Sand dunes are predominantly distributed in arid regions. Automatic mapping and regionalization of sand dunes in large-scale areas are crucial to understanding the evolution trends of aeolian sand environments. Different from existing studies primarily focused on mapping the extent of desert areas, this study proposes a framework for automatic identification and comprehensive regionalization based on dunes morphology. First, the basal terrain of the dune area is constructed, and the difference between this basal terrain and the DEM is calculated using threshold segmentation to delineate the extent of dunes. Further, some landscape metrics are selected to quantify the collective morphological characteristics of sand dunes. Then, a spatially constrained multivariate clustering method is applied to regionalize dunes comprehensively. Compared to existing DEM-based dune extraction methods, this method can represent dune characteristics more accurately. The application in the Grand Erg Oriental achieved a high extraction accuracy of 94.17%, indicating its suitability for identifying dunes with diverse types in large-scale areas. a six-region map is generated that can clearly demonstrate diverse landscape patterns of dunes. The results indicate that the subregions containing branching linear dunes and network dunes have the highest area proportions, accounting for 27.68% and 26.83% of the total study area, respectively. This study provides valuable reference for aeolian geomorphology research specifically offering support for studies in the Grand Erg Oriental region.

Surface and subsurface anomalies, hydrological conditions, and dynamic interactions between embedded thematic layers influence groundwater recharge potential (GRP). Conducting a GRP study plays an essential role in promoting the sustainable use of groundwater resources amid a growing population and unplanned urbanization. This study focuses on assessing GRP in the semi-arid eastern plains of Rajasthan by delineating groundwater potential zones (GPZs) using an integrated approach involving remote sensing and geographical information system (RS-GIS) technique and analytical hierarchy process (AHP) method. Research findings indicate that the region dominated by fine sand, silt and clay, pediment-pediplain complex, aeolian sand sheet, higher drainage density, cambisols soil, river channels, floodplains, water bodies, soil hydraulic conductivity and higher surface wetness significantly contributed to good recharge potential in plains of the region. Additionally, lineaments, hills and valleys regulate water movement. A strong negative correlation (-0.78) between decadal-mean-depth fluctuation and GPZs frequency classes validates identifying high potential zones in areas with low mean-depth fluctuation. Sensitivity analysis highlights geology and geomorphology as crucial factors. However, the study addresses potential limitations and challenges, such as data scaling and spatial resolution issues due to nonlinear pixel fusion algorithms and AHP method-related limitations in model interpretation. The current study presents a convenient approach for improving groundwater resource management in hydrogeologically sensitive and drought-prone regions.

Sandy soils present more than 70% of sand in their composition. This soil type presents rapid water infiltration, susceptibility to drought and erosion by wind, and low ability to hold water and nutrients. Therefore, this environment is not appropriate for agricultural activities under conventional tillage. Thus, this review aims to study sandy soils and the main challenges necessary to achieve sustainable and efficient production in this soil type. Physical, chemical, and biological soil properties studied include hydrophobicity, compaction, runoff and erosion, fertility, pathogen management, and salinity. Considering all literature cited, the main challenge for achieving efficient management of sandy soils comprises identifying the correct balance and the type of organic matter applied in these sandy areas. No-tillage management and crop rotation comprise the most promising management techniques for sandy soil cultivation developed until now. This paper reviews of the main issues found for the proper cultivation of sandy soils. The increasing global pressure for land resources requires developing methodologies for the sustainable use of sandy soils for agricultural purposes aimed at sustaining the growth of the world's population.

Soil moisture and nitrogen (N) fertilizer control the balance between nitrous oxide (N2O) production and consumption in soil. However, the impact of nitrification and urease inhibitors on soil N2O production and consumption under varying soil moisture levels remains insufficiently understood. In this study, a soil column experiment was conducted to investigate N2O concentrations and accumulation at different soil depths (0, 5, 15, 30, and 60 cm) in sandy soil over two months. The soil was collected from a drip-irrigated field subjected to longterm cotton cultivation in an arid region. Four fertilizer treatments were applied: urea, urea + nitrification inhibitor (Dicyandiamide, DCD), urea + nitrification and urease inhibitors [N-(n-butyl) thiophosphoric triamide, NBPT], and an unfertilized control. These treatments were tested under three soil moisture levels [23%, 46%, and 70% water-filled pore space (WFPS)]. The results showed that treatments with inhibitors significantly reduced cumulative surface N2O emissions by 33.2%-58.2% compared to urea alone. Notably, the treatment with both DCD and NBPT achieved the greatest reductions in surface emissions and in N2O concentrations at 5 cm and 15 cm soil depths at 70% WFPS. Additionally, across all N fertilizer sources, 70% WFPS led to increased N2O concentrations in the soil profile compared to lower soil moisture levels. Column N2O accumulation was positively correlated with surface cumulative N2O emissions under all three moisture conditions. Our study highlights that under high soil moisture conditions, DCD and NBPT can significantly mitigate intense N2O emissions in sandy soils. This emission reduction is likely attributed to enhanced nitrification within the 0-15 cm soil layer rather than reduced N2O diffusivity and denitrification along the soil profile. Therefore, we recommend applying nitrification and urease inhibitors under high soil moisture conditions as an effective strategy to reduce N2O emissions in sandy soils.

This work integrates taphonomic (archaeofaunistics and bioarchaeology) and geoarchaeological (geormorphology, pedologic, sedimentological and micromorphological analyses) information to discuss the depositional and postdepositional history of both surface and buried archaeological record related to past hunter-gatherer populations from the Central Pampean Dunefields of Argentina (South America). Radiocarbon and optically stimulated luminescence dating suggest three temporal clusters of occupations in the Laguna Chica locality: one during the middle Holocene (similar to 8050-6535 years cal. B.P.) and two in the late Holocene (similar to 3350-2870 and similar to 1640-1535 years cal. B.P.). Middle Holocene burials found at the present lake shore are hosted in aeolian sediments that accumulated under arid/semiarid conditions. Modern lacustrine dynamics derived from contraction/expansion cycles have exposed burials, archaeofauna, and stone tools, resulting in displacements, fragmentation and loss. A palimpsest of cultural and natural material spanning similar to 8000 years resulted from this paleoenvironmental setting. Late Holocene human activities might have been related to a transitional landscape, where aeolian processes took place under an expanding lacustrine scenario (i.e., relatively wetter conditions). Our stratigraphic assessment suggests that human occupations were syndepositional agents with episodes of aeolian sand activity and landscape stability. The taphonomic and geoarchaeological evidence from Laguna Chica locality show that the empirical evidence traditionally used to evaluate hunter-gatherer settlement patterns (e.g., abundance and diversity of archaeological evidence and their spatial association in surface or stratigraphic units) and human diet breadth changes (e.g., Ntaxa) may simply reflect the cumulative action of lacustrine erosion of dunes. While both the Laguna Chica surface and stratigraphic records have complex formation histories, the buried context could be interpreted with greater detail through taphonomic and sedimentological analyses.

Aeolian sand widespread in the arid and semi-arid regions has been taken use as the cost-optimal subgrade filling materials. Under the drought climate, the performance of the compacted aeolian sand subgrade is largely dependent on its unsaturated strength. In this work, the shear strength with respect to the matric suction of unsaturated aeolian sand was investigated. A series of triaxial tests were conducted on the compacted specimens with different matric suctions. Results showed that the shear strength of specimen firstly increased with matric suction and then dropped off to a certain value. The maximum shear strength was reached at the matric suction of 40 kPa, which locates in the residual zone on the soil-water characteristic curve (SWCC) of the tested soil. Such phenomena were analysed from the perspective of capillary pore distribution, as well as the internal tri-phase (air-water-solid) structure that identified by microfocus X-ray computed tomography (mu CT) technique. According to the capillary pore size distribution of the specimen, pores with radius smaller than 21 mu m are theoretically saturated with water at suction of 10 kPa. The identified delimiting pore radius was found to be comparable to that of 25 mu m as identified by mu CT. On this basis, the role of water bridges in unsaturated aeolian sand and the pore size-level that govern the mechanical properties were discussed.

Aeolian-fluvial processes are crucial in shaping landforms. Despite the advancements in understanding the sedimentary processes of aeolian-fluvial interactions, the sedimentary patterns of these interactions are complex in spatiotemporal scale, and the records of Holocene small-scale aeolian-fluvial interaction sedimentary is insufficient, especially in the Tibetan Plateau region. Therefore, this study focuses on analyzing the sedimentary patterns of aeolian-fluvial interactions and their response to climate change in the Paiku Co basin of the southern Tibetan Plateau (TP). Through the examination of aeolian-fluvial sequences, Optically Stimulated Luminescence (OSL) dating is utilized to establish a chronological framework. Furthermore, proxy indices are explored to identify potential sediment models and their reactions to climate change. The findings indicate that fluvial activity predominated during a relatively warm and wet period around 5.1-4.6 ka, while thicker aeolian sands accumulated extensively during 4.6-4.1 ka as the climate transitioned to cold and dry conditions. On a millennial scale, the aeolian-fluvial interaction sedimentation is characterized by alternating deposition of clay layers and medium to fine sand. This sedimentation pattern is predominantly influenced by climate change. Overall, the findings shed light on the complex coupling between aeolian and fluvial processes in response to past climate changes, which has important implications for understanding the landscape evolution and environmental changes in this sensitive high-altitude region.

This meta-analysis assessed soil organic carbon (SOC) percent changes in sandy soils, transitioning from conventional tillage (CT) to conservational tillage (CST) in arid and semi-arid climates. High levels of SOC in sandy soils are difficult to attain especially when precipitation levels are very low, contributing to low biomass production, and increased decomposition of organic matter. While CT practices are known to reduce SOC through the breakdown of soil aggregates, accelerated decomposition of soil organic matter, and promote erosion, CST methods (i.e., mulch tillage, no tillage, reduced tillage, ridge tillage, etc.) offer the potential to preserve soil aggregates and increase SOC concentration. Analyzing 55 peer-reviewed publications in arid and semi-arid climates with >= 45 % sand content, this study compared SOC content between CST and CT over short- and long-term periods (349 paired observations). Results showed that CST increased SOC in sandy soils, with an estimated 12.74 +/- 1.46 % increase. Specifically, reduced tillage (RdT), mulch tillage (MchT), and no tillage (NT) exhibited the highest increases of SOC by 18.94 +/- 2.48 %, 11.45 +/- 2.46 %, and 10.06 +/- 2.46 %, respectively, compared to CT. Studies with durations of up to 15 years (n = 297) showed a progressive increase in SOC concentrations under CST; however, the long-term stability of the accrued carbon content in sandy soils of arid and semi-arid climates is still uncertain, as studies extending beyond 15 years (n = 52) did not demonstrate significant changes in SOC levels. CST significantly raised SOC concentrations in precipitation up to 600 mm, though no significant changes were observed for precipitation over 600 mm. In soils with over 56 % sand content, CST increased SOC by approximately 13 %. This study highlights both positive and limited impacts of CST practices for soil conservation and climate change mitigation, emphasizing their significance for both existing agricultural areas in arid regions and those in parts of the world where aridity is on the rise.

The permanent displacement of earth slopes during earthquake shaking is a key indicator for landslide hazard assessment. Previous studies mostly attempt to evaluate the earthquake-induced displacement of dry or saturated soil slopes, while it is less common to deal with partially saturated soils. In the present study, a simplified procedure is proposed to account for the seismic-induced excess pore pressure in slopes with partially saturated sandy soils. The effect of matric suction, suction stress, and excess pore pressure on the yield acceleration of partially saturated sandy slopes is investigated, and the coupled Newmark sliding block method, known as the flexible soil columns with dynamic shear modulus and damping ratio, is modified to estimate the seismic slope displacement. Detailed discussions are made about the effect of different degrees of saturation on the excess pore pressure ratio, yield acceleration, and slope displacement. The numerical results show that the excess pore pressure ratio tends to exponentially increase with saturation, and the change of yield acceleration and displacement with saturation can be divided into suction stress dominant and excess pore water pressure dominant stages.

Optimizing plant density and nutrient availability is essential for sustaining high forage yields and promoting environmental health, especially in semi-arid regions with sandy soil. Nonetheless, the mechanisms by which stoichiometric features govern nutrient utilization and forage output are still unidentified. We executed a two-year field experiment, integrating six nitrogen rates (0 (N0), 104 (N1), 138 (N2), 173 (N3), 207 (N4), and 242 (N5) kg N ha-1) and four planting densities (3 (D1), 3.5 (D2), 4 (D3), and 4.5 (D4) million plants ha-1). The C, N, and P contents, along with the C:N:P stoichiometry of different oat organs (leaf, stem, and root) and soil, were determined. It was found that the growth of oats in this area was limited by soil N. The pasture biomass increased nonlinearly with increasing planting density and N rate, and the maximum thresholds for C, N, and P uptake were 389.43 g kg-1, 11.19 g kg-1, and 3.10 g kg-1 at N3, respectively. The maximum thresholds for C, N, and P uptake were 356.45, 9.47, and 2.78 g kg-1 at D3, respectively, with an optimal biomass of 9221.74 kg ha-1; at a planting density of D3, the maximum thresholds for C, N, and P uptake were 329.39, 8.54, and 2.47 g kg-1, with an optimal biomass of 6276.10 kg ha-1. SEM showed that N rate and density increases significantly changed the ecological balance of the soil. The C:N and C:P ratios in oat leaves tend towards lower values, while the N:P ratio tends towards higher values; in contrast, the C:N and C:P ratios in oat stems tend towards higher values, and the N:P ratio tends towards lower values. The nutrient use strategy maintains the stoichiometric balance at the organ level, which in turn improves the accumulation of oat biomass. The best NUE was obtained at an N rate and density of N3D3 with a 144% biomass increase as compared to N0D2. This study provides new insights into nutrient allocation, usage strategies, and the stability of oats in actual sandy land production.