Background and AimsSoil salinization is a major cause of land degradation and ecological damage. Traditional soil salinity monitoring techniques are limited in coverage and scalability, while remote sensing offers broader applicability and efficiency. This study addresses spatiotemporal variations in soil salt content (SSC) inversion across crop types in Tongliao City, Inner Mongolia, China, using an innovative integration of multi-temporal data and crop cover types, improving remote sensing monitoring accuracy.MethodsField sampling data and Sentinel-2 images from June to September in 2021 and 2022 were utilized. The deep learning U-net model classified key crops, including sunflower (33%), beet (12%), and maize (55%), and analyzed the effects of crop coverage on SSC across multiple time series. Six spectral variables were selected using the SVR-RFE model (R2 = 0.994, MAE = 0.016). SSC prediction models were developed using three machine learning methods (DBO-RF, PSO-SVM, BO-BP) and a deep learning method (Transformer).ResultsConsidering crop coverage variations improved the sensitivity of spectral variables to SSC response, enhancing predictive accuracy and model stability. Crop classification showed that the salinity index (SIs) correlated more strongly with SSC than the vegetation index (VIs), with SI6 having the highest correlation coefficient of 0.50. The Transformer model, using multi-time series data, outperformed other algorithms, achieving an average R2 of 0.71. The SSC inversion map from the Transformer model closely matched field survey trends.ConclusionThis research provides a novel approach to soil salinity prediction using satellite remote sensing, offering a scalable solution for monitoring salinization and valuable insights for environmental management and agricultural planning.

The studied region is located in the southwestern Iran and on the border of Iran and Iraq. In the past, this region had dense palm groves and abundant plants. However, due to the decrease in upstream discharge, in recent years, saline and sodium seawater has intrusion in the river and affected the agricultural lands along its sides. This event has caused irreparable and serious damage to the agricultural industry in the region, turning this area into a graveyard of date palm trees. Understanding the characteristics of agricultural soils for their improvement and/or planting appropriate plants is one of the goals of sustainable agriculture. Considering the damage of the studied area from the intrusion of salt water in the Arvand River, this study investigated important characteristics of soil salinity including EC, pH, C.E.C, SAR and ESP. In this research, sampling of agricultural soils along the riverside was carried out in three different horizons and two line parallel to the river and at two different distances. Statistical methods of correlation coefficient, hierarchical analysis and factor analysis were used to identify the factors affecting soil quality and the relationships between parameters. The results showed that due to the intrusion of sodium seawater, the soils of the studied area have become saline-sodium, and the salinity level in the soils near the river mouth is higher than that in the soils on the upstream side of the river. In terms of fertility, the cation exchange capacity is in the medium range, and the clay texture and abundant organic matter of the soil as a result of the remaining plant and tree residues have an important effect on this parameter.

Introduction Salt stress has emerged as a predominant abiotic factor that jeopardizes global crop growth and yield. The plant hormone salicylic acid (SA) has notable potential in mitigating salt toxicity, yet its mechanism in enhancing the salinity tolerance of tobacco plants is not well explored. Methods This study aimed to assess the potential benefits of exogenous SA application (1.0 mM) on tobacco seedlings subjected to saline soil conditions. Results The foliar spray of SA partially mitigated these salt-induced effects, as evidenced by a reduction of malondialdehyde content, and improvements of leaf K+/Na+ ratios, pigment biosynthesis, and electron transport efficiency under NaCl stress. Additionally, SA increased the contents of total phenolic compound and soluble protein by 16.2% and 28.7% to alleviate NaCl-induced oxidative damage. Under salt stressed conditions, the activities of antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, catalase, and peroxidase increased by 4.2%similar to 14.4% in SA sprayed tobacco seedlings. Exogenous SA also increased ascorbate and glutathione levels and reduced their reduced forms by increasing the activities of glutathione reductase, ascorbate peroxidase, monodehydroascorbate reductase and dehydroascorbate reductase. qRT-PCR analysis revealed that the key genes regulating SA biosynthesis, carbon assimilation, the antioxidant system and the ascorbate-glutathione cycle were activated by SA under conditions of salt stress. Discussion Our study elucidates the physiological and molecular mechanisms of exogenous SA in enhancing plant salt tolerance and provides a practical basis for crop improvement in saline environments.

Climate change intensifies soil salinization and jeopardizes the development of crops worldwide. The accumulation of salts in plant tissue activates the defense system and triggers ethylene production thus restricting cell division. We hypothesize that the inoculation of plant growth-promoting bacteria (PGPB) producing ACC (1aminocyclopropane-1-carboxylate) deaminase favors the development of arbuscular mycorrhizal fungi (AMF), promoting the growth of maize plants under saline stress. We investigated the efficacy of individual inoculation of PGPB, which produce ACC deaminase, as well as the co-inoculation of PGPB with Rhizophagus clarus on maize plant growth subjected to saline stress. The isolates were acquired from the bulk and rhizospheric soil of Mimosa bimucronata (DC.) Kuntze in a temporary pond located in Pernambuco State, Brazil. In the first greenhouse experiment, 10 halophilic PGPB were inoculated into maize at 0, 40 and 80 mM of NaCl, and in the second experiment, the PGPB that showed the best performance were co-inoculated with R. clarus in maize under the same conditions as in the first experiment. Individual PGPB inoculation benefited the number of leaves, stem diameter, root and shoot dry mass, and the photosynthetic pigments. Inoculation with PGPB 28-10 Pseudarthrobacter enclensis, 24-1 P. enclensis and 52 P. chlorophenolicus increased the chlorophyll a content by 138%, 171%, and 324% at 0, 40 and 80 mM NaCl, respectively, comparing to the non-inoculated control. We also highlight that the inoculation of PGPB 28-10, 28-7 Arthrobacter sp. and 52 increased the content of chlorophyll b by 72%, 98%, and 280% and carotenoids by 82%, 98%, and 290% at 0, 40 and 80 mM of NaCl, respectively. Coinoculation with PGPB 28-7, 46-1 Leclercia tamurae, 70 Artrobacter sp., and 79-1 Micrococcus endophyticus significantly increased the rate of mycorrhizal colonization by roughly 50%. Furthermore, co-inoculation promoted a decrease in the accumulation of Na and K extracted from plant tissue, with an increase in salt concentration, from 40 mM to 80 mM, also favoring the establishment and development of R. clarus. In addition, coinoculation of these PGPB with R. clarus promoted maize growth and increased plant biomass through osmoregulation and protection of the photosynthetic apparatus. The tripartite symbiosis (plant-fungus-bacterium) is likely to reprogram metabolic pathways that improve maize growth and crop yield, suggesting that the AMFPGPB consortium can minimize damages caused by saline stress.

The use of exclusion fencing as part of wildlife conservation programs has been increasing in recent years, particularly in Australia. Soil corrosion damage sustained on fences is a significant management concern as the weakened fence netting can provide opportunities for feral animal incursions into fenced safe havens. Soil corrosivity risk mapping can assist with the design of fenced nature reserves to reduce the frequency of fence repair and replacement. However, very little research has focused on developing methods for accurately predicting fence corrosion rates in different surface soil environments. This paper assesses the use of different soil attributes as corrosivity indicators for identifying areas of low, moderate and high fence corrosion risk in different soil environments present in South Australia (20 field sites). Zinc corrosion rates measured on zinc-aluminium fence samples (buried at sites for 9 months) ranged by a factor of nearly 50, with low rates of fence corrosion (0.1-0.7 mu m/year) observed at five sites, medium rates (0.7-2.1 mu m/year) observed at 10 sites, and extreme rates (>8.4 mu m/year) observed at four sites. Fence corrosion risk was predicted using soil pH, soil salinity and texture data, and a soil corrosivity risk index developed for use in arid soils in South Australia. Predicted zinc corrosion rates matched field observations at 45 % of field sites. The highest rates of zinc corrosion (>4.2 mu m/year) were observed at field sites with highly alkaline (pH > 8.5) and highly saline (ECe >= 5 dS/m) soils. An improved fence corrosion risk classification method, referred as the Fence Corrosion Risk Decision Tree was developed using these soil pH and salinity thresholds, which correctly predicted fence corrosion risk at 67 % of field sites at Olympic Dam and Farina and 50 % of field sites on the Yorke Peninsula. Further research is needed to assess the ability of this method to predict long-term fence damage (>2 years exposed to soil conditions).