Abandoned farmlands are increasing due to socio-economic changes and land marginalization, and they require sustainable land management practices. Biocrusts are a common cover on the topsoil of abandoned farmlands and play an important role in improving soil stability and erosion resistance. The critical functions of biocrusts are known to mostly rely on their biofilaments and extracellular polymeric substances (EPS), but how these components act at microscopic scale is still unknown, while rheological methods are able to provide new insights into biocrust microstructural stability at particle scale. Here, bare soil and two representative types of biocrusts (cyanobacterial and moss crusts) developed on sandy (Ustipsamments) and sandy loam (Haplustepts) soils in abandoned farmlands in the northern Chinese Loess Plateau were collected at a sampling depth of 2 cm. Changes in the rheological properties of the biocrusts were analyzed with respect to their biofilament network and EPS contents to provide possible explanations. The rheological results showed that compared with bare soil, storage and loss moduli were decreased by the biocrusts on sandy soil, but they were increased by the biocrusts on sandy loam soil. Other rheological parameters tau max, gamma L, gamma YP, and Iz of biocrusts on both soils were significantly higher than those of bare soil, showing higher viscoelasticity. And the moss crusts had about 10 times higher rheological property values than the cyanobacterial crusts. Analysis from SEM images showed that the moss crusts had higher biofilament network parameters than the cyanobacterial crusts, including nodes, crosslink density, branches, branching ratio and mesh index, and biofilament density, indicating that the biofilament network structure in the moss crusts was more compact and complex in contrast to the cyanobacterial crusts. Additionally, EPS content of the moss crusts was higher than that of the cyanobacterial crusts on both soils. Overall, the crosslink density, biofilament density, and EPS content of the biocrusts were significantly and positively correlated with their gamma YP and Iz. The interaction between crosslink density and biofilament density contributed 73.2 % of gamma YP, and that between crosslink density and EPS content contributed 84.0 % of Iz. Our findings highlight the biocrusts-induced changes of abandoned farmland soil rheological properties in drylands, and the importance of biocrust biofilament network and EPS in maintaining abandoned farmland soil microstructural stability to resist soil water/wind erosion and degradation, providing a new perspective for sustainable management of abandoned farmlands.

Application of organic mulches has repeatedly been shown to reduce infestation with Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), the Colorado potato beetle (CPB). In order to determine if the nutritional status of potatoes as affected by mulch could explain the mulch effects in potatoes against CPB, we determined potato leaf nutrient composition in unmulched control plots and plots mulched with grass-clover or triticale-vetch and assessed mulch effects on CPB damage and development in the field during 3 years and under controlled conditions. In mulched plots, foliar Mo, Cl, and K contents were consistently higher than those without mulch, and leaf damage by CPB was reduced significantly. In addition, increased B contents were associated with undamaged plant material, while higher Zn contents were associated with leaves damaged by CPB. Under controlled conditions, CPB fitness was not affected by mulch application. Overall, reduced CPB damage could not be clearly attributed to altered foliar nutrient contents due to mulching. It is thus more likely that CPB reductions in mulched systems are due to mechanisms other than an altered nutrient balance.

Roads in places with seasonal frost undergo several freeze-thaw (F-T) cycles annually, resulting in variable degrees of deterioration in the mechanical properties of the subgrade. To methodically investigate the mechanical properties of subgrade clay during freeze-thaw cycles and to develop a precise constitutive model, triaxial tests were conducted under the most unfavorable soil conditions. The studies indicate that the degrading impact of the freeze-thaw cycle on the mechanical characteristics of the soil predominantly transpires during the initial freeze-thaw cycle. Soil strength reaches its minimum after the third freeze-thaw cycle, followed by a slight increase, and ultimately stabilizes between the fifth and seventh cycles. The maximum strength reduction at confining pressures of 100 kPa, 200 kPa, and 300 kPa was 39%, 37%, and 33%, respectively. As confining pressure escalates, the reduction in soil strength lessens. The soil demonstrates differing degrees of degradation following F-T cycles at both high and low compaction levels, with the degradation becoming increasingly evident as compaction intensifies. Utilizing the experimental database, a genetic algorithm (GA) enhanced backpropagation neural network (BPNN) model (GA-BPNN) and a BP-aided Duncan-Chang (D-C) model were developed to forecast the mechanical properties of freeze-thaw clay. The R2 values for the two models on the test set were 0.995 and 0.967, respectively. The efficacy of these two models demonstrates that machine learning can attain commendable outcomes in extensive data structures (total stress-strain curve) as well as exhibit superior performance in limited data (model parameters) while developing the constitutive model of soil.

This direction paper explores the evolving landscape of physics-informed machine learning (PIML) methodologies in the field of geotechnical engineering, aiming to provide a comprehensive overview of current advancements and propose future research directions. Recognising the intrinsic connection between geophysical phenomena and geotechnical processes, we delve into the inter of physics-based models and machine learning techniques. The paper begins by elucidating the significance of incorporating physics-informed approaches, emphasising their potential to enhance the interpretability, accuracy and reliability of predictive models in geotechnical applications. We review recent applications of PIML in soil mechanics, hydrology, geotechnical site investigation, slope stability analysis and foundation engineering, showcasing successes and challenges. Furthermore, we identify promising avenues for future research in geotechnical engineering, including the integration of domain knowledge, model explainability, multiphysics and multiscale problems, complex constitutive models, as well as digital twins and large AI models within PIML frameworks. As geotechnical engineering embraces the paradigm shift towards data-driven methodologies, this direction paper offers valuable insights for researchers and practitioners, guiding the trajectory of PIML for sustainable and resilient infrastructure development.

Waterfront and submarine retaining structures are normally exposed to catastrophic seepage conditions under the effect of tidal and occasionally heavy rainfall effect, resulting in a decreased passive earth thrust and thus the higher risk of instability of retaining structures. To examine the effect of seepage flow on the magnitude and distribution of passive earth thrust, this paper assumes a composite curved-planar failure surface and presents a modified method of passive earth pressure considering the seepage flow effect. The flow field and pore pressure are firstly solved by the two-dimensional (2D) Laplace equation using the Fourier series expansion. The effective reaction force acting on the composite failure surface is then obtained using a modified K & ouml;tter equation. Compared to conventional methods based on limit equilibrium, the present method facilitates a straightforward assessment of both the magnitude and distribution of passive earth thrust without the prior assumption of the application point. The outcomes highlight that the passive earth thrust decreases with the ratios of permeability coefficients. The greater effective friction angle and a smaller ratio of permeability coefficients result in the lower application point of the passive earth thrust.

Agricultural land has long been regarded as a resource for food production, but over time, the effects of climate change have reduced the ability of soil to produce food efficiently. Nowadays, farmers have moved from traditional to modern techniques of farming. Across the globe, plastic mulching has become widely used on farmlands. According to a few studies, the breakdown of plastic mulches releases microplastics (MPs) into the soil. Despite studies reporting the presence of MPs in soils, there are limited studies on the sources and impacts on soil organisms, plant growth, fruits, and human health. This study evaluated research articles collected from the Web of Science to assess the origin of MP in soil and crops and its effects on soil organisms, plants, and humans. It was observed that MPs come from different sources such as waste water, organic fertilizer, irrigation water, sewage, and sludge. Plastic mulching, which can spread across agricultural fields at varying depths, is the dominant source. Furthermore, it was observed that MPs alter crop quality, reduce the leaf count of wheat, and decrease the root length of crops such as maize, water spinach, black gram, and garden cress. MP can decrease the abundance of soil microarthropods and nematodes, damage the intestinal walls of earthworms, and reduce the feeding and excretion of snails. MP causes liver damage, inflammation, respiratory irritation, and immunological issues. Ultimately, these contaminants (MPs) can transfer and have been detected in fruits and vegetables, which pose adverse effects on human health.

This study evaluates DNA damage and multi-element exposure in populations from La Mojana, a region of North Colombia heavily impacted by artisanal and small-scale gold mining (ASGM). DNA damage markers from the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay, including micronucleated binucleated cells (MNBN), nuclear buds (NBUDs) and nucleoplasmic bridges (NPB), were assessed in 71 exposed individuals and 37 unexposed participants. Exposed individuals had significantly higher MNBN frequencies (PR = 1.26, 95% CI: 1.02-1.57, p = 0.039). Principal Component Analysis (PCA) identified the Soil-Derived Mining-Associated Elements (PC1), including V, Fe, Al, Co, Ba, Se and Mn, as being strongly associated with high MNBN frequencies in the exposed population (PR = 10.45, 95% CI: 9.75-12.18, p < 0.001). GAMLSS modeling revealed non-linear effects of PC1, with greater increases in MNBN at higher concentrations, especially in exposed individuals. These results highlight the dual role of essential and toxic elements, with low concentrations being potentially protective but higher concentrations increasing genotoxicity. Women consistently exhibited higher MNBN frequencies than men, suggesting sex-specific susceptibilities. This study highlights the compounded risks of chronic metal exposure in mining-impacted regions and underscores the urgent need for targeted interventions to mitigate genotoxic risks in vulnerable populations.

Phosphorus and potassium are essential macronutrients, and potassium dihydrogen phosphate, a compound containing both, plays a vital role in plant growth and reproduction. However, its rapid leaching poses significant environmental concerns, lessening its practical utility. To overcome this issue, a biodegradable hydrogel based on amla was synthesized through graft polymerization and evaluated as a water-retaining material for agricultural applications, specifically for the controlled release of fertilizers. The synthesized hydrogel was characterized using FTIR, SEM, XRD, and TGA. Its swelling properties, water retention capacity, porosity, and density were also examined. The biodegradable nature of the synthesized hydrogel was confirmed via soil burial and composting techniques, with FTIR used to validate the degradation. The hydrogel degraded almost entirely within 64 days in compost soil and 72 days in burial soil. Finally, potassium dihydrogen phosphate release studies were conducted, and the data were analyzed using Fick's law of diffusion and various kinetic models (zero order, first order, Higuchi, and Korsemers Peppas). The release pattern was measured via UV spectrophotometry over 45,000 min, demonstrating controlled nutrient delivery. These findings suggested that the synthesized hydrogel matrix has strong potential as an effective water retention system and for regulated nutrient release.

Soil liquefaction caused by earthquakes is a devastating occurrence that can compromise the foundations of buildings and other structures, leading to considerable economic losses. Among the new remedies against liquefaction, Induced Partial Saturation (IPS) is regarded as one of the most promising technologies. In order to improve liquefaction resistance and the fluid phase's compressibility, gas or air bubbles are introduced into the pore water of sandy soils. This article deals with the general laboratory evaluation of a sand under partially saturated conditions and under cyclic loading to assess if this technology is applicable for a ground improvement of the examined soil. The use of the Axis Translation Technique for sample desaturation and diffusion-stable butyl membranes significantly influences the laboratory results. Additionally, it is found that the trapped air bubbles of the partially saturated samples act like a damping mechanism, which are reflected in the stress paths of the deviator stress q over the mean pressure p with an inclination of 1 : 3. Zum Verfl & uuml;ssigungsverhalten von teilges & auml;ttigtem SandDie durch Erdbeben verursachte Bodenverfl & uuml;ssigung ist ein verheerendes Ereignis, das die Fundamente von Geb & auml;uden und anderen Bauwerken gef & auml;hrden und zu erheblichen wirtschaftlichen Verlusten f & uuml;hren kann. Die induzierte partielle S & auml;ttigung (Induced Partial Saturation, IPS) gilt als eine der vielversprechendsten Technologien unter den neuartigen Baugrundverbesserungen gegen Verfl & uuml;ssigung. Um den Verfl & uuml;ssigungswiderstand und die Kompressibilit & auml;t der fl & uuml;ssigen Phase zu verbessern, werden dabei Gas- oder Luftblasen in das Porenwasser sandiger B & ouml;den eingebracht. Dieser Beitrag besch & auml;ftigt sich mit der generellen labortechnischen Evaluierung eines Sandes unter teilges & auml;ttigten Verh & auml;ltnissen und unter zyklischer Beanspruchung zur Beurteilung, inwiefern sich diese Baugrundverbesserung f & uuml;r den untersuchten Boden eignet. Die Verwendung der Axis Translation Technique zur Probenentw & auml;sserung und die Verwendung von diffusionsstabilen Butylmembranen haben einen erheblichen Einfluss auf die Laborergebnisse. Au ss erdem ist festzustellen, dass die eingeschlossenen Luftblasen der teilges & auml;ttigten Proben wie eine D & auml;mpfung wirken und sich in den Spannungspfaden der Deviatorspannung q & uuml;ber dem mittleren Druck p mit einer Neigung 1 : 3 widerspiegeln.

The increasing expenses and environmental repercussions associated with phosphorus (P) fertiliser underscore the necessity for precision-managed application methods. These changes affect pastoral systems, where cool-season grasses like perennial ryegrass and meadow fescue form beneficial relationships with Epichlo & euml; endophytes. Understanding how fertilisers influence these endophytes, host grasses, and insect pests is crucial, as Epichlo & euml; endophytes enhance resistance to some herbivorous insects. This study examined the indirect impact of various P fertiliser regimes on cool-season grasses, which serve as food sources for porina larvae (Wiseana copularis), a significant pasture pest in New Zealand. Endophyte-infected (Epichlo & euml; sp. LpTG-3 strain AR37) perennial ryegrass and meadow fescue infected with E. uncinata (strain MaxR (AR1017)), alongside their endophyte-free counterparts were grown in P-enriched soil with varying Olsen P levels (9, 18, 28, and 78 mg/L). Freeze-dried foliage was added to semi-synthetic diets and fed to porina larvae in a no-choice assay. Measurements included diet consumption, porina survival, weight gain. Measurements in foliage included fungal alkaloid concentration, fungal biomass, and plant nutrient levels. Endophyte infection of AR37 and MaxR significantly reduced porina diet consumption, larval weight gain and survival irrespective of soil Olsen P levels to the plant. Loline alkaloid concentration in MaxR-infected herbage increased with increasing soil Olsen P levels while fungal mass remained unchanged. In endophyte-free grasses, porina larvae significantly increased their diet consumption, weight gain and survival as the Olsen P level available to the host plant increased. While endophyte strains AR37 and MaxR continue to protect their hosts under different Olsen P regimes, these results suggest that the improved performance of porina on endophyte-free plants is largely driven by P-induced changes in food quality. Here, we discuss the implications of porina damage in New Zealand pastures in the context of decreasing P availability.