Eco-friendly dual-edged management of fly ash and its antagonistic interplay with Meloidogyne incognita on beetroot (Beta vulgaris L.)

Exploiting fly ash as an ecofriendly pesticide/nematicide on Abesmoschus esculuntus: Insights into soil amendment-induced antioxidant fight against nematode mediated ROS

Conventional pest control measures, such as chemical pesticides and nematicides, have limited efficacy and raise environmental concerns, necessitating sustainable and eco-friendly alternatives for pest management. Therefore, to find a complementary eco-friendly pesticide/nematicide, this study investigated the role of fly ash (FA) in managing a notorious pest, Meloidogyne javanica and its impact on the growth and physiology of Abelmoschus esculentus. Molecular characterization using SSU and LSU rDNA gene markers confirmed the identity of Indian M. javanica as belonging to the same species. Biotic stress induced by nematode infection was significantly alleviated (P < 0.05) by FA application at a 20% w/v, regulating of ROS accumulation (44.1% reduction in superoxide anions and 39.7% reduction in hydrogen peroxide content) in the host plant. Moreover, FA enhanced antioxidant defence enzymes like superoxide dismutase (46.6%) and catalase (112%) to combat nematode induced ROS. Furthermore, the application of FA at a 20% concentration significantly improved the biomass and biochemical attributes of okra. Fly ash also upregulated the activity of the important osmo-protectant proline (11.5 μmol/g FW) to mitigate nematode stress in host cells. Suppression of disease indices like gall index and reproduction factor, combined with in-vitro experiments, revealed that FA exhibits strong nematode mortality capacity and thus can be used as a sustainable and eco-friendly control agent against root-knot nematodes.

Potential use of fly ash in structural fill application: a review

Globally, over the years, fly ash (FA) has been successfully used in structural fills as a substitute for conventional infill material. As per the global industry trends and forecast report, the utilization rate of FA in 2021 was 74% in China, 65% in India, and 70% in the United States (US). Despite substantial research being done on the usage of FA as a substitute all over the world, only up to 15% by mass of total produce has been utilized as a replacement for infill soils. This indicates that there is a lot of potential for increased usage. From the view point of increasing the utilization rate, the present study focuses on summarizing the geotechnical properties of FA by taking strength characteristics into account as compared to conventional infill material. Moreover, this review underlines the chemical composition, index, and engineering properties. Firstly, it reviews the current state of the application of FA in structural fills by considering 141 articles that have been published since 2004 to till date. Secondly, it emphasizes the limited literature available on structural fill applications of FA. It also recommends the classification of FA besides the existing ASTM codes. Moreover, considering future research, this review also highlights the gaps in the previous studies, such as the need for amendments in existing standard codes for FA utilization as structural fill.

Exploring the scientific research on coal fly ash and agriculture: knowledge mapping and future research directions

This paper aims at synthesizing the scientific research on coal fly ash and agriculture using bibliometric analysis. The research on fly ash and agriculture has grown at 6.7% annually during 1973-2022, where much attention has been received after 2007. The number of publications on coal fly ash and agriculture reached above 100 in the year 2010, which further increased to 299 by 2020. The research productivity has been assessed as the most influential countries, journals, and documents in terms of a number of publications and citations on fly ash and agriculture. India is the most productive country in terms of knowledge on coal fly ash and agriculture with 38% of the global publications, while Environmental Science and Pollution Research is the leading journal with 19 publications. The article on assessing the impact of fly ash incorporation in soil systems by Pandey and Singh (2010), having 349 citations with 26.85 citations per year is one of the leading publications globally. Further, science mapping has been conducted to comprehend the current research focus and discover the emerging themes for future research. The finding of the thematic map based on the level of development and importance indicate that FA can be effectively explored as soil-additive for improved physical, chemical and biological properties and enhanced plant nutrients. The findings provide several aspects of fly ash and suggest future research directions to study the potential of using coal fly ash in agriculture to gain an agronomic advantage.

Coal fly ash application as an eco-friendly approach for modulating the growth, yield, and biochemical constituents of Withania somnifera L. plants

The solid waste known as fly ash, which is produced when coal is burned in thermal power plants, is sustainably used in agriculture. It is an excellent soil supplement for plant growth and development since it contains some desired nutrients (macro and micro), as well as being porous. The present study was done to evaluate the effect of different fly ash levels on Withania somnifera. The present study aimed to assess the impact of various fly ash (FA) concentrations on growth, yield, photosynthetic pigments, biochemical parameters, and cell viability of W. somnifera. The results showed that FA enhanced physical and chemical properties of soil like pH, electric conductivity, porosity, water-holding capacity, and nutrients. The low doses of FA-amended soil (15%) significantly increased the shoot length (36%), root length (24.5%), fresh weight of shoots and roots (107.8 and 50.6%), dry weight of shoots and roots (61.9 and 47.1%), number of fruits (70.4%), carotenoid (43%), total chlorophyll (44.3%), relative water content (109.3%), protein content (20.4%), proline content (110.3%), total phenols (116.1%), nitrogen (20.3%), phosphorus (16.9%), and potassium (26.4%). On the other hand, the higher doses, i.e., 25% of fly ash showed a negative effect on all the above parameters and induced oxidative stress by increasing lipid peroxidation (33.1%) and hydrogen peroxide (102.0%) and improving the activities of antioxidant enzymes and osmolytes. Compared to the control plants, the plants growing in soil enriched with 15 and 25% fly ash had larger stomata pores when examined using a scanning electron microscope. In addition, according to a confocal microscopic analysis of the roots of W. somnifera, higher fly ash concentrations caused membrane damage, as evidenced by an increase in the number of stained nuclei. Moreover, several functional groups and peaks of the biomolecules represented in the control and 15% of fly ash were alcohols, phenols, allenes, ketenes, isocynates, and hydrocarbons. Gas chromatography-mass spectrometry analysis of the methanol extract of W. somnifera leaves cultivated in soil amended with 15% fly ash shows the presence of 47 bioactive compounds. The most abundant compounds in the methanol extract were cis-9-hexadecenal (22.33%), n-hexadecanoic acid (9.68%), cinnamic acid (6.37%), glycidyl oleate (3.88%), nonanoic acid (3.48%), and pyranone (3.57%). The lower concentrations of FA (15%) can be used to enhance plant growth and lower the accumulation of FA that results in environmental pollution.

Additive facilitated co-composting of lignocellulosic biomass waste, approach towards minimizing greenhouse gas emissions: An up to date review

Although the composting of lignocellulosic biomass is an emerging waste-to-wealth approach towards organic waste management and circular economy, it still has some environmental loopholes that must be addressed to make it more sustainable and reliable. The significant difficulties encountered when composting lignocellulosic waste biomass are consequently discussed in this study, as well as the advances in science that have been achieved throughout time to handle these problems in a sustainable manner. It discusses an important global concern, the emission of greenhouse gases during the composting process which limits its applicability on a broader scale. Furthermore, it discusses in detail, how different organic minerals and biological additives modify the physiochemical and biological characteristics of compost, aiming at developing eco-friendly compost with minimum odor, greenhouse gases emission and an optimum C/N ratio. It brings novel insights by demonstrating the effect of additives on the microbial enzymes and their pathways involved in the degradation of lignocellulosic biomass. This review also highlights the limitations of the application of additives in composting and suggests possible ways to overcome these limitations in the future for the sustainable and eco-friendly management of agricultural waste. The present review concludes that the use of additives in the co-composting of lignocellulosic biomass can be a viable remedy for the ongoing issues with the management of lignocellulosic waste.

Mechanistic Insights and Potential Use of Siderophores Producing Microbes in Rhizosphere for Mitigation of Stress in Plants Grown in Degraded Land

Plant growth performance under a stressful environment, notably in the agriculture field, is directly correlated with the rapid growth of the human population, which triggers the pressure on crop productivity. Plants perceived many stresses owing to degraded land, which induces low plant productivity and, therefore, becomes a foremost concern for the future to face a situation of food scarcity. Land degradation is a very notable environmental issue at the local, regional, and global levels for agriculture. Land degradation generates global problems such as drought desertification, heavy metal contamination, and soil salinity, which pose challenges to achieving many UN Sustainable Development goals. The plant itself has a varied algorithm for the mitigation of stresses arising due to degraded land; the rhizospheric system of the plant has diverse modes and efficient mechanisms to cope with stress by numerous root-associated microbes. The suitable root-associated microbes and components of root exudate interplay against stress and build adaptation against stress-mediated mechanisms. The problem of iron-deficient soil is rising owing to increasing degraded land across the globe, which hampers plant growth productivity. Therefore, in the context to tackle these issues, the present review aims to identify plant-stress status owing to iron-deficient soil and its probable eco-friendly solution. Siderophores are well-recognized iron-chelating agents produced by numerous microbes and are associated with the rhizosphere. These siderophore-producing microbes are eco-friendly and sustainable agents, which may be managing plant stresses in the degraded land. The review also focuses on the molecular mechanisms of siderophores and their chemistry, cross-talk between plant root and siderophores-producing microbes to combat plant stress, and the utilization of siderophores in plant growth on degraded land.