Limestone Soils Research Articles

Unveiling the Effects of Phosphorus on the Mineral Nutrient Content and Quality of Alfalfa (Medicago sativa L.) in Acidic Soils

Alfalfa (Medicago sativa L.) grown in acidic soils is often affected by phosphorus (P) deficiency, which results in reduced mineral nutrient content and forage quality. In this context, the effects of phosphorus (P) fertiliser remain unclear. In this study, we analysed the effects of P application on mineral nutrient content and forage quality in aluminium (Al)-sensitive (Longzhong) and Al-tolerant (Trifecta) alfalfa cultivars cultivated in two acidic soil environments. Mineral nutrient content and quality were affected by genotype, soil type, and P treatment concentration (p < 0.001). In limestone soil, for Longzhong and Trifecta, the optimal potassium (K), calcium (Ca), and magnesium (Mg) contents as well as crude protein content (CP) and ether extract (EE) values were observed at 20 mg P kg−1, that of the P content was observed at 40 mg P kg−1, and the minimum neutral detergent fibre (NDF) acid detergent lignin (ADL) values were observed at 40 mg P kg−1. In yellow soil, the maximum K, Ca, Mg, and P contents in Longzhong and Trifecta were observed at 40 mg P kg−1, whereas the maximum CP, EE, and ADL values were observed at 20 mg P kg−1. Our study provides an empirically based framework for optimising alfalfa fertilisation programmes in acidic soils.

Land suitability evaluation in the Northern Limestone Mountains of Tuban Regency, East Java for torch ginger (Etlingera elatior Smith) cultivation

Torch ginger (Etlingera elatior) is a herbaceous plant from Southeast Asia, traditionally used as herbal medicine by local people due to its antibacterial, antiviral, anti-inflammatory, anti-allergic, antioxidant, and anti-cancer properties. Despite its various benefits, this plant has struggled to enter the market because it has not been cultivated on a large scale. Therefore, the opportunity for commercial cultivation of this plant remains wide open. Tuban Regency is a potential agricultural district in Java, strategically positioned on the main road between Central Java Province and East Java Province. Unfortunately, little research has been conducted on land suitability evaluation in Tuban Regency’s agricultural areas. This research aimed to evaluate land suitability for torch ginger cultivation in Tuban Regency. Based on the studies conducted, agricultural land in Tuban Regency is quite fertile, but adequate irrigation is necessary to help the plants survive during the dry season. Torch ginger naturally grows in densely vegetated areas with sufficient water availability. Therefore, cultivating torch ginger in Tuban requires several special treatments, such as maintaining water availability, providing shade and mulch to regulate temperature and humidity, applying phosphorus and organic fertilizers to address phosphorus fixation in limestone soil, and using growth regulators like paclobutrazol to overcome flowering inhibition. From the various literature that has been studied, it was found that the land in the Northern Limestone Mountains of Tuban Regency, is quite fertile and suitable for agricultural land.

Chromosome‐level genome assembly of a rare karst‐growing Rhododendron species provides insights into its evolution and environmental adaptation

AbstractRhododendron is a significant plant genus, with over 600 identified species in China. The subgenus Hymenanthes holds the largest number of Rhododendron germplasms and showcases strong environmental adaptability. However, there remains a lack of understanding regarding Rhododendron's evolution and environmental adaptations. Rhododendron bailiense Y.P.Ma, C.Q.Zhang & D.F.Chamb., an exceedingly rare species, thrives in the alkaline karst landforms of Guizhou, southwest China, different from the typical growing environment of other Rhododendron species. In this study, we present a chromosome‐level genome assembly of R. bailiense, revealing a genome size of 923.3 Mb, a contig N50 of 24.5 Mb, and a total of 47 567 predicted genes. An evolutionary analysis indicated that R. bailiense diverged from its ancestors prior to the other subgenus Hymenanthes rhododendrons, with the expanded and contracted genes being notably enriched in “stress response” and “growth,” respectively. Rhododendron bailiense is predominantly found on limestone soil in the mountains of Guizhou, with only two wild populations known. The genome of R. bailiense contained a high copy number of ankyrin repeat (ANK) and Ca2+‐ATPase (CAP) genes, primarily involved in Ca2+ transport, shedding light on how R. bailiense copes with karst high‐calcium stress. In contrast, the structures of the ANKs displayed unique characteristics, while the CAPs showed conservatism. The R. bailiense genome provides new insights into the adaptation and evolutionary history of Rhododendron plants in karst environments, potentially offering valuable information for adaptive breeding and ecological enhancement in such challenging settings.

Greater variation of soil organic carbon in limestone- than shale-based soil along soil depth in a subtropical coniferous forest within a karst faulted basin of China

Lithology strongly influences soil microbial traits and edaphic factors and in turn soil organic carbon (SOC) dynamics. However, the effect of lithology on microbial traits, edaphic factors and resulting SOC physical fractions variation along soil depth remains inadequately understood in karst faulted basin of China. This understanding is critical for improving SOC stability. By separating SOC into labile particulate organic carbon (POC) and stable mineral-associated organic carbon (MAOC) over karst limestone and non-karst shale soil in a subtropical coniferous forest, we aimed to assess potential regulatory mechanisms underlying lithology-associated SOC stability variations across soil depth by integrating soil nutrients, mineralogical characteristics, and microbial traits. We found that SOC and its fractions were higher in limestone than in shale soil, which implying vegetation restoration effects on SOC and its fractions partly depending on lithology. Additionally, we found that the effects of soil depth on SOC and its fractions were greater in limestone soils than shale soils, and the ratios of MAOC to SOC (MAOC:SOC) and MAOC to POC (MAOC:POC) show a opposite trend in response to soil depth between two the lithologies. Variation partitioning and random forest analyses revealed that among multiple factors, the variation of SOC stability assessed via MAOC:SOC was mainly explained by microbial traits than soil nutrients and mineral properties. Contrast to soil depth, structural equation modeling analyses showed that lithology was the primary factor controlling the SOC stability when microbial traits, soil nutrients and mineralogical characteristics were controlled as conditional variables. Overall, these results highlight the crucial role of lithology in regulating the SOC stability along soil depth, which improve our understanding and management of soil carbon (C) pool in karst faulted basin of southwest China.

Significant Differences in Microbial Soil Properties, Stoichiometry and Tree Growth Occurred within 15 Years after Afforestation on Different Parent Material.

The mineralogical composition of the parent material, together with plant species and soil microorganisms, constitutes the foundational components of an ecosystem's energy cycle. Afforestation in arid-semi arid regions plays a crucial role in preventing erosion and enhancing soil quality, offering significant economic and ecological benefits. This study evaluated the effects of afforestation and different parent materials on the physicochemical and microbiological properties of soils, including microbial basal respiration (MR), as well as how these changes in soil properties after 15 years influence plant growth. For this purpose, various soil physicochemical parameters, MR, soil microbial biomass carbon (Cmic), stoichiometry (microbial quotient = Cmic/Corg = qMic and metabolic quotient = MR/Cmic = qCO2), and tree growth metrics such as height and diameter were measured. The results indicated that when the physicochemical and microbiological properties of soils from different bedrock types, along with the average values of tree growth parameters, were analyzed, afforestation areas with limestone bedrock performed better than those with andesite bedrock. Notably, sensitive microbial properties, such as Cmic, MR, and qMic, were positively influenced by afforestation. The highest values of Cmic (323 μg C g-1) and MR (1.3 CO2-C g-1 h-1) were recorded in soils derived from limestone. In contrast, the highest qCO2 was observed in the control plots of soils with andesite parent material (7.14). Considering all the measured soil properties, the samples can be ranked in the following order: limestone sample (LS) > andesite sample (AS) > limestone control (LC) > andesite control (AC). Similarly, considering measured plant growth parameters were ranked as LS > AS. As a result, the higher plant growth capacity and carbon retention of limestone soil indicate that it has high microbial biomass and microbial activity. This study emphasizes the importance of selecting suitable parent material and understanding soil properties to optimize future afforestation efforts on bare lands.

Innovative reuse of mineral waste for treatment of a contaminated soil by fluorine: synthesis of hydroxyapatite (HAP) and chemical performance assessments.

This research aimed to introduce a novel method for the valorization of mineral waste, focusing on the development of hydroxyapatite (HAP) as an effective and economical adsorbent for immobilizing fluoride ions (F-) in soil. Hydroxyapatites were produced through the reaction between potassium dihydrogen phosphate (KH2PO4) and calcium-abundant limestone soil (CLS). X-ray diffraction analyses revealed that the primary phases in HAPCLS were brushite (CaHPO5·2H2O) and hydroxyapatite (Ca10(PO4)6(OH)2). The FTIR spectra exhibited characteristics akin to natural HAP, including the presence of orthophosphate groups (PO43-), hydroxyl groups (OH-), and both A/B types of carbonates in the apatite structure. The morphology of the synthesized HAP, as observed through SEM-EDS, was consistent with that of phosphocalcic hydroxyapatite crystals. The EDS results indicated a Ca/P atomic ratio of 1.7 for HAPCLS, aligning closely with the typical hydroxyapatite stoichiometry (Ca/P = 1.67). The application of HAP to reduce fluoride (F-) levels in soil proved to be successful; introducing 1% of various HAP formulations reduced the fluoride concentration from 51.4mg/kg in untreated soil to levels below the IWSI limit (10mg/kg), achieving a reduction to 8.1mg/kg for HAPCLS. The sequential extraction of fluoride demonstrated that after soil treatment, fluoride was predominantly removed from the residual fraction (Fraction 4) and was effectively sequestered by the hydroxyapatites (Ca10(PO4)6(OH)2) through anionic exchange with hydroxide ions (OH-), resulting in the formation of stable and insoluble fluorapatite (Ca10(PO4)6F2).

Cadmium accumulation and transfer in yellowish-brown and limestone soils of five potato varieties based on a pot experiment in the central Hanjiang River basin

Cadmium accumulation and transfer in yellowish-brown and limestone soils of five potato varieties based on a pot experiment in the central Hanjiang River basin

Overestimating the involvement of nitric acid derived from nitrification in carbonate dissolution under a calcareous soil system

This study aimed to quantify the effect of base cation exchange (BCE) in the buffering of nitric acid produced by soil nitrification and evaluate the impact of this process on karst carbon sinks. We collected limestone soils from subtropical karst regions in southern China and established five pot simulation experiments with different fertiliser gradients. The results follow: (1) Soil calcium carbonate (CaCO3) and alkaline cations decreased gradually with increasing nitrogen application. Furthermore, the concentrations of soil leachate nitrate (NO3–N), calcium (Ca), and magnesium (Mg) gradually increased and varied within the ranges of 0.15–15.33, 28.10–85.76, and 6.53–34.35 mg L−1, respectively. (2) Soil buffering against nitrification-generated acid could be accomplished fully in the top 10 cm of the soil. At a fertiliser application rate of 100 kg N ha−1a−1, nitrification acid production was fully buffered by BCE, and soil CaCO3 was dissolved entirely by soil CO2. When the fertiliser application rate increased from 250 to 700 kg N ha−1a−1, BCE buffered approximately 55% of the H+. Soil carbonate buffering was approximately 45%. (3) Losses of Ca and Mg from the soil were induced by three processes: carbonic acid dissolving soil CaCO3, BCE and nitric acid dissolving soil CaCO3. Previous studies have ignored the contribution of BCE to groundwater Ca and Mg, leading to an overestimation of approximately 55% in the previously calculated proportion of nitric acid involved in the dissolution of carbonates.

Lithology-driven soil properties control of N2O production by ammonia oxidizers in subtropical forest soils

Lithology can strongly influence soil's physical and chemical properties, significantly affecting soil nitrogen (N) transformation rates. Ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB) and complete ammonia oxidizers (comammox Nitrospira) constitute the major producers of soil nitrous oxide (N2O), but the importance of different lithology on their relative contributions still poorly understood, especially in terms of newly discovered and widespread comammox. To address this knowledge gap, three nitrification inhibitors, acetylene (ammonia oxidizers inhibitor), 1-octyne (AOB inhibitor) and 3,4-dimethylpyrazole phosphate (DMPP) (both AOB and comammox inhibitor), were used to selectively inhibit the activity of different ammonia oxidation groups in order to discriminate their respective roles in N2O production in forest soils developed on different lithologies (limestone and clastic rock). The results showed that AOB dominated N2O production (63.5 ± 3.3 %) in limestone soils with ammonium amendment, followed by AOA (34.5 ± 7.6 %), while comammox contributed 1 % of total N2O production with N2O yield of 0.03 ± 0.04 %. Higher N2O production by AOB in limestone soils is associated with higher soil pH, exchangeable calcium/magnesium and lower short-range order iron/aluminum minerals. However, the N2O yield by comammox (0.12 ± 0.12 %) in clastic rock soils was comparable to that by AOA (0.15 ± 0.14 %) and AOB (0.20 ± 0.13 %). Based on the results of the correlation analysis, comammox in the clastic rock soils produce greater amounts of N2O is closely related to the higher soil organic carbon and available phosphorus. The present study provided evidence that the lithology-driven soil properties markedly affect the N2O production from different ammonia oxidizers.

Effects of humic acid and mineral Zn fertilizer on Zn uptake and maize yield in soils formed on limestone and marl parent materials

In this study, the effects of zinc (Zn) and humic acid (HA) applications on soils (12 Aridisol soil samples) formed on limestone and marl parent materials, which are very common in Türkiye, were tested by incubation, adsorption, and greenhouse experiments. Adsorption experiments were carried out using the batch sorption technique, and the Langmuir and Freundlich isotherm parameters were calculated. In the incubation, soils were incubated with control, HA, Zn, and HA+Zn, and the DTPA-Zn was tested in five different periods (1, 7, 15, 30, and 90th days). Maize was grown for eight weeks in pots in the greenhouse. The maximum Zn adsorption for all soils ranged between 3333 and 6250 mg kg-1 in marl soils and 1042 and 5263 mg kg-1 in limestone soils, which decreased to ranges between 2631 and 5555 mg kg-1 in marl soils and 1052 and 5000 mg kg-1 in limestone soils with HA appli-cation, respectively. The desorption rate (%) of adsorbed Zn increased as the initial Zn concentration increased in all soil series formed on marl (smectite clay mineral) and lime-stone (kaolinite clay mineral) parent materials. The effects of humic acid and Zn applica-tion on the fresh and dry weights of maize were found to be statistically significant at the 5% level for marl and limestone parent material. Humic acid application increased the fresh weight of maize compared with that of the control. The highest available Zn was determined in Başkuyu series (0.79 mg kg-1) formed on marl parent material, while the lowest available Zn was obtained in Saraççeşme series (0.60 mg kg-1) formed on limestone parent material. In the greenhouse, HA increased the fresh weight of maize in soils formed on both parent materials by 0.4 and 19.6%, respectively, compared to the control. Zn fertili-zation with HA further increased the fresh and dry yields, with 12 mg kg-1 performing bet-ter. Smax (maximum Zn adsorption of the soil) parameters of soils were negatively corre-lated with EC, Pav, Kav, organic matter, silt, clay, total N, and cation exchange capacity (CEC) of the samples. Although HA alone increases the availability of Zn in plants, HA + Zn appli-cations should be applied together to obtain higher yields.

Elevated Altitude and Limestone Soil Promoted Fungal Diversity in Rhizosphere Soil of Sophora japonica

Soil microorganisms play a crucial role in mediating material transformation and nutrient cycling. However, little attention has been paid to the relationships between microbial communities and altitude and lithology in karst regions. Sophora japonica cv. Jinhuai is an officinal plant cultivated in karst areas, and there is a correlation between the dynamics of microbial community and ecological factors. This study examined the diversity of microbial communities in the rhizosphere of S. japonica under different lithologies and altitudes in karst regions of northern Guangxi, China using high-throughput sequencing technology. It was found that the bacterial community consisted of 37 phyla, including Proteobacteria. The fungal community mainly comprised 15 phyla, including Ascomycota. The fungal Shannon and Chao1 indices increased with altitude, while the bacterial Shannon index decreased. The fungal Shannon indices in limestone soil were higher than those in dolomite. The soil’s microbial Shannon and Chao1 indices were positively affected by pH, while the available phosphorus and potassium had the opposite effect. Research shows that altitude, lithology, pH, and available phosphorus were the crucial factors influencing the rhizosphere soil microbial community. This study provides references for understanding the relationship between plants and microorganisms and the microbial distribution strategy of rocky desertification habitats in the future.

Natural colonisation rates in a UK upland landscape under different conservation management approaches following sheep removal

Abstract Natural colonisation could provide a cost‐effective means to increase woodland coverage across the UK uplands. However, there is a shortage of evidence of which factors affect the success of natural colonisation, including grazing management. The species of grazer, grazing intensity and the stage of regeneration may alter the impact of grazing on the ability of trees to colonise an area. In this study, we quantify the effect of removing sheep from an area in the Yorkshire Dales National Park, England, and explore whether cattle or ungrazed management alters tree colonisation rates. We also tested other environmental factors such as distance from woodland, elevation and soil geology to understand the other constraints on natural colonisation. Naturally colonised trees were recorded within 60 plots at Ingleborough National Nature Reserve and surrounding Yorkshire Wildlife Trust reserves. A series of generalised linear models, with a negative binomial distribution, were created to understand the effects that years since removal of sheep, current management, elevation, distance from woodland and soil geology had on the number of naturally colonising trees. The number of naturally colonising trees per hectare was 16% higher each year after sheep removal, with both cattle and ungrazed management being equally effective in promoting natural colonisation. Natural colonisation decreased by 25% for every additional 100 m from the nearest woodland and naturally colonising trees were much more frequent on limestone soil. Practical implication. This study shows that sheep grazing is a key limiting factor of natural colonisation in the UK uplands. Significant natural colonisation was possible on both cattle grazed and ungrazed sites and developed at a similar rate, highlighting a change in grazing animal can be as important as grazing cessation. Tree planting will still be required to restore tree cover to areas away from seed sources and improve diversity of future woodlands.

Influences of nitrogen input forms and levels on phosphorus availability in karst grassland soils

The availability of soil phosphorus (P), a crucial nutrient influencing plant productivity and ecosystem function, is impacted by continuously increasing nitrogen (N) enrichment, which changes the soil P cycle. The effect of varying forms of N input on soil P dynamics in P-limited karst grassland ecosystems remains unclear. To address this knowledge gap, we conducted a greenhouse experiment to explore the effects of various forms of N addition [Ca(NO3)2, NH4Cl, NH4NO3, Urea] on soil P fractions in these ecosystems, applying two levels (N1: 50 mg N kg−1soil, N2: 100 mg N kg−1soil) of N input in two soils (yellow soil, limestone soil). Results indicated that P fractions in both soil types were significantly affected by N additions, with yellow soil demonstrating a higher sensitivity to these additions, and this effect was strongly modulated by the form and level of N added. High N addition, rather than low N, significantly affect the P fractions in both soil types. Specially, except for Ca(NO3)2, high N addition significantly increased the available P in both soils, following the order: Urea and NH4NO3 > NH4Cl > Ca(NO3)2, and decreased NaHCO3-Pi in both soils. High N addition also significantly reduced NaOH-Po and C.HCl-Po fractions in yellow soil. Additionally, the response of root biomass and alkaline phosphatase activity in both soils to N input paralleled the trends observed in the available P fractions. Notably, changes in soil available P were strongly correlated with plant root biomass and soil alkaline phosphatase activity. Our study highlights that the N addition form significantly influences soil P availability, which is closely tied to plant root biomass and alkaline phosphatase activity. This finding underscores the importance of considering N input form to boost soil fertility and promote sustainable agriculture.

Effectiveness of Reducing Hardness in the Filtration Process Using Mixed Media with Detention Time Variations

The problem that is often faced in groundwater management, especially deep groundwater such as boreholes is hardness. This can happen because in the process of taking it from the soil through various layers of soil including limestone soil containing Ca and Mg, so that the water becomes hard. Hard water is found in areas where the top soil layer is thick and there is limestone formation. This study aims to identify the physical quality and hardness level of clean water sourced from dug wells and drilled wells, after treatment through filtration methods. Filtration is carried out using mixed media with variations in residence time in the filtration media, namely 30 minutes, 60 minutes and 90 minutes. The results showed that the effectiveness of reducing hardness in dug wells and drilled wells was highest for a variation in 90 minutes, For dug wells, the effectiveness of 90 minutes of residence time reached 9.18% and for drilled wells, the effectiveness reached 16.36%.

The Quantity and Quality of Humic Substances following Different Land Uses in Karst Peak-Cluster Depression in Guangxi, China

There were some ecological and environmental problems in limestone soil in the karst peak-cluster depression in Pingguo City of Guangxi, such as the destruction of soil structure, soil acidification and soil fertility decline, and these problems were closely related to soil organic matter. The soil in this site was classified as Cambisols. Therefore, this project took soil under five major land uses (grassland, afforestation, sugarcane field, corn field and pitaya field) in the karst area of Guangxi as the research object. The contents and molecular structure properties of humic acids, fulvic acids and humins in soils were studied by solid-state 13C nuclear magnetic resonance spectroscopy and elemental composition. From the perspective of the chemical structure of humic substances, the differences in the quantity and structural characteristics of humic acids, fulvic acids and humins in different land uses were revealed. The results showed that the organic carbon content of both afforestation (34.83 g kg−1) and natural restored grassland (31.67 g kg−1) were significantly higher than that of sugarcane field (17.60 g kg−1), corn field (16.35 g kg−1) and pitaya field (14.31 g kg−1) (p < 0.05). The contents of three humic fractions in grassland were relatively high, and the contents of three humic fractions in sugarcane field were relatively low (p < 0.05). The structural characteristics of humic substances showed that the protein components of the three humic fractions in the afforestation were high, indicating that the humic substances in the afforestation contained more unstable components. The Alkyl C/O-alkyl C and Hydrophobic C/hydrophilic C ratios of the three humic fractions of corn field were high, indicating high stability and maturity in humic substances in corn field.

A comprehensive analysis of time-dependent performance of a solar chimney power plant equipped with a thermal energy storage system

Solar Chimney Power Plants (SCPP) are among the promising solar thermal electricity generation technologies. Equipped with a Thermal Energy Storage (TES) system, such technologies can overcome variations in the main driving factors such as solar radiation and ambient air temperature. This article presents a comprehensive semi-analytical model of a TES to predict the time-dependent performance of an SCPP. By introducing a Quality Factor of power generation (QF) that includes energy conversion efficiency and capacity factor, the effects of 15 TES materials have been studied on the plant performance. Results indicate no significant difference between water TES and clay or soil type, and water-filled bags or tubes are relatively ineffective in improving performance compared to them. Among the various TES materials analyzed, a type of wet soil, i.e., the specific wet mixture of clay, sand, and silt in closed and dark-colored bags, show excellent performance in both QF enhancement and having low Heat Penetration Depth (HPD) simultaneously. The QF and HPD are directly affected by thermal effusivity and thermal diffusivity, respectively. Implementing wet soil TES for the studied power plant (Manzanares) enhances the QF from 7.46 % (for limestone soil) to 10.95 %. Water-filled bags demonstrate a heat penetration depth of 0.4 m, while wet soil exhibits a slightly greater depth of 0.5 m. Furthermore, water-filled bags experience a broader temperature range of 40 °C, whereas wet soil undergoes a comparatively smaller temperature variation of 26 °C. Furthermore, the capacity factor raises from 41.18 % to 61.07 % when utilizing wet soil TES compared to water-filled bags.

Hydrological characteristics and available water storage of typical karst soil in SW China under different soil–rock structures

Soil hydrological characteristics are influenced by factors such as parent rock weathering, human activities, and soil texture. However, the influence of the complex soil–rock structures and heterogeneous soil types on soil hydrological characteristics resulting from the weathering of carbonate rocks into soils on slopes in the karst region of SW China is not fully understood. The relationships between zonal and nonzonal soil hydrological characteristic differences, land uses, and soil–rock structures were analyzed using a typical watershed in the SW China karst region. In this study, (1) the difference between zonal and nonzonal soil hydrological characteristics is significant. For infiltration capacity (Ks), yellow soil (19.50 ∼ 1058.00 cm·d-1) < limestone soil (34.50 ∼ 2364.00 cm·d-1), while for soil available water storage, limestone soil on the dolomitic slope (43.26 mm) > yellow soil (20.16 ∼ 35.25 mm) > limestone soil on the limestone slope (17.73 ∼ 34.72 mm). (2) Land-use practices and soil–rock structures have long affected the hydrological characteristics of soil in karst. (3) The bare bedrock on carbonate slopes leads to a reduction in the total amount of soil per unit area on the slope, which compresses the space for vegetation growth and reduces the total amount of water provided by the soil for vegetation growth per unit area, which confirms one of the reasons for the low plant biomass in karst. These results suggest that the utilization of soil water in karst areas should consider the weights of soil type, lithology, and soil–rock structures.

The effect of soil management method on some characteristics of limestone soils in the Muthanna desert

Four areas were selected in the Al-Rehab region, the desert of Muthanna Governorate, which differs in the management style, the duration of agricultural exploitation, and the quality of irrigation water. It was taken in each Pedon region, and the morphological and chemical measurements were revealed and conducted. It was found that the thickness of the A horizon ranged between 10-15 centimeters and the thickness of the B horizon between 25-45 centimeters in all study pedons. The administration style did not affect Hue, as all horizons were within the color (10YR) and chroma, as the colors ranged from light white to very bale brown (10 YR7/4) and white (10YR8/1), the soil texture was between Sandy loam, Sandy clay loam, Loamy Sand. As for the chemical properties, the percentage of lime CaCO3 ranged between (250-400) gm/km-1 and the percentage of gypsum ranged between (1.2-1.8) g. km-1 The electrical conductivity EC ranged between (3.9-18)ds.m-1 , while the organic matter was between (2.1- 13.5) and the CEC values ranged between (12-18Coml.kg). Keywords: soil management, calcareous soils

Response of the Desertification Landscape Patterns to Spatial–Temporal Changes of Land Use: A Case Study of Salaxi in South China Karst

Land use change and karst desertification (KD) are interdependent. It is crucial to investigate the relationship between the KD landscape and spatial–temporal changes in land use for effective and sustainable KD management practices in karst plateau mountains. In this study, we analyzed the spatial and temporal characteristics, evolution in the pattern of land use, and KD in the Salaxi study area from 2009 to 2019, using the landscape pattern index and KD evolution trajectories, and discussed their response relationships. The results revealed the following: (1) In Salaxi, cultivated land predominantly transformed into shrubland, grassland, and woodland. The area of grassland, construction land, and garden land significantly increased, with respective increments of 379.85%, 157.14%, and 1847.81%. Conversely, the area of unutilized land decreased from 53.56 hm2 to 8.55 hm2, with the proportion declining from 0.62% to 0.10%. KD primarily occurs in shrubland, cultivated land, and woodland. (2) The areas of non-KD and potential KD have increased. There was a noticeable conversion of light and medium KD into potential KD, with areas of 1206.84 hm2 and 459.47 hm2, respectively. The KD landscape is dominated by stable and weakening ecological restoration. The comprehensive ranking of the incidence of soil KD in the study area is as follows: yellow soil &gt; yellow-brown soil &gt; coarse bone soil &gt; limestone soil &gt; purple soil. (3) The land use landscape index, the evenness index, and the fragmentation index in the demonstration area increased by 0.263, 0.120, and 0.534, respectively, while the KD landscape index, evenness index, and fragmentation index decreased by 0.360, 0.123, and 1.098, respectively. Additionally, the spreading index and aggregation index of the land use landscape decreased by 9.247 and 3.086, respectively, while the KD landscape’s spreading index and aggregation index increased by 6.688 and 0.430, respectively. Both the sub-dimension indexes of the land use landscape and the KD landscape increased by 0.009. Overall, the landscape pattern of KD changes in response to land use variations and different land types exhibited varying responses to KD. The study of KD and land use landscape patterns can provide references for national strategies on KD control and the development of ecological industries.

Implementation of active and passive control strategies for power generation in a solar chimney power plant: A technical evaluation of Manzanares prototype

Nowadays, it is necessary to develop sustainable energy suppliers according to the concerning environmental issues. Solar energy is one of the appropriate solutions. Solar Chimney Power Plant (SCPP) represents a viable form of solar thermal electricity generation technology. Temporal variations in the driving factors of the plant, especially solar radiation, cause significant fluctuations in output power. This study evaluates active and passive control strategies for achieving more stable power generation in SCPP using Fuzzy Logic Control (FLC) and Thermal Energy Storage (TES) systems. The governing equations for performance modeling have been solved by a developed MATLAB code and validated with experimental data from the Manzanares prototype. Using TES reduced output power fluctuations and showed daily electrical energy generation of 331.9, 314.3, and 308.7 kWh for sand, limestone soil, and water-filled bags, respectively. Implementing an active control strategy with the FLC system alone provided a 25 and 30-kW baseload generation in the mid-hours of the day. Finally, integrating the FLC and TES systems in a hybrid control strategy continued a base load power generation of 12 and 16 kW up to 4 h after sunset, utilizing limestone soil and water-filled bags, respectively.