Explore the vast range of titles available.

Aims Soil salinization has been an important environmental problem globally, particularly in oasis areas in arid zones. The advantages of using multi-source data, combining radar and optical remote sensing data, and applying machine learning-based algorithms to these data could be beneficial for addressing the soil salinization problem. Methods This study combines the environmental covariates extracted from the Gaofen-3 (GF-3) radar data, Landsat-8 multispectral data, and digital elevation model (DEM) data to explore the advantages of radar remote sensing in detecting soil salinity. The soil salinity distribution degree in the Keriya Oasis is mapped using a machine-learning-based method, and the advantages of different sensor images in predicting soil salinity are evaluated. Three soil salinity inversion models are constructed using measured electrical conductivity (EC) data, the random forest (RF), gradient boosting tree (GDBT), and extreme gradient boosting (XGBoost) models. Results The best accuracy corresponding to an R 2 of 0.87, and a root mean square error (RMSE) of 6.02 is achieved by the RF model on the GF-3 + Landsat-8 data. Therefore, the use of multi-source data is a more effective method for mapping soil salinity in the study area. The mapping results of the optimal model demonstrate that natural factors significantly influence the distribution of soil salinity. Conclusion The radar polarization decomposition characteristics are incorporated into the inversion of soil salinity modeling as an environmental covariate, providing an innovative and efficient method for soil salinity estimation in arid areas.

An investigation of soil salinization was carried out in the Nanshantaizi area (Northwest China) with WET Sensor. This device can measure such soil parameters as bulk soil electrical conductivity, water content, and the pore water electrical conductivity that are important for soil salinization assessments. A distribution map of soil salinization was produced, and the factors influencing soil salinization and its processes were discussed in detail. The study shows that moderately salinized to salt soils are mainly observed in the alluvial plain, where groundwater level is high and lateral recharge water contains high salinity. Nanshantaizi is covered by slightly salinized soils. The soil salinization distribution estimated by WET Sensor is generally consistent with the actual levels of salinization. Soil salinity in Nanshantaizi is mostly of natural origin and accumulated salts could leach to deeper soils or aquifers by water percolation during irrigation. Groundwater evaporation, groundwater level depth and quality of recharge water are important factors influencing soil salinization in the alluvial plain.

Remote sensing (RS) technology can rapidly obtain spatial distribution information on soil salinization. However, (1) the scale effects resulting from the mismatch between ground-based “point” salinity data and remote sensing pixel-based “spatial” data often limit the accuracy of remote sensing monitoring of soil salinity, and (2) the same salinity RS monitoring model usually provides inconsistent or sometimes conflicting explanations for different data. Therefore, based on Landsat 8 imagery and synchronously collected ground-sampling data of two typical study regions (denoted as N and S, respectively) of the Yichang Irrigation Area in the Hetao Irrigation District for May 2013, this study used geostatistical methods to obtain “relative truth values” of salinity corresponding to the Landsat 8 pixel scale. Additionally, based on Landsat 8 multispectral data, 14 salinity indices were constructed. Subsequently, the Correlation-based Feature Selection (CFS) method was used to select sensitive features, and a strategy similar to the concept of ensemble learning (EL) was adopted to integrate the single-feature-sensitive Bayesian classification (BC) model in order to construct an RS monitoring model for soil salinization (Nonsaline, Slightly saline, Moderately saline, Strongly saline, and Solonchak). The research results indicated that (1) soil salinity exhibits moderate to strong variability within a 30 m scale, and the spatial heterogeneity of soil salinity needs to be considered when developing remote sensing models; (2) the theoretical models of salinity variance functions in the N and S regions conform to the exponential model and the spherical model, with R2 values of 0.817 and 0.967, respectively, indicating a good fit for the variance characteristics of salinity and suitability for Kriging interpolation; and (3) compared to a single-feature BC model, the soil salinization identification model constructed using the concept of EL demonstrated better potential for robustness and effectiveness.

The scarcity of freshwater resources has increased the use of nonconventional water resources such as brackish water, reclaimed water, etc., especially in water-scarce areas. Whether an irrigation cycle using reclaimed water and brackish water (RBCI) poses a risk of secondary soil salinization to crop yields needs to be studied. Aiming to find an appropriate use for different nonconventional water resources, pot experiments were conducted to study the effects of RBCI on soil microenvironments, growth, physiological characteristics and antioxidation properties of crops. The results showed the following: (1) compared to FBCI, the soil moisture content was slightly higher, without a significant difference, while the soil EC, sodium and chloride ions contents increased significantly under the RBCI treatment. With an increase in the reclaimed water irrigation frequency (Tri), the contents of EC, Na+ and Cl− in the soil decreased gradually, and the difference was significant; the soil moisture content also decreased gradually. (2) There were different effects of the RBCI regime on the soil’s enzyme activities. With an increase in the Tri, the soil urease activity indicated a significant upward trend as a whole. (3) RBCI can alleviate the risk of soil salinization to some extent. The soil pH values were all below 8.5, and were without a risk of secondary soil alkalization. The ESP did not exceed 15 percent, and there was no possible risk of soil alkalization except that the ESP in soil irrigated by brackish water irrigation went beyond the limit of 15 percent. (4) Compared with FBCI, no obvious changes appeared to the aboveground and underground biomasses under the RBCI treatment. The RBCI treatment was conducive to increasing the aboveground biomass compared with pure brackish water irrigation. Therefore, short-term RBCI helps to reduce the risk of soil salinization without significantly affecting crop yield, and the irrigation cycle using reclaimed-reclaimed-brackish water at 3 g·L−1 was recommended, according to the experimental results.

【Objective】The expansion of saline soils at the western foot of Helan Mountain, particularly in Alashan Left Banner, poses significant threats to agriculture and ecosystem health. This study systematically analyzes the causes of soil salinization in this region and proposes mitigation strategies.【Method】The research focused on two key irrigation areas: Yaoba Oasis, which relies on groundwater for irrigation, and the Luanjingtan Yellow River Irrigation Area, which utilizes Yellow River water for irrigation. Both natural factors, such as climate, soil parent material, hydrological conditions, and anthropogenic factors, including irrigation methods and cropping patterns, were examined for their roles in soil salinization.【Result】High evaporation and elevated salt content in the soil parent material are the primary drivers of salt accumulation. In Yaoba Oasis, improper irrigation and cropping practices, coupled with excessive groundwater extraction, intensify soil salinization. In the Twin Well Beach area, early flood irrigation combined with soil moisture leakage led to salinization in the downstream region. Additionally, in areas practicing drip irrigation, the absence of adequate leaching and field drainage creates risks of secondary salinization. To address these issues, we recommend: ① Implementing water-saving irrigation techniques, groundwater recharge projects, crop structure adjustments, and enhanced drainage systems; ② Determining critical groundwater depths and adopting salt leaching and irrigation methods tailored to soil texture and cropping patterns, and improving drainage infrastructure to ensure coordinated irrigation and drainage management.【Conclusion】Effective management of saline soils at the western foot of Helan Mountain requires moving beyond traditional approaches to incorporate tailored strategies that reflect the distinct salinization dynamics of Yaoba Oasis and the Luanjingtan Irrigation Area. This study advocates for a coordinated groundwater management plan emphasizing “source replenishment and salt control” in Yaoba Oasis, alongside an integrated approach combining “water-saving irrigation, targeted salt leaching, and synchronized irrigation-drainage” in the Yellow River irrigation district. Due to the complexity of soil salinization in this region, sustainable reclamation depends on adopting holistic, site-specific practices that integrate multiple control measures and move beyond conventional single-focus water management methods.

Not only is solving freshwater resource shortages effective but also an important measure for realizing the sustainable development of agriculture through the development and use of unconventional water resources. This pot experiment investigated the role of exogenous silicon in the risk of secondary soil salinization and the growth physiology of Lvxiu pakchoi cabbage under irrigation by using brackish water alone (BW), reclaimed water alone (RW), and compound irrigation with brackish water and reclaimed water at a ratio of 1:1, as well as the distribution of silicon in a soil–crop system. The results showed that with the extension of the spraying period of silicon fertilizer, the electrical conductivity (EC) decreased under 1:1 compound irrigation. The pH values in all treatments ranged from 7.95 to 8.10 without a potential risk of alkalization. Spraying silicon fertilizer had a positive effect on increasing the ratio of exchangeable potassium to sodium in soil. Spraying silicon fertilizer significantly reduced the percentage of exchangeable sodium (ESP) and the sodium adsorption ratio (SAR) in soils irrigated using BW, and increased the soil ESP and SAR under compound irrigation and RW irrigation, but these factors did not exceed the threshold of soil salinization. The proper application of silicon fertilizer had no significant effect on the total silicon content in the soil but increased the total silicon content in the plants to some extent. In addition, the yield was improved through proper silicon fertilizer application. In summary, exogenous silicon has positive effects on soil physical and chemical properties and crop growth, and relieves secondary salinization risk under compound irrigation via brackish water and reclaimed water.

In this study, the Senegal River, being the main source of water, plays a crucial role in the area’s agricultural development. Irrigation on the M’Pourie plain using water from the Senegal River is carried out without any prior sanitation control. An evaluation of the quality of irrigation water and its impact on soil salinization in different agricultural plots soil salinity is crucial for the effective utilization of traditional irrigation water over extended periods. Comprehensive physico-chemical analyses were conducted across nine locations on the M’Pourie plain in Rosso during the dynamic seasons of 2021-2023. Nevertheless, a relatively small number of studies have employed soil salinity indexing methods to examine the consequences of river irrigation on soil salinity. The analysis and interpretation of the results obtained were based both on classic methods (average and correlations) and more advanced techniques such as principal component analysis (PCA) and the Piper diagram which allow characterization and a spatial typology of water. Analysis of the Piper diagram highlights the distinction between two groups of water, weakly and moderately mineralized, ranging from 52.22 μS.cm-1 in the dry season to 72.22 μS.cm-1 in the rainy season, presenting a sodium-potassium bicarbonate facies The variability of irrigation water supplies, proves to be important in the functioning of an agro-systems. Two modes of operation have become individualized: the dry phase mode, characterized by very strong mineralization of the water linked to a significant load of dissolved elements, and the wet phase mode, whose water quality is poorly mineralized but shows the impact that its irrigation water can represent in the loading of organic and mineral pollution and the need for strict control of these waters upstream before their agricultural use. The results of this study show the absence of risks of soil salinization in relation to the chemical nature of irrigation water and the impact of agriculture on the M’Pourie plain.

Soil salinization process is a complex non-linear dynamic evolution. To classify a system with this type of non-linear characteristic, this study proposed a mixed master/slave chaotic system based on Chua’s circuit and a fractional-order Chen-Lee chaotic system to classify soil salinization level. The subject is the soil in Xinjiang with different levels of human interference. A fractional-order Chen-Lee chaotic system was constructed, and the spectral signal processed by the Chua’s non-linear circuit was substituted into the master/slave chaotic system. The chaotic dynamic errors with different fractional orders were calculated. The comparative analysis showed that 0.1-order has the largest chaotic dynamic error change, which produced two distinct and divergent results. Thus, this study converted the chaotic dynamic errors of fractional 0.1-order into chaotic attractors to build an extension matter-element model. Finally, we compared the soil salt contents (SSC) from the laboratory chemical analysis with the results of the extension theory classification. The comparison showed that the combination of fractional order mixed master/slave chaotic system and extension theory has high classification accuracy for soil salinization level. The results of this system match the result of the chemical analysis. The classification accuracy of the calibration set data was 100%, and the classification accuracy of the validation set data was 90%. This method is the first use of the mixed master/slave chaotic system in this field and can satisfy certain soil salinization monitoring needs as well as promote the application of the chaotic system in soil salinization monitoring.

Factual materials on salt-affected soils in the Barguzin Depression (Buryat Republic) are generalized. A geomorphic map of the depression has been developed. The distribution of salt-affected soils and the specificity of salinization in different geomorphic regions are characterized. These soils tend to be developed within the low lacustrine–alluvial plain of the depression, on the floodplain of the Barguzin River and its tributaries. Smaller areas of salt-affected soils are found on the river terraces. They are virtually absent on ancient sandy ridged terraces (kuituns). The genesis and chemistry of soil salinization are mainly related to the discharge of slightly saline deep water along tectonic faults and fissures. An additional source of soil salinity is represented by surface water flows. The presence of permafrost preventing the leaching of salts and the cryoarid climate favoring the migration of salts toward the soil surface during the dry spring and early summer periods and during the soil freezing in the winter contribute to the soil salinization. Slightly saline hydromorphic solonchakous soils predominate among salt-affected soils of the depression; the portion of semihydromorphic saline soils is smaller. Automorphic saline soils rarely occur in the depression. Strongly saline soils— solonchaks—are widespread within lacustrine depressions around salt lakes. Soils of the soda and sulfate salinization predominate. The content of chlorides is small; their increased amounts, as well as the presence of sulfates, are indicative of the discharge of dee ground water onto the surface. The soda type of salinization is also related to the discharge of deep stratal water with further transformation of salt solutions during freeze–thaw cycles. Under anaerobic conditions, the formation of soda is favored the processes of sulfate reduction.

This paper discusses the dynamics of ecosystems and their components in connection with the development of the Aral Sea environmental crisis. The theoretical basis of this study was the idea that the vegetation dynamics under the conditions of deltaic landscape desertification represents an anthropogenically-induced natural hologenetic process involving the replacement of vegetation typical for hydromorphic floodplain and reed-bed biotopes with vegetation of semihydromorphic meadow and solonchak biotopes resulting in the formation of zonal vegetation typical for automorphic biotopes. These endo–ecogenetic successions are determined by the directed reduction in moisture supply in biotopes and accompanying salinization and evolution of soils. The changes occur in both successional and catastrophic ways. In the northern, undeveloped part of the Amu Darya River delta, the reduction of the sea water surface and a sharp drop in water reserves resulted by the 1990s in the formation of environmental conditions typical for desert landscapes: the climate parameters and their regime became close to desert ones, while the groundwater level fell to a depth of 5–10 m, thus, making groundwaters inaccessible to plant roots. Reconstruction of the reservoir system and flooding of former marine bays contribute to the formation of hydromorphic conditions on local sites. Geobotanical studies commenced in the Amu Darya River delta in 1979 and involved route surveys and surveys of topo–ecological profiles passing through the main deltaic relief elements (levees, their slopes, and interchannel depressions) were repeated in the monitoring mode in 1985, 1993, and 1999. Route surveys performed in 2017 showed that the current vegetation dynamics stage involves the formation of desert plant communities. Black saxaul ( Haloxylon aphyllum (Minkw.) Iljin) first discovered in the Muynak district in 1993 is actively spreading in the most part of the undeveloped delta that has turned into a wasteland after the extinction of common reed ( Phragmites australis (Cav.) Trin. ex Steud.) communities in the 1970s–1980s. The desert species Krasheninnikovia ceratoides (L.) Gueldenst. that has invaded degrading tugai and sparse arborescent saltwort ( Salsola dendroides Pall.) monocoenoses on takyr solonchak soils around the same years formed extensive thickets north of the city of Kungrad. Observations on topo–ecological profiles made it possible to examine individual changes and stages in more detail. On the right bank of the Akdar’ya River that feeds the Mezhdurechenskoe Reservoir, on the Porlytau topo–ecological profile located 3 km southwest of the upland of the same name, over the course of the 40-year observation period, the river washed away a section of the near-channel floodplain and levee 500 m wide and was incised 9 m into the ground following a drop in the erosion base level (i.e., water level in the eastern part of the Greater Sea) by 26 m. Plant communities successions develop slowly. They follow the path of successional replacement of an arboreal Рoplar tugai ( Populus ariana + Populus pruinosa + Elaeagnus angustifolia – Mixteherbosa with a shrubby tugai with Tamarix ramosissima Ledeb. ending in a nearby section of the interchannel depression with a catastrophic change: the death of the Halostachys belangeriana (Moq.) Botsch. community. This community was formed in 1985 as a result of soil salinization in the area previously occupied by reeds. In 2017, a slow surface desalination process that began in 1993 due to the illuviation of salts from upper (0–10 cm) horizons to lower ones continued in the soil at all survey points on the profile. For the first time, the desert shrub species Krasheninnikovia ceratoides (L.) Gueldenst. was recorded on the tugai fringe in 2017; over time, this species will probably colonize this entire site characterized by the profile. In the northeastern part of the delta, on the Kunyadarya topo–ecological profile that begins on the right bank of the dry channel of the same name and descends in the southeastern direction to the coastal plain, a degrading Populus diversifolia-Halimodendron halodendron tugai on the levee is being replaced by a tamarisk tugai, which is indicated by the species composition of the community: Populus diversifolia-Tamarix laxa + Halimodendron halodendron + T. ramosissima – Atriplex tatarica . In 2017, black saxaul was first recorded in a community formed by tall well-developed tamarisks and succulent saltworts located further along the profile on the levee slope. The profile enters a coastal solonchak plain with a Halostachys belangeriana – Climacoptera aralensis community. The salinity profiles of soils under all plant communities have a similar feature: the salt content reaches its maximum in the upper part of the profile (0–10 cm); then it sharply decreases in the 10–20-cm horizon and does not change down the profile to a depth of 50 cm. Salinity profiles of soils on two sites occupied by the tugai have the maximum similarity. The uppermost (0–5 cm) horizon is less saline or somewhat washed out from salts compared to the deeper (5–10 cm) horizon featuring the maximum salt content. In the Halostachys belangeriana community, the salt content reaches its maximum (8.28%) in the surface soil horizon (0–5 cm), then it sharply decreases to 2% in the 10–20-cm horizon, and further decreases down the profile to almost 1%. The salinity profile under tamarisk communities differs from other profiles: overall, it is slightly saline and has two maxima: mild surface salinity (0.5% at a depth of 0–5 cm) and medium salinity (0.8%) at a depth of 20–30 cm. Salinity profiles of soils on the Kunyadarya topo–ecological profile indicate progressive salinization of soils with a clearly pronounced surface-accumulative profile under the impact of pulsating secondary hydromorphism in this area provoked by water flows from the Dzhiltyrbas Bay towards the sea that occur on a periodic basis. In 2017, a newly-formed young woody tugai on the bank of an irrigation canal crossing the degrading Yerkin tugai was described. It differs from the degrading tugai forests described earlier in its full-fledged structure (it has three storeys) and in richness of its plant species composition (12 species). Two liana species are present, and renewal of predominant tree species occurs. The soil under the young tugai is alluvial–meadow–tugai (hydromorphic); it is slightly saline (0.36%) only in the near-surface horizon (0–5 cm). Comparison of data collected on topo–ecological profiles with data collected in the course of previous observations made it possible for the first time to conclude that the changes of plant associations in woody tugai communities in the undeveloped part of the delta under the desertification conditions occurs mainly in a successional way; while herbaceous and shrub communities, especially halophilic ones and their variants, are characterized by predominantly catastrophic changes. After their death, long-lasting wastelands are formed on lands previously occupied by such communities where favorable conditions for the introduction of species with different ecology are created. In local hydromorphic conditions with floodplain regimes, the formation and existence of tugai plant communities is possible. The practical significance of the results is that they characterize the diversity of environmental conditions and processes currently occurring in the vegetation and landscapes in the undeveloped part of the Amu Darya River delta and can be applied in resource use and biodiversity conservation practices.