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"Soil environment"
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A world without soil : the past, present, and precarious future of the Earth beneath our feet
A scientist's manifesto addressing a soil loss crisis accelerated by poor conservation practices and climate change.
Book
Modelling root-soil interactions using three-dimensional models of root growth, architecture and function
Three-dimensional root architectural models emerged in the late 1980s, providing an opportunity to conceptualise and investigate that all important part of plants that is typically hidden and difficult to measure and study. These models have progressed from representing pre-defined root architectural arrangements, to simulating root growth in response to heterogeneous soil environments. This was done through incorporating soil properties and more complete descriptions of plant function, moving into the realm of functional-structural plant modelling. Modelling studies are often designed to investigate the relationship between root architectural traits and root distribution in soil, and the spatio-temporal variability of resource supply. Modelling root systems presents an opportunity to investigate functional tradeoffs between foraging strategies (i.e. shallow vs deep rooting) for contrasting resources (immobile versus mobile resources), and their dependence on soil type, rainfall and other environmental conditions. The complexity of the interactions between root traits and environment emphasises the need for models in which traits and environmental conditions can be independently manipulated, unlike in the real world. We provide an overview of the development of three-dimensional root architectural models from their origins, to their place today in the world of functional-structural plant modelling. The uses and capability of root architectural models to represent virtual plants and soil environment are addressed. We compare features of six current models, RootTyp, SimRoot, ROOTMAP, SPACSYS, R-SWMS, and RootBox, and discuss the future development of functional-structural root architectural modelling. Functional-structural root architectural models are being used to investigate numerous root-soil interactions, over a range of spatial scales. They are not only providing insights into the relationships between architecture, morphology and functional efficiency, but are also developing into tools that aid in the design of agricultural management schemes and in the selection of root traits for improving plant performance in specific environments.
Journal Article
The phytohormones underlying the plant lateral root development in fluctuated soil environments
Background
Plants rely heavily on the formation of post-embryonic organs, such as leaves, branches, and lateral roots, to adapt to varying soil conditions. Lateral roots (LR) play a crucial role in the plant root system, serving as the primary factor in the exploration of water and nutrients in the soil. The development of LR is meticulously controlled by phytohormones to respond to the information obtained from the surrounding soil. This regulation ensures an optimal arrangement of lateral roots, enabling efficient nutrient absorption and adaptation to the challenging environmental conditions.
Scope
This review summarizes recent progress in understanding the mechanisms of lateral root layout in different soil micro-environments and the role of phytohormones in mediating LR development for soil adaptation.
Conclusions
The intricate signaling network governing LR layout involves interactions among various soil factors, which are mediated by phytohormones. Despite its complexity, recent studies have yielded significant insights that can be applied to optimize LR arrangement in soil profiles through genetic and cultivation methods to enhance crop yield and stress tolerance.
Journal Article
Effects of Two Trichoderma Strains on Plant Growth, Rhizosphere Soil Nutrients, and Fungal Community of Pinus sylvestris var. mongolica Annual Seedlings
Trichoderma spp. are proposed as major plant growth-promoting fungi that widely exist in the natural environment. These strains have the abilities of rapid growth and reproduction and efficient transformation of soil nutrients. Moreover, they can change the plant rhizosphere soil environment and promote plant growth. Pinus sylvestris var. mongolica has the characteristics of strong drought resistance and fast growth and plays an important role in ecological construction and environmental restoration. The effects on the growth of annual seedlings, root structure, rhizosphere soil nutrients, enzyme activity, and fungal community structure of P. sylvestris var. mongolica were studied after inoculation with Trichoderma harzianum E15 and Trichoderma virens ZT05, separately. The results showed that after inoculation with T. harzianum E15 and T. virens ZT05, seedling biomass, root structure index, soil nutrients, and soil enzyme activity were significantly increased compared with the control (p < 0.05). There were significant differences in the effects of T. harzianum E15 and T. virens ZT05 inoculation on the growth and rhizosphere soil nutrient of P. sylvestris var. mongolica (p < 0.05). For the E15 treatment, the seedling height, ground diameter, and total biomass of seedlings were higher than that those of the ZT05 treatment, and the rhizosphere soil nutrient content and enzyme activity of the ZT05 treatment were higher than that of the E15 treatment. The results of alpha and beta diversity analyses showed that the fungi community structure of rhizosphere soil was significantly different (p < 0.05) among the three treatments (inoculated with T. harzianum E15, T. virens ZT05, and not inoculated with Trichoderma). Overall, Trichoderma inoculation was correlated with the change of rhizosphere soil nutrient content.
Journal Article
Chemical Processes Affecting the Mobility of Heavy Metals and Metalloids in Soil Environments
The mobility, bioavailability, and toxicity of metal(loid)s are influenced by their interactions with phyllosilicates, organic matter, variable charge minerals, and microorganisms. Physicochemical processes influencing the chemistry of metal(loid)s in soil environments include sorption/desorption, solution complexation, oxidation-reduction, and precipitation-dissolution reactions. In particular, the sorption/desorption reactions of metal(loid)s on/from soil sorbents are influenced by pH, nature of soil components, and presence and concentrations of cations and inorganic anions. In recent years, many extraction tests have been used for assessing trace elements mobility and phytoavailability. Chemical speciation of toxic elements may be achieved by spectroscopic analyses (XAS), which provide information about oxidation state, symmetry, and identity of the coordinating ligand environment, and possible solid phases.
Journal Article
Numerical simulation and experimental study of three-phase distribution characteristics of leaked light non-aqueous phase liquid from buried pipelines in soils containing groundwater and gas
Leakage accidents of buried pipelines have become increasingly common due to the prolonged service of some pipelines which have been in use for more than 150 years. Therefore, there is an urgent need for accurate prediction of pollution scope to aid in the development of emergency remediation strategies. This study investigated the distribution of a light non-aqueous phase liquid in soils containing gas and water through numerical simulations and laboratory experiments. Firstly, a three-dimensional porous medium model was established using ANSYS FLUENT, and for the first time, the distribution of gas and groundwater in soil environments was simulated in the model. Subsequently, the distribution of the three phases of diesel, gas, and water in soil was studied with different leakage velocities and it was found that the leakage velocity played a significant role in the distribution. The areas of diesel in soils at 60 min were 0.112 m
2
, 0.194 m
2
, 0.217 m
2
, and 0.252 m
2
, with corresponding volumes of 0.028 m
3
, 0.070 m
3
, 0.086 m
3
, and 0.106 m
3
, respectively, for leakage velocities of 1.3 m/s, 3.4 m/s, 4.6 m/s, and 4.9 m/s. Calculation formulas for distribution areas and volumes were also developed to aid in future prevention and control strategies under different leakage velocities. The study also compared the distribution areas and volumes of diesel in soils with and without groundwater, and it was found that distribution scopes were larger in soils containing groundwater due to capillary force. In order to validate the accuracy of the numerical simulation, laboratory experiments were conducted to study the diffusion of oil, gas, and water under different leakage velocities. The results showed good agreement between the experiments and the simulations. The research findings are of great significance for preventing soil pollution and provide a theoretical basis for developing scientifically sound soil remediation strategies.
Journal Article
Relationship Between Plant Diversity and Soil Environment in Karst Urban Remnant Mountains: A Comparative Analysis of Two Types
Understanding the characteristics of plant diversity and its relationship with the soil environment in urban remnant habitats before and after their transformation into parks is of great significance for strengthening urban biodiversity conservation. To investigate the changes in plant diversity characteristics and their relationship with the soil environment following the transformation of urban remnant natural mountains (URNM) into urban remnant mountain parks (URMP), we conducted a study in the urban area of Guiyang City, China. We sampled 90 plots across five typical URNM and five typical URMP. Plant diversity and its relationship with soil properties were evaluated using four taxonomic diversity indices and 9 soil physicochemical properties. The results showed that URNM exhibited higher plant diversity and richer species richness compared to URMP. In URNM, plant survival conditions deteriorate with the elevation of slope position, resulting in the highest plant diversity at lower slopes and the lowest at upper slopes. However, intense human disturbances lead to the opposite pattern in URMP. Additionally, soil bulk density, total phosphorus, and total potassium (TK) were found to be higher in URMP than in URNM. C/N, C/P, and soil organic carbon were identified as the main factors influencing plant diversity in URNM, with explanatory rates of 20.1%, 15.4%, and 8.6%, respectively. In URMP, TK was the most significant factor, explaining over 55.9% of plant diversity. These findings indicate that the transformation of karst urban remnant mountains into parks leads to a simplification of plant species composition and a reduction in plant diversity. This process also alters the characteristics of soil environmental factors and their relationship with plant diversity. These changes highlight the need for careful management strategies in urban park development to mitigate biodiversity loss and maintain soil health, which are crucial for the sustainability of urban ecosystems. The transformation of karst urban remnant mountains into mountain parks had not only simplified the composition of plant species and reduced biodiversity, but also changed the characteristics of soil environmental factors and their distribution pattern with plant diversity, thus reshaping their mutual relationship.
Journal Article
Chickpea shows genotype-specific nodulation responses across soil nitrogen environment and root disease resistance categories
Background
The ability of chickpea to obtain sufficient nitrogen via its symbiotic relationship with
Mesorhizobium ciceri
is of critical importance in supporting growth and grain production. A number of factors can affect this symbiotic relationship including abiotic conditions, plant genotype, and disruptions to host signalling/perception networks. In order to support improved nodule formation in chickpea, we investigated how plant genotype and soil nutrient availability affect chickpea nodule formation and nitrogen fixation. Further, using transcriptomic profiling, we sought to identify gene expression patterns that characterize highly nodulated genotypes.
Results
A study involving six chickpea varieties demonstrated large genotype by soil nitrogen interaction effects on nodulation and further identified agronomic traits of genotypes (such as shoot weight) associated with high nodulation. We broadened our scope to consider 29 varieties and breeding lines to examine the relationship between soilborne disease resistance and the number of nodules developed and real-time nitrogen fixation. Results of this larger study supported the earlier genotype specific findings, however, disease resistance did not explain differences in nodulation across genotypes. Transcriptional profiling of six chickpea genotypes indicates that genes associated with signalling, N transport and cellular localization, as opposed to genes associated with the classical nodulation pathway, are more likely to predict whether a given genotype will exhibit high levels of nodule formation.
Conclusions
This research identified a number of key abiotic and genetic factors affecting chickpea nodule development and nitrogen fixation. These findings indicate that an improved understanding of genotype-specific factors affecting chickpea nodule induction and function are key research areas necessary to improving the benefits of rhizobial symbiosis in chickpea.
Journal Article
Succession of bacterial community structure in response to a one-time application of biochar in barley rhizosphere and bulk soils
Biochar is often used as an amendment to enhance soil fertility by directly increasing soil pH and nutrient availability. However, biochar may also improve soil fertility indirectly by altering the succession of bacterial communities that, in turn, may alter nutrient supply and availability. To determine how biochar affects soil bacterial richness and diversity, as well as how bacterial communities respond to biochar across space and time, we studied the rhizosphere and bulk soils of potted barley plants for 2 years. Adding biochar significantly increased bacterial community richness (Chao 1 richness index) by the end of the second year in the rhizosphere (P = 0.037), but in bulk soils, we observed an increase in richness in Year 1 that dissipated by Year 2. In contrast to richness, adding biochar only had a significant effect on bacterial community diversity (Shannon diversity index) in Year 1 seedling stage (P < 0.001), but the effect dissipated thereafter. We also found that adding biochar increased the relative abundances of Actinobacteria and Proteobacteria but decreased the relative abundances of Acidobacteria and Chloroflexi, suggesting these communities were sensitive to biochar inputs. The biochar-sensitive genera belonging to Actinobacteria and Proteobacteria made up 45%–58% of sensitive taxa in both rhizosphere and bulk soils. Of the Proteobacteria sensitive to adding biochar, Nitrosospira and Sphingomonas were most abundant in the rhizosphere relative to bulk soils. However, despite the initial increase of biochar sensitive responders in the rhizosphere, their numbers decreased after 2 years and had 179 fewer genera than bulk soils. Our findings suggest the effect of adding biochar was relatively short-lived and that the influence of the plant phenology was a stronger driver of bacterial community change than biochar inputs 2 years after its application. Altogether, the succession of soil bacterial community structure reflected changes in the soil environment induced by the combined effect of biochar, rhizospheric inputs, and plant phenology, suggesting that changes in microbial community composition observed after amending soils with biochar, may also contribute to changes in soil fertility.
Journal Article
Synergistic effect on the performance of ash-based bricks with glass wastes and granite tailings along with strength prediction by adopting machine learning approach
The study proposes a novel and sustainable method to appropriately utilize wastes from granite as well as glass industries in brick manufacturing. An ecofriendly and low-cost manufacturing process of ash-based bricks pertaining to the Indian standard codal provisions that can be adopted on the commercial scale is deliberated. The research also recommends the method for predicting the strength of the ash-based bricks using machine learning algorithms like random forests and decision trees. For positive synergy in the performance, both the granite tailings and glass waste must be used together. Using the granite tailings and glass waste together led to a significant reduction of 75% in the fly ash requirement without compromising the brick’s performance. The addition of the granite tailings and glass waste in the mix could increase the strength of the brick by 90.5% and 37.7%, respectively. Beyond 30% dosage of granite, tailings are not recommended as they may lead to the poor gradation of particles and weak bonding in the microstructure. The glass waste in the mixture should not be more than 15% as it causes the dilution of pozzolanic reactions thereby forming fewer hydrated compounds. Brick’s durability is known after exposing the specimens for 1 year to sewers and biogenic corrosion environment, marine environment, and saline soil environment, respectively. The inclusion of the industrial wastes significantly reduced the specimen damage in the extreme environmental conditions along with the least absorption rates. The dosage of ash, granite tailings, and glass waste has to be maintained around 15%, 30%, and 15%, respectively for attaining the optimum performance. Out of the generated machine learning algorithms, only random forests could be able to predict the values accurately with
R
2
values at 0.90 and with comparatively lesser errors.
Journal Article