Although interactions between plants and microbes at the plant–soil interface are known to be important for plant nutrient acquisition, relatively little is known about how root exudates contribute ...to nutrient exchange over the course of plant development. In this study, root exudates from slow‐ and fast‐growing stages of Arabidopsis thaliana plants were collected, chemically analysed and then applied to a sandy nutrient‐depleted soil. We then tracked the impacts of these exudates on soil bacterial communities, soil nutrients (ammonium, nitrate, available phosphorus and potassium) and plant growth. Both pools of exudates shifted bacterial community structure. GeoChip analyses revealed increases in the functional gene potential of both exudate‐treated soils, with similar responses observed for slow‐growing and fast‐growing plant exudate treatments. The fast‐growing stage root exudates induced higher nutrient mineralization and enhanced plant growth as compared to treatments with slow‐growing stage exudates and the control. These results suggest that plants may adjust their exudation patterns over the course of their different growth phases to help tailor microbial recruitment to meet increased nutrient demands during periods demanding faster growth.
Here, we found that the fast‐growing stage root exudates induced higher nutrients mineralization resulted in better plant growth as compared to treatments with slow‐growing stage exudates and the controls. Plants appear to recruit specific beneficial microbiomes throughout their different growth phases, thereby tailoring microbial activities to meet increased nutrient demands during fast‐growing stages.
Biodiversity loss has become a global concern as evidence accumulates that it will negatively affect ecosystem services on which society depends. So far, most studies have focused on the ecological ...consequences of above-ground biodiversity loss; yet a large part of Earth’s biodiversity is literally hidden below ground. Whether reductions of biodiversity in soil communities below ground have consequences for the overall performance of an ecosystem remains unresolved. It is important to investigate this in view of recent observations that soil biodiversity is declining and that soil communities are changing upon land use intensification. We established soil communities differing in composition and diversity and tested their impact on eight ecosystem functions in model grassland communities. We show that soil biodiversity loss and simplification of soil community composition impair multiple ecosystem functions, including plant diversity, decomposition, nutrient retention, and nutrient cycling. The average response of all measured ecosystem functions (ecosystem multifunctionality) exhibited a strong positive linear relationship to indicators of soil biodiversity, suggesting that soil community composition is a key factor in regulating ecosystem functioning. Our results indicate that changes in soil communities and the loss of soil biodiversity threaten ecosystem multifunctionality and sustainability.
The quest for enhancing agricultural yields due to increased pressure on food production has inevitably led to the indiscriminate use of chemical fertilizers and other agrochemicals. Biofertilizers ...are emerging as a suitable alternative to counteract the adverse environmental impacts exerted by synthetic agrochemicals. Biofertilizers facilitate the overall growth and yield of crops in an eco-friendly manner. They contain living or dormant microbes, which are applied to the soil or used for treating crop seeds. One of the foremost candidates in this respect is rhizobacteria. Plant growth promoting rhizobacteria (PGPR) are an important cluster of beneficial, root-colonizing bacteria thriving in the plant rhizosphere and bulk soil. They exhibit synergistic and antagonistic interactions with the soil microbiota and engage in an array of activities of ecological significance. They promote plant growth by facilitating biotic and abiotic stress tolerance and support the nutrition of host plants. Due to their active growth endorsing activities, PGPRs are considered an eco-friendly alternative to hazardous chemical fertilizers. The use of PGPRs as biofertilizers is a biological approach toward the sustainable intensification of agriculture. However, their application for increasing agricultural yields has several pros and cons. Application of potential biofertilizers that perform well in the laboratory and greenhouse conditions often fails to deliver the expected effects on plant development in field settings. Here we review the different types of PGPR-based biofertilizers, discuss the challenges faced in the widespread adoption of biofertilizers, and deliberate the prospects of using biofertilizers to promote sustainable agriculture.
Various applications of biopolymer-based soil treatment (BPST) in geotechnical engineering have been implemented in recent years, including dust control, soil strengthening and erosion control. ...Despite BPST methods can ensure the effectiveness of engineering while meeting environmental protection requirements, BPST technology requires further validation in terms of site applicability, durability, and economic feasibility. This study aims to provide a state-of-the-art review and future prospective of BPST. Current biopolymer types, engineered and assessed in laboratory scales, are described along with site implementation attempts. The effect of biopolymers on soil behavior is reviewed with regard to geotechnical engineering application and practice, including soil consistency limits, strength parameters, hydraulic conductivity, soil-water characteristics, and erosion control. The economic feasibility and sustainability of BPST application in ground improvement and earth stabilization practices is discussed. This review postulates biopolymers to be a promising new, environmentally friendly ground improvement material for geotechnical and construction engineering practice.
Abstract The current study investigated the primary and secondary compressibility characteristics of organic clay with two biopolymers, Chitosan ( D ch ) and Casein ( D ca ) at dosages of 0.5%, 1%, ...2%, and 4%. The primary compression index ( C c ) values were reduced by 18% and 59% at dosage ( D ch and D ca ) of 4% at a consolidation pressure of 800 kPa. The secondary compression indices of chitosan and casein-treated soils fell below the normal range specified for organic soils and lay in the range of 0.01–0.017. The biopolymers also accelerated the consolidation process at all dosages ( D ch ) and 2% D ca . The hydraulic conductivity increased for all dosages of chitosan whereas it declined for all dosages of casein compared to untreated soil. The reliability analysis was conducted for biopolymer-treated soils and presented a rational approach toward the selection of a suitable liner. Chitosan failed to achieve a target reliability index of 3 whereas casein-amended samples attained values equal to and greater than 3 at all dosages and consolidation pressures at COV of K max = 20%. At all dosages, the casein-treated soils exhibited reliability index values greater than 3 up to COV of K max = 40% indicating the higher stability of casein mixes as a liner material.
Plants interact simultaneously with each other and with soil biota, yet the relative importance of competition vs. plant–soil feedback (PSF) on plant performance is poorly understood. Using a ...meta‐analysis of 38 published studies and 150 plant species, we show that effects of interspecific competition (either growing plants with a competitor or singly, or comparing inter‐ vs. intraspecific competition) and PSF (comparing home vs. away soil, live vs. sterile soil, or control vs. fungicide‐treated soil) depended on treatments but were predominantly negative, broadly comparable in magnitude, and additive or synergistic. Stronger competitors experienced more negative PSF than weaker competitors when controlling for density (inter‐ to intraspecific competition), suggesting that PSF could prevent competitive dominance and promote coexistence. When competition was measured against plants growing singly, the strength of competition overwhelmed PSF, indicating that the relative importance of PSF may depend not only on neighbour identity but also density. We evaluate how competition and PSFs might interact across resource gradients; PSF will likely strengthen competitive interactions in high resource environments and enhance facilitative interactions in low‐resource environments. Finally, we provide a framework for filling key knowledge gaps and advancing our understanding of how these biotic interactions influence community structure.
Soil contamination by heavy metals constitutes an important environmental problem, whereas field applicability of existing remediation technologies has encountered numerous obstacles, such as long ...operation time, high chemical cost, large energy consumption, secondary pollution, and soil degradation. Here we report the design and demonstration of a remediation method based on a concept of asymmetrical alternating current electrochemistry that achieves high degrees of contaminant removal for different heavy metals (copper, lead, cadmium) at different initial concentrations (from 100 to 10,000 ppm), all reaching corresponding regulation levels for residential scenario after rational treatment time (from 30 min to 6 h). No excessive nutrient loss in treated soil is observed and no secondary toxic product is produced. Long-term experiment and plant assay show the high sustainability of the method and its feasibility for agricultural use.
As a waste‐derived soil amendment with a long history, biochar has received extensive attention for its capability to improve soil fertility/health; remove or immobilize contaminants in soil, water ...and air; and mitigate climate change. With the aim of producing engineered biochars with excellent performances, new trends in biochar pyrolytic production and modification strategies have emerged. This review critically summarizes novel pyrolysis methods (e.g., microwave‐assisted pyrolysis, co‐pyrolysis and wet pyrolysis) and modification approaches (e.g., mineral modification, photocatalytic modification, electrochemical modification) with a focus on (a) the mechanisms involved in environmental remediation processes including soil immobilization, contaminant adsorption and catalytic oxidation; (b) effects of feedstock and pyrolysis conditions on physicochemical properties; (c) sustainability considerations in novel modification and pyrolysis strategies; and (d) the feasibility of extrapolating the results from wastewater treatment to soil remediation. It is argued that in order to achieve the maximum net environmental benefits, ‘greener’ modification methods are warranted, and the risks associated with pyrolysis of contaminated feedstock in soil amendment and contaminant sorption can be minimized through various novel approaches (e.g., co‐pyrolysis). Furthermore, novel pyrolysis methods can be combined with emerging modification strategies to synthesize more ‘effective’ biochars. Considering the similar aims of modification (e.g., increase surface area, introduce oxygen‐containing functional groups, increase aromaticity), the applicability of several novel approaches could in future can be expanded from contaminant adsorption/degradation in aqueous media to soil remediation/fertility improvement.
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