The agronomic efficiency of conventional silicon (Si) fertilizers is frequently limited by their low bioavailability in soil. Consequently, nano-silica (nano-Si) has gained increasing attention as a sustainable alternative due to its enhanced availability and potentially superior physiological effectiveness in plants. The present study aimed to synthesize nano-Si from rice husk (RH), and its effects on growth, oxidative stress responses, and nutrient status of durum wheat. Nano-Si was characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). SEM observations showed a hierarchical structure consisting of micro-scale porous frameworks formed by agglomerated nano-sized primary particles lower than 80 nm, while largely preserving the native siliceous architecture. FTIR and XRD analyses confirmed that the material was predominantly amorphous Si with characteristic Si-O-Si functional groups. A pot experiment was conducted in which nano-Si and sodium silicate were applied at rates of 0, 25, 50, and 100 mg kg− 1 to wheat plants grown under drought conditions. Applied Si did not significantly influence total dry weight; however, grain yield responded strongly to nano-Si, with the highest yield recorded at 25 mg kg− 1. This treatment also resulted in higher chlorophyll content and relative water content, along with lower H2O2 accumulation and membrane permeability, and enhanced antioxidant enzyme activities, particularly ascorbate peroxidase. In contrast, sodium silicate produced weaker physiological responses and was associated with increased H2O2 levels. Nano-Si application increased plant Si and P concentrations. Nano-Si outperformed Na-Si in improving grain yield, photosynthesis, water relations, and oxidative stress tolerance in wheat, indicating its potential as a sustainable Si fertilizer.

Boron (B) toxicity causes oxidative stress, damaging plant membranes, chloroplasts, proteins, and lipid metabolism, leading to reduced productivity. This study hypothesizes that hydrolyzed keratin (HK) from sheep wool (SW) can mitigate B toxicity. The experiment was conducted under greenhouse conditions with lettuce plants. The experimental subjects included control, HK, boron-toxic conditions (BT), and BT+HK applications. Plant samples were analyzed for weight, B and N concentrations, and relative chlorophyll content. Additionally, the effects of oxidative stress in plants were determined through H2O2 accumulation, antioxidant enzyme activity, and molecular-level changes, which were identified using Fourier Transform Infrared Spectroscopy (FTIR). The HK effectively mitigates the impact of B toxicity on lettuce growth and health. Under normal conditions, HK increased dry weight from 2.46 g to 3.40 g plant-1, and under B toxicity, it raised dry weight to 2.64 g plant-1. HK also enhanced nitrogen concentrations in both inner and outer leaves, while reducing B levels in both leaf types. HK reduced hydrogen peroxide (H2O2) levels, alleviating oxidative stress, and decreased superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities, suggesting improved antioxidant defense. The highest chlorophyll content was observed in HK-treated plants, indicating better photosynthesis. FTIR analysis revealed that HK restored structural integrity in carbohydrates, proteins, and cell membranes in the inner leaves, which were altered by B toxicity. These results highlight HK's potential in enhancing plant growth, nutrient uptake, and oxidative stress management under B-toxicity, while demonstrating the utility of FTIR in identifying molecular-level changes in plants.

Heavy metal/metalloid contamination in agriculture threatens food safety, with arsenic (As) and cadmium (Cd) commonly accumulating due to industrial activities and certain farming practices. This study evaluated the ability of poultry litter incineration ash (PLIA) to reduce As and Cd uptake in radish. Characterization of PLIA was performed using FTIR, Raman, and XRD. The experiment was established under controlled conditions with the treatments as follows: control, As + Cd, As + Cd + 10 g kg−1 PLIA, As + Cd + 20 g kg−1 PLIA, and As + Cd + 40 g kg−1 PLIA. As + Cd treatment increased As from 0.30 to 12 mg kg−1 in leaves and from 0.68 to 132 mg kg−1 in tubers. Cd concentrations increased from 1.58 to 120 mg kg−1 in leaves and from 0.48 to 25.4 mg kg−1 in tubers. PLIA reduced both As and Cd accumulation: the 20 g kg⁻1 PLIA dose produced the lowest As concentration in leaves, while 10 g kg−1 resulted in the lowest As in tubers; for Cd, the lowest leaf concentrations occurred at 10–20 g kg−1, and tuber Cd decreased to 17.6 mg kg−1 with 10 g kg−1 PLIA. Although As + Cd caused slight, non-significant reductions in plant-biomass, PLIA at 10 g kg−1 increased plant dry weight. PLIA improved P and K nutrition but decreased Ca and Mg in tubers, with Mg increasing in leaves. PLIA demonstrated strong potential to immobilize As and Cd in soil and reduce their transfer to edible plant tissues.

Abstract Sustainable recycling of biomass ash is critical for circular nutrient management, requiring proper modification before agricultural use. This study converted poultry litter‐derived boiler ash (BA) and wet ash (WA) into basal and top‐dressing fertilizers and evaluated their physicochemical properties, mineralogical changes, and agronomic performance. Both ashes were leached with sulfuric acid; the resulting filter cakes were treated with nitric acid to produce basal fertilizers with nutrient ratios expressed as N:P 2 O 5 :K 2 O (BABF 3.62:11.2:8.61; WABF 3.82:8.91:9.11), while ammonium nitrate was added to the leachates to obtain top‐dressing fertilizers with nutrient ratios (BATF 19.3:2.47:10.1; WATF 21.2:2.93:7.72). Acid treatment reduced the highly alkaline pH (11.5–12.0) to acidic levels (pH <5) and increased electrical conductivity (EC) and water‐soluble nutrients. Nitrogen (N) was enriched in top‐dressing fertilizers (up to 21.2%), whereas phosphorus (P) remained higher in basal formulations. Fertilizer applications significantly increased plant dry weight (up to 79.9 g pot −1 ) compared to control (10.4 g pot −1 ) and conventional fertilization (72.3 g pot −1 ). Plant N, P, iron (Fe), and zinc (Zn) concentrations increased markedly, with BA‐based treatments enhancing P and micronutrient uptake, and WA‐based treatments promoting biomass production. Available‐P, potassium (K), and Zn also increased after harvest. Ash‐derived fertilizers improved plant growth and soil fertility, performing comparably or better than conventional fertilizers. Producing both basal and top‐dressing fertilizers offers a promising strategy for sustainable nutrient recovery.

Sheep wool (SW) is mostly underutilized and is treated as waste. This study investigates its ability to retain water in the soil. After determining the chemical composition of SW, it was mixed with soil at ratios of 97.5:2.5 and 95:5-(soil:SW) in the first experiment, and 99:1, 98:2, and 97:3 in the second experiment. Silage maize plants were then grown in these soil-SW mixtures. Thermal camera imaging showed that SW treatments reduced canopy temperatures, indicating lower water and heat stress. Chlorophyll content increased with SW addition, peaking in the SW1 treatment (97.5:2.5 w/w) in the first experiment and in the SW2 treatment (98:2 w/w) in the second experiment. Stomatal resistance was generally higher in the first experiment but decreased with increasing SW levels in the second. Stomatal density increased across all SW treatments in both experiments. Pot weight confirmed that SW-treated pots retained more water. In the first experiment, maize dry weight increased with the SW1 treatment, while the highest dry weight was observed in SW2 treatment during the second experiment. Nutrient analysis showed significant increases in N and P concentrations with SW treatments. Potassium levels increased in the first experiment, while Ca and Mg showed variable responses across experiments. Manganese, Zn and Cu concentrations also increased with SW treatments. This study highlights the potential of SW as a soil conditioner for improving water retention, nutrient uptake, and plant growth. Further research is recommended to optimize SW application rates across crop species and environmental conditions.

The effects of hydrolyzed keratin (HK) treatments on the growth, cadmium (Cd) accumulation, nitrogen (N) concentration, and FTIR spectral properties of lettuce grown in Cd-contaminated soil was investigated. Curly lettuce was grown in a naturally lit greenhouse. The treatments were as follows: 1-Control 2-Cd-contaminated [Cd, 30 mg Cd kg-1 kg-1]: 3-Cd+HK1 [30 mg Cd and 1.0 mL HK kg-1] 4-Cd+HK2 [30 mg Cd and 2.0 mL HK kg-1]. Cadmium-contamination improved weights of lettuce plants compared to the control, with a similar trend observed in the Cd+HK treatments. The Cd in control plants was 0.48 mg kg-1, which increased to 14.1 mg kg-1 with Cd application. In contrast, HK treatments reduced Cd accumulation to below 11.5 mg kg-1. Although Cd-contamination reduced plant N concentration, the HK2 treatment mitigated Cd toxicity by enhancing N concentrations compared to Cd treatments. FTIR analysis revealed that the spectral region between 1039 and 1392 cm-1 remained unaffected across treatments. However, marked spectral shifts were observed: the peak at 1645 cm-1 in control plants shifted to 1630 cm-1 with Cd-contamination and broadened with Cd+HK1 treatment, while Cd+HK2 restored it to a pattern like the control. Unique peaks at 1720 cm-1 appeared in the HK treatments, and the peak at 2100 cm-1, absent in Cd treatments, reemerged with HK. Additionally, peaks at 2345 and 3738 cm-1, conspicuously present or absent in control plants, were intensified with Cd+HK treatments. Hydrolyzed keratin reduces Cd accumulation in lettuce, partially alleviates Cd-induced stress, and induces specific structural changes detectable by FTIR.

Cadmium (Cd) contamination of agricultural soils threatens crop productivity and food safety. The chemical form of iron (Fe) fertilizer can influence Cd mobility and plant uptake. This study evaluated the effects of different Fe sources on Cd accumulation, Fe nutrition, and growth of spinach and lettuce grown in Cd-contaminated soil. Spinach was cultivated in soil amended with 30 mg Cd kg-1 and treated with FeSO4, FeCl3, or Fe-EDDHA, while lettuce received Fe-EDDHA at 5, 10, 20, and 40 mg Fe kg-1. Cadmium stress reduced plant biomass in both crops. Fe-EDDHA enhanced both Fe and Cd uptake, resulting in the highest Cd concentrations in plant tissues, reaching 315 mg kg-1 in spinach. FeCl3 similarly increased Cd concentration in spinach during the first harvest, whereas FeSO4 and FeCl3 had no significant effect during the second harvest. Spectroscopic analyses suggested that inorganic Fe sources may have promoted the formation of secondary Fe-bearing phases potentially associated with reduced Cd mobility, whereas Fe-EDDHA may have contributed to maintaining Cd in relatively more mobile and potentially bioavailable forms through metal-organic interactions. These observations indicate that Fe source can influence Cd behavior in soil-plant systems. Although Fe-EDDHA effectively improved Fe nutrition, its application in Cd-contaminated soils may increase Cd uptake and therefore should be considered with caution.

Effectiveness of the applied fertilizers is low in silage maize cultivation due to excessive irrigation. This study investigated the primary and residual efficiency of rice husk biochar (RHBC)-based organo-mineral fertilizers (OMFs) in silage maize. RHBC was treated with different N sources and acids to produce biochar-based OMFs, and the primary and residual effects of these fertilizers were compared with diammonium phosphate (DAP) fertilizer. The current experiment consisted of four treatments including a control, DAP, OMF1(RHBC + H₂SO₄+ DAP), OMF2 (RHBC + H₃PO₄ + NH₄NO₃), OMF3 (RHBC + DAP), OMF4 (RHBC + H₃PO₄ + Urea). In the first maize experiment, P treatments increased dry weight from 1.84 to over 3.80 g plant− 1, with OMF3 reaching the highest value (4.08 g). While differences among P sources were minor initially, residual effects in the second crop were more evident, with OMF1, OMF3, and OMF4 yielding significantly higher biomass than DAP and OMF2. Plant N and P concentrations also increased with fertilization, peaking in OMF3 (31.3 and 4.35 g kg− 1, respectively), and remained elevated in OMF3 and OMF4 during the second crop. OMF3 also led to the highest chlorophyll, lowest anthocyanin levels, and maximum soil available P. DAP released N rapidly, posing leaching risks, while OMF3 provided slower N and higher P release, improving nutrient efficiency. OMFs, especially OMF3, improved plant growth, nutrient uptake, and P availability in the soil, demonstrating their potential to enhance silage maize production and nutrient management.

Cauliflower is one of the major brassica vegetables that receive attention due to the presence of glucosinolates that are known to have health benefits. These metabolites are a part of plant defence system and influenced under stress conditions. Light Emitting Diodes (LED) are gaining interest as to provide artificial light at different wavelengths that modulate morphological, physiological and biochemical responses of plants. The objective of the present study was to explore salt stress response of cauliflower (Brassica oleracea var. botrytis) seedlings that are grown under different LED light wavelengths in terms of morphological parameters, antioxidant enzyme activities and glucosinolate contents. The seedlings were treated with 200 mM NaCl to generate salt stress or without NaCl as the control and were grown under different LED light wavelengths including red, blue, red+blue, red+far red, blue+far red and white (control) lights. Shoot and root growth parameters, antioxidant enzymes activity (CAT, SOD, APX), H2O2 content, aliphatic and indole glucosinolates were determined. The findings revealed that salt and light treatments independently influenced shoot and root growth. The antioxidant enzymes CAT and APX activities were highest in the control plants of blue and blue+far red lights whereas SOD activity was highest in salt treated plants under blue light. Aliphatic and indole glucosinolate content varied among LED light treatments. Salt treatment decreased the aliphatics while indoles particularly the glucobrassisin was increased with the influence of salinity and light wavelengths. The results demonstrated the salt stress response of cauliflower seedlings by elucidating changes in the antioxidant enzymes, glucosinolate contents, major shoot and root growth parameters under a range of different light wavelengths. These findings may provide a comprehensive understanding of the influence of different light wavelengths in mediating plant stress response.

This study investigates the effects of hydrolyzed keratin (HK) on the growth and Ca and Mg uptake of lettuce plants under natural and light-emitting diode (LED) lighting conditions in cocopeat and soil environments. Lettuce plants were grown under natural light in cocopeat and soil, and simultaneously under blue (B), blue + far-red (B + FR), red (R), R + B, R + FR, R + B + FR, and white (W) light conditions. The fertilizer treatments consisted of control, HK, Ca + Mg, and HK + Ca + Mg. The highest fresh and dry weights of lettuce plants were observed with HK treatment in cocopeat, and HK + Ca + Mg treatment in soil. Among different LED light sources, the highest fresh and dry weights were recorded under the R light, followed by R + B + FR, R + B, and W, with the weakest growth observed under B + FR, R + FR, and B. Regardless of light source, HK and Ca + Mg treatments improved fresh and dry weights compared to the control. All treatments increased Ca and Mg concentrations compared to the control, with the highest Mg concentration observed under HK + Ca + Mg treatment and the highest Ca concentration is found with HK + Ca + Mg and Ca + Mg treatments. The highest N concentrations were observed in cocopeat with HK treatments and in soil with HK + Ca + Mg, compared to the control. The Ca concentration was higher under B + FR and R + FR, and Mg concentration was highest under R and R + B. HK, Ca + Mg, and HK + Ca + Mg treatments consistently improved the nutritional status of lettuce plants, making HK a promising organic amendment for enhancing plant growth and nutrient uptake in both soil and soilless cultivation systems.

Arsenic (As) in soils threatens plant growth and food safety, requiring sustainable mitigation. This study examined the conversion of sheep wool (SW) to hydrolyzed keratin (HK) and its impact on spinach under As stress. The treatments were as follows: 1-Control, 2-As toxicity [As, 30 mg As kg− 1], 3-As + HK1 [30 mg As and 1.0 mL HK kg− 1 soil], 4-As + HK2 [30 mg As and 1.5 mL HK kg− 1 soil], 5-As + HK3 [30 mg As and 2.0 mL HK kg− 1 soil]. Fourier transform infrared spectroscopy (FTIR) analysis revealed that while both SW and HK shared similarities due to their keratin content, hydrolysis introduced significant modifications. Peaks at 1527, 1643, and 2347 cm⁻¹ observed in SW were altered, with stronger peaks at 1373 and 1585 cm⁻¹ and new peaks at 2550 and 3250 cm⁻¹ appearing in HK, indicating increased solubility and functionalization. In As-contaminated soil, HK application especially at the highest dose significantly improved spinach biomass and reduced As accumulation from 0.75 to 0.22 mg kg⁻¹, while also enhancing plant N concentrations. FTIR analysis of spinach showed that As toxicity weakened peaks at 1028, 2920, and 3275 cm⁻¹ and eliminated those at 1236, 1317, and 1402 cm⁻¹, indicating disrupted cell wall structure or reduced carbohydrate synthesis. HK application partially restored these peaks and introduced a new one at 2328 cm⁻¹. Hydrolyzed keratin enhances plant growth and mitigates As toxicity, demonstrating its potential as a sustainable amendment for improving crop resilience in contaminated soils.

Sheep wool (SW) serves as a slow-release organic fertilizer, and its effectiveness can be enhanced through alkaline hydrolysis to break down keratin. The resulting keratin hydrolysate can support plant growth and improve mineral nutrition. Keratin hydrolysate obtained from sheep wool via the alkaline hydrolysis method was applied to lettuce, spinach, and radish plants at levels of 0, 0.5, 1.0, 1.5, 2.0, and 3.0 mL kg− 1. Before starting the experiment, the molecular and chemical structure of sheep wool hydrolysate (SWH) was determined using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy and Raman Spectroscopy. At the end of the study, the effects of SWH on plant growth and mineral nutrition were determined. Based on the experimental results, several amino acids, including alanine, glycine, tryptophan, valine, and methionine, were identified in the composition of the hydrolysate. Treatments with SWH significantly enhanced the growth of lettuce, spinach, and radish plants. Furthermore, these treatments led to a notable increase in the total nitrogen (N) concentration in the plants. Specifically, the calcium (Ca), magnesium (Mg), and iron (Fe) concentrations significantly increased in both lettuce and spinach. Additionally, SWH treatments elevated the zinc (Zn) concentration in radish tubers and the manganese concentration in lettuce plants. The copper (Cu) concentration in the plants also rose significantly following SWH treatments. The use of keratin hydrolysate derived from SW through the alkaline hydrolysis method demonstrates its potential to promote plant growth, emphasizing its significance in waste recovery and its transformation into a valuable resource.

BackgroundNitrate accumulation in leafy vegetables poses health risks for humans.AimsThe effect of hydrolyzed keratin (HK) on the development of lettuce grown under natural and various LED light sources, as well as its impact on reducing nitrate accumulation, was investigated in hydroponic systems.MethodsHK was obtained from sheep wool, and its structural and molecular properties were determined using scanning electron microscopy (SEM) and confocal Raman spectroscopy. The plants were grown in a cocopeat. The light sources used in the experiment included Blue, Blue + Far-red, Red, Red + Blue, Red + Far-red, Red + Blue + Far-red, White, and natural light (NL), with HK concentrations in the nutrient solution set at 0, 25, and 50 mg N L-1 for the plants grown under these conditions.ResultsAccording to the results obtained from the research, the best plant growth and the highest nitrate accumulation were observed in plants grown under NL conditions. Among the LED light sources, the most ideal treatments for high yield and low nitrate accumulation were those with Red and Red + Blue + Far-red. The most significant outcome of this study was that the addition of HK to the nutrient solution led to a significant reduction in nitrate concentrations in the lettuce plants across all treatments except for the blue light source. The addition of HK to the nutrient solution decreased nitrate in most light treatments, highlighting its potential as a valuable additive in controlled agriculture.ConclusionThese findings emphasize the potential to optimize light conditions and nutrient formulations to enhance plant health and safety in indoor cultivation.

Cadmium (Cd) is a toxic heavy metal that adversely affects humans, animals, and plants. The effects of a composite organo-mineral fertilizer (WASH), derived from sheep wool (SW) and chicken manure incineration ash (CMA) on the growth, nutrient uptake, metabolic activity, and oxidative stress responses of lettuce plants under Cd toxicity and varying light conditions were investigated. The functional properties of WASH, compared to its raw materials (SW and CMA), were assessed using Fourier Transform Infrared Spectroscopy (FTIR). Lettuce plants were grown under both natural and light-emitting diode (LED) light conditions to evaluate the performance of WASH.The treatments were: control, Cd toxicity (20 mg Cd kg-1), Cd + WASH1 (1 g kg-1), and Cd + WASH2 (2 g kg-1). Fourier transform infrared spectroscopy analysis suggests that WASH retains distinct functional groups from its precursors, SW and CMA, which contribute to its efficacy. Under both light conditions, WASH treatments, particularly at a dose of 2 g kg-1, improved plant growth by mitigating Cd-induced oxidative stress, as evidenced by reduced H₂O₂ levels and normalized antioxidant enzyme activities (Superoxide dismutase: SOD, catalase: CAT and ascorbate peroxidase: APX). WASH treatments significantly reduced Cd accumulation in plant tissues and enhanced the uptake of nitrogen (N), phosphorus (P), and potassium (K). The effects of WASH were more pronounced under LED lighting, with greater improvements in plant growth and metabolic activity measured by FTIR analysis. WASH has significant potential as a sustainable soil amendment to combat Cd toxicity and enhance nutrient uptake. Future studies should focus on evaluating the effectiveness of WASH across various Cd-contaminated soil types and plant species to optimize its application in agriculture.

This study aims to investigate strategies to minimize nitrate accumulation in lettuce to mitigate its potential harmful effects on human health. Lettuce cultivation under light-emitting diode lighting (LED) is becoming increasingly popular, and determining the effects of different LED sources on lettuce nutrition and nitrate accumulation is an important topic. The effects of different nitrate levels in the nutrient solution and different LED sources on lettuce nutrition and nitrate accumulation have been investigated under controlled conditions. Lettuce plants were grown for 48 days under White (W), Blue (B), Blue + Far Red (B + FR), Red (R), Red + Blue (R + B), Red + Far Red (R + FR), Red + Blue + Far Red (R + B + FR) LED lights using nutrient solutions containing 20, 24, and 28 mM nitrate. The highest marketable yield was obtained under B lighting, followed by R, R + B, R + FR, and R + B + FR. To reduce nitrate accumulation, lighting setups using W, R + B + FR, R + B, and R have proven to be advantageous. In these treatments, nitrate levels were determined to be 1039, 1118, 1167, and 1170 mg kg-1, which were lower compared to the other treatments. The concentrations of measured nutrients in plants were highest under B + FR, R + FR, and R + B lighting. The total chlorophyll concentration increased with the N dose, with the highest levels observed in the B, B + RF, and R + B + FR treatments. In conclusion, LED lighting influences lettuce nutrition and nitrate accumulation, with W, R + B + FR, R + B, and R treatments most effective in reducing nitrate levels. These findings should be validated in commercial greenhouse conditions to assess their practical applicability for large-scale production.

Purpose: This study thoroughly investigates innovative amendment salicylic acid (SA) modified rice husk biochar (SABC) designed to improve boron (B) and salinity tolerance in lettuce, providing a comprehensive exploration of their potential effects in alleviating stress-induced challenges. Methods: Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy were used for the molecular and chemical characterization of the biochar samples. The treatments consisted of control, 40 mM NaCl plus 20 mg B kg-1 (NaCl + B), and 40 mM NaCl plus 20 mg B kg-1 and 5 g kg-1 SA-modified rice husk biochar (NaCl + B + SABC). Results: Under conditions of salt and B toxicity, SABC treatment significantly prevented the decrease in plant weight induced by stress. SABC reduced the concentrations of B, sodium (Na), and chloride (Cl) in plants, while increasing the concentrations of potassium (K) and silicon (Si). The hydrogen peroxide concentration, which increased as a result of B and salt toxicity, was decreased with SABC. The activities of the antioxidant enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APX) showed a significant increase under stress, but due to the positive effect of SABC in reducing B and salt stress, there was a decrease in the activities of these enzymes. Conclusions: The results obtained from this study indicate that SABC is effective in reducing boron and salt stress. Testing the SABC molecule in different plants and under various stress conditions could provide significant contributions to the stress literature.

Salt stress, which impairs plant growth and induces oxidative stress, presents a major challenge in agriculture. In response, biochar has emerged as a promising soil amendment, capable of enhancing plants' stress tolerance mechanisms. This study investigated the impact of rice husk biochar (RBC), derived from rice husks, on enhancing salt stress tolerance in lettuce plants grown under greenhouse conditions. Molecular and chemical characterization of the biochar samples was performed using Scanning Electron Microscopy (SEM) and Raman spectroscopy. Salinity reduced the fresh and dry weights of the plants from 25.0 g plant-1 and 1.83 g plant-1 to 20.4 g plant-1 and 1.42 g plant-1, respectively. The application of RBC recovered the growth decline caused by salinity, increasing the fresh and dry weights of the plants to 28.1 g plant-1 and 1.83 g plant-1, respectively. While the concentrations of sodium and chloride in plants decreased with RBC application, potassium and silicon concentrations significantly increased. As a result of salt stress, hydrogen peroxide levels (H2O2) increased in plant tissues, and a decrease in H2O2 levels was observed with an increase in superoxide dismutase, catalase, and ascorbate peroxidase activities. Consequently, RBC proved to be effective in enhancing salt tolerance in lettuce plants. In conclusion, while RBC demonstrates significant potential for enhancing salt tolerance, its successful application depends on several factors such as biochar dosage, application method, soil type, and plant species, underscoring the need for further research to elucidate the mechanisms at play and optimize its use for sustainable soil management in saline conditions.

This study aims to apply circular economy principles through waste-to-energy processes to safely dispose of harmful materials, generate sustainable energy, and produce fertilizer. Poultry litter incineration ash (PLA) was acidified and enriched with urea to create a compound fertilizer, UMPLA, with a 4-14-5 composition. As a new material, molecular structure and functional groups of UMPLA were determined using SEM, XRD and RAMAN techniques. The effectiveness of UMPLA was tested on sugar beet, comparing it to the reference fertilizer (12-30-12) at both full and half-reduced P doses. The results showed that using an equal or half-reduced dose of UMPLA produced root yields equivalent to those achieved with the reference fertilizer. The P and Mg concentrations of the leaves increased to the same extent with both fertilizers compared to the control. However, reduced UMPLA resulted in lower P and Mg concentrations compared to the full dose. While, the fertilizer applications did not significantly affect the Fe and Cu concentrations in the plants, Zn and Mn concentrations decreased. Refined sugar yield (RSY) increased significantly with fertilizer applications compared to the control. Both fertilizers had a similar effect on RSY, and even the reduced UMPLA application produced a RSY comparable to that of the full-dose fertilizers. Neither the reference nor UMPLA treatments had any negative effects on root K, Na, α-amino N, or dry matter content. UMPLA was as effective as the widely used 12-30-12 fertilizer for sugar beet. These findings suggest that PLA, an increasingly abundant waste, can be effectively used as an alternative fertilizer raw material in plant production.

The study aimed to explore how phosphoric acid-modified rice husk biochar (PBC) affects the growth and concentrations of essential and non-essential elements in two crops: lettuce as the primary crop and arugula as the secondary crop. The treatments consisted of a no P fertilized control and 250 mg P kg-1 sourced either from PBC, triple super phosphate (TSP) or phosphoric acid (PA). When subjected to phosphorus (P) sources, both lettuce and arugula exhibited a noteworthy rise in their dry weights compared to the control plants. PBC treatments significantly increased P concentration in both plants. Although the PBC treatment decreased lettuce nitrogen (N) concentration, it had no impact on arugula N concentration. Phosphorus treatments resulted in a decrease in lettuce K concentration, whereas it increased in arugula. Calcium (Ca), magnesium (Mg) and sulfur (S) concentrations in both plants were not affected by P sources. The zinc (Zn) concentrations of the plants notably decreased with P treatments. Moreover, P treatments led to a reduction in manganese (Mn) concentration specifically in arugula. PBC significantly increased the silicon (Si) concentrations of lettuce plants. The application of PA significantly increased the vanadium (V) concentration in arugula. Phosphoric acid treatments resulted in an increase in the plant bromine (Br) concentrations. To conclude, PBC may serve as an alternative P source, potentially being as effective as or even more effective than other P sources in influencing plant nutrition, without causing an undesirable elevation of non-essential elements in plants.