Geochemical studies examining surface aeolian sediments are significant for understanding Earth's surface processes and determining sediment provenance in arid and semi-arid regions. However, there is limited research on the geochemical comparison of aeolian sediments formed under distinctive tectonic and climatic settings. Surficial sand samples from the Taklamakan Desert and Horqin Sandy Land in northern China were collected, and the major, trace, and rare earth elements (REEs) in the bulk samples, fine fractions (75 mu m) of sand were analyzed. This study aimed to explore the spatial variation in the geochemical composition of aeolian sand and its drivers. The results show that differences between the two regions are primarily caused by the intensity of chemical weathering, sedimentary recycling, and provenance. The mean chemical proxy of alteration (72.3 vs. 77.8) and the Parker's weathering values (37.8 vs. 55.8) both suggest the bulk samples from the Horqin Sandy Land experienced more intense chemical weathering, whereas physical weathering is a dominant process in the Taklamakan Desert. These differences may be attributed to the different climatic conditions in the two regions and the exposure time to weathering. A combination of the index of compositional variability and immobile trace element ratios shows that aeolian sand in the Horqin Sandy Land underwent more intense sedimentary recycling than sediments in the Taklamakan Desert. REEs ratios (such as Cr/V and Y/Ni) and the Al2O3-CaO*+Na2O-K2O (A-CN-K) diagram indicate aeolian sand in the Taklamakan Desert is probably derived from mixed source rocks of tonalite, granite, and granodiorite. Eu anomaly vs. (La/ Yb) N diagrams suggest that the primary source-rocks contributing to the coarse and fine fractions in the Horqin Sandy Land are different but mainly derived from the Great Hinggan Mountains. Differences in the provenance of the fine- and coarse-grained fractions are primarily controlled by interactions between wind and fluvial systems. This study confirms that surface processes and sediment provenance in drylands of northern china have distinct spatial differences, implying that geochemical signatures in aeolian sand need to be interpreted in the specific climatic and tectonic contexts.

Beach aeolian sand transport is one of the most complicated but significant processes in beach-dune interactions. Focusing on tidal and morphological effects, field observations over several tidal cycles were carried out successively on two macrotidal and gently sloped beaches to clarify the characteristics, dominant factors and possible mechanism of aeolian sand transport in the intertidal zone. The results show that there is a clear time window for aeolian sand transport in the intertidal zone under the joint effect of tidal action and ridge morphology. During ebb tide, the factors controlling the initialization of intertidal aeolian sand transport shifted sequentially from ridge inundation (controlled by tide) to seepage, capillary and drying processes. During the time window, the fluctuations of dew point appear to be a good indicator of the variations in aeolian transport rates. During flooding, the dominant factor for the cessation of intertidal aeolian sand transport is inundation (controlled by the tidal elevation). Further exploration shows that for the wide and gently sloped beachface, the presence of intertidal ridges may be necessary for the aeolian process to entrain and transport sand from the moist intertidal zone. Finally, a conceptual model for the intertidal aeolian sand process under the joint effect of tide and ridge morphology is proposed. (c) 2021 Elsevier B.V. All rights reserved.

Soil organic carbon (SOC), soil inorganic carbon (SIC) and silt and clay are the main cementing substances formed by soil aggregates in arid areas. In this study, SOC, SIC and total nitrogen (TN) contents were analysed for different soil aggregate fractions that were reclaimed from different times (5, 15, 20, 35, 40, 50 and 60 years), in northwest China. Our results show that, as cultivation time increased from 0 to 60 years, the number of >2, 2-0.25 and 0.25-0.053 mm aggregates increased from 2.76%, 7.23% and 1.40% to 12.44%, 18.32% and 7.88%, respectively, and the stability of aggregates gradually increased from 0 to 0.43. We also found that the OC in the >2, 2-0.25 and 0.25-0.053 mm aggregates increased from 4.97, 3.81 and 2.63 g kg(-2) to 9.45, 7.16 and 4.22 g kg(-2), and the TN content increased from 0.70, 0.54 and 0.37 g kg(-2) to 1.05, 0.90 and 0.70 g kg(-2), while the IC in the >2 mm aggregates decreased from 7.22 to 6.22 g kg(-2), and the IC content of the 2-0.25 mm aggregates increased from 5.16 to 7.3 g kg(-2). Increasing the silt and clay particle content of soil may be an effective means to achieve continuous improvements in agricultural productivity for newly reclaimed land in the ecologically fragile marginal oasis area.

The potential for significant variability in potato (Solanum tuberosum L.) yield and quality caused by soil properties can be employed as a foundation for site-specific soil management. The current work investigated the relationship of soil properties, including the texture, moisture, and nitrate-nitrogen, with the variability of potato yield and quality on 28 ha center-pivot irrigated fields located in northwest China, where the soil was improved in 2014 by mixing Aeolian sandy soil with feldspathic sandstone. Geostatistic and correlation analyses were utilized to extract the relationships among soil properties and potato tuber properties. K-means clustering methods were utilized to establish critical sample points and soil factors for spatial variability of potato yield and quality. The spatial dependence of the potato tuber yield and quality varied from weak to strong, and most had unstable spatial structure considering the soil temporal variability, except reducing sugar content. More than 66% of the correlation coefficients between soil sand content and tuber variables were significant. The evaluation of the K-means clustering algorithms' effectiveness showed that circle minus v-All, PC-All, and texture had superior prediction results for tuber yield, dry matter content, and starch, respectively. N-All and soil texture datasets exhibited the best performance for reducing sugar content. Unsatisfactory prediction results were obtained for protein and VC. The results can be utilized to realize different objectives for in-field site-specific potato management.

Ploughing and overgrazing increase the risk of land degradation in arid zones, while silting and wind erosion are the consequences, some plants disappear and others persist and adapt. Fixing moving sediments in risk areas. To this aim, we focused on identifying steppe plants that can grow in a silted environment and to determine their distribution rate on the sand dunes. We carried out these vegetation inventories in the Mokrane region (Laghouat) in March 2019, using the floristic transect method. The height of Aeolian deposits was measured under all points every 20 cm along the tape of the floristic transect in the study area after slope correction by the topographic levelling method. We have identified 11 plant species. The heights of the fixed Aeolian deposits by the plants ranged from 28 cm to 63 cm, which is lower than those of the non-fixed deposits, ranged from 36 cm to 97 cm. For the three perennials (Aristida pungens, Retama raetam, Astragalus armatus), the elevations of the underlying Aeolian deposits were not statistically different; noting that Aristida pungens had the lowest values up to 29 cm. Aeolian deposits in the study area formed a microdunes that did not exceed 1 m. The height of the sediments accumulated under the canopy provided information on the role of perennial species in sand fixation and the order of plant establishment on the trapped sediments.

We here review what is known about the dunefields and fluvial systems of the Kalahari Basin in terms of geological setting and Quaternary dynamics and set out what has been hypothesized about the provenance of Kalahari sand so far. Previous work has tackled this problem by applying a limited number of techniques (mostly sediment textures and heavy minerals) to parts of the large dryland. The generally highly quartzose mineralogy of aeolian dunes and their compositional variability have been only broadly evaluated and several sedimentological issues have thus remained controversial, including the relative role played by fluvial processes versus aeolian reworking of older sediments and weathering controls. This reveals a need for a systematic provenance study that considers the entire basin. For this reason, here we combine original petrographic, heavy-mineral, and detrital-zircon geochronology data with previously published clay-mineral, geochemical, and geochronological information to present the first comprehensive provenance study of the vast Kalahari sand sea. Our multi-proxy dataset comprises 100 samples, collected across the Kalahari Basin from 11 degrees S (NW Zambia) to 28 degrees S (NW South Africa) and from 15 degrees E (Angola) to 28 degrees 30 degrees W (Zimbabwe). Kalahari aeolian-dune sand mostly consists of monocrystalline quartz associated with durable heavy minerals and thus drastically differs from coastal dunefields of Namibia and Angola, which are notably richer in feldspar, lithic grains, and chemically labile clinopyroxene. The western Kalahari dunefield of southeastern Namibia is distinguished by its quartz-rich feldspatho-quartzose sand, indicating partly first-cycle provenance from the Damara Belt and Mesoproterozoic terranes. Within the basin, supply from Proterozoic outcrops is documented locally. Composition varies notably at the western and eastern edges of the sand sea, reflecting partly first-cycle fluvial supply from crystalline basements of Cambrian to Archean age in central Namibia and western Zimbabwe. Basaltic detritus from Jurassic Karoo lavas is dominant in aeolian dunes near Victoria Falls. Bulk-sediment petrography and geochemistry of northern and central Kalahari pure quartzose sand, together with heavy-mineral and clay-mineral assemblages, indicate extensive recycling via aeolian and ephemeral-fluvial processes in arid climate of sediment strongly weathered during previous humid climatic stages in subequatorial Africa. Distilled homogenized composition of aeolian-dune sand thus reverberates the echo of paleo-weathering passed on to the present landscape through multiple episodes of fluvial and aeolian recycling. Intracratonic sag basins such as the Kalahari contain vast amounts of quartz-rich polycyclic sand that may be tapped by rivers eroding backwards during rejuvenation stages associated with rift propagation. Such an event may considerably increase the sediment flux to the ocean, fostering the progradation of river-fed continental embankments, as documented by augmented accumulation rates coupled with upward increasing mineralogical durability in the post-Tortonian subsurface succession of the Zambezi Delta.

Nanotechnology has the potential to increase the efficiency and quality of agricultural production. So, this research work was carried out to assess the effect of some soil conditioners at different rates and foliar application of antioxidant on the performance of wheat plants grown on sandy soil. The treatments were T1: Control (without soil addition);T2: 0.50%Normal compost (bulky);T3: 0.25% Nano compost;T4: 0.50% Nano compost;T5: 0.50% Normal agricultural gypsum (bulky);T6: 0.25% Nano agricultural gypsum;T7: 0.50% Nano agricultural gypsum; T8: 0.50% Normal sugar lime mud (bulky);T9: 0.25% Nano sugar lime mud;T10: 0.50% Nano sugar lime mud; F1: without proline and F2: with proline.Wheat plants treated with compostpossessed the highest values of all growth criteria (e.g.,fresh and dry weights, plant height and leaf area), photosynthetic pigments (after 70 days from sowing), yield, its component, and grains quality (at harvest stage) under sandy soil conditions followed by that treated with agricultural gypsum than the plants treated with sugar lime mud, while the untreated wheat plants with any soil conditioner (control treatment) possessed the lowest values of all aforementioned traits. Nano form was superior compared to the normal form with all studied soil amendments. Also, all aforementioned traits increased as the rate of Nano form increased with all studied soil amendments.Regarding the foliar application, the proline treatment was superior compared to the control treatment (without foliar application). The control treatment (without soil and foliar applications) led to raising the enzymatic antioxidants content in the straw of wheat plant after 70 days from sowing, where the cultivation without any both soil conditioners and proline caused an increase in wheat self-production from these antioxidants to scavenge the ROS (or as named free radicals) resulting due to the poverty of sandy soil, thus increase of tolerance. Generally, it can be concluded that all the studied soil conditioners (i.e., gypsum, compost, and sugar lime mud) in either normal form or Nano form have a beneficial effect on improving the performance and productivity of wheat plants grown under sandy soil conditions. Also, the findings of the current work confirmed proline is one of the plant's protective ways from the poverty of sandy soil fertility, where it works as an antioxidant and leads to an increase in wheat plant tolerance to the poverty of sandy soil fertility.

Table grapes arc harvested from November until early February in the Orange River Region of South Africa, where a functional leaf canopy is present for up to six months of post-harvest. Seasonal uptake and partitioning of mineral nutrients by 'Sultanina' grapevines in this long-season area were quantified in a preliminary investigation. Entire grapevines growing on two different soil types were sampled during the growing season. On sandy soil, further from the river, grapevine vigour was not excessive; however, on the fertile alluvial soil vigour was higher with active post-harvest re-growth. At budbreak, reserve N played an important role on the sandy soil, while it was less important on the alluvial one. During the post-harvest period, 34.3% of the annual N-requirement was absorbed by grapevines cultivated on sandy soil at post-harvest, while only 17.0% was absorbed on the alluvial soil. Approximately 4.0 kg N was utilized for the production of one ton of fresh grapes. A major fraction of the annual P-requirement (41.9%) was absorbed post-harvest by grapevines on the sandy soil. Grapevines on alluvial soil absorbed more P at pre-harvest; however, P was somehow lost post-harvest. Comparable amounts of K and Mg were absorbed by both selections of grapevines. Sandy soil grapevines absorbed K and Mg at post-harvest, while a net loss occurred for those of alluvial soil. Calcium utilized by sandy soil grapevines was less than half that utilized by those of alluvial soil. The seasonal absorption pattern of Ca was comparable for both soils. Results suggest that that seasonal uptake and partitioning of mineral nutrients are affected by soil type and grapevine vigour.

A bentonite-humic acid (B-HA) mixture added to degraded soils may improve soil physical and hydraulic properties, due to effects such as improved soil structure and increased water and nutrient retention, but its effect on soil physicochemical and biological properties, and grain quality is largely unknown. The effect of B-HA, added at 30 Mg ha-1, was studied at 1, 3, 5 and 7 years after its addition to a degraded sandy soil in a semi-arid region of China. The addition of B-HA significantly increased water-filled pore space and soil organic carbon, especially at 3 to 5 years after its soil addition to the soil. Amending the sandy soil with B-HA also increased the content of microbial biomass (MB)-carbon, -nitrogen and -phosphorus, and the activities of urease, invertase, catalase and alkaline phosphatase. The significant effect of maize (Zea mays L.) growth stage on soil MB and enzyme activities accounted for 58 and 84% of their total variation, respectively. In comparison, B-HA accounted for 8% of the total variability for each of the same two variables. B-HA significantly enhanced soil properties and the uptake of N and P by maize in semi-arid areas. The use of B-HA product would be an effective management strategy to reclaim degraded sandy soils and foster sustainable agriculture production in northeast China and regions of the world with similar soils and climate.

Oasis and desert are the dominant landscapes in arid and semi-arid regions, especially in northwestern China where the oasis-desert evolution mechanisms are important for understanding modern surface processes and future environmental evolution of the region. Nevertheless, the response of the physicochemical indicators of surface sediments to oasis-desert evolution is poorly studied and it is unclear how reliable these indicators are for paleoenvironmental reconstruction. A spatio-temporal approach consisting of measurements of surface-sediment grain-size, nutrient contents and elemental ratios was used to characterize a series of modern stages of oasis-desert evolution in the Taklimakan desert. The applicability of the indicators to two sequences of alternating fluviolacustrine-wetland and aeolian sand deposits in the same region was evaluated. The results show that the oasis sediments are characterized by high contents of fine-grained particle (End-Member 1, EM1), TOC (Total organic Carbon), TN (Total Nitrogen), and MgO/SiO2, and low values of the eluvial coefficient (SiO2/(MgO + CaO + K2O + Na2O)). By contrast, the desert sediments are characterized by high values of coarse-grained particle (End-Member 3, EM3), low soil nutrients and MgO/SiO2, and an increased eluvial coefficient. In the two sedimentary sections, the physicochemical properties of the clay-silt layers resemble those of modern oasis sediments, especially washland, and the properties of the interbedded aeolian sand resemble those of modern desert deposits. The observed co-variation of grain size, soil nutrients and geochemical ratios of the surface samples shows that our approach can be used to determine the trends of past oasis-desert evolution. The reconstruction suggests that oasis formation largely depended on the development of a fluviolacustrine-wetland environment, whereas oasis degradation was closely related to strong aeolian activity. The findings provide new insights into the selection of appropriate indicators for analyzing oasis-desert sediments and for reconstructing the evolution of oasis-desert landscapes.