Excessive Soil Research Articles

Cooperative Action of Fulvic Acid and Bacillus paralicheniformis Ferment in Regulating Soil Microbiota and Improving Soil Fertility and Plant Resistance to Bacterial Wilt Disease.

Excessive continuous cropping and soil degradation, such as acidification, hardening, fertility decline, and the degradation of microbial community, lead to the epidemic of soilborne diseases and cause great loss in agriculture production. Application of fulvic acid can improve the growth and yield of various crops and effectively suppress soilborne plant diseases. Bacillus paralicheniformis strain 285-3 producing poly-gamma-glutamic acid is used to remove the organic acid that can cause soil acidification and increase the fertilizer effect of fulvic acid and the effect of improving soil quality and inhibiting soilborne disease. In field experiments, the application of fulvic acid and Bacillus paralicheniformis ferment effectively reduced the incidence of bacterial wilt disease and improved soil fertility. Both fulvic acid powder and B. paralicheniformis ferment improved soil microbial diversity and increased the complexity and stability of the microbial network. For B. paralicheniformis ferment, the molecular weight of poly-gamma-glutamic acid became smaller after heating, which could better improve the soil microbial community and network structure. In fulvic acid and B. paralicheniformis ferment-treated soils, the synergistic interaction between microorganisms increased and the number of keystone microorganisms increased, which included antagonistic bacteria and plant growth-promoting bacteria. Changes in the microbial community and network structure were the main reason for the reduced incidence of bacterial wilt disease. Application of fulvic acid and Bacillus paralicheniformis ferment improved soil physicochemical properties and effectively controlled bacterial wilt disease by changing microbial community and network structure and enriching antagonistic and beneficial bacteria. IMPORTANCE Continuous cropping tobacco has led to soil degradation and caused soilborne bacterial wilt disease. Fulvic acid as a biostimulator was applied to restore soil and control bacterial wilt disease. For improving its effect, fulvic acid was fermented with Bacillus paralicheniformis strain 285-3 producing poly-gamma-glutamic acid. Fulvic acid and B. paralicheniformis ferment inhibited bacterial wilt disease, improved soil quality, enriched beneficial bacteria, and increased microbial diversity and microbial network complexity. Some keystone microorganisms in fulvic acid and B. paralicheniformis ferment-treated soils had potential antimicrobial activity and plant growth-promoting attributes. Fulvic acid and B. paralicheniformis 285-3 ferment could be used to restore soil quality and microbiota and control bacterial wilt disease. This study found new biomaterial to control soilborne bacterial disease by combining fulvic acid and poly-gamma-glutamic acid application.

Labile carbon inputs support the recovery of bacterial communities, but not fungal communities, from a simulated bovine urine event

Inputs of carbon to soil may be used to stimulate microbial growth and immobilize excess nitrogen from sources such as livestock urine. However, the growth responses of microbial taxa to carbon inputs under conditions of excess soil nitrogen remain poorly understood. Using DNA metabarcoding and a field-based soil lysimeter experiment, we characterised the temporal responses (up to 112 days) of bacterial and fungal communities to a simulated bovine urine event plus inputs of labile carbon (sucrose) at two concentrations. Fungal communities were impacted more strongly than bacterial communities by carbon inputs following the simulated urine event, with more variable responses among taxa. Chytridiomycota and Glomeromycota richness were most negatively affected, and Tremellomycetes richness most positively affected, by carbon inputs. A minority of fungal ASVs had greatly increased proportional abundances in response to carbon, while fungal trophic composition became highly dominated by saprotrophs by the experiment end. Bacterial taxa showed consistent trends of declining (to about 14 days) and recovering (to 112 days) richness in response to urine and carbon inputs, but carbon-related evenness and proportional abundance trends varied between taxa. Proportional abundances of Actinobacteria, Bacteroidetes, Betaproteobacteria, and Gammaproteobacteria increased in response to carbon, whereas proportional abundances of Acidobacteria, candidate division WPS-1, Planctomycetes, Deltaproteobacteria, and Verrucomicrobia decreased. These results show that labile carbon inputs to limit nitrate leaching support the recovery of bacterial communities to bovine urine events but may have long-term impacts on fungal community composition and function, with potential consequences for soil food webs, carbon sequestration, and agricultural productivity.

Engineering Design, Kinematic and Dynamic Analysis of High Lugs Rigid Driving Wheel, a Traction Device for Conventional Agricultural Wheeled Tractors

Traction failure on loose terrain is common in conventional agricultural wheeled tractors due to poor traction ability and lower power transfer efficiency of drive wheels, which leads to excessive energy consumption and soil compaction in agriculture. To overcome the problem, this paper presents a new design of a rigid lugged wheel for use in field tillage operations. This wheel was designed according to field operational requirements and also provided with rubber pads for smooth on-road drives. Kinematic and dynamic analysis of new wheel designs were carried out to study how they move, how they interact with the soil, and how they generate drive force in loose terrain soil. The relationship of wheel lug motion trajectories, displacement, and velocity of the wheel relative to field conditions, different travel reduction rates, and lug penetration/wheel sinkage were analyzed. Wheel-terrain interaction and shear stress-shear displacement relationships when the wheel is driven in soft, deformable terrain were studied using classic soil mechanics principles. It is found that the component of thrust in the direction of driving, i.e., driving force, is ranged between 81.52% and 86.17%, while the vertical component is reported to be less than 30% and further decreases to 9%, which is the compaction avoiding factor. The relationships, thus developed, of wheel parameters, soil stress and thrust characteristics, and wheel drive force were derived and revealed that the traction performance, power transfer efficiency, and trafficability of tractors in loose terrain can be improved by using the newly proposed wheel. A finite element method was used to analyze the designed wheel model for structural stability and optimization. The theoretical analysis results of the new drive wheel are convincing, so further tests and field operation research are recommended for sustainable adoption.

GIS-Based Soil Erosion Risk Assessment in the Watersheds of Bukidnon, Philippines Using the RUSLE Model

The sustainability of watersheds for supplying water and for carbon sequestration and other environmental services depends to a large extent on their susceptibility to soil erosion, particularly under changing climate. This study aimed to assess the risk of soil erosion in the watersheds in Bukidnon, Philippines, determine the spatial distribution of soil loss based on recent land cover maps, and predict soil loss under various rainfall scenarios based on recently reported climate change projections. The soil erosion risk assessment and soil loss prediction made use of GIS and the RUSLE model, while the rainfall scenarios were formulated based on PAGASA’s prediction of drier years for Bukidnon in the early-future to late-future. Results showed that a general increase in soil loss was observed in 2015, over the period from 2010 to 2020, although some watershed clusters also showed a declining trend of soil erosion, particularly the Agusan-Cugman and Maridugao watershed clusters. Nearly 60% of Bukidnon has high to very severe soil loss rates. Under extreme rainfall change scenario with 12.61% less annual rainfall, the soil loss changes were only +1.37% and −2.87% in the category of none-to-slight and very severe, respectively. Results showed that a decrease in rainfall would have little effect on resolving the excessive soil erosion problem in Bukidnon. Results of this study suggest that having more vegetative land cover and employing soil conservation measures may prove to be effective in minimizing the risk of soil erosion in the watersheds. This study provides valuable information to enhance the sustainability of the watersheds. The erosion-prone areas identified will help decision-makers identify priority areas for soil conservation and environmental protection.

Soil cadmium stress affects the phyllosphere microbiome and associated pathogen resistance differently in male and female poplars.

Microorganisms associated with the phyllosphere play a crucial role in protecting plants from diseases, and their composition and diversity are strongly influenced by heavy metal contaminants. Dioecious plants are known to exhibit sexual dimorphism in metal accumulation and tolerance between male and female individuals. Hence, in this study we used male and female full-siblings of Populus deltoides to investigate whether the two sexes present differences in their phyllosphere microbiome structures and in their associated resistance to the leaf pathogenic fungus Pestalotiopsis microspora after exposure to excess soil cadmium (Cd). We found that Cd-treated male plants grew better and accumulated more leaf Cd than females. Cd stress reduced the lesion areas on leaves of both sexes after pathogen infection, but male plants exhibited better resistance than females. More importantly, Cd exposure differentially altered the structure and function of the phyllosphere microbiomes between the male and female plants, with more abundant ecologically beneficial microbes and decreased pathogenic fungal taxa harbored by male plants. In vitro toxicity tests suggested that the sexual difference in pathogen resistance could be attribute to both direct Cd toxicity and indirect shifts in the phyllosphere microbiome. This study provides new information relevant for understanding the underlying mechanisms of the effects of heavy metals involved in plant-pathogen interactions.

Solubility of soil phosphorus in extended waterlogged conditions: An incubation study

Understanding how extended excess soil moisture exacerbated by extreme weather events affects changes in iron (Fe) chemistry is crucial for assessing environmental risk associated with soil phosphorus (P) in high P soils. The objective of our study was to assess the effects of three soil moisture regimes (field capacity, water saturation, and waterlogging), two Fe3+ nitrate level (Fe3+ nitrate addition and no Fe3+ nitrate addition), and the duration of incubation (0, 3, 7, 14, 21, 28, 35, 49, 63, 90, and 120 days) on the (i) reduction of ferric (Fe3+) to ferrous (Fe2+) iron, (ii) solubility of soil P, and (iii) soil microbial biomass and greenhouse gas emissions. Surface soils (0–20 cm) were collected from a maize silage field located in the Fraser Valley (British Columbia, Canada). Decreased redox potential (Eh) of 155 mV in waterlogged soils coincided with the reduction of Fe3+ to Fe2+ of about 1190 mg kg−1 and an increase in soil pH of 0.8 unit compared to field capacity regime at 120 days after pre-incubation (P < 0.001). The increase of pH is due to the microbially-mediated reduction of metal cations which consumes H+ cations. Water-extractable P (Pw) concentrations increased with increasing soil moisture regimes from 1.47 to 2.27, and 2.58 mg kg−1 under field capacity, water saturation, and waterlogged regime respectively. Mehlich-3 extractable P concentrations significantly decreased from 196 to 184 and 172 mg kg−1 under water saturation, field capacity, and waterlogged regime respectively. Concomitant to Pw concentrations, microbial biomass carbon and nitrogen as well as DOC, CO2 and N2O emissions increased with increasing soil moisture regimes. The Fe3+ nitrate addition had an inhibitory effect on Fe reduction, Pw concentration at the first 35 days, and DOC but a stimulating effect on N2O emission. A high N2O emission at the first 63 days, CO2 emission after 35 days, and a non-remarkable concentration of Fe2+ at the first 63 days with Fe3+ nitrate addition under waterlogged soil suggests that NO3− is more preferable than Fe3+ as an electron acceptor. Our results showed that soils maintained under extended anoxic conditions could increase the soluble and available P and subsequent risk of P transport to surface and drainage waters, whereas Fe3+ nitrate addition could minimize or delay this effect.

Tree growth periodicity in the ever‐wet tropical forest of the Americas

Abstract The occurrence of annual growth rings in tropical trees—the result of the seasonal activity of vascular cambium—has been explained by seasonal water deficit or flooding periods. However, little is known about the drivers of annual tree‐ring formation under tropical hyper‐humid conditions without clear seasonal dry periods or flooding (ever‐wet conditions). Shelford's law states that the deficit or the excess of environmental resources limits plant growth. Accordingly, we hypothesize that excess soil moisture, a slight seasonal reduction of precipitation and a reduction in light availability determine rhythmic growth in ever‐wet tropical forests. We first assessed the occurrence of rhythmic growth in 14 tree species from the Biogeographic Chocó Region (annual rainfall 7200 mm) using three methods: Radiocarbon (14C) dating (all studied species), tree‐ring synchronization (4 species that have replicates) and automatic dendrometers (two species). Then, we assessed the effect of environmental drivers (rainfall, short‐wave radiation, temperature and soil moisture) on tree growth based on tree ring and dendrometer observations. We present evidence of annual tree‐ring formation in all 14 studied tree species. Depending on the tree species, we observed positive and negative correlations between growth, water availability and light availability. These relationships suggest that both excess or deficit of environmental resources may explain the seasonal pattern of tree growth. Although we cannot differentiate between excess soil water and low light availability by high cloudiness, we suggest that cloudiness frequency could affect tree growth in these forests. Synthesis. We reveal the annual formation of growth rings in the unexplored wetter‐end tropical forests, where seasonal growth depends on either high soil moisture and hypoxia or light limitations by cloudiness and photosynthesis constraints.

Application of Computational Intelligence Methods in Agricultural Soil–Machine Interaction: A Review

Rapid advancements in technology, particularly in soil tools and agricultural machinery, have led to the proliferation of mechanized agriculture. The interaction between such tools/machines and soil is a complex, dynamic process. The modeling of this interactive process is essential for reducing energy requirements, excessive soil pulverization, and soil compaction, thereby leading to sustainable crop production. Traditional methods that rely on simplistic physics-based models are not often the best approach. Computational intelligence-based approaches are an attractive alternative to traditional methods. These methods are highly versatile, can handle various forms of data, and are adaptive in nature. Recent years have witnessed a surge in adapting such methods in all domains of engineering, including agriculture. These applications leverage not only classical computational intelligence methods, but also emergent ones, such as deep learning. Although classical methods have routinely been applied to the soil–machine interaction studies, the field is yet to harness the more recent developments in computational intelligence. The purpose of this review article is twofold. Firstly, it provides an in-depth description of classical computational intelligence methods, including their underlying theoretical basis, along with a survey of their use in soil–machine interaction research. Hence, it serves as a concise and systematic reference for practicing engineers as well as researchers in this field. Next, this article provides an outline of various emergent methods in computational intelligence, with the aim of introducing state-of-the-art methods to the interested reader and motivating their application in soil–machine interaction research.

Foamed concrete utilizing excavated soil and fly ash for urban underground space backfilling: Physical properties, mechanical properties, and microstructure

Backfilling abandoned urban underground spaces with foamed concrete utilizing excavated soil and fly ash is an environmentally sustainable method. However, a comprehensive evaluation of backfilling-related performance is required. This study develops a foamed concrete utilizing excavated soil and fly ash and examines the physical properties, mechanical properties, and microscopic properties. The results show that the water–solid ratio and soil content have a significant impact on workability and overall stability. Excessive foam and soil will reduce the overall stability of foamed concrete. The UCS dropped as foam, soil, and fly ash content increased. The stress–strain behavior is closely related to Young's modulus but has nothing to do with the UCS. However, the crack initiation and propagation are closely related to the UCS and ingredients, but not to Young's modulus. The lower UCS specimens have compression damage, but the higher UCS specimens frequently suffer deadly piercing and additional splitting damage. Increasing foam, soil, and fly ash content typically improves ductility, which is favorable for guaranteeing the safety of backfilling projects. A proper amount of fly ash can lower pore size and improve pore roundness, according to microstructural development, but an increase in foam content has the opposite effect. The results also imply a significant correlation between the microstructure and macroscopic mechanical strength when the foam content and water-to-solid ratio varied. However, there was a poor correlation between microstructure and macroscopic mechanical strength as soil content and fly ash content changed. Finally, a mechanism of strength and failure development was proposed.

Aerification Strategies Affecting Golf Green Subsurface Properties

Golf greens often become compacted due to: 1. Construction of less-than-ideal soil containing high percentages of silt and clay. 2. Extensive traffic not only from daily play but continuous maintenance often with heavy machinery. 3. Traffic not being sufficiently curtailed during periods of excessive soil moisture. A two-year field experiment was conducted on a 14-year-old U.S. Golf Association (USGA)-specified Crenshaw creeping bentgrass [Agrostis stolonifera L. var palustris (Huds.)] research putting green in Clemson, SC, to evaluate the effects of varying spring HTA size and timing on turfgrass rooting, soil organic matter (OM) and soil properties. Spring HTA treatments included 1.2-cm i.d. tines spaced at 5.1 cm x 5.1 cm in March and May (standard); 1.2-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March only (2x); 0.9-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March and May; and 0.6-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March, April, May and June. All aerification was to a depth of 7.6 cm, with cores removed. Plots aerified with 0.6-cm tines had the least 2-year reduction in dry root weight (DRW). Plots aerified with 1.2-cm tines in March only (2x) had the greatest reduction in DRW and had the deepest thatch mat depth (TMD) across both years. This “doubling up” treatment would not be advisable on greens where low root mass or thatch accumulation is a concern. Plots aerified with 1.2-cm tines had higher thatch OM content in Year 2. Plots aerified with 0.6-cm tines had higher soil OM content across both years. Repetitive equal depth aerification did not create a layer of increased compaction. Turf managers can vary their spring HTA size and timing to increase TQ during periods where this is important (e.g., for a tournament) with manageable effects on surface, OM, and soil properties.

Rice-based Cropping System Intensification in the Coastal Saline area of Bangladesh: Problems and Prospects

The coastal zone environment of Bangladesh is characterised geographically by river deltas and estuaries, where tidal and riverine flooding and varying salinity levels affect agriculture and livelihoods. In this area, the land and agricultural productivity is very low because of several constraints, particularly waterlogging, high salinity of soil and water, freshwater scarcity for crop irrigation and natural disaster. In this review, the objectives are to focus on the limiting factors for crop intensifying and highlighting the opportunities to increase coastal agriculture while enhancing farmer’s livelihoods. Some recent studies demonstrated many opportunities for increasing cropping systems that have not yet been exploited extensively. Rainwater or low saline river water storing in the internal canal can fulfil the water requirement for dry season rice and non-rice crops, thereby increasing growth and yield. Early establishment of “Rabi” crops (non-rice) can utilize maximum low-saline soil water and escape high salinity/drought or heat/storms at later period of the growing stages, but this early sown Rabi crops needs early harvest of Aman rice around 15-30 days earlier than farmer practices. Moreover, early sowing by zero tilled dibbling (such as sunflower, maize, wheat, and potato) in wet soils results in higher yield potential. Using rice straw mulch ~5 t ha-1 has been shown to be highly beneficial for ameliorating soil constraints. A recent study revealed that straw mulch application on soil surface increased soil water and soil solute potential in the upper root zone, reduced soil salinity, soil strength, and cracking which attributed to higher yield. Considering the successful dry season crop establishment and yield potential requires early drainage to remove excess soil water and a drainage system that mitigates waterlogging from heavy rainfall events during the growing season. We expect this review will facilitate the future research planning and execution in this vulnerable coastal environment. Bangladesh Rice J. 25 (2) : 31-43, 2021

Pollution and Climatic Influence on Trees in the Siberian Arctic Wetlands

Siberian Arctic wetlands located within the planetary “warming hotspot” experience pronounced climate-driven vegetation cover changes. Together with warming, wetlands, which are located within the influence of Norilsk copper and nickel industry (69.35° N, 88.12° E), have been strongly influenced by industrial pollutions (sulfur dioxide mostly) since the 1940s. In addition, petroleum products release occurred in 2020 that potentially influenced vegetation vigor. We studied the combined effect of climate warming and pollution on the larch (Larix sibirica Ledeb.) and shrubs’ (Salix spp. and alder, Duschekia fruticosa) growth. Using satellite data (MODIS and Sentinel) processing, we mapped wetlands within the study area. We used on-ground survey, and applied dendrochronology, climate variables, and emissions rate analysis. We sampled woods (kerns) and, based on the tree ring analysis, generated trees and shrubs growth index (GI) chronologies. We analyzed the influence of the SO2 emissions and eco-climate variables (air temperatures, precipitation, soil moisture, and drought index SPEI) on the larch and shrubs GI. We mapped GPP and NPP (gross and net primary productivity) and vegetation index NDVI and temporal trends of these indexes based on the MODIS-derived products. We found that chronic SO2 influence led to larch trees GI decrease that was followed by tree mortality, which was observed until the end of 1990. Since the beginning of the 2000s, the GI of larch and shrubs has increased, which is correlated with elevated air and soil temperature and growth season prolongation, whereas excessive soil moisture negatively influenced GI. Together with that, increasing trends of vegetation indexes (GPP, NPP, and NDVI) were observed on the part of wetland within the zone of former trees’ heavy damage and mortality. The trends began mostly in 2003–2005 and were caused by emissions volume decrease and warming, together with resistant species’ (willows, graminoids, bushes, and birch) growth and invasion. We suggested that increasing productivity trends might partly be attributed to nitrogen fertilization caused by NOx emissions. Finally, we found that diesel fuel spill which happened in 2020 caused no influence on the larch, whereas some aquatic species (mosses mostly) were damaged.

Учет переувлажнения грунтов при проектировании нагельного крепления склонов

Nail slope support has proven itself as an effective engineering protection measure, which is used to increase the stability of slopes, and involves the installation of drilling-injection ground nails together with a flexible cover system. The article considers the issue of improving the existing design methodology of this type of structure, which will include an assessment of the overall stability of the slope, an assessment of the local stability of the surface layer, considering soil moisture saturation, checking the strength of the nail on the ground and material, as well as checking the strength of the nail attachment (ground nail and steel network) on slice. To achieve this goal, there was carried out a selection of soil nailing support for the considered engineering-geological section using the Plaxis 2D PC and there was offered an analytical method for calculating slope stability. The authors also propose a method that can be used for assessing the strength characteristics of soils of the surface layer, considering excessive soil water saturation.

Cryohydromorphic paleosols in the north of West Siberia as indicators of the warm stages of the Late Pleistocene and their link to the cryogenesis development

The aim of the study. The aim of the study was to find and justify specifics of the paleosol development in the north of West Siberia, revealing soils levels, associated with climate warming during sea isotope stages (SIS), namely MIS-5, MIS-3 and at the end of MIS-2. Location and time of the study. The research was conducted during the last 10 years in the representative area between the Polar Circle and the sub-latitudinal sector of the Ob river all over the area. We carried out paleopedological and paleocryological investigations with fieldwork in the basin of the Vakh River (right tributary of Ob), the Taz and Nadym Rivers, where the soil pits were studied, and paleosols were discovered for the first time. Methods. The methodology has been focused on detailed study of the paleosols discovered by the present authors based on the investigation in respect to the interaction of paleopedogenetic and cryogenetic processes. Also, the encountered paleosols have been, as well compared to the surface Holocene soils that comprises an important element of analysis of the paleopedological records. For age determination we applied radiocarbon dating of organic residues and humus, contained in the paleosols, as well as U/Th-dating in paleosols. Results. Several paleosol levels were identified in the study area. The paleosol of the early substage of MIS-5 (MIS-5e) had signs of forest pedogenesis without permafrost, whereas the soils of late substages of MIS-5 and MIS3 showed evidence of gleying and cryogenesis; the paleosol corresponding to the end of MIS-2 was best represented by gleyic pedosediments in the ice-wedge pseudomorphs. The studied paleosols indicate the permafrost state of the soil-forming sediments in all phases of the Late Pleistocene with the exception of MIS-5e; the finding is important for the paleoenvironmental reconstruction. The article presents the data about wide distribution in the study region of the polygonal structures represented by the ice-wedge pseudomorphs formed in the coldest phases MIS-4 and MIS-2. The pseudomorphs were developed syn-cryogenically when permafrost still existed and were closely related to the formation of cryohydromorphic paleosols. Within the entire sequence of MIS-3 deposits initially ground wedges are common, also indicating syn-cryogenic development, however, under less strong freezing conditions than during MIS-2. Yet at the end of MIS-3 in the upper part of the sequence cryohydromorphic soils appeared again, as a sign of approaching to the MIS-2 cryochron. It was shown that the fills of the ice wedge pseudomorphs contain well preserved redeposited materials of the cryohydromorphic paleosols, including fragments of the humus horizons. It was suggested that the material from such redeposited pedosediments could be used for the radiocarbon dating and for sampling for the paleobotanical investigations. Conclusions. The obtained results cast doubt on the hypothesis of domination of the cold deserts and ice sheets in the study region during the Pleistocene and hence the formation of only extremal soils. There is evidence indicating the existence of well-developed vegetation and soil cover during the cryochrons with sufficient and in some areas excessive soil moisture, due to shallow permafrost table. The interaction of the paleopedogenetic and paleocryogenic processes resulted in rather informative relict objects, and their studies provide highly reliable results about the factors of past pedogenesis.

Urban gardens: contribution of small green spaces to sustainable drainage

With climate change increasingly imminent, populations living in urban areas are even more vulnerable to flooding, landslides and other socio-environmental problems caused by poor drainage and excessive soil sealing. Between skyscrapers and the excess of streets and impermeable pavements, urban gardens emerge as an ecological and functional alternative for the improvement of drainage and for the renewal of urban infrastructure. This article aimed to analyze the permeable areas of urban gardens, as well as characterize the infrastructure of these spaces. Six vegetable gardens of distinct neighborhoods of the city of São Paulo were selected for this analysis. These spaces were mapped, visited and measured their permeable and impermeable areas. The results show that these small green spaces analyzed have high permeability rate; most have rainwater capture for irrigation of the beds and two of them preserve their springs. It is concluded, therefore, that the urban gardens studied have the potential to reduce the impact and speed of rainwater, increase the absorption of rainwater by the soil and capture rainwater.

River flooding mechanisms and their changes in Europe revealed by explainable machine learning

Abstract. Climate change may systematically impact hydrometeorological processes and their interactions, resulting in changes in flooding mechanisms. Identifying such changes is important for flood forecasting and projection. Currently, there is a lack of observational evidence regarding trends in flooding mechanisms in Europe, which requires reliable methods to disentangle emerging patterns from the complex interactions between flood drivers. Recently, numerous studies have demonstrated the skill of machine learning (ML) for predictions in hydrology, e.g., for predicting river discharge based on its relationship with meteorological drivers. The relationship, if explained properly, may provide us with new insights into hydrological processes. Here, by using a novel explainable ML framework, combined with cluster analysis, we identify three primary patterns that drive 53 968 annual maximum discharge events in around a thousand European catchments. The patterns can be associated with three catchment-wide river flooding mechanisms: recent precipitation, antecedent precipitation (i.e., excessive soil moisture), and snowmelt. The results indicate that over half of the studied catchments are controlled by a combination of the above mechanisms, especially recent precipitation in combination with excessive soil moisture, which is the dominant mechanism in one-third of the catchments. Over the past 70 years, significant changes in the dominant flooding mechanisms have been detected within a number of European catchments. Generally, the number of snowmelt-induced floods has decreased significantly, whereas floods driven by recent precipitation have increased. The detected changes in flooding mechanisms are consistent with the expected climate change responses, and we highlight the risks associated with the resulting impact on flooding seasonality and magnitude. Overall, the study offers a new perspective on understanding changes in weather and climate extreme events by using explainable ML and demonstrates the prospect of future scientific discoveries supported by artificial intelligence.

Improved analytical solution of lateral soil restraint for pipes buried in dry sand considering arching effects

Abrupt transverse ground movements induced by landslide, strike-slip offset, and excavation can exert excessive soil restraints on buried pipes and threaten the pipe safety. The determination of lateral soil restraint is, therefore, a key factor for the evaluation of buried pipes in such areas. However, effective analysis solutions to assess the area of failure zone of surrounding soils and to estimate the soil resistance on pipes are still limited. In this work, an improved implicit limit equilibrium model is proposed to calculate the ultimate lateral soil restraint of buried pipes in dry sand, in which the effect of active soil wedge is considered, and the heights of equal settlement plane in both passive and active wedges can be estimated. Comparisons are made between collected physical modeling results and calculations from different methods. Results show that the proposed method yields a better approximation to the measured data. Parametric studies are subsequently conducted, which illustrate that the ultimate soil lateral restraint is influenced by the pipe diameter, internal friction angle, and constrained modulus of soil. The influence of effective soil unit weight is minimal. The proposed method is beneficial for safety evaluation of buried pipes subject to lateral dragging.

Impact of Climate Change on Soil Erosion

Global warming is expected to result in a more vigorous hydrological cycle, including total rainfall and more frequent high-intensity rainfall events, which affect soil erosion and cause a threat to agricultural land sustainability and productivity, particularly in tropical and subtropical regions. This study aims to determine the effects of climate change on soil erosion in Taiwan. This experiment assesses the risk of soil erosion in Taiwan over 2 – 200 years. To determine the predictor of soil erosion risk, the study used USPED. Result showed there was an increase in sediment yield because of soil erosion. Hence, targeting conservation practices to erosion-prone areas, expanding conservation coverage, and adapting agronomic practices may be necessary to prevent excessive soil erosion under climate change scenarios that include intensified precipitation.

Numerical Modeling of Liquefaction-Induced Downdrag: Validation against Centrifuge Model Tests

Earthquake-induced soil liquefaction can cause soil settlement around piles, resulting in drag load and pile settlement after shaking stops. Estimating the axial load distribution and pile settlement is important for designing and evaluating the performance of axially loaded piles in liquefiable soils. Commonly used neutral plane solution methods model the liquefiable layer as an equivalent consolidating clay layer without considering the sequencing and pattern of excess pore pressure dissipation and soil settlement. Moreover, changes in the pile shaft and the tip resistance due to excess pore pressures are ignored. A TzQzLiq numerical model was developed using the existing TzLiq material and the new QzLiq material for modeling liquefaction-induced downdrag on piles. The model accounts for the change in the pile’s shaft and tip capacity as free-field excess pore pressures develop or dissipate in soil. The developed numerical model was validated against data from a series of large centrifuge model tests, and the procedure for obtaining the necessary information and data from those is described. Additionally, a sensitivity study on TzLiq and QzLiq material properties was performed to study their effect on the developed drag load and pile settlement. Analysis results show that the proposed numerical model can reasonably predict the time histories of axial load distribution and settlement of axially loaded piles in liquefiable soils both during and postshaking.

Изменчивость морфоструктурных показателей разных возрастных поколений в популяциях сосны (Pinus sylvestris L.) в условиях постоянного избыточного увлажнения почв северной тайги Архангельской области

The data is presented for studying the variability of morphostructural parameters of different age (g1 and g2) pine populations under conditions of constant excessive soil moisture of the northern taiga of the Arkhangelsk region. The frequency of occurrence distribution of the age and morphostructural parameters (size of the trunk and crown, self-pruning, length of coarse bark, size and number of side shoots, length and life span of needles) of trees is shown. It has been established that pine trees with smaller trunk and crown sizes, worse self-pruning are more common. Greater height and diameter of the trunk, length and diameter of the crown, better self-pruning, a greater length of the coarse bark is observed in the older generation (g2). This is due to the older age of the trees. It has been established that the relationship between the height of the trunk and the age of the trees is higher in the samples of young generative trees. It was revealed that the young generation (g1) has a significantly greater length and mass of cones, the length, width and height of the apophysis of seed scales compared to the older generation (g2).