Fly Ash–Silica Solubilizing Bacteria Consortium: A Bio-Mineral Approach for Enhanced Soil Health and Paddy Productivity in Alfisols of the Cauvery Delta Zone of Tamil Nadu

Fly Ash–Silica Solubilizing Bacteria Consortium: A Bio-Mineral Approach for Enhanced Soil Health and Paddy Productivity in Alfisols of the Cauvery Delta Zone of Tamil Nadu | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Fly Ash–Silica Solubilizing Bacteria Consortium: A Bio-Mineral Approach for Enhanced Soil Health and Paddy Productivity in Alfisols of the Cauvery Delta Zone of Tamil Nadu G Porkodi, G. Anand, P. Ramamoorthy, R. Abirami, S. Sheeba This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7446758/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Fly ash, a by-product, contains a rich array of minerals and has demonstrated potential as a soil amendment. However, its synergistic interaction with organic and microbial inputs for improving crop productivity, particularly in silicate-deficient soils, remains insufficiently characterized. The present investigation was conducted during the Rabi season of 2024–2025 at Melpuliyankudi village, Cuddalore District, Tamil Nadu, with the objective of evaluating the integrated effects of fly ash, farmyard manure (FYM), green manure (GM), and silicate solubilizing bacteria (SSB) on rice yield and soil fertility. The experiment was laid out in a randomized block design (RBD) comprising thirteen treatments with three replications on sandy clay loam soils characterized by low organic carbon and deficient macronutrient status. Among the treatments, the integrated application of Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB significantly outperformed others, recording the highest grain yield (6623 kg ha⁻¹) and straw yield (8005 kg ha⁻¹), along with enhanced uptake of nitrogen (N), phosphorus (P), potassium (K), and silicon (Si). Post-harvest soil analysis revealed substantial improvements in available nutrient status under integrated nutrient management regimes. The findings underscore the potential of leveraging industrial by-products in combination with biological and organic amendments to sustainably enhance rice productivity and soil health. Further long-term studies across diverse agro-ecological zones are warranted to validate these outcomes and formulate region-specific nutrient management strategies. Flyash SSB Soil fertility Nutrient dynamics Silica uptake Rice yield Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Silicon (Si) is not classified as an essential nutrient for higher plants, extensive research has demonstrated its significant role in promoting optimal growth and physiological development in numerous plant taxa, with pronounced benefits observed in tropical graminaceous species such as Oryza sativa [ 1 , 2 ]. Rice ( Oryza sativa L.) is a vital dietary staple for over three billion people across Asia, particularly valued for its role in regional food security. In the Indian state of Tamil Nadu, rice is cultivated year-round under submerged lowland conditions [ 3 , 4 ]. This continuous cropping system accelerates the depletion of silicon (Si) reserves in the soil, leading to nutrient deficiency. Notably, rice is among the most efficient accumulators of silicon, a nutrient that significantly contributes to the plant's ability to withstand various biotic and abiotic stress factors [ 5 ]. Fly ash is a fine particulate material consisting primarily of non-combustible mineral residues from coal, along with small amounts of unburned carbon resulting from incomplete combustion [ 6 ]. Irrespective of its source, fly ash consistently contains appreciable concentrations of silicon, making it a potential alternative silicon amendment for agricultural soils [ 2 , 5 , 7 ]. Although fly ash contains a substantial quantity of silicon, most of it exists in forms that are not readily soluble. Plants, including rice, can absorb silicon only in its bioavailable form, primarily as monosilicic acid (H₄SiO₄), which is present in very limited amounts despite the high total silicon content [ 8 ]. Fly ash serves as a slow-release source of silicon, enabling a regulated supply that mitigates the risk of excessive silicon accumulation in rice plants [ 9 ]. The application of silicate-solubilizing bacteria (SSB) significantly promotes the mobilization of insoluble silicate minerals into plant-available forms, predominantly monosilicic acid. This biotransformation is facilitated through several microbial-mediated mechanisms, including rhizosphere acidification, exudation of organic acids and siderophores, and the enzymatic breakdown of mineral structures [ 10 ]. Consequently, the enhanced solubilization of silicon increases its availability to rice roots, thereby reinforcing cell wall architecture and augmenting the plant's resilience against both biotic and abiotic stressors [ 11 , 12 ]. Contemporary research predominantly emphasizes chemical strategies to enhance silicon availability, often neglecting biologically driven approaches that offer greater sustainability. Notably, there is a paucity of integrated studies evaluating the co-application of fly ash and silicate-solubilizing bacteria (SSB) as a bio-mineral consortium for improving rice ( Oryza sativa L.) productivity in the Alfisols of Cauvery Delta Zone, which are inherently deficient in plant-available silicon and organic carbon. This study aims to elucidate the effects of the Fly Ash–SSB consortium on the growth, yield, and stress tolerance of rice, while concurrently assessing its synergistic influence on the mobilization of bioavailable silicon and the enrichment of essential soil nutrients. 2. Materials and Methods 2.1 Site Description and Soil Characteristics A field experiment was conducted during the Rabi season of 2024–2025 at a farmer’s field in Melpuliyankudi village, Cuddalore District, Tamil Nadu, situated under the agro-climatic jurisdiction of Cauvery Delta Zone. The experimental site is characterized by a tropical climate and sandy clay loam soils. Pre-experimental composite soil samples collected from the 0–15 cm depth revealed a neutral soil reaction (pH 7.21), non-saline electrical conductivity (0.85 dS m − 1 ), and low organic carbon content (4.16 g kg − 1 ), as determined by the Walkley and Black method [ 13 ]. The available nitrogen (201 kg ha − 1 ), phosphorus (13.2 kg ha − 1 ), and potassium (244 kg ha − 1 ) were quantified using alkaline KMnO₄ method [ 14 ], sodium bicarbonate extraction [ 15 ], and neutral ammonium acetate method [ 13 ], respectively. Micronutrients such as Zn (0.61 mg kg − 1 ), Cu (0.76 mg kg − 1 ), Fe (7.62 mg kg − 1 ), and Mn (3.57 mg kg − 1 ) were extracted using the DTPA method [ 16 ], indicating variable micronutrient availability in the initial soil condition. The available silicon content of the soil was 60.70 mg ha − 1 , and the water-soluble silicon content was 21.49 kg ha − 1 . These were quantified using the ammonium acetate (0.5 M, pH 4.8) extraction method [ 31 ], for available silicon, and the distilled water (1:10) extraction method [ 32 ], for water-soluble silicon. 2.2 Treatment Details A randomized block design (RBD) comprising thirteen treatment combinations with three replications was employed to assess the interactive effects of fly ash (applied at 15, 20, and 25 t ha⁻¹), farmyard manure (FYM; 12.5 t ha⁻¹), green manure (GM; 6.25 t ha⁻¹), and silicate-solubilizing bacteria (SSB) on rice performance. A control treatment devoid of any amendments was included for baseline comparison. The complete treatment structure is presented in Table 1 . Table 1 Details of treatments used in the experiment Treatment Code Treatment Description T1 Control (No amendment) T2 Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ T3 Fly Ash @ 20 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ T4 Fly Ash @ 25 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ T5 Fly Ash @ 15 t ha⁻¹ + GM @ 6.25 t ha⁻¹ T6 Fly Ash @ 20 t ha⁻¹ + GM @ 6.25 t ha⁻¹ T7 Fly Ash @ 25 t ha⁻¹ + GM @ 6.25 t ha⁻¹ T8 Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB T9 Fly Ash @ 20 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB T10 Fly Ash @ 25 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB T11 Fly Ash @ 15 t ha⁻¹ + GM @ 6.25 t ha⁻¹ + SSB T12 Fly Ash @ 20 t ha⁻¹ + GM @ 6.25 t ha⁻¹ + SSB T13 Fly Ash @ 25 t ha⁻¹ + GM @ 6.25 t ha⁻¹ + SSB 2.3 Source and Application of inputs Fly ash sourced from Neyveli Lignite Corporation was air-dried, passed through a 2 mm sieve, and subjected to physicochemical characterization. The material exhibited an alkaline pH of 8.51, electrical conductivity (EC) of 1.57 dS m⁻¹, and bulk density (BD) of 1.12 Mg m⁻³. Nutrient analysis revealed available nitrogen (34.15 mg kg⁻¹), phosphorus (9.53 mg kg⁻¹), and potassium (61.42 mg kg⁻¹), available silica (152 mg kg − 1 ) in addition to calcium, magnesium, and DTPA-extractable micronutrients, following standard protocols [ 13 , 16 ]. Well-decomposed farmyard manure (FYM) and green manure (sun hemp, Crotalaria juncea ) were incorporated as per treatment specifications. Silicate-solubilizing bacteria (SSB) were applied in liquid formulation through seedling root dipping at the time of transplanting and subsequently by soil drenching on the 7th and 30th days after transplanting. 2.4 Crop Management Rice (Oryza sativa L.) was employed as the test crop for this investigation. The experimental field was prepared using conventional tillage operations, and uniform seedlings were transplanted on 16 October 2024, maintaining a spacing of 20 × 15 cm. The crop was cultivated under assured irrigation, adhering to recommended agronomic and plant protection practices as prescribed for the region [ 17 ]. All treatment plots received a uniform basal application of chemical fertilizers according to standard fertilizer recommendations to isolate and assess the specific effects of organic amendments and fly ash on crop performance. 2.5 Data Collection and Analysis Grain and straw yields were quantified at physiological maturity on 11 February 2025. Post-harvest soil samples were collected from the 0–15 cm depth and analyzed for available nitrogen, phosphorus, and potassium following standard protocols. Plant tissues were oven-dried, finely ground, and digested using a tri-acid mixture (HNO₃:H₂SO₄:HClO₄, 9:1:4). Nutrient uptake was calculated by multiplying nutrient concentrations with respective dry matter yields. Silicon uptake in both grain and straw was determined through alkaline extraction and quantified using the molybdenum blue colorimetric method [ 18 ]. The experimental data were subjected to analysis of variance (ANOVA) for randomized block design (RBD) to evaluate treatment effects. Mean comparisons were performed using the Critical Difference (CD) test at a 5% probability level. Standard Error of Difference (SEd) and CD values were used to assess statistical significance across treatments [ 19 ]. 3. Results and Discussion 3.1 Influence on Grain and Straw Yields The integrated application of fly ash, farmyard manure (FYM), and silicate-solubilizing bacteria (SSB) markedly enhanced rice yield. Among the treatments, T8 (Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB) recorded the maximum grain and straw yields of 6,623 and 8,005 kg ha⁻¹, respectively, representing a 47.8% increase in grain yield over the control (T1: 4,480 kg ha⁻¹ for grain and 4,594 kg ha⁻¹ for straw), thereby demonstrating the synergistic effect of integrated nutrient management on rice productivity (Fig. 1). The observed yield enhancement can be attributed to the synergistic benefits of the integrated treatment: fly ash contributed essential macro- and micronutrients; farmyard manure (FYM) improved soil physical properties and stimulated microbial activity; and silicate solubilizing bacteria (SSB) facilitated the dissolution of silicate minerals, thereby enhancing nutrient solubilization and uptake [ 20 , 21 ]. 3.2 Silica Uptake in Grain and Straw Silicon uptake plays a critical role in reinforcing plant structure, enhancing photosynthesis, and improving resistance to biotic and abiotic stresses [ 22 ]. The highest silica uptake occurred under T10 (Fly Ash @ 25 t ha⁻¹ + FYM + SSB) with grain and straw values of 33.1 and 211.9 kg ha⁻¹, respectively. T9 and T8 also showed substantial increases (T9: grain 30.6; straw 182.1; T8: grain 26.8; straw 167.6 kg ha⁻¹) (Fig. 1). This enhancement is attributable to the solubilization of fly ash–bound silica by SSB via organic acid and chelator production [ 23 ]. While higher fly ash rates improved silica uptake further, T8 emerged as the optimal treatment, balancing yield enhancement, nutrient uptake, soil fertility, and economic efficiency [ 24 ]. 3.3 Correlation between Yield and Silicon Uptake The results demonstrate a positive correlation between silicon (Si) uptake and rice yield (Fig. 2). Treatment T8 (Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB) not only recorded the highest grain yield (6,623 kg ha⁻¹) but also exhibited substantial silica uptake in both grain (26.8 kg ha⁻¹) and straw (167.6 kg ha⁻¹). This trend continues with T9 and T10, where increased rates of fly ash further enhanced silica uptake (T10: 33.1 in grain and 211.9 kg ha⁻¹ in straw) and maintained high yields (though slightly lower than T8). This strong alignment indicates that higher Si uptake correlates with greater biomass and grain formation. Silicon's role in strengthening cell walls, improving water-use efficiency, and stress resistance contributes significantly to yield enhancement [ 25 ]. The SSB-mediated solubilization of silica from fly ash amplifies Si bioavailability, thus improving plant health and productivity [ 26 ]. Therefore, the yield increase observed in treatments like T8–T10 is directly linked to improved silicon nutrition. This supports the view that silicon is not just a beneficial element but a yield-determining factor under integrated nutrient management practices [ 27 ]. 3.4 Pest Resistance Gains with Higher Silicon Silicon-treated rice reduced FAW (Fall Army Worm - Spodoptera frugiperda ) larval weight gain by 36% compared to controls, irrespective of injury-induced priming [ 28 ]. A treatment such as T8, with a ~ 62% increase in total silicon uptake relative to the control, could be expected to reduce fall armyworm larval weight gain by approximately 36%, based on comparable outcomes in silicon-amended rice. Similarly, T10’s ~ 104% Si uplift may impart even greater resistance, potentially exceeding a 50% reduction in pest performance. Field evidence supports these expectations: silicon amendments (e.g., 300 kg SiO₂ ha⁻¹) significantly decreased damage from stem borers, leaf folders, and planthoppers and improved yield by 16.4%. Silicon amendment significantly decreased survival rates in first and third instars of leaf folder larvae ( Cnaphalocrocis medinalis ), primarily via enhanced leaf silicification and primed antioxidant pathways [ 29 ]. Finally it highlights the positive association between silica uptake (both grain and straw) and final yield, suggesting that treatments enhancing silica accumulation tend to improve productivity (Fig. 3 ). 3.5 Post-Harvest Soil Fertility and Nutrient Uptake The integrated application of fly ash, farmyard manure (FYM), and silicate-solubilizing bacteria (SSB) markedly improved post-harvest soil fertility and nutrient uptake in rice (Fig. 4 & 5 ). Treatment T8 (Fly ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB) achieved the highest concentrations of available macronutrients in the post-harvest soil, with N, P, and K levels of 280.00, 12.68, and 238.00 kg ha⁻¹, respectively, compared to 187.00, 10.90, and 140.00 kg ha⁻¹ in the control. These improvements are attributable to the intrinsic nutrient content of fly ash, the organic matter and nutrient contributions from FYM, and the enhanced mineralization of organic matter stimulated by SSB-mediated microbial activity [ 30 ]. In parallel, T8 also exhibited superior plant nutrient uptake, with total N, P, and K assimilation reaching 66.20, 22.50, and 49.05 kg ha⁻¹, respectively, far exceeding control values (N: 39.10; P: 8.59; K: 21.60 kg ha⁻¹). This enhancement is likely due to the synergistic effects of improved nutrient availability in the rhizosphere, increased root proliferation from FYM-induced improvements in soil structure, and enhanced solubilization of nutrient-bearing minerals via SSB activity [ 20 ]. Silica uptake in grain and straw of paddy The uptake of silica by paddy grain and straw was significantly influenced by the application of fly ash in combination with organic amendments and silicate solubilizing bacteria (SSB) (Table 2 ). The grain silica uptake ranged from 17.6 kg ha⁻¹ (control) to a maximum of 33.1 kg ha⁻¹ (T10: Fly ash @ 25 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB). Similarly, straw silica uptake varied between 112.8 kg ha⁻¹ in control and 211.9 kg ha⁻¹ in T10, recording nearly a 88% increase over control. Among the treatments, combined application of fly ash, FYM and SSB (T8–T10) or fly ash, green manure and SSB (T11–T13) significantly enhanced silica uptake compared to sole application of fly ash with FYM or GM (T2 -T7). The beneficial effect was more pronounced in higher fly ash levels (25 t ha⁻¹), indicating that increased external supply of amorphous silica along with microbial solubilization improved plant availability. The observed improvement can thus be ascribed to the combined effect of fly ash as a direct source of silica [ 30 ], organic manures enhancing mobilization through complexation and microbial activity [ 34 ] and SSB promoting solubilization of minerals into plant-available monosilicic acid [ 35 ], collectively resulting in greater silica uptake efficiency. Comparable results have also been documented by earlier researchers. [ 36 ] highlighted that organic amendments play a crucial role in mobilizing silicon from native soil pools. The addition of organic matter enhances soil microbial activity and releases organic acids, which solubilize bound forms of silicon, thereby increasing the pool of plant-available silicic acid. This indicates that integrating organic amendments with external sources of Si, such as fly ash, can significantly improve the efficiency of silicon mobilization and cycling within the rice ecosystem [ 36 ]. The combined application of fly ash and microbial inoculants led to higher silica accumulation in rice tissues compared to individual applications [ 37 ]. The presence of silicate solubilizing bacteria (SSB) in particular enhanced the release of available silicon from fly ash particles, which in turn increased plant uptake and assimilation. Enhanced silica accumulation in rice has been widely recognized to contribute to structural strengthening of cell walls, improved resistance to lodging, and greater tolerance to biotic and abiotic stresses [ 38 ]. These findings support the present study, where the integration of fly ash, organic amendments, and SSB showed a synergistic effect in improving both grain and straw silica uptake in paddy [ 37 ]. Table 2 Effect of fly ash, organic amendments, and silicate solubilizing bacteria (SSB) on silica uptake (kg ha − 1 ) in paddy grain and straw Tr. No. Treatment details Silica uptake kg ha − 1 Grain Straw T1 Control 17.6 112.8 T2 Fly Ash @ 15 t ha -1 + FYM @ 12.5 t ha -1 19.5 129.5 T3 Fly Ash @ 20 t ha -1 + FYM @ 12.5 t ha -1 21.7 134.3 T4 Fly Ash @ 25 t ha -1 + FYM @ 12.5 t ha -1 23.6 146.2 T5 Fly Ash @ 15 t ha -1 + GM @ 6.25 t ha -1 19.1 122.4 T6 Fly Ash @ 20 t ha -1 + GM @ 6.25 t ha -1 21.4 130.5 T7 Fly Ash @ 25 t ha -1 + GM @ 6.25 t ha -1 22.4 139.5 T8 Fly Ash @ 15 t ha -1 + FYM @ 12.5 t ha -1 + SSB 26.8 167.6 T9 Fly Ash @ 20 t ha -1 + FYM @ 12.5 t ha -1 + SSB 30.6 182.1 T10 Fly Ash @ 25 t ha -1 + FYM @ 12.5 t ha -1 + SSB 33.1 211.9 T11 Fly Ash @ 15 t ha -1 + GM @ 6.25 t ha -1 + SSB 24.3 156.3 T12 Fly Ash @ 20 t ha -1 + GM @ 6.25 t ha -1 + SSB 28.5 170.7 T13 Fly Ash @ 25 t ha -1 + GM @ 6.25 t ha -1 + SSB 31.7 204.2 Mean 14.28 154.5 SEd 0.34 3.02 CD(P = 0.05) 0.69 6.23 The study clearly establishes that the integrated use of fly ash, organic manures, and silicate-solubilizing bacteria (SSB) is an effective strategy for improving rice productivity, nutrient uptake, and soil fertility in silicate-deficient sandy clay loam soils. Among the different combinations, Fly Ash @ 15 t ha − 1 + FYM @ 12.5 t ha − 1 + SSB excelled in enhancing grain yield, nutrient uptake, and maintaining post-harvest soil fertility, while Fly Ash @ 25 t ha − 1 + FYM/GM + SSB recorded the highest silica accumulation in both grain and straw. The synergistic effect of fly ash as a direct source of silica, FYM/GM as mobilizers, and SSB as solubilizers ensured greater availability of plant-available silicic acid, leading to improved uptake efficiency. Enhanced silica content not only contributed to better plant growth, resistance to lodging, and stress tolerance but also improved straw residue quality, which upon recycling can enrich soil fertility. These findings underscore the potential of utilizing industrial by-products like fly ash in combination with organic and microbial inputs as a sustainable nutrient management strategy for rice-based systems under similar agro-ecological conditions. Declarations Consent to Participate : Consent was obtained from every researcher who participated in the experiment. Consent for Publication: The authors have given permission for this research paper to be published in the journal. Competing Interest : The authors declare no competing interests Funding: As part of the first author's required research duties, there is no funding assistance for the research for this study. Author Contribution Authors acknowledge the support of the Sugarcane Research Station, Cuddalore, for offering the research facilities during the course of the investigation of this research. Author Contributions Conceptualization: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami and S. Sheeba] Methodology: [G. Porkodi, S. Sheeba] Formal analysis: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami] Investigation: [G. Porkodi, G. Anand, R.Abirami] Writing -original draft: [G. Porkodi, G. Anand, R.Abirami] Writing review and editing: [G. Porkodi, G. Anand, R.Abirami]; Supervision:[ G. Porkodi, G. Anand, R.Abirami, S. Sheeba]. Acknowledgements: Authors acknowledge the support of Sugarcane Research Station, Cuddalore for offering the research facilities during the course of investigation of this research. Author Contributions Conceptualization: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami and S. Sheeba] Methodology: [G. Porkodi, S. Sheeba] R. Anitha, R. Nageswari, V. Dhanushkodi, M. Yuvaraj] Formal analysis: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami] Investigation: [G. Porkodi, G. Anand, R.Abirami] Writing -original draft: [R. Anitha, C. Tamil selvi, P. Jeyakumar] Writing review and editing: [G. Porkodi, G. Anand, R.Abirami]; Supervision:[ G. Porkodi, G. Anand, R.Abirami, S. Sheeba]. Data Availability: All relevant data are within the research paper. References Chaiwong, N. & Prom-U-Thai, C. Significant roles of silicon for improving crop productivity and factors affecting silicon uptake and accumulation in rice: a review. 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Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 09 May, 2026 Reviews received at journal 12 Jan, 2026 Reviewers agreed at journal 03 Jan, 2026 Reviewers agreed at journal 20 Nov, 2025 Reviews received at journal 05 Nov, 2025 Reviewers agreed at journal 29 Oct, 2025 Reviewers invited by journal 07 Sep, 2025 Editor assigned by journal 27 Aug, 2025 Submission checks completed at journal 27 Aug, 2025 First submitted to journal 24 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7446758","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":512280744,"identity":"a308afae-a757-4480-8752-e1dd3849fad0","order_by":0,"name":"G Porkodi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2klEQVRIiWNgGAWjYHACZgYGNgkGBvYGmABjA27FKFp4DpOmBUhJJBPpKnP23scGH8osGOQj3x978LONQZ6/gbntAT4tlj3HjRNnnJNgMLydzG7Y28ZgOOMAY7sBPi0GN9KYD/O2AbXMTmaT4G1jYNzAwAjkEqVl5mE2yb9tDPZEaUkGaZGXYGaTBtqSSFCLZc8xZkOgX3gMeJLNpGXOSSTPOExAizl7G7PEh7I6Ofn2g88k35TZ2Pa3tz/D7zAozWNwAExLgOMJL4AHp3wDAZWjYBSMglEwcgEAG348Cqak2KMAAAAASUVORK5CYII=","orcid":"","institution":"Tamil Nadu Agricultural University","correspondingAuthor":true,"prefix":"","firstName":"G","middleName":"","lastName":"Porkodi","suffix":""},{"id":512280745,"identity":"ab673892-b6d2-43f7-a53b-4c31b877c43e","order_by":1,"name":"G. Anand","email":"","orcid":"","institution":"ICAR-Krishi Vigyan Kendra","correspondingAuthor":false,"prefix":"","firstName":"G.","middleName":"","lastName":"Anand","suffix":""},{"id":512280746,"identity":"68a521fc-7997-4540-8a2c-39f788c7094b","order_by":2,"name":"P. Ramamoorthy","email":"","orcid":"","institution":"Don Bosco College of Agriculture","correspondingAuthor":false,"prefix":"","firstName":"P.","middleName":"","lastName":"Ramamoorthy","suffix":""},{"id":512280747,"identity":"c07a0e0a-a563-4d1c-b4bb-683b1d2326c3","order_by":3,"name":"R. Abirami","email":"","orcid":"","institution":"Ph.D, Tamil Nadu Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"R.","middleName":"","lastName":"Abirami","suffix":""},{"id":512280748,"identity":"380b7324-f3f5-4c15-a673-3ff2df81e0f2","order_by":4,"name":"S. Sheeba","email":"","orcid":"","institution":"Agricultural College and Research Institute","correspondingAuthor":false,"prefix":"","firstName":"S.","middleName":"","lastName":"Sheeba","suffix":""}],"badges":[],"createdAt":"2025-08-24 14:23:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7446758/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7446758/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91162536,"identity":"2336f5e3-db88-4be7-98ad-7d1dea145a48","added_by":"auto","created_at":"2025-09-12 09:35:35","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":53433,"visible":true,"origin":"","legend":"\u003cp\u003ePanels \u003cstrong\u003eA\u003c/strong\u003e and \u003cstrong\u003eB\u003c/strong\u003edepict silica uptake (kg ha⁻¹) in rice grain and straw, respectively, across thirteen treatments (T1–T13). The color gradient from light yellow to deep blue represents increasing silica accumulation, with the highest uptake recorded in treatments receiving combined applications of fly ash, farmyard manure (FYM), and silicate-solubilizing bacteria (SSB). Panels \u003cstrong\u003eC\u003c/strong\u003e and \u003cstrong\u003eD\u003c/strong\u003eillustrate grain yield (kg ha⁻¹) and straw yield (kg ha⁻¹), respectively, for the same set of treatments. Darker shades correspond to higher yields, indicating that treatments with optimal fly ash rates (notably T8) achieved superior productivity.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7446758/v1/d24779a17504246209de97e9.jpg"},{"id":91162538,"identity":"de57ada3-6399-4d56-a4b8-60f847ff3136","added_by":"auto","created_at":"2025-09-12 09:35:35","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":73878,"visible":true,"origin":"","legend":"\u003cp\u003eHere, the relationship between silicon uptake (in grain and straw) and grain yield across different treatments. You can see a positive trend indicating that increased silica uptake, particularly in straw is associated with higher grain yield.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7446758/v1/e185a81320290a21267aabd0.jpg"},{"id":91162994,"identity":"c83373bd-9e4d-4023-99db-8853b385c941","added_by":"auto","created_at":"2025-09-12 09:43:35","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":133109,"visible":true,"origin":"","legend":"\u003cp\u003eRepresented the reduction of pest damage due to increases in the silicon uptake.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7446758/v1/02f383b6fc7b0e446c77d507.jpg"},{"id":91162539,"identity":"e63550d6-0827-458c-889d-8f43b58d862d","added_by":"auto","created_at":"2025-09-12 09:35:35","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":108885,"visible":true,"origin":"","legend":"\u003cp\u003ePost-harvest available nutrient content (kg ha⁻¹) in soil as influenced by different treatments. The 3D bubble plot depicts the concentrations of nitrogen (N, blue), phosphorus (P, orange), and potassium (K, grey) across treatments. Higher values of all three macronutrients were observed in treatments receiving integrated applications of fly ash, farmyard manure (FYM), and silicate-solubilizing bacteria (SSB), with Treatment T8 showing the highest levels. The elevated nutrient availability can be attributed to the direct nutrient supply from fly ash and FYM, as well as enhanced mineralization and nutrient mobilization driven by SSB activity.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7446758/v1/9d9478b9f06bf79548679f86.jpg"},{"id":91162546,"identity":"5dd284cd-b33b-421d-a163-347275259e74","added_by":"auto","created_at":"2025-09-12 09:35:35","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":97683,"visible":true,"origin":"","legend":"\u003cp\u003eNutrient uptake (kg ha⁻¹) in rice as influenced by different treatments. The bar plot represents nitrogen (N, light blue) and phosphorus (P, dark blue) uptake, while the line plot represents potassium (K, green). Among the treatments, T8 (Fly Ash @ 15 t ha⁻¹ + FYM @ 12.5 t ha⁻¹ + SSB) recorded the highest uptake for all macronutrients (N: 66.2 kg ha⁻¹, P: 22.5 kg ha⁻¹, K: 49.05 kg ha⁻¹). This enhancement is attributed to improved nutrient availability in the rhizosphere, better root proliferation due to improved soil structure from FYM, and microbial-mediated nutrient solubilization by silicate-solubilizing bacteria (SSB).\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7446758/v1/4cfe4c70b217a4088b2fc52f.jpg"},{"id":91164437,"identity":"11c09758-f896-4ee6-8744-66fc05de0a10","added_by":"auto","created_at":"2025-09-12 10:07:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1219044,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7446758/v1/9f0f7790-90b3-4014-b516-8395657cffb9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Fly Ash–Silica Solubilizing Bacteria Consortium: A Bio-Mineral Approach for Enhanced Soil Health and Paddy Productivity in Alfisols of the Cauvery Delta Zone of Tamil Nadu","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eSilicon (Si) is not classified as an essential nutrient for higher plants, extensive research has demonstrated its significant role in promoting optimal growth and physiological development in numerous plant taxa, with pronounced benefits observed in tropical graminaceous species such as \u003cem\u003eOryza sativa\u003c/em\u003e [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Rice (\u003cem\u003eOryza sativa\u003c/em\u003e L.) is a vital dietary staple for over three billion people across Asia, particularly valued for its role in regional food security. In the Indian state of Tamil Nadu, rice is cultivated year-round under submerged lowland conditions [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. This continuous cropping system accelerates the depletion of silicon (Si) reserves in the soil, leading to nutrient deficiency. Notably, rice is among the most efficient accumulators of silicon, a nutrient that significantly contributes to the plant's ability to withstand various biotic and abiotic stress factors [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Fly ash is a fine particulate material consisting primarily of non-combustible mineral residues from coal, along with small amounts of unburned carbon resulting from incomplete combustion [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Irrespective of its source, fly ash consistently contains appreciable concentrations of silicon, making it a potential alternative silicon amendment for agricultural soils [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Although fly ash contains a substantial quantity of silicon, most of it exists in forms that are not readily soluble. Plants, including rice, can absorb silicon only in its bioavailable form, primarily as monosilicic acid (H₄SiO₄), which is present in very limited amounts despite the high total silicon content [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Fly ash serves as a slow-release source of silicon, enabling a regulated supply that mitigates the risk of excessive silicon accumulation in rice plants [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The application of silicate-solubilizing bacteria (SSB) significantly promotes the mobilization of insoluble silicate minerals into plant-available forms, predominantly monosilicic acid. This biotransformation is facilitated through several microbial-mediated mechanisms, including rhizosphere acidification, exudation of organic acids and siderophores, and the enzymatic breakdown of mineral structures [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Consequently, the enhanced solubilization of silicon increases its availability to rice roots, thereby reinforcing cell wall architecture and augmenting the plant's resilience against both biotic and abiotic stressors [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Contemporary research predominantly emphasizes chemical strategies to enhance silicon availability, often neglecting biologically driven approaches that offer greater sustainability. Notably, there is a paucity of integrated studies evaluating the co-application of fly ash and silicate-solubilizing bacteria (SSB) as a bio-mineral consortium for improving rice (\u003cem\u003eOryza sativa\u003c/em\u003e L.) productivity in the Alfisols of Cauvery Delta Zone, which are inherently deficient in plant-available silicon and organic carbon. This study aims to elucidate the effects of the Fly Ash\u0026ndash;SSB consortium on the growth, yield, and stress tolerance of rice, while concurrently assessing its synergistic influence on the mobilization of bioavailable silicon and the enrichment of essential soil nutrients.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Site Description and Soil Characteristics\u003c/h2\u003e\u003cp\u003eA field experiment was conducted during the Rabi season of 2024\u0026ndash;2025 at a farmer\u0026rsquo;s field in Melpuliyankudi village, Cuddalore District, Tamil Nadu, situated under the agro-climatic jurisdiction of Cauvery Delta Zone. The experimental site is characterized by a tropical climate and sandy clay loam soils. Pre-experimental composite soil samples collected from the 0\u0026ndash;15 cm depth revealed a neutral soil reaction (pH 7.21), non-saline electrical conductivity (0.85 dS m\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and low organic carbon content (4.16 g kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), as determined by the Walkley and Black method [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The available nitrogen (201 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), phosphorus (13.2 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and potassium (244 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) were quantified using alkaline KMnO₄ method [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], sodium bicarbonate extraction [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], and neutral ammonium acetate method [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], respectively. Micronutrients such as Zn (0.61 mg kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Cu (0.76 mg kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Fe (7.62 mg kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and Mn (3.57 mg kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) were extracted using the DTPA method [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], indicating variable micronutrient availability in the initial soil condition. The available silicon content of the soil was 60.70 mg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and the water-soluble silicon content was 21.49 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. These were quantified using the ammonium acetate (0.5 M, pH 4.8) extraction method [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], for available silicon, and the distilled water (1:10) extraction method [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], for water-soluble silicon.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Treatment Details\u003c/h2\u003e\u003cp\u003eA randomized block design (RBD) comprising thirteen treatment combinations with three replications was employed to assess the interactive effects of fly ash (applied at 15, 20, and 25 t ha⁻\u0026sup1;), farmyard manure (FYM; 12.5 t ha⁻\u0026sup1;), green manure (GM; 6.25 t ha⁻\u0026sup1;), and silicate-solubilizing bacteria (SSB) on rice performance. A control treatment devoid of any amendments was included for baseline comparison. The complete treatment structure is presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDetails of treatments used in the experiment\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatment Code\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTreatment Description\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eControl (No amendment)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha⁻\u0026sup1; + GM @ 6.25 t ha⁻\u0026sup1;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha⁻\u0026sup1; + GM @ 6.25 t ha⁻\u0026sup1;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha⁻\u0026sup1; + GM @ 6.25 t ha⁻\u0026sup1;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha⁻\u0026sup1; + GM @ 6.25 t ha⁻\u0026sup1; + SSB\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha⁻\u0026sup1; + GM @ 6.25 t ha⁻\u0026sup1; + SSB\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha⁻\u0026sup1; + GM @ 6.25 t ha⁻\u0026sup1; + SSB\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Source and Application of inputs\u003c/h2\u003e\u003cp\u003eFly ash sourced from Neyveli Lignite Corporation was air-dried, passed through a 2 mm sieve, and subjected to physicochemical characterization. The material exhibited an alkaline pH of 8.51, electrical conductivity (EC) of 1.57 dS m⁻\u0026sup1;, and bulk density (BD) of 1.12 Mg m⁻\u0026sup3;. Nutrient analysis revealed available nitrogen (34.15 mg kg⁻\u0026sup1;), phosphorus (9.53 mg kg⁻\u0026sup1;), and potassium (61.42 mg kg⁻\u0026sup1;), available silica (152 mg kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in addition to calcium, magnesium, and DTPA-extractable micronutrients, following standard protocols [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Well-decomposed farmyard manure (FYM) and green manure (sun hemp, \u003cem\u003eCrotalaria juncea\u003c/em\u003e) were incorporated as per treatment specifications. Silicate-solubilizing bacteria (SSB) were applied in liquid formulation through seedling root dipping at the time of transplanting and subsequently by soil drenching on the 7th and 30th days after transplanting.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Crop Management\u003c/h2\u003e\u003cp\u003eRice (Oryza sativa L.) was employed as the test crop for this investigation. The experimental field was prepared using conventional tillage operations, and uniform seedlings were transplanted on 16 October 2024, maintaining a spacing of 20 \u0026times; 15 cm. The crop was cultivated under assured irrigation, adhering to recommended agronomic and plant protection practices as prescribed for the region [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. All treatment plots received a uniform basal application of chemical fertilizers according to standard fertilizer recommendations to isolate and assess the specific effects of organic amendments and fly ash on crop performance.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Data Collection and Analysis\u003c/h2\u003e\u003cp\u003eGrain and straw yields were quantified at physiological maturity on 11 February 2025. Post-harvest soil samples were collected from the 0\u0026ndash;15 cm depth and analyzed for available nitrogen, phosphorus, and potassium following standard protocols. Plant tissues were oven-dried, finely ground, and digested using a tri-acid mixture (HNO₃:H₂SO₄:HClO₄, 9:1:4). Nutrient uptake was calculated by multiplying nutrient concentrations with respective dry matter yields. Silicon uptake in both grain and straw was determined through alkaline extraction and quantified using the molybdenum blue colorimetric method [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The experimental data were subjected to analysis of variance (ANOVA) for randomized block design (RBD) to evaluate treatment effects. Mean comparisons were performed using the Critical Difference (CD) test at a 5% probability level. Standard Error of Difference (SEd) and CD values were used to assess statistical significance across treatments [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Influence on Grain and Straw Yields\u003c/h2\u003e\u003cp\u003eThe integrated application of fly ash, farmyard manure (FYM), and silicate-solubilizing bacteria (SSB) markedly enhanced rice yield. Among the treatments, T8 (Fly Ash @ 15 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB) recorded the maximum grain and straw yields of 6,623 and 8,005 kg ha⁻\u0026sup1;, respectively, representing a 47.8% increase in grain yield over the control (T1: 4,480 kg ha⁻\u0026sup1; for grain and 4,594 kg ha⁻\u0026sup1; for straw), thereby demonstrating the synergistic effect of integrated nutrient management on rice productivity (Fig.\u0026nbsp;1). The observed yield enhancement can be attributed to the synergistic benefits of the integrated treatment: fly ash contributed essential macro- and micronutrients; farmyard manure (FYM) improved soil physical properties and stimulated microbial activity; and silicate solubilizing bacteria (SSB) facilitated the dissolution of silicate minerals, thereby enhancing nutrient solubilization and uptake [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e\u003cb\u003e3.2 Silica Uptake in Grain and Straw\u003c/b\u003e\u003c/h2\u003e\u003cp\u003eSilicon uptake plays a critical role in reinforcing plant structure, enhancing photosynthesis, and improving resistance to biotic and abiotic stresses [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The highest silica uptake occurred under T10 (Fly Ash @ 25 t ha⁻\u0026sup1; + FYM\u0026thinsp;+\u0026thinsp;SSB) with grain and straw values of 33.1 and 211.9 kg ha⁻\u0026sup1;, respectively. T9 and T8 also showed substantial increases (T9: grain 30.6; straw 182.1; T8: grain 26.8; straw 167.6 kg ha⁻\u0026sup1;) (Fig.\u0026nbsp;1). This enhancement is attributable to the solubilization of fly ash\u0026ndash;bound silica by SSB via organic acid and chelator production [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. While higher fly ash rates improved silica uptake further, T8 emerged as the optimal treatment, balancing yield enhancement, nutrient uptake, soil fertility, and economic efficiency [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Correlation between Yield and Silicon Uptake\u003c/h2\u003e\u003cp\u003eThe results demonstrate a positive correlation between silicon (Si) uptake and rice yield (Fig.\u0026nbsp;2). Treatment T8 (Fly Ash @ 15 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB) not only recorded the highest grain yield (6,623 kg ha⁻\u0026sup1;) but also exhibited substantial silica uptake in both grain (26.8 kg ha⁻\u0026sup1;) and straw (167.6 kg ha⁻\u0026sup1;). This trend continues with T9 and T10, where increased rates of fly ash further enhanced silica uptake (T10: 33.1 in grain and 211.9 kg ha⁻\u0026sup1; in straw) and maintained high yields (though slightly lower than T8). This strong alignment indicates that higher Si uptake correlates with greater biomass and grain formation. Silicon's role in strengthening cell walls, improving water-use efficiency, and stress resistance contributes significantly to yield enhancement [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The SSB-mediated solubilization of silica from fly ash amplifies Si bioavailability, thus improving plant health and productivity [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Therefore, the yield increase observed in treatments like T8\u0026ndash;T10 is directly linked to improved silicon nutrition. This supports the view that silicon is not just a beneficial element but a yield-determining factor under integrated nutrient management practices [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Pest Resistance Gains with Higher Silicon\u003c/h2\u003e\u003cp\u003eSilicon-treated rice reduced FAW (Fall Army Worm - \u003cem\u003eSpodoptera frugiperda\u003c/em\u003e) larval weight gain by 36% compared to controls, irrespective of injury-induced priming [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. A treatment such as T8, with a\u0026thinsp;~\u0026thinsp;62% increase in total silicon uptake relative to the control, could be expected to reduce fall armyworm larval weight gain by approximately 36%, based on comparable outcomes in silicon-amended rice. Similarly, T10\u0026rsquo;s\u0026thinsp;~\u0026thinsp;104% Si uplift may impart even greater resistance, potentially exceeding a 50% reduction in pest performance. Field evidence supports these expectations: silicon amendments (e.g., 300 kg SiO₂ ha⁻\u0026sup1;) significantly decreased damage from stem borers, leaf folders, and planthoppers and improved yield by 16.4%. Silicon amendment significantly decreased survival rates in first and third instars of leaf folder larvae (\u003cem\u003eCnaphalocrocis medinalis\u003c/em\u003e), primarily via enhanced leaf silicification and primed antioxidant pathways [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Finally it highlights the positive association between silica uptake (both grain and straw) and final yield, suggesting that treatments enhancing silica accumulation tend to improve productivity (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Post-Harvest Soil Fertility and Nutrient Uptake\u003c/h2\u003e\u003cp\u003eThe integrated application of fly ash, farmyard manure (FYM), and silicate-solubilizing bacteria (SSB) markedly improved post-harvest soil fertility and nutrient uptake in rice (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u0026amp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Treatment T8 (Fly ash @ 15 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB) achieved the highest concentrations of available macronutrients in the post-harvest soil, with N, P, and K levels of 280.00, 12.68, and 238.00 kg ha⁻\u0026sup1;, respectively, compared to 187.00, 10.90, and 140.00 kg ha⁻\u0026sup1; in the control. These improvements are attributable to the intrinsic nutrient content of fly ash, the organic matter and nutrient contributions from FYM, and the enhanced mineralization of organic matter stimulated by SSB-mediated microbial activity [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In parallel, T8 also exhibited superior plant nutrient uptake, with total N, P, and K assimilation reaching 66.20, 22.50, and 49.05 kg ha⁻\u0026sup1;, respectively, far exceeding control values (N: 39.10; P: 8.59; K: 21.60 kg ha⁻\u0026sup1;). This enhancement is likely due to the synergistic effects of improved nutrient availability in the rhizosphere, increased root proliferation from FYM-induced improvements in soil structure, and enhanced solubilization of nutrient-bearing minerals via SSB activity [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eSilica uptake in grain and straw of paddy\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe uptake of silica by paddy grain and straw was significantly influenced by the application of fly ash in combination with organic amendments and silicate solubilizing bacteria (SSB) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The grain silica uptake ranged from 17.6 kg ha⁻\u0026sup1; (control) to a maximum of 33.1 kg ha⁻\u0026sup1; (T10: Fly ash @ 25 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB). Similarly, straw silica uptake varied between 112.8 kg ha⁻\u0026sup1; in control and 211.9 kg ha⁻\u0026sup1; in T10, recording nearly a 88% increase over control.\u003c/p\u003e\u003cp\u003eAmong the treatments, combined application of fly ash, FYM and SSB (T8\u0026ndash;T10) or fly ash, green manure and SSB (T11\u0026ndash;T13) significantly enhanced silica uptake compared to sole application of fly ash with FYM or GM (T2 -T7). The beneficial effect was more pronounced in higher fly ash levels (25 t ha⁻\u0026sup1;), indicating that increased external supply of amorphous silica along with microbial solubilization improved plant availability.\u003c/p\u003e\u003cp\u003eThe observed improvement can thus be ascribed to the combined effect of fly ash as a direct source of silica [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], organic manures enhancing mobilization through complexation and microbial activity [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] and SSB promoting solubilization of minerals into plant-available monosilicic acid [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], collectively resulting in greater silica uptake efficiency.\u003c/p\u003e\u003cp\u003eComparable results have also been documented by earlier researchers. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] highlighted that organic amendments play a crucial role in mobilizing silicon from native soil pools. The addition of organic matter enhances soil microbial activity and releases organic acids, which solubilize bound forms of silicon, thereby increasing the pool of plant-available silicic acid. This indicates that integrating organic amendments with external sources of Si, such as fly ash, can significantly improve the efficiency of silicon mobilization and cycling within the rice ecosystem [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe combined application of fly ash and microbial inoculants led to higher silica accumulation in rice tissues compared to individual applications [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. The presence of silicate solubilizing bacteria (SSB) in particular enhanced the release of available silicon from fly ash particles, which in turn increased plant uptake and assimilation. Enhanced silica accumulation in rice has been widely recognized to contribute to structural strengthening of cell walls, improved resistance to lodging, and greater tolerance to biotic and abiotic stresses [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. These findings support the present study, where the integration of fly ash, organic amendments, and SSB showed a synergistic effect in improving both grain and straw silica uptake in paddy [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eEffect of fly ash, organic amendments, and silicate solubilizing bacteria (SSB) on silica uptake (kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in paddy grain and straw\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTr. No.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTreatment details\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eSilica uptake kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGrain\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eStraw\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e17.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e112.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha\u003csup\u003e-1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e19.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e129.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha\u003csup\u003e-1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e21.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e134.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha\u003csup\u003e-1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e23.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e146.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha\u003csup\u003e-1\u003c/sup\u003e + GM @ 6.25 t ha\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e19.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e122.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha\u003csup\u003e-1\u003c/sup\u003e + GM @ 6.25 t ha\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e21.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e130.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha\u003csup\u003e-1\u003c/sup\u003e + GM @ 6.25 t ha\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e22.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e139.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha\u003csup\u003e-1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e-1\u003c/sup\u003e + SSB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e26.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e167.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha\u003csup\u003e-1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e-1\u003c/sup\u003e + SSB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e182.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha\u003csup\u003e-1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e-1\u003c/sup\u003e + SSB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e33.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e211.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 15 t ha\u003csup\u003e-1\u003c/sup\u003e + GM @ 6.25 t ha\u003csup\u003e-1\u003c/sup\u003e + SSB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e24.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e156.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 20 t ha\u003csup\u003e-1\u003c/sup\u003e + GM @ 6.25 t ha\u003csup\u003e-1\u003c/sup\u003e + SSB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e170.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFly Ash @ 25 t ha\u003csup\u003e-1\u003c/sup\u003e + GM @ 6.25 t ha\u003csup\u003e-1\u003c/sup\u003e + SSB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e31.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e204.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMean\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e14.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e154.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSEd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCD(P\u0026thinsp;=\u0026thinsp;0.05)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e6.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe study clearly establishes that the integrated use of fly ash, organic manures, and silicate-solubilizing bacteria (SSB) is an effective strategy for improving rice productivity, nutrient uptake, and soil fertility in silicate-deficient sandy clay loam soils. Among the different combinations, Fly Ash @ 15 t ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e + FYM @ 12.5 t ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e + SSB excelled in enhancing grain yield, nutrient uptake, and maintaining post-harvest soil fertility, while Fly Ash @ 25 t ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e + FYM/GM\u0026thinsp;+\u0026thinsp;SSB recorded the highest silica accumulation in both grain and straw. The synergistic effect of fly ash as a direct source of silica, FYM/GM as mobilizers, and SSB as solubilizers ensured greater availability of plant-available silicic acid, leading to improved uptake efficiency. Enhanced silica content not only contributed to better plant growth, resistance to lodging, and stress tolerance but also improved straw residue quality, which upon recycling can enrich soil fertility. These findings underscore the potential of utilizing industrial by-products like fly ash in combination with organic and microbial inputs as a sustainable nutrient management strategy for rice-based systems under similar agro-ecological conditions.\u003c/p\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cb\u003eConsent to Participate\u003c/b\u003e:\u003c/strong\u003e\u003cp\u003eConsent was obtained from every researcher who participated in the experiment.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConsent for Publication:\u003c/strong\u003e\u003cp\u003eThe authors have given permission for this research paper to be published in the journal.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003e\u003cb\u003eCompeting Interest\u003c/b\u003e:\u003c/strong\u003e\u003cp\u003eThe authors declare no competing interests\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e\u003cp\u003eAs part of the first author's required research duties, there is no funding assistance for the research for this study.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthors acknowledge the support of the Sugarcane Research Station, Cuddalore, for offering the research facilities during the course of the investigation of this research. Author Contributions Conceptualization: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami and S. Sheeba] Methodology: [G. Porkodi, S. Sheeba] Formal analysis: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami] Investigation: [G. Porkodi, G. Anand, R.Abirami] Writing -original draft: [G. Porkodi, G. Anand, R.Abirami] Writing review and editing: [G. Porkodi, G. Anand, R.Abirami]; Supervision:[ G. Porkodi, G. Anand, R.Abirami, S. Sheeba].\u003c/p\u003e\u003ch2\u003eAcknowledgements:\u003c/h2\u003e\u003cp\u003eAuthors acknowledge the support of Sugarcane Research Station, Cuddalore for offering the research facilities during the course of investigation of this research. Author Contributions Conceptualization: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami and S. Sheeba] Methodology: [G. Porkodi, S. Sheeba] R. Anitha, R. Nageswari, V. Dhanushkodi, M. Yuvaraj] Formal analysis: [G. Porkodi, G. Anand, P.Ramamoorthy, R.Abirami] Investigation: [G. Porkodi, G. Anand, R.Abirami] Writing -original draft: [R. Anitha, C. Tamil selvi, P. Jeyakumar] Writing review and editing: [G. Porkodi, G. Anand, R.Abirami]; Supervision:[ G. Porkodi, G. Anand, R.Abirami, S. Sheeba].\u003c/p\u003e\u003ch2\u003eData Availability:\u003c/h2\u003e\u003cp\u003eAll relevant data are within the research paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eChaiwong, N. \u0026amp; Prom-U-Thai, C. Significant roles of silicon for improving crop productivity and factors affecting silicon uptake and accumulation in rice: a review. \u003cem\u003eJ. Soil Sci. Plant Nutr.\u003c/em\u003e \u003cstrong\u003e22\u003c/strong\u003e, 1970\u0026ndash;1982 (2022).\u003c/li\u003e\n\u003cli\u003ePeera, S. K. P. G., Balasubramaniam, P. \u0026amp; Mahendran, P. P. Effect of silicate solubilizing bacteria and fly ash on silicon uptake and yield of rice under lowland ecosystem. \u003cem\u003eJ. Appl. Nat. 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F., \u0026amp; Yamaji, N. (2015). A cooperative system of silicon transport in plants. \u003cem\u003eTrends in Plant Science\u003c/em\u003e, 20(7), 435\u0026ndash;442.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"silicon","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scon","sideBox":"Learn more about [Silicon](https://www.springer.com/journal/12633)","snPcode":"12633","submissionUrl":"https://submission.nature.com/new-submission/12633/3","title":"Silicon","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Flyash, SSB, Soil fertility, Nutrient dynamics, Silica uptake, Rice yield","lastPublishedDoi":"10.21203/rs.3.rs-7446758/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7446758/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFly ash, a by-product, contains a rich array of minerals and has demonstrated potential as a soil amendment. However, its synergistic interaction with organic and microbial inputs for improving crop productivity, particularly in silicate-deficient soils, remains insufficiently characterized. The present investigation was conducted during the Rabi season of 2024\u0026ndash;2025 at Melpuliyankudi village, Cuddalore District, Tamil Nadu, with the objective of evaluating the integrated effects of fly ash, farmyard manure (FYM), green manure (GM), and silicate solubilizing bacteria (SSB) on rice yield and soil fertility. The experiment was laid out in a randomized block design (RBD) comprising thirteen treatments with three replications on sandy clay loam soils characterized by low organic carbon and deficient macronutrient status. Among the treatments, the integrated application of Fly Ash @ 15 t ha⁻\u0026sup1; + FYM @ 12.5 t ha⁻\u0026sup1; + SSB significantly outperformed others, recording the highest grain yield (6623 kg ha⁻\u0026sup1;) and straw yield (8005 kg ha⁻\u0026sup1;), along with enhanced uptake of nitrogen (N), phosphorus (P), potassium (K), and silicon (Si). Post-harvest soil analysis revealed substantial improvements in available nutrient status under integrated nutrient management regimes. The findings underscore the potential of leveraging industrial by-products in combination with biological and organic amendments to sustainably enhance rice productivity and soil health. Further long-term studies across diverse agro-ecological zones are warranted to validate these outcomes and formulate region-specific nutrient management strategies.\u003c/p\u003e","manuscriptTitle":"Fly Ash–Silica Solubilizing Bacteria Consortium: A Bio-Mineral Approach for Enhanced Soil Health and Paddy Productivity in Alfisols of the Cauvery Delta Zone of Tamil Nadu","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 09:35:31","doi":"10.21203/rs.3.rs-7446758/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-09T11:33:11+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-13T03:53:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"320236438419269566526086573450804465201","date":"2026-01-03T08:02:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"219306306148986294439707409366127399452","date":"2025-11-20T15:31:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-05T16:04:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"305594906575837654664098702624816274255","date":"2025-10-29T08:31:27+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-07T06:04:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-27T04:07:09+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-27T04:07:05+00:00","index":"","fulltext":""},{"type":"submitted","content":"Silicon","date":"2025-08-24T14:17:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"silicon","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scon","sideBox":"Learn more about [Silicon](https://www.springer.com/journal/12633)","snPcode":"12633","submissionUrl":"https://submission.nature.com/new-submission/12633/3","title":"Silicon","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ff217c25-d85e-433b-9201-1ef8aadc19c0","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-09T11:33:11+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-16T11:38:15+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 09:35:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7446758","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7446758","identity":"rs-7446758","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}