%) > Control (C, 69.58%) and for maize FS (100%) > FL (96.37%) > SS (93.05%) > SL (90.04%)> C (89.81%). The best irrigation regime was Saline Limited for winter wheat and maize, provided rainfall is sufficient. The experiments confirm that saline irrigation water appears to be economically attractive to farmers in the short term and ecological hazards can still be controlled with proper leaching. [ABSTRACT FROM AUTHOR]

Soil salinization poses a significant constraint on the sustainable development of agriculture. While satellite remote-sensing data enables salinity monitoring over large spatial scales, its coarse resolution limits monitoring accuracy. On the other hand, unmanned aerial vehicle (UAV) remote-sensing data offers greater accuracy in salinity monitoring but covers a smaller area compared to satellite remote sensing. To address the need for both high precision and wide-range monitoring, we developed a soil salinity monitoring model integrating ground, UAV, and satellite data. Field experiments were conducted in the Shahaoqu irrigation area, Inner Mongolia, China, from August 11 to 15, 2019. During this period, we collected satellite remote-sensing images, UAV remote-sensing images, and soil salinity data. Spectral bands from the remote-sensing data were utilized to construct separate vegetation and salinity indices, which were further filtered using the variable importance in projection (VIP) algorithm. The soil salinity monitoring model was then constructed using the extreme learning machine (ELM) algorithm. Several soil salinity monitoring models were developed, including SSMM-UAV (based on ground-UAV data at a resolution of 6.5 cm), SSMM-UAV-upscaling (obtained by upscaling the results of SSMM-UAV to a 16 m scale), SSMM-satellite (based on ground-satellite data at a 16 m scale), and SSMM-UAV-satellite (constructed using ground-UAV-satellite data at a 16 m scale). The results revealed that SSMM-UAV accurately monitored soil salinity at the UAV scale, with R2 values exceeding .81 and RMSEs below 0.11% for both the model modelling set and validation set. SSMM-UAV-upscaling demonstrated consistency with SSMM-UAV and effectively represented salinity conditions at the 16 m scale. In contrast, SSMM-satellite exhibited inferior performance, with R2 values of .42 and .32 for the modelling set and validation set, respectively, and RMSEs of 0.15% and 0.17%, respectively. By incorporating ground-UAV-satellite data, SSMM-UAV-satellite improved the R2 of SSMM-satellite by more than .09 and reduced the RMSEs by at least 0.08%. Furthermore, the area covered by satellite data was ca. 85 times larger than that covered by UAV data. The synergistic use of UAV and satellite data in salinity monitoring enhances the accuracy of satellite remote sensing and expands the monitoring range of UAV remote sensing. The findings of this study provide a reference for high precision and largescale salt monitoring through the synergistic integration of ground, UAV, and satellite data. [ABSTRACT FROM AUTHOR]

Subsurface pipe drainage (SPD) is an important technique for the improvement of saline–alkali lands in China. Winter irrigation after crop harvest is a key measure used in the Yellow River irrigation area in northwest China to reduce soil salinity in the root zone of crops. To optimize winter irrigation under SPD, the calibrated HYDRUS-2D model was utilized in this study to investigate the effects of soil texture (clay loam, silt loam, loam, and sandy loam), initial soil salinity (1, 3, 5 g/kg), and the winter irrigation quotas (80, 100, 120, 150, 180 mm) on the rate of soil desalination. In this study, soil salinity levels during the stable production of common crops such as sunflower and corn in the Yinbei Irrigation District in Ningxia, China, were taken as the thresholds, efficient utilization of irrigation water was considered, and suitable crops and appropriate winter irrigation quotas for different soil textures and levels of soil salinity were proposed. Soil with a salt content of 1~3 g/kg is suitable for the planting of corn with 80 mm of irrigation water. Sandy loam soil with a salt content of 3~5 g/kg is suitable for sunflower–corn intercropping with 120 mm of irrigation water. Sandy loam soil with a salt content exceeding 5 g/kg is suitable for the planting of sunflower with 80 mm of irrigation water. Other types of soils need to be improved by reducing the spacing between subsurface pipes, using desulfurized gypsum, biochar, and other additives. People engaged in agriculture can utilize this research to determine the appropriate volumes of irrigation water, crop types, planting systems, and subsurface pipe parameters based on local conditions. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of freshwater fish ponds on water and salt transport in cultivated wasteland in salinized areas, a typical study area was selected in the middle and lower reaches of the Hetao Irrigation District in China in the Yichang Irrigation Domain, and the temporal and spatial changes in the salinity of soil and salinity of groundwater and fish pond water in the cultivated–wasteland–fish pond system were characterized through the monitoring of the environmental information of soil and groundwater at the boundaries of the cultivated land, wasteland, and fish ponds. Salinity changes and groundwater migration in different periods were determined, and the response of soil salinity to the depth of groundwater burial was analyzed, as well as the effect of fish ponds on soil salinization. The results showed that the amount of groundwater migrating from cropland to wasteland during the simulation period in 2022 was 2700 m3, the amount of groundwater migrating from wasteland to fish ponds was 630 m3, and the amount of groundwater migrating from fish ponds to wasteland during the fall watering period was 440 m3. From an overall perspective, the average soil salinity of wasteland was 1.56 times higher than that of the boundary of fish ponds. Not only do fish ponds play a positive role in the ecosystem, but they also have a desalinization effect that reduces soil salinity significantly. Groundwater depth and soil salinity have an exponential relationship; when the depth of groundwater is greater than 1.75 m, the soil salinity varies little with the depth of groundwater and the soil salinity is less than 0.66 ds/m, which can be determined as the critical depth, and the average depth of groundwater in cultivated land in the study area is 1.5 m. Therefore, it is necessary to reasonably control the water level of fish ponds, so as to make the groundwater depth of cultivated land control between 1.75 m and 2.0 m, and to prevent soil salinization. [ABSTRACT FROM AUTHOR]