Abstract
In this study, suitable fly ash (FA) was selected for agricultural purposes according to combined characteristic soils and water. The two FAs from the Tuticorin Thermal Power Plant (FA-TTPP) and Sripathy Thermal Power Station (FA-STPS) and physio-chemical analysis of soil and water samples from the five different sites (1–5) in Viruthunagar district, Tamilnadu is made. X-ray diffraction analysis (XRD) of FAs showed that quartz (SiO2), mullite (Al6Si2O), and hematite (Fe2O3) are available that enhance plant growth. The Fourier-transform infrared spectroscopy (FTIR) results confirmed that Si–O–Si, Al–O–Si, HO–OH, and OH bonding present in the FAs support to meet the required plant nutrients in the soil. Scanning electron microscopy analysis (SEM) of FA-TTPP revealed compact microspheres with regular, smooth, and irregular textures while FA-STPS showed glassy, unshaped fragments that may help to improve the texture of field sites. Energy dispersive X-ray spectroscopy (EDX) analysis found that FAs have essential macro- and micronutrients to minimize the soil nutrient and thus help to improve plant productivity. Sites 1 and 2 have acidic soil conditions and are recommended to use both FAs since they are alkaline in nature. FA can improve the water-holding capacity of sandy loam soils of sites 2, 3, and 4 due to the presence of fineness content in FA. Site- 1 has iron deficiency which can be remediated with rich iron FA-STPS. It is recommended to use optimum FA based on soil and water to improve agricultural efficiency.
1 Introduction
Worldwide, agriculture contributes a crucial part to the entire life and foundation of countries and provides food, raw materials, and employment opportunities for the population [1]. Nations' economic growth and poverty reduction heavily rely on agriculture [2, 3]. As a result of the pandemic, the population impacted by malnutrition has increased by 132 million, highlighting the significance of global agricultural food production. Nonetheless, around 690 million people were affected by hunger even before Covid-19 [4]. However, 2.3 billion tons of cereals are needed to feed the world's population of 7.9 billion. Food cultivation must increase by 50% annually to meet current demand [5, 6]. Global food security will require an estimated 60% increase in agricultural production by 2050 [7, 8]. Therefore, a sustainable food supply for all human beings is a major challenge in the world [9]. Nowadays, genetic modification, chemical fertilizers, growth enhancers, pesticides, herbicides, and soil sterilizers are helping to decrease crop growth cycles and increase crop yields [10]. Altogether, the unfavorable effects of agroecosystem function drawbacks diminished soil organic matter, microbial diversity, and mesofauna diversity [11, 12]. Hence, agriculture must provide food and fiber to present society while protecting the environment for future generations [13]. In this regard, sustainable food production needs soil health with improved fertilizer efficiency. Generally, farmers use toxic chemical fertilizers and pesticides to improve crop growth and kill pests. It affects the soil environment and enters the human body through food chains [14, 15]. In these situations, organic manure and bio-pesticides of natural origins manage the fertility of crops and control pests [16]. Many researchers attempted different types of manures, composts, and fertilizers to improve soil health and agricultural productivity. Eco-friendly sustainable fertilizers cum pesticide is challenging for present generations. Coal Fly Ash (FA) is an eco-friendly and promising sustainable mineral fertilizer and pesticide [14, 17].
Globally, 53% of electricity is generated by lignite coal at present. In India, coal-fired plants generate 70% of electricity [18]. Furthermore, the proportion of Indians relying on electricity generation has increased due to urbanization and is likely to reach 40% by 2030 [19]. Thermal power plants are the foundation for electricity production in India mainly depending on Indian coal as fuel [20, 21]. Coal power plants create FA as a part of their devastation disposal process. The smaller particles are collected from the flue gases using electrostatic precipitators, desulfurization systems, and bag houses and transported to a FA landfill [22]. The Indian grade coal has a 30–60% ash content [23]. Every year, governments dedicate more efforts and money to managing the FA [24]. Worldwide, FA generation was 300–600 million tons by 2020, which covered up to 3,235 km2 of land for disposal [25, 26]. India produced 271 MT of FA in 2021–2022 from 200 power plants. According to the Indian Ministry of Power and Administration's Coal Ash Report (2022), India has used 259.86 MT of the total FA generation of 270.82 MT. As a result, unutilized FA needs 2,300 ha of land, and 1.3 billion cubic meters of water will be needed for ash ponds, further aggravating the existing FA disposal problems [27].
Nonetheless, it is necessary to increase FA usage for environmental consideration and economic profit rather than dumping it as solid waste [18, 28–31]. The improper disposal of FA can lead to environmental problems such as metal toxicity and human health problems. In particular, heavy metals significantly harm the liver, kidneys, and nervous system and affect the lungs, bones, stomach, and intestine [18, 32, 33]. Heavy metals such as As, B, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Se, Sn, V, W, and Zn increase the alkalinity of a water body [34]. FA landfilling can release toxic compounds into the environment, especially leachates and dust [35, 36]. FA contaminates through leachate, which allows trace elements to enter groundwater, air emissions, and dust that causes smog [37]. There is a high risk of pollution from coal ash ponds, particularly in waterways and soil. The calcium content of the FA can raise the pH of water.
It is necessary to utilize the FA to the maximum extent to meet sustainable objective goals [38]. In addition, industrialization and urbanization force us to recycle waste. FA is used in many areas, such as a composite cement and mineral additive of concrete, which reduces greenhouse gas emissions, as a substitute for aggregates in road construction, as an agent of producing mineral wool, and as a source of metal [30, 39, 40]. FA acts as a liming agent and absorbs trace elements by ion exchange in aqueous solutions [41, 42]. FA can also be a cost-effective substitute for lime for the remediation of acidic soils [43]. FA can also have agronomical applications and remediate soils with low fertility [44]. FA is an amorphous ferro-alumino silicate substance that resembles soil but lacks phosphate, nitrogen, and organic carbon [29].
FA has rich nutrients and enormous possibilities in developing plant production, soil health, and controlling insects. In India, only a limited amount of FA has been used in agriculture, even though the supply of FA is free of charge to farmers within three hundred kilometers of the plant [45]. Adding FA to loamy soils can alter soil structure and improve microporosity [46]. FA is the source of essential micro, macro, and trace elements that boost plant growth and yields [47]. It can exacerbate the soil's specific nutritional shortage and can change the nutrient composition [48]. It increases soil sulfates, carbonates, bicarbonates, chlorides, phosphorus, potassium, calcium, magnesium, manganese, zinc, copper, and boron levels [14].
FA enhances soil properties physicochemically and biologically [47]. FA (10–40% w/w) amendments improve soil texture, structure, soil electrical conductivity, dry density, water holding capacity, soil microporosity, pH, and coefficient of permeability from 5 to 50% [49, 50]. FA improves the infiltration rate in clay soils while it reduces the infiltration rate in coarse-textured soils [29]. Thus, it enhances cation exchange functions, as stabilizing agent to prevent soil desertification, improving soil conditions [51, 52].
In recent years, FA has been investigated as a conditioner and low-cost fertilizer, and numerous field studies have examined the impact of FA (100–650 t ha−1) as a soil amendment, enhancing plant growth and yield [53]. For instance, the successful utilization of FA (25%) in a sunflower (Helianthus annuus L.) field increased the growth of the plant, seed yield, and oil content and modified the water-holding capacity in the soil [54, 55]. The yield, pigment content, nitrate reductase activity, total protein, and carbohydrate content of beetroot (Beta Vulgaris L.) significantly increased in soil amended with FA (15%) [50, 56]. FA treatments 4–16% and 25% increased the growth of the potato (Solanum tuberosum L.) [57]. Deteriorated soils were treated with 7%, 14%, and 20% of FA weight/soil weight (i.e., 50 t ha−1, 100 t ha−1, and 150 t ha−1, respectively). FA application of up to 25% FA weight resulted in increased yields of oilseeds [32]. Soybean [(Glycine max (L.) Merr.] yielded well when FA replaced 30%, and wheat (Triticum aestivum L.) yielded maximum when replaced with 30%–60% FA. Alfalfa (Medicago sativa L.) also achieved better growth after the FA addition of 30–40% in pigeon peas (Cajanus cajan L.) [14, 42, 58].
The addition of 40–60% FA improved the yield of Indian mustard (Brassica Juncea). FA increased the yield of carrot (Daucus carota L.) at 30% addition, tomato (Lycopersicon esculentum) at 40% FA addition, chili (Capsicum annuum) at 10% addition, and marigold (Calendula officinalis L.) at 40% addition. Successful FA application increased the yield of Safed Musli (Chlorophytum borivililanum) and turnip (Brassica Rapa L.) cby up to 10 tons/hectarec [14, 18, 31, 59–61]. The use of FA (10%) in soil improved the growth and yield of physic nut (Jatropha curcas L.) [61]. Moreover, FA soil amendments showed positive responses in Mentha Piperita (50%), Mung bean (Vigna radiata) (20%), and Urad bean (Vigna mungo) (20%) [57, 60]. The three different studies showed the addition of FA improved the growth and yield of rice (Oryza sativa L.) by 2–8%, 40%, and 90 Mg ha−1 [62, 63]. Also, FA (50%) in upland soils increased the growth, yield, and antioxidant parameters of wild rice [18].
Overall, FA is replaced up to 60% of various soil amendments and provides nutrients, better physicochemical properties, higher microbial activity, and better plant growth. It is visible that the dosage of FA varies from one crop variety to another crop variety. Even for the same type of crop, the FA dosage is not similar. The possible reason could be due to the character of the soil, water, and climatic condition deciding the necessary dosage of the FA for the plants. In addition to that, the amount, character (properties), and quality of FA are also changing depending upon the type of coal (peat, lignite, sub-bituminous coal, bituminous coal, anthracite, graphite, cannel coal, and coking coal) and their degree of purity used in power plant [63].
The optimum amount of FA gives more yield to the plants without harmful effects on the soil. Excessive FA addition without adequate characterization and physical-chemical analysis of soil and water and FA causes negative effects on the plant and soil. In 2021–2022, India used FA at 0.06 percent in the agricultural sector. The reason for the limited agricultural utilization of FA may be a lack of awareness about the soil fertilizing ability of FA among the farmers. Unknown physical and chemical characteristics since it has different compositions controlled by the source of coal. Analyzing FA, soil, and water before applying them to an agriculture field is essential to ensure that the materials are safe and suitable for agricultural use. Unfortunately, it was not given importance for FA characterization before being applied in the field. Therefore, physical-chemical and elemental analysis is necessary to find the suitability of the agronomical application of FA. It can help to provide recommendations and guidelines for FA dosage for individual crops, soil types, and water types. So, characterization studies can help to formulate FA-based fertilizers and pesticides for different plants, soils, and waters. This study provides insight into the character of waters, soils, and FAs in this region and recommends choosing the FA based on the water and soil quality. This study also aims to move towards an integrated analysis of soil, water, and FA for the increased utilization of FA for potential sustainable agriculture to propose a road map for future research from the farmer's perspective.
2 Materials and methods
2.1 Study area
The FA samples for this study were collected from Tuticorin Thermal Power Plant (FA-TTPP) and Sripathy Thermal Power Station (FA-STPS), Sivakasi, Tamilnadu. During the study period, soil (0–30 cm depth) and water samples were randomly collected from Erichanatham, Sevalur, Alagapuri, Puvani, and P. Meanatchipuram at a distance of 19, 22, 25, 43, and 43 km from Virudhunagar, respectively. The graphical locations of experimental sites (1–5) are shown in Fig. 1. Virudhunagar district (southwestern part of Tamilnadu, India) is located between 9° 12′ N and 9° 47′ N latitude, 77° 23′ E and 78° 25′ E longitude, with a topographic area of about 4,243 square kilometers [64]. Agriculture is the primary source of employment in this region, so this study aims to characterize the FAs, soils, and water to make suitable soil amendments for agronomical applications [65]. Virudhunagar experiences deficit rainfall, receiving most of its precipitation during the northeast monsoon, and actual annual rainfall is 862.4 mm [66].
Graphical location of soils and water sampling
Citation: International Review of Applied Sciences and Engineering 15, 1; 10.1556/1848.2023.00661
This region has a subtropical climate with hot and dry weather for about nine months of the year [67]. The average annual temperatures are 23.78 °C (min) and 33.95 °C (max), respectively [68]. Geographically, this district is divided into two regions: the foothills of the Western Ghats and the plains. The foot mount has rich clay soils with good grassland. In addition, this region's soil types include laterite, black earth, sand, and black cotton soils [69]. Maize is the main crop grown, then paddy, sugarcane, cholam, cotton, pulses, and groundnuts are the crops grown in this area. Horticultural crops grown in this district are mango, guava, banana, amla, tomato, brinjal, bhandi, onion, coriander, chili, and flowers like jasmine, arali, and tuberose.
2.2 Characterization of FA
2.2.1 X-ray diffraction
X-ray diffraction (XRD) is a technique used to assess the crystallographic structure of FA samples with an X-ray diffractometer. The main instruments are an XRD generator, goniometer, radiation detector, and measurement system [70, 71]. The minerals of FAs were investigated using an X-ray diffractometer (BRUKER D8) and were recorded in the range of 80–100°. Origin 8.1 Pro software and PCPDWIN are used to analyze the output data through its peak value of the FA samples.
2.2.2 Fourier transform infrared
Fourier transforms infrared (FT-IR) technique is used to examine the FA sample's composition structure and chemical bonds. It also can identify organic functional groups in FA samples [70, 72]. An IRTracer-100 FTIR spectrometer was used to acquire FTIR spectra of FA samples within a KBr wafer over the range of 4,000–400 cm−1 with a nominal resolution of 2 cm−1.
2.2.3 Scanning Electron Microscopy and Energy dispersive X-ray spectroscopy
Scanning Electron Microscopy (SEM) is used to investigate the microstructure's external surface structure and external elemental distribution of individual FA particles. An electron beam generates signals to scan the sample surface to analyze the microstructure [72]. The three operating modes of SEM analysis are electrodynamics scattering, secondary electron imaging, and backscattered electron imaging [73]. SEM analysis was performed using a ZEISS EVO18 CARK electron microscope to determine surface morphology and to provide imaging information about the surface texture of FA particles. Energy-dispersive X-ray spectroscopy (EDX) examined the elemental composition of FA [42].
2.3 Properties of FA, soil, and water
FA samples were examined physicochemically for color, texture, pH, and electrical conductivity (EC). The pH of FA directly determines macronutrient availability and micronutrient availability [51]. Dark brown color FA indicates high unburnt carbon and low lime presence, whereas tan color indicates the presence of high lime content [74, 75]. The pH indicates whether FA is acidic or alkaline. Based on pH, FAs are classified into three categories: slightly alkaline 6.5–7.5, moderately alkaline 7.5–8.5, and strongly alkaline >8.5 [47]. The soil samples were dried and passed through a 2-mm sieve to determine physicochemical properties such as texture, pH, electrical conductivity, total nitrogen, phosphorus, potassium, iron, manganese, zinc, and copper. Generally, the level of EC impacts the concentration of salts, and low levels may affect plant health and yield [75]. In addition, the water samples were analyzed for physio-chemical properties for agronomical assistance. The two critical factors that matter for excellent irrigation water analysis are total dissolved solids (TDS) and sodium adsorption ratio (SAR) [76].
3 Result and discussion
3.1 XRD
FA-TTPP and FA-STPS was obtained from thermal power plant and determined the structure of the crystalline from XRD analysis [77]. A comparison of the XRD patterns of FA-TTPP and FA-STPS is shown in Fig. 2. It is observed that the XRD patterns show the major crystalline phases in the FAs are quartz (SiO2), mullite (Al6Si2O), and hematite (Fe2O3) [23, 71, 78, 79]. In both FAs, the main constituents are oxides of Si and Al, which are beneficial and cost-effective nutrients for improving crop yields [80, 81]. Soil application of Fe2O3 can significantly increase plant root elongation and photosynthesis rate [81]. Hence, XRD patterns confirmed the significant nutrients present for plant growth in both FA samples. A study reported the XRD pattern of the soil that contains similar minerals of FA [82].
XRD pattern of FA-TTPP and FA-STPS
Citation: International Review of Applied Sciences and Engineering 15, 1; 10.1556/1848.2023.00661
3.2 FTIR
The FTIR spectra of FA-TTPP and FA-STPS are shown in Fig. 3. It shows the characteristic peaks at 456 cm−1, 569 cm−1, 779 cm−1, 1,097 cm−1, 1,600 cm−1, 3,434 cm−1, and 3,765 cm−1. The characteristic main band at 1,097 cm−1 represents the asymmetric stretching vibration of Si–O–Si and Al–O–Si [23, 79]. The band associated with the O–H stretching is located at about 3,434 cm−1 and 3,765 cm−1 [23, 83]. Both FAs peaks are similar and related to amorphous silica appearing at about 1,097 cm−1. FTIR confirmed the bonding and structure of natural FA.
FTIR profiling FA-TTPP and FA-STPS
Citation: International Review of Applied Sciences and Engineering 15, 1; 10.1556/1848.2023.00661
3.3 SEM-EDX
SEM analysis of FA-TTPP particles shown in Fig. 4 (A and B), consisting of a spherical structure with micropores on the few spheres' surfaces [84]. The appearance of the microstructure of the original FA correlates with that reported by Davidovits [85]. Although the FA-TTPP particles were the same, their shape varied from round to angular [86, 87]. Figure 4 (C and D) shows the glassy, unshaped fragments in FA-STPS. It also consists of very high concentrations of unburned carbon and larger mean particle sizes. It has a large surface area, a light texture, and is porous in particles [87]. Therefore, the FA morphology may be controlled by the combustion temperature and the cooling rate [88].
SEM profiling FA-TTPP (A&B) and FA-STPS (C&D)
Citation: International Review of Applied Sciences and Engineering 15, 1; 10.1556/1848.2023.00661
The FA-TTPP and FA-STPS were determined using the EDX spectrum (Figs 5 and 6), and Table 1 shows a comparison of the elemental composition with their weight percentage. Due to the low calcium content (0.4 and 2.2%), the collected samples belong to F-type. EDX analysis shows that silicon is the primary constituent in the FA-TTPP and FA-STPS samples. Aluminum in FA-TTPP is three times higher than in FA-STPS. The iron of FA-STPS is two times higher than FA-TTPP. Titanium, magnesium, copper, potassium, and calcium are the remaining elements present in both FAs. Calcium in FA-STPS is more than 5 times elevated in FA-TTPP. EDX analysis shows that silicon is the primary constituent in the FA-TTPP and FA-STPS samples. Potassium (K) is a crucial nutrient for crop growth and yield [89]. Additionally, it aids in insect control and improves nitrogen absorption efficiency [90]. Copper is available only in the FA-TTPP, and chloride, sodium, and molybdenum are present in the FA-STPS. EDX has proved the availability of the various necessary nutrients in both FAs. Hence, it can be used as the ameliorating soil material and fertilizing agent.
Energy-dispersive X-ray (EDX) profiling FA-TTPP
Citation: International Review of Applied Sciences and Engineering 15, 1; 10.1556/1848.2023.00661
Energy-dispersive X-ray (EDX) profiling FA-STPS
Citation: International Review of Applied Sciences and Engineering 15, 1; 10.1556/1848.2023.00661
Comparison of the elemental composition of FA samples
| Element | Weight % of FA-TTPP | Weight % of FA-STPS |
| C | 9.8 | 15.1 |
| O | 48.0 | 44.4 |
| Mg | 0.8 | 1.1 |
| Al | 13.5 | 4.8 |
| Si | 22.0 | 20.0 |
| Fe | 3.1 | 7.3 |
| K | 0.6 | 1.2 |
| Ca | 0.4 | 2.2 |
| Ti | 1.1 | 0.4 |
| Cu | 0.6 | – |
| Cl | – | 0.7 |
| Na | – | 1.6 |
| MoL | – | 1.1 |
3.4 Physio-chemical analysis
Table 2 shows the color, pH, and EC of the FA-TTPP and FA-STPS. The FA-TTPS is mild alkaline and FA-STPS is moderate. Generally, pH depends on the S, Ca, and Mg content in parent coal [91]. So that can be used to neutralize acidic soil [92]. Due to its high silt content, FA can be classified as silt loam so that it may be amended with sandy soils [93]. The silt and clay content increased as the proportion of FA in the mixture increased. Further, FA increased the fine content of the soil, causing the soil to change to clay. This decreases soil porosity and thus inhibits the plant life cycle [93]. However, the minimum amount of FA application in the soil can give better agronomical results. Furthermore, both FAs may increase water retention capacity by increasing infiltration rates and reducing water logging in sandy soils [94].
pH and EC of FA-TTPP and FA-STPS
| Parameter | FA-TTPP | FA-STPS |
| Color | Tan | Dark grey |
| pH | 7.56 ± 0.05 | 8.02 ± 0.05 |
| Electric conductivity (EC) | 248 ± 10 μs cm−1 | 234 ± 10 μs cm−1 |
| Texture | Slit loam | Silt loam |
3.5 Soil analysis
The five different soil samples were collected and tested for properties. Table 3 shows the soil analysis of soil samples. The soil investigation indicates various soil types, such as loamy, sandy-loamy, and clayey-loamy. The five soil samples had pH of 8.1, 7.4, 8.2, 6.3, and 6, respectively. Hence, sites 4 and 5 soils have low pH that may be neutralized with FA. The remaining three sites (1–3) soils are slightly alkaline, so less FA can benefit plant growth. Soil texture influenced the amount of nutrient availability [95]. The structure of the soil affects aeration, root penetration, soil–water relationship, and nutritional content. Sandy soil has poor moisture retention. Hence, FA application can help to improve moisture retention and the nutrient concentration of sandy soil. The soil at site-3 is loamy sand, whose inability to hold water makes it more prone to fertilizer loss. Soil nutrient analysis showed that N, P, and K levels were below the required amount, which may affect plant growth and yield. Therefore, applying FA with organic manure may improve N, P, and K nutrients, soil composition, fertility, and fauna, which has long-term positive effects on crop production. Site 1 has a lower iron content than the permissible limit. Therefore, site 1 may be treated with iron-rich FA-STPS. Also, potassium deficiencies were found in soil samples from sites 1 to 5. Thus, FA-STPS may meet nutrient deficiencies. Aluminum was not analyzed in soil samples. FA-TTPP is, however, recommended for soils with low aluminum content. Since the soil is rich in calcium carbonate, fruit trees, vegetables, coconut, corn, cotton, and sunflower can be planted in sites 1 and 3. In addition, due to the high EC, coconut, tamarind, sapota, guava, pomegranate, jujube, corn, and sunflower can grow on site 5.
Physio-chemical properties of soil samples
| Parameter | Permissible limits | Soil (Site-1) | Soil (Site-2) | Soil (Site-3) | Soil (Site-4) | Soil (Site-5) |
| Texture | – | Loamy | Sandy loam | Clay loam | Sandy loam | Sandy loam |
| Calcium Carbonate | – | Medium | Nil | Medium | Nil | Nil |
| EC (dSm−1) | <1 | 0.1 | 0.2 | 1.2 | 0.3 | 0.4 |
| pH | 6–8.5 | 8.1 | 7.4 | 8.2 | 6.3 | 6.0 |
| N (kg ha−1) | 240–480 | 65.8 | 57.4 | 11.2 | 68.6 | 64.6 |
| P (kg ha−1) | 11–22 | 8.7 | 4.5 | 5.5 | 5.5 | 5.3 |
| K (kg ha−1) | 110–280 | 92.89 | 101.6 | 52.6 | 106.67 | 54 |
| Fe (ppm) | 0.5–5.0 | 0.3 | 0.7 | 0.9 | 2 | 1.2 |
| Mn (ppm) | 0.1–0.5 | 3.2 | 4.3 | 3.8 | 4 | 3.4 |
| Zn (ppm) | 0.02–0.2 | 0.3 | 0.5 | 0.1 | 0.7 | 0.1 |
| Cu (ppm) | 0.01–0.05 | 0.2 | 0.4 | 0.5 | 0.5 | 0.4 |
3.6 Analysis of water sample
Five water samples were tested to investigate the irrigation water quality parameters that may help analyze reactivity with soil and FA and plant growth. Table 4 shows the water analysis for the water sample. The pH of collected water samples is within the acceptable FAO permissible limits for irrigation water (6.80–8.40) [96, 97]. There may be the possibility of carbonate salt precipitation due to the high pH on site-3. Hence this water is not hazardous to crops. The EC of the water samples was within limits and therefore it poses no threat to crops [98].
Physio-chemical properties of water
| Properties | Water (Site-1) | Water (Site-2) | Water (Site-3) | Water (Site-4) | Water (Site-5) |
| pH | 7.6 | 7.9 | 8.1 | 6.8 | 7.1 |
| EC (dS/L) | 1.2 | 1.9 | 1.0 | 1.8 | 1.7 |
| Carbonate (mg L−1) | 0 | 0 | 0.2 | 0.1 | 0 |
| Bicarbonate (mg L−1) | 6 | 7.8 | 0.6 | 5 | 4 |
| The residual sodium carbonate (RSC) index | – | – | – | – | – |
| Chloride (mg L−1) | 5.2 | 11.2 | 3.2 | 7.2 | 5.4 |
| Sulphate (mg L−1) | 0.8 | 1 | – | – | 0.6 |
| Calcium (mg L−1) | 4.9 | 4.8 | 3.7 | 4.8 | 3.9 |
| Magnesium (mg L−1) | 1.5 | 5.2 | 5.0 | 6.4 | 2.9 |
| Potassium (mg L−1) | 0.07 | 0.12 | 0.11 | 0.2 | 0.19 |
| Sodium (mg L−1) | 5 | 8 | 1.19 | 4.5 | 4.8 |
| Sodium Absorption Ratio (SAR) | 2.8 | 3.58 | 0.572 | 3.7 | 3.7 |
The potassium level of water samples was within the FAO permissible level FAO of 5 mg L−1 and can support plant growth [97]. Sodium levels are optimum within the FAO allowable range of 0–50.0 mg L−1 [99]. Calcium and magnesium values were also within FAO-acceptable irrigation limits [100, 101]. As a result, the water samples' SAR is less than 10, indicating high quality [101]. Overall, water analysis indicates that the irrigation water quality of experimental sites is good, and the study recommends that FA can be applied for soil amending applications.
4 Conclusion
Based on the characterization of FAs, soil study, and water analysis, the following conclusions were made:
Microstructural characterization studies showed that important micro- and macronutrients other than nitrogen and phosphorus are present in FA-TTPP and FA-STPS. XRD patterns showed that quartz (SiO2), mullite (Al6Si2O), and hematite (Fe2O3) are present in both FAs, which can promote plant growth. The FTIR spectra show that stretching vibrations of the Si–O–Si, Al–O–Si, HO–OH, and OH bonding were seen in both FAs, which indicates strong mineral bonds such as quartz and mullite. SEM analysis showed compact microspheres with regular, smooth, and irregular textures, while FA-STPS showed glassy, unshaped fragments. EDX indicates the types of elements (nutrients) such as Si, Al, Fe, Mg, K, Ca, Cu, Ti, Na, and Cl. Silicon was found to be the majority mineral, and a similar amount is found in both FAs. FA-TTPP has three times higher aluminum content than FA-STPS, while FA-STPS has two times less iron content. Hence, FA-TTPP and FA-STPS can act as soil amelioration agent and helps to promote plant growth.
The pH of the FA-TTPP and FA-STPS is moderately alkaline, and it can neutralize acidic soils (sites 4 & 5). Since sites 1 and 3 have loamy and clayey texture with high fine particles, it is recommended to use minimum FA quantity in the fields.
Soil analysis showed the soil's nutrients are lower than the required amount, which will reduce plant growth. The iron content on site 1 is lower than the level required to cause iron chlorosis. It is recommended to amend the iron-rich FA-STPS on site 1. In addition, soil samples 1–5 showed a potassium deficiency that could be remedied by the FA-STPS. Also, it suggests applying the FA with organic manure for the nitrogen and phosphorous contents on soil sampling sites 1 to 5 to increase crop production.
Monitoring water quality is necessary for the sustainability of plant growth and yield. The collected water samples are of excellent quality, and all the properties are within limits. Hence, the water can be irrigated with FA and soil. Overall, the characterization study of the FA, soil, and water give insights to farmers for the proper utilization of FA for agronomical applications.
Author contribution
Mr. Nittin Johnson Jeyaraj: literature search, investigation, methodology framing, writing – original draft.
Dr. Vanitha Sankararajan: supervision, suggestion, writing – reviewing, and editing.
Availability of data and materials
Not applicable.
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Funding
Research support provided by Kalasalingam Academy of Research and Education.
Acknowledgments
Author Nittin Johnson Jeyaraj gratefully acknowledges the International Research Centre (IRC), Kalasalingam Academy of Research and Education (KARE) for providing a University Research Fellowship (URF) and Instrumental research facilities.
References
- [1]↑
F. Saeed, M. Afzaal, and A. Khalid, “Role of mycoprotein as a non-meat protein in food security and sustainability: a review,” Int. J. Food Prop, vol. 26, pp. 683–695, 2023. Available: https://doi.org/10.1080/10942912.2023.2178456.
- [2]↑
D. Cervantes-Godoy and J. Dewbre, Economic Importance of Agriculture for Poverty Reduction, 2010. https://doi.org/10.1787/5kmmv9s20944-en.
- [3]↑
A. Raihan, An Econometric Evaluation of the Effects of Economic Growth, Energy Use, and Agricultural Value Added on Carbon Dioxide Emissions in Vietnam. Springer Nature Singapore, 2023.
- [4]↑
J. von Braun, K. Afsana, L. O. Fresco, and M. H. A. Hassan, “Science for transformation of food systems: opportunities for the UN Food Systems Summit,” Sci. Innov. Food Syst. Transform, vol. 921, 2023.
- [5]↑
D. M. Mahapatra, K. C. Satapathy, and B. Panda, “Biofertilizers and nanofertilizers for sustainable agriculture: phycoprospects and challenges,” Sci. Total Environ., vol. 803, 2022, Art no. 149990. https://doi.org/10.1016/j.scitotenv.2021.149990.
- [6]↑
B. A. Omran and K.-H. Baek, “Control of phytopathogens using sustainable biogenic nanomaterials: recent perspectives, ecological safety, and challenging gaps,” J. Clean. Prod., vol. 372, 2022, Art no. 133729. https://doi.org/10.1016/j.jclepro.2022.133729.
- [7]↑
K. A. Ammar, A. M. S. Kheir, and B. M. Ali, “Developing an analytical framework for estimating food security indicators in the United Arab Emirates: a review,” Environ. Dev. Sustain., 2023. Available: https://doi.org/10.1007/s10668-023-03032-3.
- [8]↑
D. Hou, “Sustainable soil management for food security,” Soil Use Manag., vol. 39, pp. 1–7, 2023. https://doi.org/10.1111/sum.12883.
- [9]↑
V. Sandström, J. Kaseva, and M. Porkka, “Disparate history of transgressing planetary boundaries for nutrients,” Glob. Environ. Chang, vol. 78, 2023. Available: https://doi.org/10.1016/j.gloenvcha.2022.102628.
- [10]↑
S. Husain, A. Nandi, and F. Z. Simnani, “Emerging trends in advanced translational applications of silver nanoparticles: a progressing dawn of nanotechnology,” J. Funct. Biomater., vol. 14, p. 47, 2023. Available: https://doi.org/10.3390/jfb14010047.
- [11]↑
W.-P. Zhang, D. Fornara, and H. Yang, “Plant litter strengthens positive biodiversity--ecosystem functioning relationships over time,” Trends Ecol \& Evol, 2023.
- [12]↑
D. Derrien, P. Barré, and I. Basile-Doelsch, “Current controversies on mechanisms controlling soil carbon storage: implications for interactions with practitioners and policy-makers,” A. Review. Agron. Sustain. Dev., vol. 43, 2023. Available: https://doi.org/10.1007/s13593-023-00876-x.
- [13]↑
H Bamdad, S. Papari, G. Lazarovits, and F. Berruti, “Soil amendments for sustainable agriculture: microbial organic fertilizers,” Soil Use Manag., vol. 38, pp. 94–120, 2022. https://doi.org/10.1111/sum.12762.
- [14]↑
L. Panda and S. Dash, “Characterization and utilization of coal fly ash: a review,” Emerg. Mater. Res., vol. 9, pp. 921–934, 2020. https://doi.org/10.1680/jemmr.18.00097.
- [15]↑
J. Chen and Y. Li, “Coal fly ash as an amendment to container substrate for Spathiphyllum production,” Bioresour. Technol., vol. 97, pp. 1920–1926, 2006. https://doi.org/10.1016/j.biortech.2005.08.009.
- [16]↑
S. K. Shukla, S. Solomon, and L. Sharma, “Green technologies for improving cane sugar productivity and sustaining soil fertility in sugarcane-based cropping system,” Sugar Tech., vol. 21, pp. 186–196, 2019. Available: https://doi.org/10.1007/s12355-019-00706-z.
- [17]↑
H.V. Vitekari, A. P. Talele, and R. G. Mane, “Fly ash based biopesticides: a comprehensive review,” J. Pharm. Biol. Sci., vol. 2, pp. 76–82, 2012.
- [18]↑
A. Varshney, P. Dahiya, and A. Sharma, “Fly ash application in soil for sustainable agriculture: an Indian overview,” Energy Ecol. Environ., vol. 7, pp. 340–357, 2022. Available: https://doi.org/10.1007/s40974-022-00241-w.
- [19]↑
S. Arora and P. Gargava, “E-Mobility: hindrances and motivators for policies implementation in India,” Case Stud. Transp Policy, vol. 11, 2023, Art no. 100955. https://doi.org/10.1016/j.cstp.2023.100955.
- [20]↑
A. Sheokand, R. Devi, P. Singh, “Utilization of bio-organic waste as a source of electricity for sustainable development,”, vol. 11, pp. 495–501, 2022. https://doi.org/10.37273/chesci.cs205310538.
- [21]↑
D. K. Narne, T. A. R. Kumar, and R. R. Alla, “A brief review on conventional and renewable power generation scenario in India,” in Recent Advances in Power Systems: Select Proceedings of EPREC-2021, O. H. Gupta, V. K. Sood, and O. P. Malik, Eds., Singapore: Springer Nature Singapore, 2022, pp. 649–657.
- [22]↑
S. Jala and D. Goyal, “Fly ash as a soil ameliorant for improving crop production—a review,” Bioresour. Technol., vol. 97, pp. 1136–1147, 2006. https://doi.org/10.1016/j.biortech.2004.09.004.
- [23]↑
D. Das and P. K. Rout, “Coal fly ash utilization in India,” in New Horizons for Industry 4.0 in Modern Business, Springer, 2023, pp. 233–251.
- [24]↑
X. Sun, J. Li, and X. Zhao, “A review on the management of municipal solid waste fly ash in American,” Proced. Environ Sci, vol. 31, pp. 535–540, 2016. Available: https://doi.org/10.1016/j.proenv.2016.02.079.
- [25]↑
S. U. Qadir, V. Raja, and W. A. Siddiqui, “Fly-ash pollution modulates growth, biochemical attributes, antioxidant activity and gene expression in pithecellobium dulce (Roxb) benth,” Plants, vol. 8, pp. 1–18, 2019. Available: https://doi.org/10.3390/plants8120528.
- [26]↑
H. Hou, L. Su, D. Guo, and H. Xu, “Resource utilization of solid waste for the collaborative reduction of pollution and carbon emissions: case study of fly ash,” J. Clean. Prod., vol. 383, 2023. https://doi.org/10.1016/j.jclepro.2022.135449.
- [27]↑
X. Hu, X. Huang, H. Zhao, “Possibility of using modified fly ash and organic fertilizers for remediation of heavy-metal-contaminated soils,” J. Clean. Prod., vol. 284, 2021, Art no. 124713. https://doi.org/10.1016/j.jclepro.2020.124713.
- [28]↑
K. S. R. Mohan, P. Jayabalan, and A. Rajaraman, “Properties of fly ash based coconut fiber composite,” Am. J. Eng. Appl. Sci., vol. 5, pp. 29–34, 2012. https://doi.org/10.3844/ajeassp.2012.29.34.
- [29]↑
S. K. Dwibedi and V. C. Pandey, “Fly ash management fly ash management through vermiremediation,” in Bio-Inspired Land Remediation, V. C. Pandey, Ed., Cham: Springer International Publishing, 2023, pp. 241–260.
- [30]↑
A. Bhatt, S. Priyadarshini, A. Acharath Mohanakrishnan, “Physical, chemical, and geotechnical properties of coal fly ash: a global review,” Case Stud. Constr Mater., vol. 11, 2019, Art no. e00263. https://doi.org/10.1016/j.cscm.2019.e00263.
- [31]↑
A. Varshney, P. Dahiya, N. Singh, and S. Mohan, “Variations in morphological parameters and pigment content of Calendula officinalis grown in fly ash amended soil,” Plant Arch., vol. 19, pp. 2959–2963, 2019.
- [32]↑
I. Oncioiu, E. Grecu, and S. Mâşu, “The effect of fly ash on sunflower growth and human health,” Environ. Sci. Pollut. Res., vol. 25, pp. 35548–35554, 2018. Available: https://doi.org/10.1007/s11356-018-3444-6.
- [33]↑
R. Singh, N. Gautam, A. Mishra, and R. Gupta, “Heavy metals and living systems: an overview,” Indian J. Pharmacol., vol. 43, pp. 246–253, 2011. https://doi.org/10.4103/0253-7613.81505.
- [34]↑
S. K. Pandey and T. Bhattacharya, “Effect of two biodegradable chelates on metals uptake, translocation and biochemical changes of Lantana Camara growing in fly ash amended soil,” Int. J. Phytoremediation, vol. 20, pp. 214–224, 2018. https://doi.org/10.1080/15226514.2017.1365350.
- [35]↑
I. Khan and R. Umar, “Environmental risk assessment of coal fly ash on soil and groundwater quality, Aligarh, India,” Groundw Sustain. Dev., vol. 8, pp. 346–357, 2019. https://doi.org/10.1016/j.gsd.2018.12.002.
- [36]↑
Z. T. Yao, X. S. Ji, and P. K. Sarker, “A comprehensive review on the applications of coal fly ash,” Earth-science Rev., vol. 141, pp. 105–121, 2015. Available: https://doi.org/10.1016/j.earscirev.2014.11.016.
- [37]↑
M. Roy, R. Roychowdhury, and P. Mukherjee, “Remediation of fly ash dumpsites through bioenergy crop plantation and generation: a review,” Pedosphere, vol. 28, pp. 561–580, 2018. https://doi.org/10.1016/S1002-0160(18)60033-5.
- [38]↑
M. Smol, J. Duda, A. Czaplicka-Kotas, and D. Szołdrowska, “Transformation towards circular economy (CE) in municipal waste management system: model solutions for Poland,” Sustain, vol. 12, 2020. https://doi.org/10.3390/su12114561.
- [39]↑
B. Kipkemboi, T. Zhao, S. Miyazawa, “Effect of C3S content of clinker on properties of fly ash cement concrete,” Constr Build Mater., vol. 240, 2020, Art no. 117840. https://doi.org/10.1016/j.conbuildmat.2019.117840.
- [40]↑
N. L. Ukwattage, P. G. Ranjith, and M. Bouazza, “The use of coal combustion fly ash as a soil amendment in agricultural lands (with comments on its potential to improve food security and sequester carbon),” Fuel, vol. 109, pp. 400–408, 2013. https://doi.org/10.1016/j.fuel.2013.02.016.
- [41]↑
G. Y. Zhang, Z. Dou, J. D. Toth, and J. Ferguson, “Use of flyash as environmental and agronomic amendments,” Environ. Geochem. Health, vol. 26, pp. 129–134, 2004. https://doi.org/10.1023/B:EGAH.0000039575.85640.e8.
- [42]↑
M. Basu, P. B. S. Bhadoria, and S. C. Mahapatra, “Role of soil amendments in improving groundnut productivity of acid lateritic soils,” Int. J. Agric. Res., vol. 2, pp. 87–91, 2007.
- [43]↑
I. B. Gratchev, A. Shokouhi, and A. Balasubramaniam, “Feasibility of using fly ash, lime, and bentonite to neutralize acidity of pore fluids,” Environ. Earth Sci., vol. 71, pp. 3329–3337, 2014. https://doi.org/10.1007/s12665-013-2719-y.
- [44]↑
X. Huang, H. Zhao, G. Zhang, “Potential of removing Cd(II) and Pb(II) from contaminated water using a newly modified fly ash,” Chemosphere, vol. 242, 2020, Art no. 125148. https://doi.org/10.1016/j.chemosphere.2019.125148.
- [45]↑
C. Srinivasa Rao, C. Subha Lakshmi, and V. Tripathi, “Fly ash and its utilization in Indian agriculture: constraints and opportunities,” in Circular Economy and Fly Ash Management, S. K. Ghosh and V. Kumar, Eds., Singapore: Springer Singapore, 2020, pp. 27–46.
- [46]↑
L. C. Ram and R. E. Masto, “Fly ash for soil amelioration: a review on the influence of ash blending with inorganic and organic amendments,” Earth-science Rev., vol. 128, pp. 52–74, 2014. https://doi.org/10.1016/j.earscirev.2013.10.003.
- [47]↑
A. Hussain and S. Faizan, “Rhizobium induced modulation of growth and photosynthetic efficiency of Lens culinaris Medik. grown on fly ash amended soil by antioxidants regulation,” Environ. Sci. Pollut. Res., 2023. https://doi.org/10.1007/s11356-023-25616-2.
- [48]↑
M. V. Raletsena, R. Munyai, and N. I. Mongalo, “Accumulation of heavy metals, yield and nutritional composition of potato (Solanum tuberosum L.) cultivars irrigated with fly-ash-treated acid mine drainage,” Sustainability, vol. 15, p. 1327, 2023. https://doi.org/10.3390/su15021327.
- [49]↑
B. Grabowska-Polanowska, T. Garbowski, D. Bar-Michalczyk, and A. Kowalczyk, “The benefits of synthetic or natural hydrogels application in agriculture: an overview article,” J. Water L. Dev., vol. 51, pp. 208–224, 2021. https://doi.org/10.24425/jwld.2021.139032.
- [50]↑
A. Shakeel, A. A. Khan, and G. Ahmad, “The potential of thermal power plant fly ash to promote the growth of Indian mustard (Brassica juncea) in agricultural soils,” SN Appl. Sci., vol. 1, 2019. https://doi.org/10.1007/s42452-019-0404-9.
- [51]↑
C. L. Carlson and D. C. Adriano, “Environmental impacts of coal combustion residues,” J. Environ. Qual., vol. 22, pp. 227–247, 1993. https://doi.org/10.2134/jeq1993.00472425002200020002x.
- [52]↑
M. Ahmaruzzaman, “A review on the utilization of fly ash,” Prog. Energy Combust Sci, vol. 36, pp. 327–363, 2010. https://doi.org/10.1016/j.pecs.2009.11.003.
- [53]↑
C. Carlile, S. Nadiger, and J. Burken, “Effect of fly ash on growth of mustard and corn,” Biosci. Biotechnol. Res. Asia, vol. 10, pp. 551–557, 2013. https://doi.org/10.13005/bbra/1164.
- [54]↑
N. Parab, S. Mishra, and S. Bhonde, “Prospects of bulk utilization of fly ash in agriculture for integrated nutrient management prospects of bulk utilization of fly ash in agriculture for integrated nutrient management,” Bull Natl. Inst. Ecol., vol. 23, pp. 31–46, 2012.
- [55]↑
A. Shakeel, “Effect of sulphur and boron on growth and yield of sunflower (helianthus annuus L.),” Int. J. Curr. Microbiol. Appl. Sci., vol. 9, pp. 3320–3323, 2020. https://doi.org/10.20546/ijcmas.2020.908.381.
- [56]↑
A. Shakeel, A. A. Khan, and S. K. Upadhyay, “Eco-friendly dual-edged management of fly ash and its antagonistic interplay with Meloidogyne incognita on beetroot (Beta vulgaris L.),” Environ. Res., vol. 209, 2022, Art no. 112767. https://doi.org/10.1016/j.envres.2022.112767.
- [57]↑
K.V. Kumar and D. D. Patra, “Alteration in yield and chemical composition of essential oil of Mentha piperita L. plant: effect of fly ash amendments and organic wastes,” Ecol. Eng., vol. 47, pp. 237–241, 2012. https://doi.org/10.1016/j.ecoleng.2012.06.019.
- [58]↑
M. Basu, M. Pande, P. B. S. Bhadoria, and S. C. Mahapatra, “Potential fly-ash utilization in agriculture: a global review,” Prog. Nat. Sci., vol. 19, pp. 1173–1186, 2009. https://doi.org/10.1016/j.pnsc.2008.12.006.
- [59]↑
B. Hadke P, S. G. Wankhade, and S. N. Ingle, “Consequence of fym and fly ash application on yield, nutrient uptake, and quality of safed Musli grown on inceptisols,” Int. J. Curr. Microbiol. Appl. Sci., vol. 8, pp. 263–273, 2019. https://doi.org/10.20546/ijcmas.2019.805.030.
- [60]↑
A. Varshney, S. Mohan, and P. Dahiya, “Growth and antioxidant responses in plants induced by heavy metals present in fly ash,” Energy Ecol. Environ., vol. 6, pp. 92–110, 2021. https://doi.org/10.1007/s40974-020-00191-1.
- [61]↑
S. Jain and A. R. Tembhurkar, “Studies on growth and yield response of Jatropha curcas plant on fly ash amended soil,” Commun. Soil Sci. Plant Anal, vol. 53, pp. 1391–1401, 2022. https://doi.org/10.1080/00103624.2022.2046035.
- [62]↑
S. S. Bisoi, S. S. Mishra, J. Barik, and D. Panda, “Effects of different treatments of fly ash and mining soil on growth and antioxidant protection of Indian wild rice,” Int. J. Phytoremediation, vol. 19, pp. 446–452, 2017. https://doi.org/10.1080/15226514.2016.1244164.
- [63]↑
G. Jovanovski, B. Boev, and P. Makreski, “Chemistry and geology of coal: nature, composition, coking, gasification, liquefaction, production of chemicals, formation, peatification, coalification, coal types, and ranks,” ChemTexts, vol. 9, pp. 1–16, 2023. https://doi.org/10.1007/s40828-022-00177-y.
- [64]↑
M. Arunthirumeni, G. Vinitha, and M. S. Shivakumar, “Antifeedant and larvicidal activity of bioactive compounds isolated from entomopathogenic fungi Penicillium sp. for the control of agricultural and medically important insect pest (Spodoptera litura and Culex quinquefasciatus),” Parasitol. Int., vol. 92, 2023, Art no. 102688. https://doi.org/10.1016/j.parint.2022.102688.
- [65]↑
D. Neina, S. Faust, and R. G. Joergensen, “Characterization of charcoal and firewood ash for use in African peri-urban agriculture,” Chem. Biol. Technol. Agric., vol. 7, pp. 1–10, 2020. https://doi.org/10.1186/s40538-019-0171-2.
- [66]↑
B. Santhosh Kumar, J. Rajesh, C. B. Pande, and A. Varade, “Land use and cover variations and problems associated with coastal climate in a part of Southern Tamil Nadu, India, using remote sensing and GIS approach,” in Climate Change Impacts on Natural Resources, Ecosystems and Agricultural Systems, C. B. Pande, K. N. Moharir, S. K. Singh, et al., Eds., Cham: Springer International Publishing, 2023, pp. 595–613.
- [67]↑
V. Raja and M. A. Neelakantan, “Toxic uranium contamination in groundwater of Thoothukudi district, India: evaluation of health risks using the geochemical and statistical approach,” Toxin Rev., vol. 42, pp. 316–331, 2023. https://doi.org/10.1080/15569543.2022.2150648.
- [68]↑
M. Senthilkumar, “A study on the drinking water quality index and groundwater quality assessment in Virudhunagar district, Tamilnadu, India,” Int. J. Aquat. Sci., vol. 12, p. 2021, 2021.
- [69]↑
S. Madasamy, T. Rajendiran, G. Nagappan, et al., Geochemical Characterization of Groundwater and Water Quality Assessment for Sustainable Management of Hard Rock Aquifer in South India, 2021.
- [70]↑
R. Kaur and D. Goyal, “Mineralogical comparison of coal fly ash with soil for use in agriculture,” J. Mater. Cycles Waste Manag., vol. 18, pp. 186–200, 2016. https://doi.org/10.1007/s10163-014-0323-1.
- [71]↑
Z. Zhang, H. Wang, and J. L. Provis, “Quantitative study of the reactivity of fly ash in geopolymerization by ftir,” J. Sustain. Cem Mater., vol. 1, pp. 154–166, 2012. https://doi.org/10.1080/21650373.2012.752620.
- [72]↑
J. Yu, X. Li, and D. Fleming, “Analysis on characteristics of fly ash from coal fired power stations,” Energy Proced., vol. 17, pp. 3–9, 2012. Available: https://doi.org/10.1016/j.egypro.2012.02.054.
- [73]↑
D. Koga, S. Kusumi, M. Shibata, and T. Watanabe, “Applications of scanning electron microscopy using secondary and backscattered electron signals in neural structure,” Front Neuroanat., vol. 15, pp. 1–17, 2021. https://doi.org/10.3389/fnana.2021.759804.
- [74]↑
G. Dodbiba and T. Fujita, “Trends in extraction of rare earth elements from coal ashes: a review,” Recycling, vol. 8, pp. 1–18, 2023. https://doi.org/10.3390/recycling8010017.
- [75]↑
X. Ding, Y. Jiang, and H. Zhao, “Electrical conductivity of nutrient solution influenced photosynthesis, quality, and antioxidant enzyme activity of pakchoi (Brassica campestris L. Ssp. Chinensis) in a hydroponic system,” PLoS One, vol. 13, pp. 1–15, 2018. Available: https://doi.org/10.1371/journal.pone.0202090.
- [76]↑
T. F. Scherer, D. Franzen, and L. Cihacek, “Soil, water and plant characteristics important to irrigation,” North Dakota State Univ. Ext Serv., vol. 1675, pp. 1–16, 2017.
- [77]↑
G. J. McCarthy, D. M. Johansen, S. J. Steinwand, and A. Thedchanamoorthy, “X-ray diffraction analysis of fly ASH,” Adv. X-ray Anal, vol. 31, pp. 331–342, 1987. https://doi.org/10.1154/S037603080002214X.
- [78]↑
N. Funsueb, A. Thipboonraj, and A. Wannawek, “Physical properties and microstructure of traditional kaolin-based ceramics with additive fly-ash (FA),” J. Phys. Conf. Ser., vol. 2431, 2023. Available: https://doi.org/10.1088/1742-6596/2431/1/012049.
- [79]↑
V. Thi, N. Minh, and V. Pham, “Firing-associated recycling of coal-fired power plant fly ash,” J Anal Methods Chem, 2023.
- [80]↑
D. Coskun, D. T. Britto, W. Q. Huynh, and H. J. Kronzucker, “The role of silicon in higher plants under salinity and drought stress,” Front Plant Sci., vol. 7, pp. 1–7, 2016. https://doi.org/10.3389/fpls.2016.01072.
- [81]↑
L. Van Nhan, C. Ma, and Y. Rui, “The effects of Fe2O3 nanoparticles on physiology and insecticide activity in non-transgenic and Bt-transgenic cotton,” Front Plant Sci., vol. 6, pp. 1–12, 2016. Available: https://doi.org/10.3389/fpls.2015.01263.
- [82]↑
P. K. Priya, S. Vanitha, and P. Meyyappan, “Characteristic and microstructural study on an alternate material in brick manufacturing,” IOP Conf. Ser. Mater. Sci. Eng., vol. 955, 2020, Art no. 12038. https://doi.org/10.1088/1757-899X/955/1/012038.
- [83]↑
P. Rożek, M. Król, and W. Mozgawa, “Spectroscopic studies of fly ash-based geopolymers,” Spectrochim Acta Part A. Mol. Biomol. Spectrosc., vol. 198, pp. 283–289, 2018. https://doi.org/10.1016/j.saa.2018.03.034.
- [84]↑
W.-R. Lim, J.-H. Park, and C.-H. Lee, “Characterizing crystalline phase transitions in zeolitization of coal fly ash using focused ion beam-scanning electron microscopy,” Surf. Inter., vol. 36, 2023, Art no. 102536. https://doi.org/10.1016/j.surfin.2022.102536.
- [85]↑
A. M. Mustafa, A. Bakri, and H. Kamarudin, “Microstructure of different NaOH molarity of fly ash- based green polymeric cement,” J. Eng. Technol. Res., vol. 3, pp. 44–49, 2011.
- [86]↑
A. M. Mustafa Al Bakri, O. A. Abdulkareem, and H. Kamarudin, “Microstructure studies on the effect of the alkaline activators of fly ash-based geopolymer at elevated heat treatment temperature,” Appl. Mech. Mater., vol. 421, pp. 342–348, 2013. Available: https://doi.org/10.4028/www.scientific.net/AMM.421.342.
- [87]↑
A. Tejasvi and S. Kumar, “Impact of fly ash on soil properties,” Natl. Acad. Sci. Lett., vol. 35, pp. 13–16, 2012. https://doi.org/10.1007/s40009-011-0002-x.
- [88]↑
B. G. Kutchko and A. G. Kim, “Fly ash characterization by SEM-EDS,” Fuel, vol. 85, pp. 2537–2544, 2006. https://doi.org/10.1016/j.fuel.2006.05.016.
- [89]↑
M. Bhagat, S. Singh, and S. Suresh, Utilization of Value-Added Products from Fly Ash: An Industrial Waste. Elsevier Inc, 2023.
- [90]↑
B. N. Anusha, K. R. Babu, B. P. Kumar, “Integrated studies for land suitability analysis towards sustainable agricultural development in semi-arid regions of AP, India,” Geosystems Geoenviron., vol. 2, 2023, Art no. 100131. https://doi.org/10.1016/j.geogeo.2022.100131.
- [91]↑
S. K. Dwibedi, S. K. Sahu, V. C. Pandey, “Seedling growth and physicochemical transformations of rice nursery soil under varying levels of coal fly ash and vermicompost amendment,” Environ. Geochem. Health, 2021, Art no. 0123456789. https://doi.org/10.1007/s10653-021-01074-y.
- [92]↑
R. B. Yadava, S. K. Das, and P. S. Pathak, “Effect of fly ash application on soil physico-chemical properties,” Agroecol Nat. Resour. Manag., vol. 1, pp. 98–103, 2014.
- [93]↑
A. Hamanaka, T. Sasaoka, H. Shimada, and S. Matsumoto, “Amelioration of acidic soil using fly ash for mine revegetation in post-mining land,” Int. J. Coal Sci. Technol., vol. 9, pp. 1–6, 2022. https://doi.org/10.1007/s40789-022-00499-9.
- [94]↑
H. S. Dhindsa, R. D. Sharma, and R. Kumar, “Role of fly ash in improving soil physical properties and yield of wheat (Triticum aestivum),” Agric. Sci. Dig. A. Res. J., vol. 36, pp. 97–101, 2016. https://doi.org/10.18805/asd.v36i2.10626.
- [95]↑
J. Junchao, L. Chaodong, and C. Zhangyue, “Soil texture rather than water potential determines the root: shoot ratio in Ryegrass and Alfalfa,” J. Soil Sci. Plant Nutr., 2023. https://doi.org/10.1007/s42729-022-01121-2.
- [96]↑
M. Batool, M. Toqeer, and M. H. Shah, “Assessment of water quality, trace metal pollution, source apportionment and health risks in the groundwater of Chakwal, Pakistan,” Environ. Geochem. Health, 2023. https://doi.org/10.1007/s10653-023-01501-2.
- [97]↑
J. D. Oster, G. Sposito, and C. J. Smith, “Accounting for potassium and magnesium in irrigation water quality assessment,” Calif. Agric., vol. 70, pp. 71–76, 2016. https://doi.org/10.3733/ca.v070n02p71.
- [98]↑
T. A. Bauder, P. L. Waskorn, and J. G. Davis, Irrigation Water Quality Criteria (Fact Sheet No. 0.506 Crop Series), 2011, pp. 10–13.
- [99]↑
N. Tessema, D. Yadeta, A. Kebede, and G. T. Ayele, “Soil and irrigation water salinity, and its consequences for agriculture in Ethiopia: a systematic review,” Agriculture, vol. 13, p. 109, 2022. https://doi.org/10.3390/agriculture13010109.
- [100]↑
K. S. Rawat, S. K. Singh, and S. K. Gautam, “Assessment of groundwater quality for irrigation use: a peninsular case study,” Appl. Water Sci., vol. 8, pp. 1–24, 2018. https://doi.org/10.1007/s13201-018-0866-8.
- [101]↑
A. Malakar, D. D. Snow, and C. Ray, “Irrigation water quality-A contemporary perspective,” Water (Switzerland), vol. 11, pp. 1–24, 2019. https://doi.org/10.3390/w11071482.