Search Results (29)

Despite Qatar’s depressions being ecologically significant for biodiversity in arid desert regions, they remain poorly studied. This study aimed at assessing the floristic diversity of Qatar’s depression habitat and examining the key environmental drivers shaping vegetation patterns. We applied multivariate analyses, including Canonical Correspondence Analysis (CCA) and Two-Way Indicator Species Analysis (TWINSPAN), to understand the environmental factors that shape vegetation communities and classify the depression sites. A total of 139 plant species from 35 families were recorded from 26 depression sites across Qatar. Both therophytes and chamaephytes were the dominant life forms. Biregional chorotypes were the most prevalent among phytogeographical groups. CCA indicated that grazing pressure, latitude, nitrogen concentration, clay content, and soil pH were among the variables that influenced the vegetation patterns of depressions, while longitude and soil carbon content showed marginal significance in explaining the observed floristic variation. TWINSPAN classified the sites into four distinct clusters, each associated with specific indicator species and habitat conditions. Northern depressions supported higher species richness compared to central and southern depressions, which are dominated by sandy soils and experience intensive grazing patterns that reduce the floristic diversity and limited regeneration of key shrubs such as Vachellia tortilis (Forssk.) Galasso & Banfi. This study helps fill a critical knowledge gap about Qatar’s depression habitat, enhancing efforts to conserve these vulnerable ecosystems, identify ecological threats, and better understand patterns of species distribution across arid landscapes. Full article

Irish potato (Solanum tuberosum) is a critical crop for food security and economic growth in Tsangano and Angónia Districts, Central Mozambique. Challenges like inconsistent yields and variable quality are often linked to suboptimal soil conditions, which limit production. This study aimed to classify and evaluate the suitability of soils for potato cultivation in Tete Province, where detailed soil assessments remain limited. Four pedons—TSA-P01 and TSA-P02 in Tsangano and ANGO-P01 and ANGO-P02 in Angónia—were examined for bulk density, texture, pH, organic carbon, and nutrient content using a combination of pedological methods and laboratory soil analysis. To determine each site’s potential for growing Irish potatoes, these factors were compared to predetermined land suitability standards. The pedons were very deep (>150 cm) and had textures ranging from sandy clay loam to sandy loam. TSA-P02 had the lowest bulk density (0.78 Mg m⁻³) and the highest available water capacity (182.0 mm m⁻¹). The soil pH ranged from 5.6 to 7.9, indicating neutral to slightly acidic conditions. Nutrient analysis revealed low total nitrogen (0.12–0.22%), varying soil organic carbon (0.16–2.73%), and cation exchange capacity (10.1–11.33 cmol⁽⁺⁾ kg⁻¹). Pedons TSA-P01, ANGO-P1, and ANGO-P02 were characterized by eluviation and illuviation as dominant pedogenic processes, while in pedon TSA-P02, shrinking and swelling were the dominant pedogenic processes. Weathering indices identified ANGO-P01 as most highly weathered, while TSA-P02 was least weathered and had better fertility indicators. According to USDA Taxonomy, the soils were classified as Ultisols, Vertisols, and Alfisols, corresponding to Acrisols, Alisols, Vertisols, and Luvisols in the WRB for Soil Resources. All studied soils were marginally suitable for potato production (S3f) due to dominant fertility constraints, but with varying minor limitations in climate, topography, and soil physical properties. The findings hence recommended targeted soil fertility management to enhance productivity and sustainability in potato cultivation. Full article

Energy absorption capacity (EAC) is a parameter that expresses how much energy materials can store or dissipate under an external load or impact. EAC plays a critical role in understanding soil deformations and dynamic stability under impact loads (e.g., falling masses, projectile penetration, blast impacts, or vehicle collisions). Impact loads are sudden and high-accelerated forces that cause soils to deform rapidly and absorb energy differently. Understanding the EAC of soils under impact loads is critical for various geotechnical applications, particularly understanding soil behavior under blast loads, which is critical for military and civil structures, and the reinforcement of soils and design of protective structures that will be subjected to similar sudden impacts. This study aims to develop a novel experimental method and apparatus to evaluate the EAC of sandy soils under controlled laboratory conditions. A custom-designed test device was used to measure impact forces exerted by a metal sphere dropped from a fixed height onto soil samples with varying grain sizes (coarse, medium, and fine) and relative densities (40%, 70%, and 90%) under different moisture conditions (dry, optimum, and wet). The results showed that fine-grained sands exhibited the highest EAC, with absorbed energy values reaching 23.15 J, while coarse-grained sands under dense and saturated conditions exhibited the lowest capacity (22.05 J). An increase in moisture content from dry water content to optimum water content resulted in a moderate increase in energy absorption followed by a slight decrease under saturated conditions. Similarly, higher relative density marginally reduced energy absorption, reflecting reduced soil deformation at higher densities. The study introduces a potentially standardizable testing procedure for assessing soil impact response, providing valuable insights for geotechnical engineering applications, including soil stabilization, pavement design, and impact-resistant infrastructure. Full article

Water and N availability are key factors limiting crop yield, particularly in marginal soils. This study evaluated the effects of water and N stress on barley grown in marginal soils using field trials and the AgroC model. Experiments from 2020 to 2022 in Lithuania with spring barley cv. KWS Fantex under two N fertilization treatments on sandy soil provided data for model parameterization. The AgroC model simulated barley growth to assess yield potential and yield gaps due to water and N stress. Potential grain yields (assuming no water or N stress) ranged from 4.8 to 6.02 t DW ha⁻¹, with yield losses up to 54.4% assuming only N stress and 59.2% assuming only water stress, even with the N100 treatment (100 kg N ha⁻¹ yr⁻¹). A synthetic case study varying N fertilization from 0 to 200 kg N ha⁻¹ yr⁻¹ showed that increasing N still enhanced yield, but the optimal rate of 100–120 kg N ha⁻¹ yr⁻¹ depended on climatic conditions, leading to uncertainty in fertilization recommendations. This study underscores the importance of integrating advanced modeling techniques with sustainable agricultural practices to boost yield potential and resilience in marginal soils. Incorporating remote sensing data to capture soil and crop variability is recommended for improving simulation accuracy, contributing to sustainable agriculture strategies in the Baltic–Nordic region. Full article

The relevant value standards for reserved deformation of tunnels with different types of loess soil are not yet perfect. Through mathematical statistics, literature research, and other methods, 148 monitoring sections of loess tunnels with different soil types were investigated. Pearson, Kendall, and Spearman correlation coefficients were used to analyze the influence of surrounding rock grade, moisture content, and burial depth on the deformation law of tunnels, providing reference for the value of reserved deformation for loess tunnels. The research results indicate that: (1) The correlation between soil type and convergence around the tunnel is strong, followed by excavation span, and the correlation between moisture content and burial depth is weak. Therefore, the design of reserved deformation should focus on considering the soil type and excavation span. (2) For loess tunnel sections with class IV surrounding rock, the deformation allowance for cohesive loess and silty loess tunnel sections can be set within 15 cm, and for sandy loess, it can be set within 15–20 cm. (3) For the loess tunnel section with V-grade surrounding rock, the deformation margin can be determined as follows: viscous loess within 15–20 cm, silty loess within 15 cm, and sandy loess within 35–47.5 cm. (4) The moisture content is mainly distributed between 11% and 23%. It is worth noting that in sandy loess sections, the influence of moisture content on tunnel arch settlement is more significant compared to cohesive loess and silty loess sections. (5) The settlement of the arch crown is affected by changes in coverage depth and has discreteness. When the deformation margin is set to 16 cm, the assurance rate can reach 84.6%. Finally, the rationality of the proposed reserved deformation amount was verified through engineering practice. The research results can provide reference for related similar projects. Full article

Current research on soil–structure interface properties mainly focuses on sand, clay, and silt, with little attention given to sandy gravel. In order to study the effects of relative density and interface materials on the shear behavior of the sandy gravel–structure interface, a series of large-scale direct shear tests on sandy gravel were carried out, and stress–strain relationships, volume change curves, and shear strengths were investigated. The results show that the angle of internal friction of sandy gravel increases linearly with relative density (R² is 0.998), from 43.0° to 48.0° when the relative density increases from 0.3 to 0.9. The growth trend of cohesion increases, the shear behavior transitions from strain hardening to strain softening, and the shear strength increases linearly with the increase in relative density. The interfacial shear strengths and interface adhesion of sandy gravel with steel and concrete interfaces increase linearly with relative density, and the shear curves are strain hardening. Furthermore, the interface friction angle of concrete increases linearly with relative density (R² is 0.985), from 30.2° to 34.2°, while the interface friction angle of the steel interface remains relatively constant around 28.9°. Finally, relative density was introduced into the Mohr–Coulomb shear strength formula, and the relationship equations of relative density and normal pressure with the shear strength and interfacial shear strength of sandy gravel were established. The validation results show that the error margin of the formula is within 4%. This formula can be used to evaluate changes in the mechanical properties of sandy gravel formations and the bearing capacity of pile foundations after they have been disturbed by factors such as construction. Full article

The Zayandeh-Rud watershed of Iran has had water scarcity for decades, giving rise to pressures toward limiting water allocation for the agriculture sector. Marginal waters can be an alternative source for irrigated agriculture in water-scarce regions if adequately managed. One of the critical hazards for sustainable agriculture and the environment is the accumulated salinity–sodicity problem as a consequence of irrigating with unconventional waters. Applying additional water beyond the crop water requirement, known as leaching application, has been suggested as a solution to this problem. A physical model was built to investigate the effects of the severe sodicity and salinity conditions of irrigation water by creating 250 mm diameter soil columns (27 columns) filled with sandy clay loam soil. The severity of the irrigation water’s sodicity (sodium adsorption ratios (SAR): 5.27, 16.56, and 28.57) and its interactions with various leaching fractions (0%, 15%, and 30%) on critical soil chemical characteristics and corn yield were studied. Implementing a 30% leaching fraction reduced the SAR and salinity in the soil’s first layer (0–10 cm) when irrigating with saline–hyper-sodic water (SAR = 28.57 and ECiw = 9 dS/m). However, an elevated level of sodicity accumulation in the soil profile was observed, emphasizing the importance of adding calcium and magnesium amendments during the irrigation season. A noticeable increase in the efficiency of leaching applications in reducing accumulated salts and the sodicity level in the corn rootzone was detected with higher levels of irrigation water sodicity. The reduction in the accumulated salinity and sodium in the first soil layer due to implementing a 30% leaching fraction resulted in a 223.3% increase in the total biomass of silage corn. Applying a 30% leaching fraction also increased the corn biomass by 58% and 114.56% when irrigating with waters with 5.57 and 16.56 SAR values. The effectiveness of a 15% leaching fraction for enhancing the soil and crop conditions was significantly lower than that of the 30% leaching fraction. Nevertheless, in case of unavailability of sufficient water supply for irrigation purposes, applying a 15% leaching fraction could mitigate the consequences of sodic water irrigation. The results demonstrate that in the absence of the proper calcium amendments, the implementation of leaching management could still be effective in enhancing corn production under sodic water irrigation conditions. Full article

Cassava is a root storage crop that is important to the starch industry and food security. In this study, the sustainable fertilization of cassava using local placement of struvite, a fertilizer recovered from wastewater, rich in nitrogen, phosphorus, and magnesium, was investigated. It was asked if struvite is a suitable fertilizer for cassava, if it is likely to spread through the substrate (leach), and if roots can proliferate and utilize a concentrated placement of struvite. Cassava was grown in rhizoboxes under different fertilizer placement strategies: unfertilized control, homogeneous fertilizer distribution in the top 20 cm (‘homogenized’), a strip placement (‘layer’) at 20 cm depth, and a localized ‘depot’ at the same depth. Shoot and root growth responses were monitored over 8 weeks. Cassava growth was significantly improved with struvite fertilization. The fertilizer remained localized, with minimcnal spread during the 8 weeks of experimentation. Both the ‘layer’ and ‘homogenized’ struvite placements resulted in comparable biomass production, significantly greater than the unfertilized treatment. Plants in the ‘depot’ placement initially grew similar to the unfertilized treatment as roots took time to locate and proliferate into the fertilizer depot. Afterward, plants in the ‘depot’ treatment grew quickly, resulting in an intermediate biomass at harvest. Notably, cassava exhibited strong root proliferation in response to concentrated struvite, which did not compromise deep rooting but instead appeared to enhance it, increasing specific root length. These findings suggest that strip fertilization with struvite may offer a sustainable fertilization strategy for cassava, warranting further investigation in field trials. Full article

The cultivation of perennial flowering wild plant species like common tansy (Tanacetum vulgare L.) seems promising for increasing biodiversity friendliness in rather monotonous bioenergy cropping systems in Central Europe, particularly on marginal sites. However, it is still unclear for which types of marginal agricultural land common tansy would be suitable and where; as a result, low-risk indirect land-use change biomass production through common tansy could be considered. Therefore, the aim of this study was to gather initial insights into the suitability of common tansy for sandy sites by means of a 6 L-pot experiment. For this purpose, five replicates of three substrates were prepared: Luvisol topsoil (control) from a field site near the University of Hohenheim, Germany; and admixtures of 50 and 83.4weight(wt)% of sand to the control (M1, and M2), respectively. This resulted in varying sand contents of the substrates of 4.7 (control), 53.3 (M1), and 83.0wt% (M2). In autumn 2021, common tansy seeds were collected from mother plants bearing the breeder’s indentifier ‘Z.8TAV 85/78’. These plants were part of a long-term field trial initiated at Hohenheim in 2014, where common tansy was grown as part of a wild plant mixture. In June 2022, 0.5 g of the seeds were sown in each pot. The pots were placed in outdoor conditions, arranged in a randomized complete block design and watered evenly as required. At harvest in July 2023, significant differences between the substrates in terms of the above- (shoots) and belowground (roots) development of the common tansy seedlings were observed. In M1, common tansy provided notable biomass growth of 56.6% of the control, proving to be potentially suitable for low-input cultivation under sandy soil conditions. However, an even higher share of sand and low nutrient contents in M2 resulted in minor plant development (14.4% of the control). Hence, field trials on sandy soils of about 50wt% of sand in the texture under tailored fertilization and various climatic conditions are recommended. Full article

The cultivation of tiger nut (Cyperus esculentus L.) on marginal lands is a feasible and effective way to increase food production in Northern China. However, the specific influence of nitrogen fertilizer application on the growth dynamics, tuber expansion, overall yield, and nitrogen use efficiency (NUE) of tiger nuts cultivated on these sandy lands is yet to be fully elucidated. From 2021 to 2022, we conducted a study to determine the effect of N fertilizers on the leaf function morphology, canopy apparent photosynthesis (CAP), tuber yield, and NUE of tiger nut. The results indicate that the tuber yield and NUE are closely related to the specific leaf area (SLA), leaf area index (LAI), leaf nitrogen concentration per area (N_A), CAP, and tuber expansion characteristics. Notably, significant enhancements in the SLA, LAI, N_A, and CAP during the tuber expansion phase ranging from the 15th to the 45th day under the 300 kg N ha⁻¹ treatment were observed, subsequently leading to increases in both the tuber yield and NUE. Moreover, a maximum average tuber filling rate was obtained under the N300 treatment. These improvements led to substantial increases in the tuber yield (32.1–35.5%), nitrogen agronomic efficiency (NAE, 2.1–5.3%), nitrogen partial factor productivity (NPP, 4.8–8.1%), and nitrogen recovery efficiency (NRE, 3.4–5.7%). Consequently, 300 kg N ha⁻¹ of N fertilizers is the most effective dose for optimizing both the yield of tiger nut tubers and the NUE of tiger nut plants in marginal soils. Structural equation modeling reveals that N application affects the yield and NUE through its effects on leaf functional traits, the CAP, and the tuber filling characteristics. Modeling indicates that tuber expansion characteristics primarily impact the yield, while CAP predominantly governs the NUE. Above all, this study highlights the crucial role of N fertilizer in maximizing the tiger nut tuber yield potential on marginal lands, providing valuable insights into sustainable farming in dry areas. Full article

Sustainable fruit orchard development in arid areas is severely affected by the scarcity of fresh water. To mitigate the lack of fresh water, the use of low-quality water for irrigation is becoming a common practice in several margin areas. However, salinity is considered one of the most important environmental constraints limiting the successful crop production. Therefore, the effects of deficit irrigation strategies using saline water (3.1 dS m⁻¹) on soil water content, soil salinity, and yield of commercial peach orchard were investigated. Three irrigation treatments were considered: a Control, full irrigated (FI); and partial root-zone drying (PRD₅₀); and deficit irrigation (DI) strategies irrigated at 50% ETc. These levels of water supply allowed for contrasting watering conditions with clear distinction between irrigation treatments. The differential pattern in soil moisture was accompanied by that of soil salinity with an increase in all FI treatments (16–25%). The results indicated that soil salinity increased with increasing water supply and evaporative demand during the growing season from January (3.2 dS m⁻¹) to August (6.6 dS m⁻¹). Deficit irrigation strategies (DI, PRD₅₀) induced more soil salinity along the row emitter compared to the Control due to insufficient leaching fractions. By the end of the growing season, the soil salinity under long-term saline drip irrigation remained stable (5.3–5.7 dS m⁻¹). An efficient leaching action seemed to be guaranteed by rainfall and facilitated by sandy soil texture, as well as the high evaporative demand and the important salt quantity supplied, which maintain the deficit irrigation strategies as valuable tools for water saving and improving water productivity. The significant water saving of 50% of water requirements induced a fruit yield loss of 20%. For this reason, DI and PRD₅₀ could be reasonable irrigation management tools for saving water and controlling soil salinity in arid areas and on deep sandy soil. Full article

Efficient water management is crucial for sustainable agriculture and water resource conservation, particularly in water-scarce regions. This study investigated the effect of different irrigation depths on onion (Allium cepa L.) yield and water use patterns in a semi-arid tropical region of Colombia, using a completely randomized design with five treatments. The treatments ranged from 0–100% of total available water (TAW), T1 (100% of TAW), T2 (80% of TAW), T3 (60% of TAW), T4 (40% of TAW), and T5 (20% of TAW). The experiment was conducted in a greenhouse during one growing season (2022–2023). The normalized water productivity (WP *), irrigation water productivity (IWP), consumptive water productivity, blue water footprint (WF_blue), marginal water use efficiency (MWUE), and elasticity of water productivity (EWP), as well as some parameters of quality onion, were determined. The soil in the experimental field was classified as sandy loam; the results show that the WP * of onion is 17.42 g m⁻², the water production function shows the maximum production will be achieved at a water application depth of approximately 943 mm, and beyond that, the biomass yield will decrease with additional water application, IWP values for onion ranged from 2.18 to 3.42 kg m⁻³, the highest Wf_blue was in T5 (34.10 m³ t⁻¹), and low Wf_blue was T1 (20.95 m³ t⁻¹). In terms of quality, treatment T1 had the most favorable effects on bulb weight, polar diameter, and equatorial diameter, while treatment T5 had the least favorable effects. The study highlights the importance of efficient irrigation on sandy loam soils to maximize yield and water use efficiency. It provides valuable data for evaluating the potential yield benefits of precision irrigation in the study area. Optimizing irrigation depth can significantly improve onion yield and water use efficiency in semi-arid regions. Full article

Soil erosion results in land degradation and desertification in northern China. The Xilingol League of Inner Mongolia is an important part of the “Two Barriers and Three Belts”, and has been given the main function of “a windbreak and sand-fixing belt of northern China”. Accurate measuring of soil erosion moduli, analyzing the differences in soil erosion moduli across different periods and regions, are the basis for carrying out soil conservation and evaluating the effectiveness of ecological governance. Some radioisotopes are good environmental tracers because they are closely combined with the fine particles of the surface soil and are only affected by the mechanical movement of soil particles. In this paper, Taipusi Banner and Zhengxiangbai Banner, which are in the farming–pastoral ecotone in northern China, were selected as the study area. A regional reference inventory, that is, the activity of ¹³⁷Cs and ²¹⁰Pb_ex in the sample without any soil erosion, accumulation/deposition, or any kind of manual disturbances, as well as the soil erosion moduli, were determined by ¹³⁷Cs and ²¹⁰Pb_ex composite tracing technology and multiple lines of evidence. The results are as follows: (1) The regional ¹³⁷Cs reference inventory was 1928 Bq∙m⁻², and the regional ²¹⁰Pb_ex reference inventory was 10,041 Bq∙m⁻². (2) On a 50-year time scale, the soil erosion moduli in the study area ranged from 140 t∙km⁻²∙a⁻¹ to 1030 t∙km⁻²∙a⁻¹; on a 100-year scale, the soil erosion moduli in the study area ranged from 35 t∙km⁻²∙a⁻¹ to 2637 t∙km⁻²∙a⁻¹; the entire study area was in a lightly eroded state. (3) Compared with two periods before and after the 1970s, the southern parts (cultivated land and grassland) experienced an increasing trend in soil erosion moduli due to land reclamation, grassland grazing, and other activities. Due to weakening wind and increasing precipitation, soil erosion moduli in the northern parts (southern margin of the Hunshandake Sandy Land) slowed down. The study also discussed the uncertainty and application potential of isotope-tracing technology in sandy land of typical grasslands in northern China. Full article

Crops and ecosystems constantly change, and risks are derived from heavy rains, hurricanes, droughts, human activities, climate change, etc. This has caused additional damages with economic and social impacts. Natural phenomena have caused the loss of crop areas, which endangers food security, destruction of the habitat of species of flora and fauna, and flooding of populations, among others. To help in the solution, it is necessary to develop strategies that maximize agricultural production as well as reduce land wear, environmental impact, and contamination of water resources. The generation of crop and land-use maps is advantageous for identifying suitable crop areas and collecting precise information about the produce. In this work, a strategy is proposed to identify and map sorghum and corn crops as well as land use and land cover. Our approach uses Sentinel-2 satellite images, spectral indices for the phenological detection of vegetation and water bodies, and automatic learning methods: support vector machine, random forest, and classification and regression trees. The study area is a tropical agricultural area with water bodies located in southeastern Mexico. The study was carried out from 2017 to 2019, and considering the climate and growing seasons of the site, two seasons were created for each year. Land use was identified as: water bodies, land in recovery, urban areas, sandy areas, and tropical rainforest. The results in overall accuracy were: 0.99% for the support vector machine, 0.95% for the random forest, and 0.92% for classification and regression trees. The kappa index was: 0.99% for the support vector machine, 0.97% for the random forest, and 0.94% for classification and regression trees. The support vector machine obtained the lowest percentage of false positives and margin of error. It also acquired better results in the classification of soil types and identification of crops. Full article

Land degradation induced by soil erosion is widespread in semiarid regions globally and is common in the agro–pastoral ecotone of northern China. Most researchers identify soil erosion by wind and water as independent processes, and there is a lack of research regarding the relative contributions of wind and water erosion and the interactions between them in what is referred to here as compound soil erosion (CSE). CSE may occur in situations where wind more effectively erodes a surface already subject to water erosion, where rainfall impacts a surface previously exposed by wind erosion, or where material already deposited by wind is subject to water erosion. In this paper, we use the Chinese Soil Loss Equation (CSLE) and the Revised Wind Erosion Equation (RWEQ) to calculate the rate of soil erosion and map the distribution of three types of soil erosion classified as (i) wind (wind-erod), (ii) water (water-erod), and (iii) CSE (CSE-erod) for the study area that spans more than 400,000 km² of sand- and loess-covered northern China. According to minimum threshold values for mild erosion, we identify water-erod, wind-erod, and CSE-erod land as occurring across 41.41%, 13.39%, and 27.69% of the total area, while mean soil erosion rates for water-erod, wind-erod, and CSE-erod land were calculated as 6877.65 t km⁻² yr⁻¹, 1481.47 t km⁻² yr⁻¹, and 5989.49 t km⁻² yr⁻¹, respectively. Land subject to CSE-erod is predominantly distributed around the margins of those areas that experience wind erosion and water erosion independently. The CSLE and RWEQ do not facilitate a direct assessment of the interactions between wind and water erosion, so we use these equations here only to derive estimates of the relative contributions of wind erosion and water erosion to total soil erosion and the actual mechanisms controlling the interactions between wind and water erosion require further field investigation. It is concluded that CSE is an important but underappreciated process in semiarid regions and needs to be accounted for in land degradation assessments as it has substantial impacts on agricultural productivity and sustainable development in regions with sandy and/or loess-covered surfaces. Full article