Soils Of Arid Regions Research Articles

Molecular and morphological assessment of the Liopholis inornata (Rosén, 1905) species group (Reptilia: Squamata: Scincidae), with descriptions of two new species from northern Western Australia

Molecular genetic and morphological assessments were undertaken on the Liopholis inornata species group of skinks that occur on sandy soils in both mesic and arid regions of Australia. The primary objective was the taxonomic identification of two outlying peripheral populations from the North-West Cape and Purnululu National Park, in northern Western Australia. To provide adequate context, molecular genetic and morphometric variation was assessed across the wide geographic range of L. inornata, a taxon that is strongly phylogeographically structured. It was also necessary to reassess the taxonomic identity of two previously named taxa from central Australia, L. s. slateri (Storr) and L. s. virgata (Storr). Phylogenetic analyses of nuclear SNPs from extant populations confirm that L. inornata, L. s. slateri and the two outlying populations from northern Western Australia are each distinct evolutionary lineages. Prior to analyses of the extent of morphological divergence between the lineages, we assessed the extent of morphometric differences between the sexes using two well-sampled species, L. inornata and L. striata (Sternfeld) from Western Australian populations. We determined that while males have relatively longer, wider and deeper heads throughout life these differences are relatively slight and the data from both sexes could be pooled for subsequent morphological interspecific comparisons. The two outlying populations are distinguished from congeners based on phylogenetic relationships and divergence in nuclear nucleotide sequences and distinctive morphometric and colour attributes and thus represent new species. The new species both occur in biogeographically significant areas that contain several other endemic reptile species. Liopholis s. virgata, for which we currently lack genetic data, is morphometrically and chromatically different from all the other taxa and very likely represents a distinct species that is potentially extinct as it has not been sighted for more than a century.

Evidence of Mycorrhizal Fungi Associated with Arid and Semi-arid Steppe Plants

Background: The soils of arid regions, especially steppe areas, are generally poor. Despite these challenging conditions, steppe plants manage to establish and adapt. The mycorrhizal symbiotic association has a crucial role in the nutrition and stress resistance of these plants. The present research aims to identify mycorrhizal fungi in three perennial plants native to the Algerian steppe: Aristida pungens, Retama raetam and Astragalus armatus. Methods: We took soil samples under and outside vegetation, along with corresponding roots for each plant tested and covering an air of 206 km. Result: The results varied among the three species: the rhizospheric soil under A. Pungenshad a moisture content of 5.28%, an organic matter content of 1.38%, a glomalin level of 2.83 mg/g of soil and the number of spores of 461.66 spores per 100 g of soil. In addition, soil under R. raetam gave more information on pH (8.13) and an EC of 0.12 ms/cm. and for A. armatus, its abundance was linked to a CaCO3 level of 9.79%. We recorded a positive correlation of glomalin with spore count and soil moisture. All three plants studied exhibited a high rate of mycorrhization exceeding 70%, with A. Armatushaving the highest averages

Contamination characteristics of heavy metals and enrichment capacity of native plants in soils around typical coal mining areas in Gansu, China

Exploitation of mineral resources is a vital backbone of a country’s socio-economic development. However, the coal exploration would cause ecological and environmental problems such as pollutions of water, soils and atmosphere. Especially, the pollution of heavy metals of soil has become increasingly severity. Plant enrichment and tolerance to heavy metals are crucial for the phytoremediation of coal gangue mountain. In phytoremediation, phytostabilization which can reduce the metal contamination of soil by uptake and burn-off of heavy metals with highly accumulating plants, is one of the most effective techniques of eco-remediation treatment. In present work, heavy metals contamination of soil and plants in the Yaojie mining which located in arid and semi-arid area of northwest China were investigated through field investigation. To identify the suitable plants for the remediation and ecological reclamation of heavy metal contaminated soil in typical mining area, the contamination characteristics of heavy metals in the above-ground parts of 27 native plants and their surrounding non-rhizosphere soils were analyzed. After eliminated by wet digestion and high-pressure closed digestion, the mass fractions of Zinc (Zn), cadmium (Cd), chromium (Cr) and copper (Cu) were determined with inductively coupled plasma emission spectrometer, and the contents of Hydrargyrum (Hg) and Arsenic (As) were analyzed with atomic fluorescence spectrophotometer. The Nemerow pollution index showed that in the surrounding soil, the pollution index of heavy metal was 6.32, which reached the extreme severe pollution level. Among the 6 heavy metals, the most severe contamination being Hg (Pi = 8.50) and had particularly strong Coefficient of variation (CV = 105.8%), which is more likely to be caused by anthropogenic activities. In the aboveground parts of 27 plants, except for Zn, other metals exceeded the standard level, and the exceedance rates in descending order were As, Hg, Cr, Cd, and Cu. The most severe exceedance of As was found in C. virgata, which was as high as 19.20, and the average exceedance rate of As in all plants was 2.79. Bioconcentration Factor (BCF) was utilized as an indicator of the enrichments of various metals in 27 plants. The maximum value of BCF for As and Hg in C. virgata were 1.52 and 2.50, Cr and Cu in X. sibiricum were 0.72 and 2.32, Cd and Zn in S. glauca were 3.33 and 1.82. As revealed, except Cr, all the BCF of other metals are greater than 1, indicating that the three plants exhibited a strong accumulation capacity of heavy metal and are potential candidate pioneer species for the removal of heavy metals from the contaminated soil in the Yaojie mining area. This study provides a basis for plant selection for ecological restoration of contaminated soils in arid and semi-arid regions.

Response of Typical Shrubs Growth and Soil Nutrients to Graphene Addition in Impoverished Land of the Ulan Buh Desert.

Graphene can promote plant growth and improve soil conditions, but its effectiveness in enhancing infertile soils in arid regions remains unclear. This study selected three typical shrubs from the Ulan Buh Desert Nitraria tangutorum, Xanthoceras sorbifolium, and Amygdalus mongolica as research subjects. Five graphene addition levels were set: 0 mg/L (C0), 25 mg/L (C1), 50 mg/L (C2), 100 mg/L (C3), and 200 mg/L (C4).A pot experiment was conducted in June 2023 to investigate the effects of graphene addition on shrub growth and soil nutrients. The results showed that the optimal graphene addition levels for A. mongolica, X. sorbifolium, and N. tangutorum were C2, C2, and C3, respectively. Compared with the control, the total biomass of the different shrubs increased by 185.31%, 50.86%, and 161.10%, respectively. However, when the graphene addition exceeded the optimal level, shrub biomass showed a decreasing trend with increasing graphene concentration. Total shrub biomass was positively correlated with soil available nitrogen and potassium, while redundancy analysis indicated that soil organic matter was the primary factor influencing shrub growth. This suggests that graphene promotes shrub growth by affecting soil organic matter and available nutrients. Therefore, graphene addition can enhance soil fertility in barren lands in arid regions and significantly promote shrub growth. However, due to soil leaching effects, this growth-promoting effect may decrease over time.

Reclamation and Improvement of Saline Soils Using Organo–Mineral–Natural Resources, Treated Saline Water, and Drip Irrigation Technology

Reclamation and management of saline soil in arid regions fundamentally require more consideration to attain sustainable agriculture. Experiments were conducted at Abo-Kalam Farm, South Sinai, Egypt. Split-split-plot design experiments were carried out to study the effect of treatments on saline soil hydrophysical properties, sorghum, and cv. ‘Dorado’ plants during the summer season. Pea cv. ‘Entsar 3’ plants were cultivated during the winter season for the residual effect of treatments. Organo–mineral amendment (rice straw compost + mineral sulfur at different rates) was assigned as the main factor, natural rock or artificial fertilizers were assigned as subfactors, and humic acid at different rates was the sub-subfactor. Results showed that organo–mineral amendments improved the hydrophysical properties of the soil, plant nutrient uptake, crop yield, and crop water productivity; however, it diminished by 10 tons/fed (4200 m2) of compost plus 700 kg/fed of mineral sulfur. Therefore, it is recommended that economically using the combination of applying organic–mineral amendments of 4 tons/fed of compost plus 400 kg/fed of mineral sulfur and 5 kg/fed of humic acid plus natural rock fertilizer is the best safe management for reclamation and improvement of saline soils using partially treated saline irrigation water and natural resources.

The Process of Soil Carbon Sequestration in Different Ecological Zones of Qingtu Lake in the Arid-Semi-Arid Region of Western China.

As a vital component of the global carbon pool, soils in arid and semi-arid regions play a significant role in carbon sequestration. In the context of global warming, increasing temperatures and moisture levels promote the transformation of barren land into wetlands, enhancing carbon sinks. However, the overdevelopment of oases and excessive extraction of groundwater lead to the opposite effect, reducing carbon sequestration. This study examines two soil types-meadow soil (MS) and swamp soil (SS)-from Qingtu Lake, an arid lake in western China. It analyzes the sources of soil inorganic carbon, the composition and origin of dissolved organic matter (DOM), and the relationships between microbes, soil organic carbon (SOC), soil inorganic carbon (SIC), mineral composition, and soil texture. The results indicate that inorganic carbon in the study area consists of both primary carbonate minerals and secondary pedogenic carbonates. The DOM primarily consists of two components, both identified as terrestrial humic substances. In meadow soils, bacterial activity drives the weathering of plagioclase, which releases Ca2+ necessary for the formation of pedogenic carbonates. Plagioclase also provides colonization sites for microbes and, along with microbial activity, participates in the soil carbon cycle. Within the soil community, bacteria appear to play a more critical role than fungi. In contrast, microbial contributions to the carbon cycle in swamp soils are weaker, with minerals predominantly interacting with organic carbon to form mineral-associated organic matter, thus promoting the soil carbon cycle. These findings have important implications for understanding soil carbon sinks under different micro-ecological conditions in arid and semi-arid regions. Through targeted human intervention, it is possible to enhance carbon sequestration in these areas, contributing to the mitigation of global climate change.

Phytoremediation of saline soils using Glycyrrhiza glabra for enhanced soil fertility in arid regions of South Kazakhstan

This study investigates the potential of Glycyrrhiza glabra (licorice) as a biological tool for reclaiming saline soils in the arid regions of South Kazakhstan. Licorice was cultivated over three growing seasons in weakly, moderately, and highly saline soils to evaluate its effectiveness in reducing soil salinity and improving soil fertility. The results show that licorice cultivation significantly reduced total salt concentrations and improved organic matter content in weakly saline soils. For instance, in some areas, total salts decreased by 50%, and humus content increased from 1.55% to 1.70%, indicating enhanced soil fertility. In moderately saline soils, the reduction in salt levels was less significant, and the plant's biomass yield dropped to 40 t/ha, compared to 50 t/ha in weakly saline soils. However, licorice still demonstrated its ability to moderately improve soil structure and nutrient availability. In strongly saline soils, licorice's effectiveness was considerably limited, with only minor reductions in salinity and a significant decrease in biomass yield to 20-30 t/ha. The study concludes that while Glycyrrhiza glabra is highly effective in reclaiming weakly saline soils, its impact in moderately and highly saline soils requires supplemental interventions, such as leaching, to optimize its phytoremediation potential. These findings suggest that integrating biological and traditional soil reclamation methods can offer a sustainable solution for managing saline soils in arid regions.

Assessment of Activated Charcoal and Phosphorus for Promoting Maize Production

The most continuous farming practice is the yearly addition of phosphorus fertilizers to soils in arid and semi-arid regions that all suffer from shortages of phosphorus availability. A vital approach is rationalizing applied fertilizers and trying to benefit from their reservoir in yearly-fertilized old soils using an activated charcoal-fertilizer mixture. Thus, a field experiment was conducted at a private farm in Mushtuhur, Toukh, Qalyubia Governorate, Egypt. This trial was set up to study the effect of phosphorus (P) fertilizer sources (phosphoric acid Ph.A and super phosphate S.Ph), the P application rates (P0=control, P1=50%, P2=75% and P3=100% of P requirements), activated charcoal (A.Ch) rates (A.Ch0=control, A.Ch1=1, A.Ch2=3 and A.Ch3=5 g/hole, corresponding to 41, 124, and 207 kg ha-1, respectively) and the interaction between them on promoting maize growth, production and its nutrient status. Generally, adding phosphorus improved plant height (m), dry grains (t ha-1), and ash yield (t ha-1) without a significant difference between all P rates. Phosphoric acid affects most studied parameters, mainly the biological, ear, and ash yield (t ha-1); it was the best compared with superphosphate. Adding the 1st rate of A.Ch improved the studied growth and yield parameters significantly compared with the control. Slight enhancement was induced by the 2nd A.Ch dose, and there was no significant difference between the 3rd and 4th rates in most studied parameters. The heighest value of grain yield resulted from the third interaction between A. Ch3 x P0, followed by A. Ch2 x P0, and the next is Ph.A x A. Ch2 x P1 without significant difference among them. These results shed light on the fact that there is no need to add P fertilizers yearly, as described by the recommendations of the Ministry of Agriculture. Different materials can move the fixed P in old clayey soil, such as A.Ch.

Effects of Organic Fertilizer and Biochar on Carbon Release and Microbial Communities in Saline–Alkaline Soil

Climate change and aridification have increased the risk of salinization and organic carbon loss in dryland soils. Enrichment using biochar and organic fertilizers has the potential to reduce salt toxicity and soil carbon loss. However, the effects of biochar and organic fertilizers on CO2 and CH4 emissions from saline soils in dryland areas, as well as their microbial mechanisms, remain unelucidated. To clarify these issues, we performed a 5-month incubation experiment on typical soda-type saline soil from the western part of the Songnen Plain using five treatments: control treatment (CK), 5% urea (U), straw + 5% urea (SU), straw + 5% urea + microbial agent (SUH), and straw + 5% urea + biochar (SUB). Compared with the SU treatment, the SUH and SUB treatments reduced cumulative CO2 emissions by 14.85% and 35.19%, respectively. The addition of a microbiological agent to the SU treatment reduced the cumulative CH4 emissions by 19.55%, whereas the addition of biochar to the SU treatment increased the cumulative CH4 emissions by 4.12%. These additions also increased the relative abundances of Proteobacteria, Planctomycetes, and Ascomycota. Overall, the addition of biochar and organic fertilizer promoted CO2 emissions and CH4 uptake. This was mainly attributed to an improved soil gas diffusion rate due to the addition of organic materials and enhanced microbial stress due to soil salinity and alkalinity from the release of alkaline substances under closed-culture conditions. Our findings have positive implications for enhancing carbon storage in saline soils in arid regions.

Cover cropping enhanced soil aggregation and associated carbon and nitrogen storage in semi-arid silage cropping systems

Wind and water erosion in arid and semi-arid regions significantly degraded soil, reduced soil organic carbon (SOC) storage, and exacerbated the impact of climate change on agricultural productivity. Cover cropping is one of the approaches to improve soil health and reduce climate change impacts, yet its impacts on soil aggregation and associated SOC and nitrogen (N) storage in water-limited environments are poorly understood. This study aimed to evaluate soil aggregate dynamics and aggregate-associated SOC and soil total N in irrigated silage sorghum [Sorghum bicolor L. (Moench)] − corn (Zea mays L.) rotations with various cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and no cover crops (NCC). Results showed in the second year of the study that, at 0–0.1 m depth, mean weight diameter and geometric mean diameter of dry aggregates were 22–23 % and 6 % greater, respectively, with cover crops than NCC. At the same depth, cover crop treatments had 15–17 %, 15–16 %, and 13 % greater SOC in 0.25–2, 0.053–0.25, and < 0.053 mm aggregate classes, respectively, compared to NCC. Similarly, at 0–0.1 m depth, N in < 0.053 mm fraction was 8–10 % greater with cover crops than without. In the fourth year of the study, water-stable aggregates (WSA) percent did not differ among treatments, but WSA-associated SOC was 31–37 % and 12–16 % greater with cover crops at 0–0.1 and 0.1–0.2 m depths, respectively, than without. The WSA-associated N at 0–0.1 m was 21–33 % greater with cover crops than without. Despite the inconsistencies in soil aggregate stability results, cover crop-integrated silage systems showed greater SOC and N within aggregate classes and water stable aggregates. This insight is crucial for advancing sustainability in silage production systems, particularly in the context of increasing climate change and variability in erosion-prone soils of arid and semi-arid regions.

The inversion of arid-coastal cultivated soil salinity using explainable machine learning and Sentinel-2

The escalating salinization of cultivated soil poses a significant threat to the ecological environment. It is imperative to establish a monitoring system and mitigate the spread of salinization in arid and coastal areas through remote sensing, incorporating high-precision cross-regional models for soil salt content inversion. This study focuses on typical saline-alkali soils in arid and coastal regions of China. Using Sentinel 2 data (including 6 bands and 27 spectral indices), along with soil texture, moisture content, temperature, precipitation, and digital elevation model (DEM) data to establish an arid-coastal salinity inversion model. Variable selection methods such as pearson correlation coefficient (PCC), variable importance in projection (VIP), gray relational analysis (GRA), and gradient boosting machine (GBM) were used, while using 9 models including adaptive boosting (Adaboost), extremely randomized trees (ERT), and light gradient boosting machine (LightGBM). The best model was further elucidated using the Shapley additive explanations method. Results indicate that the common sensitive characteristic variables of arid-coastal areas were spectral indices and soil properties in PCC, the spectral variable bands and indices in VIP, and all variables in GRA and GBM. The best inversion model GBM-ERT (R2 = 0.91, RMSE = 1.06) in arid areas exhibited higher accuracy than the best inversion model GBM-Adaboost (R2 = 0.77, RMSE = 1.74) in coastal areas. The arid-coastal inversion model PCC-LightGBM demonstrated the best inversion performance (R2 = 0.64, RMSE = 2.29) and simulation performance in arid (R2 = 0.67) and coastal areas (R2 = 0.63). Dead fuel index (DFI) had the most significant impact on model prediction (0.89) and the second ratio index (RI2) contributed the highest relative importance (18 %) to the model. Our analysis indicates that the arid-coastal model of PCC-LightGBM established using common characteristic variables, can effectively monitor large-scale soil salinity.

Application of acoustic oscillations for accelerating the leaching process of saline soils

The escalating expansion of saline soils in arid and semi-arid regions presents a significant challenge to agricultural sustainability. In light of the widespread water scarcity, there has been a growing demand for innovative technologies aimed reducing water during the leaching of saline soils. This study explores the application of acoustic vibrations, particularly utilizing a seismic vibrator SV 10/100, to improve the efficiency of soil desalination. The mechanism of action of acoustic vibrations is explained by the formation of a vortex flow around soil particles oscillating within a defined amplitude and frequency range, thereby enhancing the dissolution of salts. This study specifically targets soda solonetz-solonchak soils with diverse mechanical compositions, situated in the Ararat plain of Armenia. Field experiments utilizing the lysimetric method were conducted in 2016. The primary aim was to determine optimal parameters of acoustic oscillations to expedite desalination process while assessing their impact on soil physical properties during leaching. Findings revealed that higher oscillation amplitudes (ranging from 4 to 7 mm) at frequencies of 10–70 Hz, within a 100-meter radius or 3.14-hectare area were watched. Specifically, oscillations at frequencies of 30–50 Hz for 1.0–1.5 h per leaching water portion (2500 m3/ha) effectively reduced the required leaching water volume and duration by 2 times when applied during soil leaching following acidification. It is important to note that the soil properties after leaching remained in the optimal ranges for the region (soil density 1.2–1.3 g/cm3, hydraulic conductivity 10–20 cm/day). Overall, this research underscores the efficacy of acoustic oscillations in expediting reclamation processes, reducing leaching water requirements, enhancing soil fertility, and facilitating integration into agricultural cycle. Therefore, the newly proposed method of utilizing acoustic vibrations shows potential for efficiently leaching saline soils.

Bioinspired 1T-MoS2-based aerogel beads for efficient freshwater harvesting in harsh environments

Freshwater scarcity is one of the most critical issues worldwide, particularly in arid regions, stemming from population growth and climate change. Inspired by the hydrophilic bump structures of desert beetles, 1T-MoS2-based aerogel beads with porous structures and CaCl2-crystal loading (termed as MoAB-m@CaCl2-n) were prepared for freshwater harvesting. Metallic-phase MoS2 nanospheres exhibit excellent photothermal conversion abilities, facilitating solar-driven water desorption and evaporation. Owing to the synergistic effect of its localized surface features, hydrophilic groups, and dispersive CaCl2 particles, MoAB-2@CaCl2-2 efficiently harvests water from atmosphere with a superior moisture adsorption capacity (0.18–0.82 g g−1) at a wide range of relative humidity (10 %-70 %). Under one-sun illumination, MoAB-2@CaCl2-2 demonstrates an outstanding solar-driven water evaporation rate of 2.25 kg m-2h−1. The water evaporation rate from soil (water content = 20 %) is 1.19 kg m-2h−1, which is sufficient for sustainable freshwater generation from the soil in arid regions. More importantly, the multifunctional MoAB-2@CaCl2-2-based homemade freshwater generation prototype delivers a certain amount of water harvesting (0.99 g g−1 day−1) on a rainy day and provides an impressive daily freshwater yield (53.7 kg m−2) under natural sunlight. The integrated device exhibits excellent efficiency and practicality and offers a feasible method for freshwater harvesting in harsh environments.

Genesis, mineralogy, and geochemistry of soil profiles developed on volcanic materials under semi-arid conditions from Central Anatolia-Turkey

Pedogenesis of volcanic soils has been studied broadly in humid regions, but very little data are present regarding these soils in arid and semi-arid regions of Turkey. This research aimed to assess the pedological processes and investigate the physical, chemical, and mineralogical characteristics of soil profiles developed from volcanic parent material. The studied soils were not classified as Andisol because they lack andic properties. The results showed that sand and coarse silt fractions exceeded 30%. The bulk density was higher than 0.90 grcm-3 in all profiles. In general, phosphate retention was low, higher than 25% in profiles but lower than 85% in all profiles. The Al + ½ Fed percentages were lower than 2% in all profiles. Selective extraction (Na–Pyrophosphate, Ammonium Oxalate, Na–Dithionite) indicated that soils lack noncrystalline minerals, such as allophane, imogolite, and iron humus complexes. The only noncrystalline minerals in high quantities are Al-humus complexes and small amounts of ferrihydrite. X-ray diffraction indicated that smectite, kaolinite and illite were dominant minerals in the clay fraction. Among the studied profiles, profiles 1 and profile 4 are classified as vitrandic Haploxerept, profile 2 as vitrandic haploxerolls, and profile 3 as vitrandic Xerorthent. The results indicated that the dominant soil-forming processes include the following: 1. desilication and the eluviations of base cations and Al from the solum; and 2. transformation of iron and aluminum from the sand and silt-size fractions into secondary clay and crystalline Fe minerals. The major factors determining soil genesis on Mt. Karacadağ appear to be climate and topography affected by the leaching regime and weathering rates.

Influence of Date Palm-Based Biochar and Compost on Water Retention Properties of Soils with Different Sand Contents

Generally, soils of arid and semi-arid regions have low water retention properties due to high sand and low organic carbon contents. This study aimed at quantifying the effect of date palm-based organic amendments (OAs) on the water retention properties of two soils (sandy loam and silty loam), as well as the influence of sand supplementation (0.5–2 mm) on the magnitude of the effect of OAs. Different grain size distributions were obtained by adding sand to natural soils. For this purpose, sand was added to the two soils (1/3 and 2/3) and different soil-OA combinations were tested at a dose of 3% by mass: compost alone, biochar alone and a mixture of biochar and compost (50:50 in mass), in addition to unamended control soils. Soil water contents were measured at nine matric potentials ranging from the saturation to the permanent wilting point. Biochar was more efficient than compost at improving soil water retention. The effect of organic amendments on water retention increased with sand content. In most cases, soil water content values were significantly higher for biochar-amended soils than for unamended or compost-amended soils. The weakness of the effect of compost addition (if alone) was probably due to its properties and notably its high mineral content and electrical conductivity. Soil sand supplementation led to higher differences between the OA-amended soils and unamended soils. Changes in available water capacity reached +26% and +80% in a sandy loamy soil enriched with 2/3 sand and amended with compost and with biochar, respectively, compared to the unamended soil. These results show that sand content (and more generally, soil texture) influences the effect of OA application. Thus, the application of biochar from date palm residues in soil seems to be an effective solution to improve the water retention properties of coarse textured soils and contribute to optimizing the use of water resources in irrigated areas.

Biochar and conservation tillage affect the agronomic performance and fatty acid composition of Nigella sativa L. under both irrigated and dryland conditions

Soils in arid and semi-arid regions like Iran have suffered greatly from low organic matter content and low water availability. Traditional tillage and the overuse of chemical fertilizers are accelerating the problems in the region. So, sensible and sustainable strategies such as conservation tillage and natural organic inputs are becoming increasingly important to enhance organic matter and humidity in the soil and grow high-quality crops in agroecosystems. Thus, in 2019 and 2020, a split-split plot arrangement within a randomized complete block design was conducted in Iran to assess the effects of irrigated conditions, tillage systems, and biochar on the aforementioned traits. There were two irrigation conditions (irrigated and dryland) as the main plots, three tillage methods (conventional, minimum, and no-tillage) as sub-plots, and two application rates for biochar (0 and 15 ton ha−1) as sub-sub plots. The findings indicated that biochar application enhanced grain yield across all tillage methods under both irrigation conditions. Biochar with minimum tillage improved oil yield by 23% and 29% compared to those that did not use biochar under the dryland and irrigated conditions, respectively. Moreover, oil yield was higher in 2020 than in 2019 for all tillage systems and biochar rates. The main components of Nigella sativa L. oil belong to linoleic, oleic, and palmitic acids. Minimum tillage with biochar under irrigated conditions in 2020 and no-tillage without biochar under dryland conditions in 2019 had the most (59%) and the least linoleic acid (53%), respectively. Conventional, minimum, and no-tillage with biochar in dryland conditions significantly increased linoleic acid by 2%, 3%, and 5% compared to those without biochar in 2020, respectively. In general, adopting biochar with minimum tillage produced the best outcomes for Nigella sativa L. yield, and grain oil quality under both irrigation conditions. It is recommended that farmers incorporate these practices to produce high-quality Nigella sativa L. in sustainable agricultural systems.

The Effect of Using a Geopedological Approach in Determining Land Quality Indicators, Land Degradation, and Development (Case Study: Caspian Sea Coast)

This study addresses the escalating global concern surrounding land degradation (LD) and its far-reaching implications on water and nutrient availability, as well as on human health and well-being. Focused on the southeastern Caspian Sea region, this research employs a novel remote sensing geo-pedological methodology to comprehensively assess soil and land quality dynamics, particularly influenced by salts, and investigates the intricate relationship between LD and soil development. The study area, marked by a susceptibility to seawater level fluctuations and diverse landforms (lagoons, barriers, and coastal plains) offers a unique opportunity for geopedologic analysis. Utilizing particle size distribution data, six distinct landforms are identified, providing insights into the region’s complex sedimentary history. A soil quality assessment is conducted remotely through the calculation of two indexes—the Integrated Quality Index (IQI) and the Nemoro Quality Index (NQI)—employing both Total Data Set (TDS) and Minimum Data Set (MDS) methodologies. The investigation highlights the role of soluble salts in shaping soil quality, thereby influencing LD and development dynamics. The differentiation of landforms significantly enhances classification accuracy, providing a more nuanced understanding of the multifaceted factors governing LD. The study’s implications extend beyond the southeastern Caspian Sea region, and demonstrate that the potential for incorporating a geopedologic approach when assessing soil and land quality dynamics in arid regions globally. Our analytic approach can inform policymakers and land managers when making decisions to combat LD and foster sustainable land development. This research also contributes towards advancing knowledge in geopedology by providing a robust foundation for future studies aimed at enhancing land management practices in the face of ongoing environmental challenges.

Comparison between two gypsum content determination methods applied to the study of soils in arid regions

With the scarcity, degradation of soils, the growing populations and the need to guarantee their food security, the valorization of gypsum soils widespread in arid and semi-arid regions is becoming a necessity. North African countries have a large part of their land area located in arid regions. It is therefore important to characterize the gypsum content using simple, rapid, economical and, environmentally friendly methods. Several methods have been proposed in the literature (chemical, thermogravimetric, and x-ray techniques). In this work, a comparison between two methods for gypsum determination in soils was undertaken. The first method of Coutinet is chemical and based on the use of BaSO4 for the precipitation of sulfate ions. The second method is Artieda method which is based on measuring the weight difference caused by the loss of crystalline water from gypsum molecules between the temperatures of 70 and 90 °C. To achieve the objective of this work, forty-three soil samples were analyzed. They were taken from two arid regions (Ouargla and Touggourt) located in the northern Sahara (Algeria). The soils contain gypsum accumulations. The results showed that most of the samples are slightly gypsiferous, with 36 and 32 samples for the Coutinet and Artieda methods respectively. A strong positive correlation (R2 = 0.95) exists between the results of the two methods studied. For gypsum contents higher than 2 %, the correlation coefficient is 0.94. However, for samples with contents less than 2 %, the correlation is very weak with R2=0.19. The Artieda method is thus encouraged for the gypsum quantification in soils of arid regions. This method is easy, requiring simple laboratory equipment (mainly a ventilated oven and a precision balance). Chemical methods have the disadvantage of being time-consuming and using expensive chemicals that are dangerous for the environment and human health.

Elemental sulfur effects on salt leaching, plant growth, nutrient uptake, and microbial diversity in an arid saline soil

The amendment of salt-affected soils with elemental sulfur (S0) has been recognized for its potential to effectively reduce soil salinity and pH, thereby enhancing soil physicochemical properties, promoting crop growth, and improving yields. Despite these known benefits, the widespread adoption of S0 for managing saline soils, particularly in arid calcareous regions, remains limited. Consequently, this study aimed to evaluate the impact of S0 on salt leaching, soil pH, nutrient uptake, plant growth, microbial diversity, and community structure under alkaline saline soil conditions. The study includes three main experiments: a preliminary column experiment without plants, a field trial with Rhodes grass (Chloris gayana), and a greenhouse pot experiment with wheat (Triticum spp.). Our findings demonstrated that S0 incorporation into the soil exerted a positive influence, resulting in increased salt removal, reduced soil pH, and improved plant growth. Specifically, soil amendment with 750 kgS0ha−1 led to a substantial salt removal, exceeding double in the column experiment, approximately 91.3 % in the field trial, and about 34.1 % in the greenhouse pot experiment compared to the control. S0 amendment also significantly lowered soil and leachate pH in both field and greenhouse trials, with reductions of 3.3 % and 6.3 %, and 8.1 % and 4.4 %, respectively, relative to the control. Calcium and phosphorus uptake by Rhodes grass increased significantly by 75 % and 14 %, respectively, compared with the control. Soil organic matter content significantly increased from 0.6 % to 1.5 % compared to that of the control. This overall enhancement in soil conditions resulted in a considerable increase in Rhodes grass and wheat yields by 13 % and 59 %, respectively. While the prokaryotic diversity (16S V4 rRNA sequencing) in the Rhodes grass field trial was not significantly affected by S0 amendments after two months, the microbial community composition showed remarkable differences between the S0-amended and control samples. Eighty-three unique taxa were exclusively found in the S0-amended samples. In conclusion, our findings suggest that the amendment of soil with S0 is a promising strategy for the sustainable management of calcareous salt-affected soils in arid regions.

Cover crop-mediated soil carbon storage and soil health in semi-arid irrigated cropping systems

Cover cropping is considered a climate-smart strategy to regenerate low-fertility soils in arid and semi-arid regions. However, the mechanisms of soil organic carbon (SOC) storage and soil health improvement in semi-arid irrigated cropping systems are poorly understood. The main goal of this study was to evaluate cover crop effects on various physical, chemical, and biological indicators of soil health in an irrigated silage corn (Zea mays L.)–sorghum [Sorghum bicolor (L.) Moench] rotation and understanding how changes in soil health contribute to SOC storage. We evaluated various SOC and nitrogen (N) pools, and microbial community structure under cover crop mixture of grasses, brassicas, and legumes (GBL), grasses and brassicas (GB), grasses and legumes (GL), and no cover crops (NCC) control for four years. Grasses included annual ryegrass (Lolium multiflorum Lam.) and winter triticale (× Triticosecale Wittmack), brassicas included turnip (Brassica rapa subsp. rapa L.) and daikon radish (Raphanus sativus var. Longipinnatus Bailey), and legumes included pea (Pisum sativum subsp. arvense L.) and berseem clover (Trifolium alexandrinum L.). Soil C pools: SOC, potentially mineralizable C, microbial biomass C, mineral-associated organic C (MAOC), and particulate organic C (POC) were greater with cover crops than without, but the effects were not consistent in all study years. Soil organic N was also greater under cover crops than under NCC. Soil C-to-N (C:N) ratio increased over the years but was similar among treatments. Cover crops used N and soil water to grow, significantly reducing soil inorganic N content and water-filled pore spaces in the first two years. However, fungal and bacterial communities grew better under cover crops with a high fungi-to-bacteria ratio than under NCC. The soil MAOC content was related to microbial community and enzyme activity while POC was affected by soil physicochemical conditions, specifically soil pH and mineral N availability, highlighting two major pathways of SOC sequestration in semi-arid cropping systems. This study showed how cover crops enhance SOC storage and soil health in semi-arid cropping systems.