Development of Sustainable Nanofertilizer via Zeolite Nanostructures Synthesized from Industrial Sludge and Enriched with Bovine-Derived Nutrients

Abstract

The focus of this research is the development of a sustainable nanofertilizer synthesized from zeolite nanostructures derived from industrial sludge with bovine-enriched nitrogen, phosphorus, and potassium (NPK) nutrients. By reusing organic and industrial byproducts, this formulation is intended to maintain or potentially increase nutrient efficiency while reducing the environmental impact. Zeolite nanostructures were synthesized by the sol–gel method and were subsequently mixed with bovine bone and blood powder to improve the nutrient content. X-ray diffraction (XRD) confirmed pure zeolitic crystalline phases, while elemental composition studies through X-ray fluorescence analysis (XRF) demonstrated high levels of Si, Al, Ca, P, K, and N species, indicating successful incorporation of nutrients and as well determining the concentration of trace elements, which is below the USEPA standard. Fourier transform infrared spectroscopy (FTIR) analysis revealed distinct bands, as seen at 3277, 1638, 1036, and 565–467 cm^–1, supportive evidence of hydroxyl, phosphate, and aluminosilicate groups. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses both indicated pores and irregular shapes of particles, which contributed to an increased surface area and possible retention of nutrients. The nanofertilizer developed was used again to evaluate its impact on maize (Zea mays L.) production relative to control (no fertilizer) and conventional fertilizer treatment. It assessed phenology, growth, and yield. Nanofertilizer treatment has greater grain yield components (8.10 t/ha) when compared with conventional ones (7.84 t/ha).This result provides evidence for the zeolite-based nanofertilizer being a sustainable, effective choice for increasing maize productivity that contributes to circular economy in agriculture.

1. Introduction

1.1. Background

The unparalleled increase in global population has heightened the demand for food, placing considerable strain on agricultural systems to increase crop yields from an already limited resource base. Meanwhile, limited cultivable land, driven by urbanization, deforestation, and soil degradation, has derived the need for new ways to increase agricultural production on the land that remains. Traditional chemical-based fertilizers helped stimulate plant growth but come with a number of negative environmental and health impacts. Their use in excess usually results in nutrient runoff into surface and groundwater systems, contributing to eutrophication and harmful aquatic ecosystem health.

Chemical fertilizers can degrade soils, promote nutrient depletion, and disrupt the natural microbiome of soil, while posing human health challenges through residual chemicals accumulating in crops. With these exacerbated issues, there is an excessive need for new fertilization methods that are also resource-efficient and environmentally sustainable, nanofertilizers will begin to fill this need. Home to features of the novel disruption of resource flow, nanofertilizers developed at the scale of nanoparticles offer increased bioavailability and targeted nutrient application to expand nutrient absorption while minimizing the total amount of fertilizer applied. By minimizing nutrient losses to the environment and optimizing resource use, nanofertilizers offer a sustainable approach to addressing the dual challenges of rising food demand and limited arable land, thereby supporting resilient and ecologically responsible agricultural systems.

This research looks into the creation of a new nanofertilizer by encapsulating necessary macronutrients such as nitrogen (N), phosphorus (P), and potassium (K) from bovine bone and blood. These organic waste products are rich in nutrients and principally underutilized in current farming systems. By combining these nutrient types with a nanosized zeolite, which is created from treated industrial sludge, the study aims to determine an environmentally friendly and efficient fertilizer. The nanozeolite serves two purposes: it adds a stable matrix for trapping all nutrients and improves the performance of the fertilizer by trapping the nutrients and controlled gradual release optimally, maximizing the nutrient for the plants while keeping minimal environmental loss. When used as a nanofertilizer, it is predicted that crop productivity will increase as the nutrient will be delivered at a higher efficiency and capacity throughout plant growth while improving soil health and sustainability by decreasing nutrient leaching, enhancing soil structure, and maintaining beneficial microbial activity within the soil. In conclusion, this study provides a viable solution to the growing issues of food security, limited land, and sustainable agricultural practices through the use of a new nanofertilizer.

The encapsulation technology is designed for the enhancement of nitrogen, phosphorus, and potassium (NPK) solubility for bioavailability to address issues that traditional fertilizers face. This approach not only encourages farming output by facilitating enhanced uptake of nutrients by crops, but it also enables the use of industrial byproduct materials, thus adhering to a circular economy. Therefore, this study provides a basis for a complete investigation into the synthesis, physicochemical characteristics, and agronomic analyses of this new nanofertilizer, emphasizing its potential to develop nutrient management methods while advancing sustainable agriculture.

More than half of all chemical fertilizers and insecticides sprayed are believed to go wasted because they leak and mineralize into the soil and water bodies. Over the past ten years, a great deal of study has been conducted on bio fertilizers, microbiomes, and soil health due to increased awareness of the negative consequences of conventional fertilizers. Conventional fertilizers are frequently employed to improve essential nutrients in the soil. These comprise diammonium phosphate, potassium, phosphorus, nitrogen, and urea. Alternatively, leaching reduces the nutrient utilization efficiency of conventional fertilizers with respect to soil fertility and results in economic consequences. There has been a dramatic decline in soil fertility due to the nutrients leaching or volatilizing out of the soil. The key contributors to this is the very low utilization rates of conventional fertilizers, as their nutrient utilization is, respectively, 35–40% for potassium, 18–20% for phosphorus, and 30–35% for nitrogen.

With some longer term projections of 11 billion or more by 2100, the world’s population is predicted to grow rapidly to 9.6 billion by 2050. This will put pressure on the planet’s finite resources to produce highly efficient agriculture in order to combat poverty and hunger globally. The developing nations of Asia, Africa, and Latin America will account for over 90% of the anticipated growth. The use of more effective mineral fertilizers is a vital strategy to meet the rise in food production required to feed this growing population and promote economic development, given the restricted number of additional arable lands and limited water resources. However, widespread environmental problems such groundwater contamination, water eutrophication, degraded soil quality, and air pollution have been brought on by the frequent use of traditional fertilizers over long periods of time. The wise and effective use of fertilizers is one of the most crucial components of modern agriculture since it can improve crop yield, lower environmental pollution, and provide food security for the world’s expanding population.

Nanofertilizers are one technique that could enhance fertilizer efficiency and reduce harmful environmental effects from chemical fertilizers. The implementation of these strategies may mean that farmers effectively increase the nutrients taken from crops and lessen nutrient losses and environmental pollution. Nanofertilizers provide multiple benefits over traditional fertilizers, like small scale, greater penetration into plant tissues, and controlled, slow nutrient release, which increases efficiency and reduces waste.

1.2. Role of Nanozeolite in Fertilizer Encapsulation

A nanozeolite is essential to the encapsulation of fertilizers, given its unique physical and chemical properties: high surface area, tunable porosity, and ion exchange capacity. The crystalline aluminosilicate framework of nanozeolites has negatively charged sites that can absorb and retain essential nutrient cations such as ammonium ion (NH⁴⁺), potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺), thereby minimizing nutrient loss through leaching and volatilization.

A nanozeolite frame structure made up of aluminosilicates can function effectively as a controlled release medium of nutrients because of the following properties: its porosity, high surface area, and the formation of negative charge sites in the frame structure through the substitution of silicon by Al³⁺. Nutrient cations such as ammonium, potassium, and calcium are retained by the zeolite through electrostatic attraction and released gradually as they are exchanged with soil cations. The stable and microporous nature of the zeolite frame structure also physically controls diffusion of the cation-based nutrients to enhance their efficiency of use and to reduce their loss by leaching and volatilization.

Furthermore, when acting as a nanocarrier, nanozeolite provides the porous matrix for the encapsulation of nutrient sources, such as bone-derived phosphate and blood-derived nitrogen. This impregnation mechanism protects sensitive bionutrients from being prematurely degraded, while allowing for a gradual and controlled release of nutrients that match the plant uptake demand. The interconnected microporous and mesoporous channels within the zeolite structure regulate the diffusion of nutrients, allowing for a sustained supply to plants over time, reducing the frequency of fertilization applications. Additionally, nanozeolite has been shown to increase soil cation exchange capacity and water retention, enhancing root growth and nutrient uptake in desirable rhizospheric conditions. At the nano level, its enhanced surface reactivity and relatively uniform dispersion make the loading and release kinematics of nutrients efficient. Overall, nanozeolite functions as a multifunctional component in nanofertilizer formulations serving simultaneously as a nutrient reservoir, protective encapsulate, and soil conditioner thereby improving fertilizer efficiency, reducing environmental impact, and supporting sustainable agricultural productivity.

1.3. Importance of Nano Fertilizer

Nanofertilizers have plenty of benefits such as increasing nutrient efficiency, reducing negative impact on the environment, and promoting sustainable agriculture practices. The nanosized particles provide a more accurate placement and lower amount of waste can lead to improved uptake of fertilizers by plants; thus reducing the possibility of soil and water contamination resulting from traditional fertilizer practices. Nanofertilizers, which can release nutrients gradually, enhance crop quality and crop productivity while simultaneously preserving soil quality. In addition, they better utilize resources and help reduce the input costs for farmers that coincide with the ideas of precision agriculture. Nanofertilizers could help reduce the environmental negative effects of modern agriculture and offer sustainable alternatives to traditional fertilizers while providing access to global food production concerns.

2. Materials and Methods

2.1. Materials and Chemicals

The experiment utilizes a variety of materials and chemicals, including a muffle furnace, grinder, crucible, beakers, oven, electronic balance, powdered nanozeolite-X, filter paper, filter funnels, round-bottom flasks, condenser, Bunsen burner, clamps and stands, bovine blood, bovine bone, soil samples, and an auger.

2.2. Sample Collection

Sludge samples were taken from the wastewater treatment plant within the Hawassa Industrial Park, located approximately 275 km south of Addis Ababa, a well-known industrial park of about 300 ha of textile and garment manufacturing plants. Soil samples were taken from the Wondo Genet Agricultural Research Center, about 25 km from Hawassa, where the site has many multidisciplinary studies to enhance sustainable agricultural development, particularly the highland and midaltitude agro ecological zones of southern Ethiopia. Bovine bone and blood samples were taken from a registered slaughterhouse in Addis Ababa to be used as nutrient sources for the experiment.

2.3. Sample Characterization

2.3.1. Elemental Analysis of the Nanozeolite, Bovine Bone Ash, and Blood Powder

XRF was utilized to identify the constituents of the samples, including heavy metals. As an advanced analysis technique, XRF determines elemental composition by exposing a material to high-energy X-ray radiation that causes the sample to emit characteristic fluorescent X-rays (Bahgaat et al., 2020). It was conducted utilizing (Thermo Scientific Niton XL2 plus XRF analyzer, South Africa) due to a rapid, precise, and accurate elemental analysis method with little sample preparation. Nondestructive and versatile, XRF is regularly used in scientific fields and industries for reliable elemental characterization (Reyes-Herrera et al., 2022).

2.3.2. Synthesis of Nano Fertilizer

The dried sludge powder was calcined at 600 °C for 2 h in an SX-2.5–10 muffle furnace to obtain a thermally treated material. After calcination, the sample was cooled to room temperature in a desiccator to prevent moisture absorption. The calcined material, with a composition of Na (12.65%), Al (15.09%), and Si (14.95%), was then mixed with 3 M NaOH solution and stirred at 3000 rpm using a magnetic stirrer until a homogeneous gel was formed via the sol–gel method. The resulting gel was aged at room temperature for 16 h, followed by continuous stirring at 80 °C for 3 h to promote nucleation and crystal growth. The mixture was subsequently filtered, and the solid residue was washed several times with distilled water until a neutral pH was achieved. Finally, the washed product was calcined again under the same conditions to obtain the final nanozeolite X.

Bovine bones were cleaned thoroughly to eliminate all remaining flesh and fat tissue and then cut into small pieces with a mechanical cutting machine. The cleaned bone pieces were subjected to calcination at 700 °C for 4 h in a muffle furnace to produce bone ash. The bone ash was ground using a high-end RRH-200 grinder into a total powder to provide a consistent powder for a subsequent mixing step. The fresh bovine blood was obtained from a local slaughterhouse and sun-dried for 1 week, effectively removing the moisture, and then ground with the same RRH-200 grinder into a uniform blood powder. The bone ash and blood powder were formulated into different mass ratios of 1:1.5, 1:1, 0.5:1, and 1:0.5 by mass, respectively. Each formulated mixture was stirred for 30 min using a magnetic stirrer to ensure each mixture was fully homogenized and each nutrient was delivered uniformly.

Figure indicates the homogenized bone–blood mixtures were then combined with nano zeolite-X, serving as a nutrient carrier matrix. The new combined mixture was stirred for a further 30 min under the same conditions to allow sufficient time for all nutrients to uniformly wet and fill into the zeolite. The slurry obtained from this process was filtered to remove the liquid from the solid phase. The resulting solid was placed into an oven and dried at 110 °C until constant weight was reached to ensure all moisture had been removed. The dried nanofertilizer was then ground into a fine powder, sealed into airtight containers, and stored under controlled conditions before physicochemical analysis and used in agriculture.

1.

Flowchart for preparation of nanofertilizer.

2.4. Characterization of Nanofertilizer

2.4.1. X-ray Diffraction

XRD was used as a rapid, noncontact, and nondestructive technique that provides detailed information about the crystallographic structure, chemical composition, and physical properties of nanomaterials. Analyzing the structure of nanomaterials can be done effectively by X-ray diffraction (XRD). The interaction of X-rays with a substance causes its atoms to scatter the radiation. When X-rays are released and interact each other in a crystalline material, the atoms’ regular organization can be revealed through a diffraction pattern that indicates the arrangement of atoms in the material.

A powder XRD analysis was performed using a SHIMANDUZ XRD 7000S diffractometer (SHIMANDUZ, Japan). An X-ray tube, sample holder, and X-ray detector are the three basic components of an X-ray diffractometer. A cathode ray tube produces X-rays by burning a filament to produce electrons, providing a voltage to accelerate the electrons toward a target and then hitting the target material electrons. Characteristic X-ray spectra are created when electrons possess enough energy to dislodge the target material’s inner shell electrons. Origin software is then used to turn the data into an XRD graph, and the Scherer equation is used to determine the crystalline size.

The Scherrer equation relates the size of crystallites in a material to the broadening of a peak in an X-ray diffraction pattern

$$D=K\lambda /\beta \cos \theta$$

where: D is the crystallite size, K is the shape factor (typically 0.9), λ is the wavelength of an X-ray, β is the peak width at half-maximum intensity, and θ is the Bragg angle. By measuring the peak width, the average crystallite size of a nanomaterial can be estimated and smaller crystallites lead to broader peaks.

2.4.2. Scanning Electron Microscopy

SEM was utilized for assessment and analysis of the microstructural features of the powder sample. It has a broad range of visualization and characterization capabilities. Not only is it important in understanding the structure and composition of nanomaterials but also enables scientists to assess and analyze nanostructures at high resolution while providing surface morphologies, topographies, elemental distributions, and nanoscale features. The analysis was carried out using the JCM-6000Plus SEM (JCM, Japan). This instrument provided high-resolution imaging suitable for structural and morphological characterization.

2.4.3. Transmission Electron Microscopy

TEM was employed as an analytical technique to visualize and characterize the synthesized materials on the nanometer and atomic scales. The technique was utilized because it allows the internal structure, morphology, and crystallinity of nanoparticles to be directly observed with very high spatial resolution.

2.4.4. Fourier Transform Infrared

FTIR spectrometers (Bruker Tensor II model) were used for the examination of the material’s interaction with infrared light to determine its molecular composition, structure, and vibrational properties. FTIR is essential for understanding the distinct characteristics and behavior of nanomaterials and for determining functional groups (chemical bonds). The analysis can identify the presence of Si–O, Al–O, and other functional groups within the nanofertilizer structure, confirming the successful synthesis of the desired framework.

2.5. Application of Nanofertilizer for Maize Production

2.5.1. Site Description

The field work was conducted at Wondogenet Agricultural Research Center (WGARC) in southern Ethiopia under rain-fed conditions during the 2024 (March to October) cropping season. The research center is located 270 km south of Addis Ababa and 14 km southeast of Shashemene. It exists within the Ethiopian Rift Valley of the Sidama regional state. The geographical coordinates of the research site are 7.09° N and 38.08° E with an altitude of 1780 m above sea level. The mean annual minimum and maximum rainfall are 709 mm and 2062 mm, respectively. The site has a mean maximum and minimum temperature of 26 and 12 °C, respectively. Wando Genet has a bimodal rainfall distribution with two rainy seasons. Short rains occur during March and May and the long rains in July-October. The dry season extends from November to February. The environment of the Wondogenet agricultural research center is suitable for maize research and production.

2.5.2. Materials and Chemicals

Hybrid maize variety BH-546, conventional fertilizer, nanofertilizers, soil sample, tractor, shovel, back weeding hoe, grain bags, reflex setup, grinder, pH meter, auger, and sieve.

2.5.2.1. Experimental Design and Treatments

The field experiment was conducted in Wondogenet Agricultural Research Center. The experiment was laid out in a randomized complete block design (RCBD) with three treatments and replicated three times (Figure ). Maize was planted at a population density of 41,667 plants/ha (intrarow spacing 30 cm and inter-row spacing of 80 cm). The experimental unit was a plot measuring 2.7 m × 4.0 m gross area a gross area of 10.8 m². To minimize edge effects, one hill at each end of the row was not included in the measurements. Each plot was made up of five rows, with nine hills each (one plot/row = 9 hills). One row of nine hills for each plot was purposively used for destructive measurements and observations to ensure the remaining central rows were used for the collection of agronomic data. Hence, the exposed central row of the plot for agronomic observation was termed the net plot area measuring 2.1 m × 2.4 m (5.04 m²). The spacing between adjacent plots was 1.0 m and blocks was 1.5 m apart to minimize plot interferences. To ensure a growing uniform plant population at establishment, one maize seed was planted per hill; an extra seed was planted, but thereafter, the hill was thinned to one good plant at emergence.

2.

Experimental field plot layout and randomization.

2.5.2.2. Land Preparation

The land was plowed by tractors, and the big clods were broken into small sizes and incorporated with soil. All the weeds and crop residue were removed from the experimental field, and then the experimental field was divided into three blocks and then each block further divided into 3 plots. Each plot was separated from the adjacent by a 1m interval, while the replicates were separated by a 1.5 m interval. Experimental plots were kept free from weeds manually, and other cultural practices such as disease and insect pest control were performed as per the recommendation for maize production. Recommended agronomic practices, such as weeding, cultivation, irrigation, fertilizer application, and disease management, were carried out uniformly during the growing season for all plots.

2.5.2.3. Fertilizer and Method of Application

The land was fertilized based on the agricultural transformation agency (ATA) recommendation of 250 kg UREA and 150NPS as a source of nitrogen and phosphorus. The whole amount of NPS (150 kg/ha) recommended to the area was applied during planting, while the recommended rate of urea (250 kg/ha) was applied into two equal splits. Split application of UREA 1/2 during planting, and the remaining half of urea was applied at knee height stage of maize.

UREA (46N-0P-0K), NPS (38N-19N-7S), and TSP (0N-46P-0K).

250 kg urea/ha = 115 N; 150 kg NPS/ha = 69P.

2.5.3. Data Collection and Analysis

• (a)Soil sampling and analysis: Soil samples at a depth of 0–20 cm were taken from 13 random spots diagonally across the experimental field using an auger. The collected soil samples were composited into one sample. The bulked soil sample was air-dried in a shade house to reduce contamination, thoroughly mixed, and ground to pass 2 mm sieve size before laboratory analysis. Then, the samples were properly labeled, packed, and transported to the laboratory. After that, soil organic carbon, total N, soil pH, available P, cation exchangeable capacity (CEC), electrical conductivity (EC), and texture were analyzed at the laboratory.
• (b)Crop Phenology

Days to tasseling: it is the duration from emergence until approximately 50% of the plants in a particular plot show signs of tassels, which are the male flowering parts that grow at the apex of the plant in each plot by counting. This trait is considered one of the most important phenological traits in maize, as it reflects the growth duration and maturity grouping of a maize variety. Early maturing maize varieties will tassel in a lower number of days relative to late-maturing varieties.

Days to silking: it is defined as the number of days from planting until approximately 50% of the plants have emerged and produced visible silks, the female flowering parts that come out of the ear. It is one of the most important phenological traits because silks receive pollen from tassels for fertilization and kernel development. Early maturing varieties will silk earlier than later maturing varieties. The distinction between days to tasseling (male flowering) and days to silking (female flowering) is also extremely important, as wide gaps between the two can reduce the success of pollination and resulting grain yield.

Days to physiological maturity: it is the number of days from planting (emergence) until the crop has completed its final growth stage and is considered to have completed dry matter accumulation of grain or seed. At physiological maturity, the maximum weight of the kernel is achieved and a “black layer” typically develops at the base of cereal grains like maize, indicating the end of nutrient and dry matter translocation from the plant to grain. Physiological maturity is an important measure because it indicates time taken in growth period, the suitability of a crop for different environments and potential yield. It is also the basis for variety comparison and some assessment of adaptability of varietals to certain agro-ecological zones.

• (c)Growth Parameters

Plant height (cm): Maize plant height is regarded as one of the most important morphological constituents that signifies growth and development of the maize crop. Plant height is measured at normal physiological maturity from the soil surface at the base of the plant to the tip of the tassel. Plant height can be impacted by genetic background of the plants, nutrient availability, soil fertility, moisture availability, and environmental factors. A desirable plant height promotes light interception and biomass production, which are essential to the grain yield. Plants that are extremely short may indicate nutritional limits, drought stress, or genetic constraints, while excessive height may contribute to lodging issues, especially where wind or high rainfall is a concern. Because of this, measuring plant height in maize can be used to evaluate performance of varieties, evaluate adaptation of the crop, measure management effectiveness, and measure yield potential.

Ear length (cm): Ear length is the straight-line measurement of the maize cob from the base, where it emerges from the shank to the tip of the cob, excluding the husk. It is one of the critical traits that contribute to yield, and longer ears generally have more kernels, and/or larger kernels, both of which are correlated with grain yield. Ear length is influenced by many factors, including genotype, environmental conditions, nutrients, and in some cases, plant density.

Breeders use ear length for selection to identify more productive varieties, as it often indicates a plant’s ability to utilize assimilates from leaves and stems for grain production. In addition to being an indicator of yield, ear length can be an indication of the efficiency of the assimilates being transferred to a reproductive organ. As such, ear length is an important metric used in the evaluation of maize hybrids and open-pollinated varieties for grain production potential.

Ear height (cm): it refers to the vertical distance from the surface of the soil to the point on the main stem where the ear is attached. Having the ear at a specific height is a key morphological trait that affects both stability and harvesting efficiency in the field. Generally, an increased ear height increases the chances for lodging, especially if the maize plant is tall and grown in a windy or rainy environment. On the other hand, decreased ear height could aid harvesting efficiency in terms of mechanical harvesting and also lodging resistance.

Number of ears per plant: The number of ears per plant in maize is a key yield-determining trait indicating the number of cobs produced per plant at harvest. Most maize varieties produce one ear per plant; however, open-pollinated and specially bred varieties can produce two or more ears under good growing conditions. The trait is governed by genetic boundaries and is also influenced by several factors such as nutrient availability, water availability, plant density, and crop management practices.

• (d)Yield Components and Yield

Number of kernels per ear: it indicates the overall quantity of grains produced on an ear (cob) of maize and is also a significant yield component trait directly contributing to grain yield at the plant and field level. The trait is determined by the number of kernel rows per ear and the number of kernels per row; these traits are a function of genetic potential and environmental conditions such as available nutrients, soil moisture, and adequate pollination conditions. Adequate nitrogen and phosphorus nutrition, proper moisture, and pollination efficiency facilitate the development of more kernels per ear through more effective ear development and fertilization success. Physical stresses, such as drought, nutrient deficiency, and heat stress during silking and grain filling early in the growing season, can reduce kernel set by inducing failure to pollinate or kernel abortion. In experimental protocols, the means of kernels per ear are determined from counting all kernels from five randomly selected ears collected from the central rows of each plot, and the mean is analyzed statistically to compare the effects between varieties or treatments.

Hundred kernel weight (g) is essentially the mass of one hundred randomly selected, properly dried maize kernels expressed in grams. This is an important yield component trait that indicates kernel size, mass density, and the potential of the plant to accumulate and partition assimilates (photosynthesis) into developing kernels during the reproductive stage. Increased hundred kernel weight suggests a greater development of the kernel, as both genetic potential, nutrient availability, water supply, and photosynthetic capacity all contribute to filling the kernel. Due to the nature of hundred kernel weight, it is a simple indicator of grain-filling efficiency as well as the ability to translocate carbohydrates, both of which ultimately contribute to final grain yield. Environmental stress including drought, nutrient deficiency, and high temperature can negatively impact hundred kernel weight by limiting carbohydrates to developing kernels, resulting in smaller or lighter grain.

Grain yield (ton ha^–1) can be identified as the total weight of harvested maize grains per unit area (ha). It is the most important agronomic parameter for the evaluation of productivity and performance of a maize variety or treatment under given conditions within a particular field. Grain yield is a function of yield components and includes factors such as the number of ears per plant, number of kernels per ear, and hundred-kernel weight, which indicate how efficient the plant has been in using the resources available. Grain yield represents the capacity of the crops to convert solar energy to foliage, and subsequently water and nutrients to economic products.

Above ground biomass (ton ha^–1): it is the cumulative dry weight of all above-ground vegetative portions, which includes the shoots leaves, stem, tassel, husk, and grains. It is a critical metric of productivity of maize in terms of photosynthesis, because above ground biomass represents the extent to which maize effectively converts solar energy and nutrients into organic compounds. Above ground biomass begins to accumulate relatively slowly in the early vegetative phase and rapidly increases after canopy closure until maximum above ground biomass is reached during the grain filling period prior to physiological maturity. Previous research suggests that above-ground biomass in maize typically ranges between 10 and 35-ton ha^–1, depending on genotype in relation to nutrient management and prevailing environmental conditions.

3. Results and Discussion

3.1. Characterization of Nanozeolite, Bone, and Blood

3.1.1. XRF Analysis

Figure shows the elemental composition of the nanozeolite, bone, and blood in relation to phosphorus (P), nitrogen (N), potassium (K), silicon (Si), and aluminum (Al). Bones have the highest ratio of phosphorus, which is related to its biochemical composition largely made of calcium phosphate and hydroxyapatite structure. Nitrogen is primarily present in the blood due to its protein content. There is more nitrogen in the blood compared to the bone due to the presence of hemoglobin and amino acids. Potassium was found in low and similar amounts in the three samples, indicating an even distribution of potassium in the three materials. Lastly, the nanozeolite has the most silicon and aluminum, corresponding with its well-known aluminosilicate framework which is essential for its ion-exchange and adsorbing traits. The fact that these components are absent in the blood and at very low levels in the bone confirms, yet again, their origins from the zeolite material. Each of the three components compositionally contributes to determine what is indeed a complementary role (i.e., the bone provides phosphorus, the blood provides nitrogen, and the zeolite provides silicon and aluminum). This combination provides perhaps the best example of how the materials investigated as a part of a nanofertilizer could be synthesized, with nutrient-rich organics (blood and bone) glued together from inorganic nanozeolites, resulting in a structurally functional and resource-efficient way to feed nutrients to the plant in a consistent and sustainable manner.

3.

Composition of raw samples (XRF analysis).

XRF results showed that Si and Al were present in the composite along with the nutrients that were indicated by the presence of N, Ca, P, and K. This means the material exists in a zeolitic aluminosilicate form and that nutrients can be incorporated into the zeolitic structure while keeping this structure intact. The calcium and phosphorus found were indicative of the presence of calcium phosphate derived from the bone. It appears that the calcium phosphate is associated with the zeolite interlayer via ion-exchange bonding and possibly by being confined within the pore of the zeolite. Similarly, the presence of potassium indicates that plant essential potassium ions occupy the negatively charged framework’s exchangeable sites in accordance with the ion-exchange ability of zeolites. The presence of nitrogen suggests that organic nitrogen of blood origin would be included in the zeolite and may be retained by adsorption or being trapped within the zeolite’s porous network.

The amount of heavy metals present in the sludge of the sample is very small compared with the USEPA standard. Converting an industrial sludge into a useful form of nanozeolite for different applications (for instance, for nanofertilizers) has no health effects and environmental problems. ,

3.2. Characterization of Synthesized Nanofertilizer

3.2.1. XRD Analysis

Figure indicates that a nanofertilizer produced from the cellulose nanozeolite, bovine blood, and bovine bone exhibits a complex crystalline/amorphous formation according to their X-ray diffraction (XRD) patterns; thus confirming successful incorporation of organic and inorganic materials.

4.

XRD graph for nanofertilizer.

The XRD pattern shows several diffracting matter peaks in the region approximately 10°–80° 2θ, revealing both crystalline and partial amorphous materials in the sample. The strongest peak is at the location of ≈30–35°, with additional peaks of lesser intensity, indicating that there is a predominant crystal structure with several additional, minor crystal structures present. There were also many peaks at 2θ values corresponding to reflections from typical zeolite structures (in particular, zeolite X, or FAU type) at the following locations: 6, 10, 15.5, 23, 26.5, and 31°. However, three of the most prominent peaks, at ∼30, 33, and 35°, indicate the presence of zeolitic framework structures, whereas the low-intensity or absent peaks (peak 10°) characteristically found in well-crystallized zeolite structures are reflective of either low crystallinity or combinations of phases, rather than an entire zeolite structure.

The X-ray diffraction (XRD) profile of nanofertilizer is defined primarily by the presence of organic materials (bones and blood). During processing at high temperatures, organic constituents break down into amorphous carbon and appear on the XRD profile as a wide hump in the 20°–30° 2θ range. The carbon also reduces the sharpness and intensity of other peaks on the profile. The bones also add a crystalline phase called hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂), which creates diffraction peaks at 2θ′s of approximately 25.9°, 31.7°, 32.9°, and 34°. The peak at ∼32°–34° may represent hydroxyapatite, and some of that peak may share space with zeolite peaks. There are very small amounts of iron oxide (from the blood) and possibly other minerals present, and if any are present, they will lower the background signal or add low-intensity peaks.

The results of the XRD show that the synthesized compounds are composed of partially crystalline zeolite phases (FAU-type), hydroxyapatite from the bones, and amorphous carbon from the breakdown of the organic materials plus small amounts of other crystalline materials (minerals). Overall, the material is a hybrid composite of partially crystalline zeolitic phases, hydroxyapatite, and amorphous carbon, resulting in a structurally complex system with potential functional advantages.

Analysis using X-ray diffraction (XRD) demonstrates that the characteristic diffraction peaks of the zeolite framework are preserved upon incorporation; therefore, the crystalline structure of the zeolite framework was not altered; however, very small alterations in peak positions (peak shifts, changes in intensity, and peak broadening) indicate that there may be lattice distortion and interactions between the incorporated species bone and blood components with the zeolite framework, which would not be seen if the two materials were only being mixed physically.

The sharp and well-defined peaks in the XRD pattern confirm that the sample has a high level of crystallinity. The most intense peak occurs at 2θ approximately 36°, which indicates that the crystallographic plane is the dominant one. Using the Scherrer equation with an assumed shape factor of 0.9 and Cu Kα radiation (λ = 0.15406 nm), as well as a full width at half-maximum (fwhm) of about 0.8° (0.014 rad), gave an average crystallite size of 10 nm, which supports the fact that the crystallite size is along the nanoscale.

3.2.2. SEM Analysis

The synthesized nanofertilizer’s surface morphology was evaluated by Scanning Electron Microscopy (SEM) at a scale of 500 nm in Figure a. The micrograph depicts irregularly shaped fine particles arranged in a loosely structured agglomerate. The individual particles’ typically below 500 nm confirms that the synthesized product is in the nanoscale range. The agglomeration of nanoparticles is most likely caused by the interparticle van der Waals forces and the generally high surface energy seen in nanostructured products. The rough and porous surface morphology gives the indication of a high specific surface area which allows for nutrient adsorption and slow release. The interparticle voids and pores seen in the micrographs within the 500 nm scale suggest that the framework is mesoporous to microporous and would be beneficial for controlled nutrient delivery with reduced leaching losses in agriculture. The heterogeneous texture further provides evidence of an organic and inorganic phase by the combination of zeolitic and bovine precursors.

5.

(a) SEM image of nanofertilizer and (b) EDX spectrum of its composition.

The energy-dispersive X-ray (EDX) spectrum of the synthesized nanofertilizer shown in Figure b demonstrates the presence of important elements such as carbon, nitrogen, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, calcium, and iron. The higher peaks for carbo, oxygen, and nitrogen suggest a hybrid organic–inorganic structure likely formed from organic matter of bovine origin and the zeolitic matrix. High levels of carbon and oxygen likely indicate the presence of organic functional groups and oxygen species adsorbed to the surface. The nitrogen peak confirms the presence of proteinaceous or amino components in the formulation, originating from bovine sources. The presence of phosphorus, sulfur, calcium, and iron confirms the enrichment of the nanofertilizer with macro- and micronutrients essential for plant development to further enhance soil health and crop productivity. The lower peaks of sodium, magnesium, aluminum, and silicon are likely related to the zeolite framework suggesting that the precursors in the nanozeolite contributed to structural stability and mineral contribution. Finally, the absence of toxic metals such as lead, cadmium, or mercury indicates the promising environmentally safe properties of the generated fertilizer for agricultural purposes.

The SEM (scanning electron microscopy) image displays that the nanofertilizer contains numerous particles which have irregular shapes, aggregated, and characterized by rough and varied surfaces. The particles are densely clumped together and have open areas between the particles as well as on their surfaces, which provides an indication of porosity. The majority of these pores and channels are due to the zeolite part of the nanofertilizer, and they provide a high surface area for absorption of nutrients to occur on. The roughness and the level of aggregation of the particles provide evidence of strong chemical bonding between the zeolite, bone, and blood-derived elements, thereby forming the nanofertilizer composite structure. The morphology of the particles is well suited for the controlled release of nutrients. The pores can function as storage locations for nutrient ions, and the winding pathways through the nanofertilizer can create delays in the diffusion of the nutrient ions, thus reducing rapid soil leaching and increasing the retention period of nutrients within the soil.

3.2.3. TEM Analysis

TEM is a type of microscopy in which a beam of electrons is sent through a very thin sample, interacting with the sample as it moves through it. The image is formed from the transmitted electrons and results in high-resolution images at the atomic level. The scale bar in the TEM image Figure indicates that the structures observed are on the nanometer scale, specifically 200 nm. This scale is important for interpreting the size of features within the image and understanding the material’s properties at the nanoscale. Nanofertilizers utilize nanoscale materials to enhance nutrient delivery and absorption in plants. Their increased surface area allows for efficient interaction with roots, promoting healthier growth. By reducing the amount of fertilizer needed, they minimize environmental impact and pollution. Additionally, they can be engineered for targeted nutrient release based on specific conditions. Overall, nanofertilizers represent a sustainable advancement in agricultural practices.

6.

TEM image of nanofertilizer.

The TEM images show irregularly shaped particles that are likely to be present in aggregate structures. The particle sizes are measured between approximately 50 to 150 nm in size when performing TEM measurements and were larger than the particle size measured via XRD, thus directly indicating that each of the TEM particles contained many smaller crystallites, confirming a polycrystalline and aggregated structure at the nanoscale. Polycrystalline, aggregated nanostructures would provide a higher surface area and improve both the nutrient loading and release characteristics.

TEM (transmission electron microscopy) images show the presence of nanoscale particles having a mixture of both crystalline regions with defined structures and less ordered amorphous materials. These particles appear to be semitransparent in appearance, and they have various contrasting shades indicating differing densities and compositions, where darkly shaded portions of the image represent dense crystalline areas (most likely zeolites) and lighter shaded portions represent either organic materials or amorphous nutrient materials. The size of these particles is on the nanometer scale, with many of them being agglomerated together. Therefore, the size of all the crystalline and amorphous materials will contribute to the overall release characteristics of the nutrients from the structured particles. Additionally, since the particles are sized so small, they provide for controlled release mechanisms to provide shorter distances for mass transfer and will allow the gradual exchange of ions over time. The coexistence of both crystalline and amorphous regions of these materials will provide for more nutrient loading and nutrient release control; thus providing for continued and efficient delivery of nutrients to the desired plant area.

3.2.4. FTIR Analysis

Figure indicates the graph of the FTIR spectrum and is generally grouped into two classes: analytical (functional group) region and fingerprint region.

7.

FTIR of Nanofertilizer.

3.2.4.1. Functional Group Region (4000–1500 cm^–1)

This area represents the first major class of the FTIR spectrum and is related to the stretching vibrations of covalent bonds inside of identifiable functional groups. Stretching vibrations involve more energy and therefore occur at high wavenumbers (above 1500 cm^–1). Most notable features: Sharp, well-defined peaks associated with fundamental bond vibrations, and the position and intensity of each peak can indicate the functional group that is present in the compound analyzed.

The broad band around 3277.35 cm^–1, which is often associated with O–H stretching vibrations. This would suggest that there was either water (adsorbed moisture) or hydroxyl groups from NaOH in the synthesis of the nanozeolite. The band at 2964.77 cm^–1, which is also supportive of C–H (aliphatic) stretching, supports the presence of the organic components.

The band at 1640.34 cm^–1 in the spectrum of the nanofertilizer represents mainly the δ O–H bending vibration of molecular water, providing evidence that adsorbed and/or bound (in the zeolite and hydroxyapatite) water is present in the fertilizer. A very slight overlapping contribution from amide I (CO) stretching would provide evidence for the retention of organic nitrogenous species from blood-derived materials. The retention of organic nitrogenous materials contributes to the nutrient composition and biochemical reactivity.

The band at 1525.26 cm^–1 assigns to the amide II vibration (N–H bending and C–N stretching) of the residual protein structures from the blood powder confirming that organic nitrogen compounds are also present in zeolite–bone-based nanofertilizers and subsequently increases the nutrient value of the fertilizer.

3.2.4.2. Finger Print Region (1500–400 cm^–1)

This is the region of the FTIR spectrum where the spectra are very complex and consist of various absorption bands formed from a combination of the bending, rocking, wagging, and twisting of the bonds. The pattern in this part of the spectrum is incredibly characteristic for each compound (similar to a fingerprint in humans).

The absorption band observed at 1036.64 cm^–1, which is mainly attributed to the asymmetric stretching of phosphate ions (PO₄ ^3–), validates the phosphate abundant structure of hydroxyapatite from the bone ash component in the nanofertilizer. A small amount of overlapping contributions from Si–O–Si or Al–O–Si stretching indicates structural interactions between the phosphate and the aluminosilicate (zeolite) phases, indicating good assimilation of the composite components of the nanofertilizer. The band observed at 877.69 cm^–1 is found to correspond to the bending vibration of the carbonate (CO₃ ^2–) groups found in B-type carbonated hydroxyapatite and, to a lesser extent, the Si–O bending of zeolite framework, confirming dynamics of carbonate incorporation and interactions associated with carbonates between mineral phases in the nanofertilizer.

The band found at 565.12 cm^–1, which is also assigned to the bending vibration of PO₄ ^3– associated with hydroxyapatite, has small contributions from the Ca–O bending vibration and zeolite lattice vibrations. This observation indicates the structural interaction of phosphate with the aluminosilicate framework in the nanofertilizer. The absorption band at 467.79 cm^–1 corresponds primarily to bending vibrations of Si–O–Al linkages in the zeolite structure which confirms the structural integrity of the aluminosilicate framework in the composite. Small contributions of Ca–O or P–O vibrations suggest a structural interaction of hydroxyapatite within the zeolite, which confirms structural integration toward a well-formed nanofertilizer, furnished by hydroxyapatite and zeolite.

3.3. Synthesis of Nanofertilizer

Table indicates a nanofertilizer synthesized from distinct nutrient profiles from both the bovine bone and blood, which means the nutrient profile reflects the combined effects of the organic materials with the nanozeolite matrix. Bovine blood is very high in nitrogen (12.86%), very low in phosphorus (0.04%), and moderate in potassium (0.2%), making it an excellent immediate nitrogen source for supporting rapid plant growth. The bovine bone is a primary source of phosphorus (15.65%) and a minor source of nitrogen (0.36%) and potassium (0.49%); thus, it will primarily contribute to root formation and early flowering while supporting strong stalk development. The nanofertilizer (0.2 g of nanozeolite mixed with the bone–blood mixture) provides an intermediate but more balanced nutrient profile. The nutrients available are nitrogen, 7.00%; phosphorus, 9.53%; and potassium, 0.55%. This shows that the nanofertilizer retains the high nitrogen availability of blood while providing a good rate of phosphorus availability contributed by the bone, while also slightly increasing the potassium.

1. Heavy Metals Present in the Sample Sludge.

element	concentration in ppm	USEPA limit in ppm
Pb	0.0037	840
Cr	0.0214	3000
Zn	0.0175	7500
Mn	0.0573	100–500
Cu	0.2140	4300
Ni	0.0600	420

Nanofertilizer behaviors related to nutrient release can vary individually with varying amounts of zeolite, bone, and blood used in the synthesis process. The zeolite is the porous framework of the matrix and contributes to the stability of the matrix, surface area, and cation exchange capacity; therefore, by increasing the proportion of the zeolite in the nanofertilizer, it would be possible to increase the retention of nutrients in the pores of the zeolite and thus create a slower release of those nutrients compared to when the proportion of the zeolite is lower and nutrients may leach out more quickly. Additionally, the mineral nutrient content of the nanofertilizer will be affected by the amount of bones incorporated into the formula. Since calcium and phosphorus, both of which are essential mineral nutrients needed by plants, are provided by the bone. The blood is supplied with nitrogen to the fertilizer; therefore, changing the amount of blood used to produce the formula will alter the amount of nitrogen available for plant use. Nitrogen is released when plants require it, which is dependent on the ratio of nitrogen, phosphorus, and potassium. Indeed, adjusting these ratios impacts nitrogen availability to plants and ultimately crop growth and the likelihood that plants will be able to utilize the fertilizer applied. Likewise, the relationship of potassium retention within and release from the zeolite is determined by cation exchange sites associated with the zeolite; therefore, depending on the ratio of the zeolite, bone, and blood, the amount of potassium available for crops will vary. Overall, adjusting proportions of the zeolite, bone, and blood when synthesizing a nanofertilizer will affect the initial composition, release rate, and physical attributes of that nanofertilizers, which will ultimately affect the growth and nutrient uptake of the crops provided with the nanofertilizers.

In practice, the nanofertilizer is able to offer a more precise and prolonged supply of nutrients that also aids in early vegetative growth (with nitrogen from the blood) and reproductive development (with phosphorus from the bone), all taking advantage of the slow-release capability of nanozeolites. Therefore, the nanofertilizer is more effective, balanced, and possibly eco-friendlier than using raw bovine blood and bone because it offers nutrient uptake without the danger of excessive nutrient runoff, while allowing cropping productivity intact.

The full conventional fertilizer regime would be to apply 250 kg ha^–1 of urea (46% N), 150 kg/ha of NPS (38% N, 19% P, 7% S), and TSP (0N–46P–0K), which provide a full supply of nutrients = 115 kg of N and 69 kg of P (per ha). A nanoblended fertilizer applied at 142 kg/ha with 7.00% N and 9.53% P provides a partial supply (9.94 kg N and 13.53 kg P per hectare), representing only about 20% of the nutrient supply of a conventional fertilizer. This shows that nanoformulations are able to provide similar nutrient availability with much lower inputs as a result of the controlled release and high efficiency of the nanomaterials, reducing nutrient loss while providing nutrition/micronutrients for all crops. Bone meal and blood meal can also be used as supplements to correct specific nutrient deficiencies if required.

3.4. Application of Nanofertilizer for Maize Production

The ability of a nanofertilizer to remain effective and available for an extended period depends on its structural stability during application to the soil and through crop development. The zeolitic framework is composed of a strong aluminosilicate frame that is highly chemically and mechanically stable under a broad range of soil conditions (pH, moisture, ionic strength, etc.); therefore, the zeolite framework does not quickly dissolve or collapse, and the nutrient ions contained within the framework are not immediately released or lost since they are contained by the framework matrix. As a consequence of the small particle size at the nanoscale, there is increased reactivity of the surface of the zeolite, while at the same time, the crystalline structure of the zeolite is kept intact to maintain the ion exchange capacity over time. The strong chemical bonding between the zeolite framework and nutrient ions reduces structural degradation due to repeated cycles of wetting and drying in addition to microbial activity in the soil. As the crop develops, the nanofertilizer will progressively provide nutrients to the crop through controlled ion exchange versus through a physical breakdown (maintaining the structural stability of the nanofertilizer providing continued availability of nutrients), thereby improving the efficiency of the nanofertilizer as compared to traditional fertilizers with fewer applications.

3.4.1. Soil Sampling and Analysis

Table indicates that preplanting soil analysis indicated that the soil had a pH of 6.53, which is slightly acidic and generally suitable for most crops, as it supports adequate nutrient availability and microbial activity. However, continuous cultivation without pH management may gradually increase acidity. The available phosphorus content (4.55 mg/kg) was low, highlighting the need for phosphorus enrichment through fertilizers such as TSP or NPS to enhance root development and energy transfer. In contrast, the total nitrogen level (0.44%) was high, suggesting sufficient nitrogen for vegetative growth, although careful management through split applications is recommended to reduce potential leaching losses.

3. Soil Analysis before Farm Practice.

parameters	value	rating
pH	6.53	slightly acidic
available phosphorus (mg/kg)	4.55	low
total nitrogen (%)	0.44	high
organic matter (%)	2.9	moderate
organic carbon content (%)	1.68	low
CEC (cmol/kg)	9.23	low
soil texture
sand (%)	40
clay (%)	36
silt (%)	24
textural class		clay loam

The soil contained 2.9% organic matter, rated as moderate, and 1.68% organic carbon, rated as low. These values indicate that while there is some organic input, additional organic amendments are necessary to improve soil fertility and structure. Incorporating compost, crop residues, or animal manure can enhance biological activity, water retention, and nutrient availability. The Cation Exchange Capacity (CEC) of 9.23 cmol/kg is considered low, reflecting a limited ability to retain essential nutrients such as calcium, potassium, and magnesium. Increasing organic matter content can improve CEC and the soil’s overall nutrient-holding capacity.

The textural composition of 40% sand, 36% clay, and 24% silt classifies the soil as clay loam, which provides a favorable balance of water retention and aeration for crop growth. Proper management practices are essential to avoiding compaction and ensuring effective root penetration. Overall, the soil is moderately fertile and is suitable for agricultural production. With targeted phosphorus application, enhanced organic matter management, and regular monitoring, this soil can support healthy crop growth and maintain productivity over multiple seasons.

3.4.2. Data Collection and Analysis

The early growth stage of maize is shown in Figure a when the crop has been successfully adjusted to all critical environmental and agronomic parameters such as, soil status, moisture access and nutrient acquisition. At this point, the corn looks good in the vegetative sense and it has been a good growing season. Figure b depicts the maturity of maize in which the crop has a full-grown vegetative stage and entered into the reproductive phase. This stage follows effective tasseling and silking that is essential for pollination and grain development. Maize photographed in this figure is physiologically mature with successful progression of growth and reproductive development under cultivation conditions.

8.

(a) Early stage of maize and (b) maturity stage of maize.

3.4.2.1. Crop Phenology

Zero fertilizer treatment (plots 1, 4, and 8): Table demonstrates maize plants under no fertilizer application phonologically developed relatively early compared to other treatments. The 50% days to tasseling averaged 59.6 days, suggesting a faster transition from vegetative to reproductive development due to nutrient limitations that typically induce accelerated maturation in response to stress. Likewise, 50% silking occurred at 66.0 days after planting, which was a little less than the application treatments. 85% physiological maturity occurred at an average of 124.7 days after planting, which was the fastest growth cycle completion for all the treatments.

4. Effect of Different Fertilizer Treatments on Maize Phenological Parameters.

treatment	plot	50% days of tasseling	50% days of silking	85% days of physiological maturity
zero fertilizer	1	60.6	66.6	125.4
	4	59.2	65.4	123.8
	8	59	66	125
	mean	59.6	66.0	124.7
common fertilizer	2	61.6	68.6	128
	6	62	68.6	127
	9	62.2	69	129.2
	mean	61.9	68.7	128.1
nanofertilizer	3	62.6	69.2	128.8
	5	61.8	68.6	129
	7	60.4	68.4	128.8
	mean	61.6	68.7	128.9

The early physiological maturity under nutrient-deficient conditions suggests limited vegetative growth and limited photosynthesis, which resulted in shorter grain-filling durations. In the absence of fertilizer application, plants typically demonstrate limited biomass accumulation and smaller ears, primarily due to insufficient nitrogen and phosphorus, which are important for leaf area expansion and kernel development. Mean growth duration for the zero fertilizer treatments was again shortened, which implies the nutrient deficient condition hastened phenological stages that potentially caused lower yield potential, which likely resulted in smaller kernels.

Common fertilizer treatment (plots 2, 6, and 9): Table shows the plots treated with common fertilizers (UREA and NPS), the two different maize plants displayed a moderate length of phenological periods, being approximately 61.9 period to tasseling, 68.7 period to silk, and 128.1 period to physiological maturity date. In relation to the zero fertilizer treatment, a common fertilizer delayed the aforementioned phenological periods by 2–3 days, which can be positive for crop performance because it meant that they were held in a vegetative state for longer periods of time resulting in a better developed leaf area and higher photosynthetic capacities.

2. Percentage Composition of NPK.

samples	concentration of each components % by mass
	N	P	K
bone	0.36	15.65	0.49
blood	12.86	0.04	0.2
nanofertilizer	7.00	9.53	0.55

The extended reproductive phase of the common fertilizer treatment suggests that the fertilizer was adequate and improved nutrient availability for nitrogen and phosphorus to support vegetative growth and reproductive organ development. Adequate nitrogen enhances adequate chlorophyll production, delaying senescence, while adequate phosphorus develops roots early and promotes uniformity in filling kernels. Likely, due to nutrient uptake, the common fertilizer group achieved better synchronization of tasseling and silking, which reduces stress from the pollination and sets more kernels. Generally, results from this finding suggest that using a common fertilizer is the ideal combination for balanced growth to maximize phenology duration for peaks in yield potential.

Due to its negatively charged aluminosilicate framework and a micropore system that has a very high cation exchange capacity, the zeolite serves as a controlled-release matrix. The nutrient ions remain in the channels of zeolites because they are held within the zeolite through electrostatic attraction and ionic exchange with cations found in natural soils, such as Na⁺, K⁺, Ca²⁺, etc. When the zeolite is in contact with soil moisture, competing cations will replace the nutrient ions as they are gradually released from the zeolite into the soil solution via diffusion through the zeolite pores. As a result, the confined pore system will prevent rapid movement of the nutrient ions, while the capacity for reversible ionic exchange will provide a balance between retention of nutrient ions and release of nutrient ions to provide a continuous and deliberate nutrient supply to plants.

Treatment with nanofertilizers (3, 5, and 7 plots): Table indicates maize receiving nanofertilizers exhibited the longest durations of phenological growth, at an average of 61.6 days until tasseling, an average of 68.7 days until silking, and an average of 128.9 days until physiological maturity. The small delay in tasseling and silking stages compared with zero fertilizer indicates improvements in vegetative growth and delayed senescence for nutrient storage resulting in biomass by the time of flowering.

Nanofertilizers enhance nutrient use efficiency via slow and controlled release of nutrients, with balanced and directed availability throughout the growth cycle. This and thus improved light interception lead to continued photosynthetic activity, longer green leaf duration, and more efficient translocation of assimilates to build to the developing kernels. Similarly, a prolonged grain filling time period contributes to the improved kernel weight and yield.

The difference in phenological duration compared with a conventional fertilizer treatment may be relatively slight; nevertheless, nanofertilizer-treated plants prolonged a stronger, healthier canopy and, thus, possibly increased grain filling as well as improved final productivity. Ultimately, the application of nanofertilizers improves not only nutrient use efficiency but also refines the physiological processes regarding yield establishment.

3.4.2.2. Growth Parameters

Zero fertilizer treatment (plots 1, 4, and 8): Table shows that zero fertilizer treatment of maize plants had moderate growth characteristics with average plant heights of 262.4 cm, 1.07 ears per plant, ear height of 102.6 cm, and ear length of 15.9 cm. These data indicate that the plants were able to finish their life cycle but were limited in their growth potential with zero-added nutrients. The lower average plant and ear height values suggest limited vegetative growth due to insufficient nutrition, particularly nitrogen and phosphorus, which are important in cell division, the increase in leaf area, and reproductive development. The importance of nitrogen is due to its role in chlorophyll formation and photosynthesis; therefore, it can be surmised that if nitrogen was limited, then maize vigor was also reduced leading to a smaller ear size. If phosphorus was limited, then root development may have been slower or energy transfer slowed, which is important to maize development during early growth increasing grain filling stages of growth. Although potassium is available in small quantities in the soil, it is possible that insufficient potassium was available to support optimal turgor pressure and enzyme activation. Therefore, the zero fertilizer treatment represents the productivity of the soil under natural nutrients and that maize was growing but not at optimal levels without a fertilizer.

5. Effect of Different Fertilizer Treatments on Maize Growth and Yield Attributes.

treatment	plot	plant height (cm)	number of ears per plant	ear height (cm)	ear length (cm)
zero fertilizer	1	257	1	95	14,6
	4	267.8	1	108.6	17.2
	8	262.4	1.2	104.2	16
	mean	262.4	1.07	102.6	15.9
common fertilizer	2	277.6	1.2	127.6	21
	6	285.8	1.2	128.4	17.2
	9	281.2	1	132	18
	mean	281.5	1.13	129.3	18.7
nanofertilizer	3	272.4	1.2	122.8	18.2
	5	278.8	1	126.6	18.8
	7	276	1	120.6	19
	mean	275.7	1.07	123.3	18.7

Common Fertilizer Application (plots 2, 6, and 9): Table indicates common fertilizer application performed the best overall with an average plant height of 281.5 cm, with 1.13 ears per plant, ear height of 129.3 cm, and ear length of 18.7 cm, thus indicating the direct role of balanced nutrients in promoting maize growth and yield components. The taller plants’ ears being placed higher is indicative of vegetative vigor and structural support associated with a healthy nitrogen supply. Nitrogen aids stem and leaf development resulting in increased photosynthesis and stored biomass. Phosphorus aided in root development, reproduction, and nutrient and water uptake efficiency. Nutritional potassium assists in grain fill capacity functions and enzyme activity for a large ear size and kernel development. Increased ears per plant and longer ear length display the relationship with a nutrient well-balanced uptake for improved reproductive efficiency. This fertilizer treatment reinforces the value of integrated nutrient NPK management toward superior maize performance in field conditions including agronomic improved vigor, more cob formed, and more grain yield potential.

Nanofertilizer treatment (plots 3, 5, and 7): Table shows that the maize within the nanofertilizer treatment exhibited similar performance to the common fertilizer treatment with a mean plant height of 275.7 cm, 1.07 ears per plant, ear height of 123.3 cm, and ear length of 18.7 cm. The performance increase compared to the zero fertilizer plots reflects the high nutrient efficiency delivery capacity of nanoformulated fertilizers. The nanofertilizer treatment formulation supplies nutrients slowly and in a controllable manner so that the plant can absorb the adequate essential N, P, and K nutrients with minimal loss to leaching or volatilization. The moderate plant height and ear height suggest that the plants achieved substantial vegetative and reproductive growth, while the long ear length indicates good grain formation; however, attainment of the long ear length comparable to the common fertilizer treatment provides strong evidence that the nanofertilizer formulations can deliver equivalent to superior nutrient efficiency with lower rates. Nitrogen increased the leaf area and chlorophyll production; the phosphorus fertilizer improved the energy-transfer function and reproductive growth; potassium fertilizer regulated the stomatal function and contributed to plant stress tolerance; thus, this treatment shows promising evidence for demonstrating the ability of nanofertilizers as a sustainable practice to replace conventional fertilizers to improve maize plant growth and yield, while minimizing fertilizer costs and environmental impacts.

Soil heterogeneity, climatic conditions, and the dissolution characteristics of the applied fertilizers account for the variable nature of the experimental plots that are part of each of the fertilization treatments (zero fertilization, commercial fertilizer, and nanofertilizer). In plots treated with zero fertilization, variability is generally the largest because the growth of the plants under that treatment solely depends on the lack of native soil nutrients, organic matter, moisture, and microbial activity that are unevenly distributed throughout a plot, thus leading to large plot-to-plot variability in the amount available to the plants for growth and nutrient uptake. In the case of the commercial fertilizer treatment, variability among the treatments is moderate but still present because nutrients are not evenly distributed after application, there is a potential for losses of nutrients through leaching, runoff, or volatilization, and differences in the root access and timing of nutrient uptake will create differences in response of the plots to the application of those nutrients. The nanofertilizer treatment exhibited a generally lower level of variability among the treatment replicates due to the zeolite-based matrix which supports a higher degree of uniformity in the retention of nutrients and a gradual release of the nutrients through diffusion and ion-exchange processes, which serves to cushion variable degrees of fluctuations in the concentrations of nutrients within the treated plots. However, there will still be residual variability as a result of slight errors in the application of the nanofertilizer, differences in the moisture of the soil that will affect the rates of diffusion of the dissolved nutrients from the zeolite matrix, and localized variations in the chemical and physical properties of the soil that will influence the dynamics of nutrient exchange and the interactions of the roots with the soil.

3.4.2.3. Yield Components and Yield

Zero fertilizer treatment (plots 1, 4, and 8): Table indicates that maize plants grown under the zero fertilizer condition exhibited their overall least performance for all yield traits (e.g., grain, biomass), reflecting the inherent constraints of nutrient-depleted soils. The average number of kernels per ear was 561.9, as the average grain yield and biomass accumulation were 5.69 t ha^–1 and 16.09 t ha^–1, respectively. The harvest index (35.31%) and hundred kernel weight (32.0 g) suggest a moderate partitioning of assimilates to the grain, despite the poor nutrient condition. Thus, while maize plants exhibit some capability to survive where nutrients are deficient, the low performance demonstrates that any ability of the maize plants to adequately survive and perform is severely curtailed without essential macronutrients (nitrogen (N), phosphorus (P), and potassium (K)) being replaced.

6. Effect of Different Fertilizer Treatments on Maize Yield and Yield Components.

treatment	plot	number of kernels per ear	hundred kernel weight (gm)	grain yield (tonha–1)	above ground biomass (tonha–1)	harvest index (%)
zero fertilizer	1	558	32.9	5.42	15.87	34.13
	4	571.4	33.1	6.08	16.90	35.94
	8	556.2	30	5.56	15.50	35.85
	mean	561.9	32.0	5.69	16.09	35.31
common fertilizer	2	612	31.8	7.69	22.46	34.24
	6	599.4	32.5	7.64	24.01	31.82
	9	556.2	30	5.56	15.50	35.85
	mean	601.0	32.8	7.84	24.17	32.49
nanofertilizer	3	602.8	34.6	8.37	23.33	35.86
	5	602.8	33.1	7.81	21.03	37.15
	7	562.8	33.9	8.13	25.79	31.50
	mean	589.5	33.9	8.10	23.38	34.84

The low yield observed under this treatment reflects also limited root and shoot growth, low leaf chlorophyll content, and limited photosynthetic capacity resulting from nitrogen deficiency. Nitrogen is vital for the synthesis of proteins, enzymatic activity, and chlorophyll, all of which, when removed, lead to chlorosis and limited vegetative growth. Likewise, phosphorus deficiency limited root growth and energy transfer, limiting reproductive development, and kernel filling. Potassium deficiency limits turgor pressure and enzymatic activity, weakens the stalk structure, and reduces the translocation of carbohydrates to the ears for filling.

Common fertilizer treatment (plots 2, 6, and 9): Table shows that the common fertilizer treatment (NPK or compound fertilizers) had a highly significant impact on all yield and growth parameters. Maize plants in this treatment produced an average of 601 kernels per ear along with a biomass yield of 24.17 t ha^–1 and a grain yield of 7.84 t ha^–1, which indicated that maize plants positively responded to an increase in the nutrient supply. The average amount of kernels per ear in this study is better than similar studies that have the values 380.6 kernel per ear. Grain yield and biomass yield both increased due to beneficial impacts of balanced N, P, and K on both vegetative and reproductive growth. Nitrogen increased plant height and leaf area and increased photosynthetic efficiency. Phosphorus increased root growth and energy transfer for flowering and grain filling, whereas potassium improved enzyme activation and grain quality.

Despite the benefits of common fertilizers for yield increases, their long-term overuse is associated with environmental, agronomic, and ecological problems. Nitrogen overapplication causes nitrate movement with water leading to contamination and eutrophication of rivers and lakes. Continuous application of acidifying fertilizers (i.e., urea or ammonium sulfate) can acidify the soil, which results in a lower pH and, consequently, lower prokaryotic (bacterial) diversity and functionality. Suboptimal nutrient supply can also cause issues with the development of micronutrient (e.g., zinc, iron) deficiencies because of chemical antagonism in the soil. Additionally, nitrogen fertilizers can cause greenhouse gas emissions (N₂O and NH₃) that can result in global warming and air pollution. Also, fertilizer residue in the soil may build-up toxic supplies over time, dependence on synthetic inputs increases costs of production while decreasing soil organic matter supply. Therefore, common fertilizers support high yields for a single season or short-term, but dependable use will lead to soil degradation and environmental consequences if not used sustainably in long-term cropping systems.

The common fertilizer treatment showed a major increase in maize productivity as a result of which the average grain yield went up to 7.84 t ha^–1 and the average harvest index to 32.49%. This signifies the vital role of the fertilizer in helping SDG 2 (Zero Hunger) by providing food through increased crop productivity. Moreover, it is a source of renewables for SDG 9 (Industry, Innovation, and Infrastructure), since the making and the use of conventional fertilizers are one of the main sectors of already existing agricultural technologies and the industrial system.

Overapplication or inefficient use frequently results in nutrient release through leaching and surface runoff, which can also pollute the oxyanion-rich water bodies with nitrates and phosphates, hence eutrophication, oxygen depletion, and aquatic biodiversity loss becoming the major concerns under SDG 14. Besides that, the release of nitrous oxide (N₂O), a very powerful greenhouse gas, causes the global temperature to rise thus climate change and instability come about, which is against the objectives of SDG 13. On the earth, the use of synthetic fertilizers may lead to soil acidification, salinity increase, and microbial imbalance; eventually, soil biodiversity and the general ecosystem will be degraded in accordance with SDG 15 (Life on Land) thereby conserving terrestrial biodiversity is contradicted.

Nanofertilizer treatment (plots 3, 5, and 7): Table shows maize plants that received nanofertilizer treatment demonstrated better and consistent performance in most of the yield parameters. The mean number of kernels per ear was 589.5 kernels per ear with the highest mean grain yield of 8.10 t ha^–1 with an mean above-ground biomass of 23.38 t ha^–1. Corn having harvest index (34.84%) and hundred kernel weight (33.9 g) were also significantly higher than other treatments, indicating effective nutrient use and better allocation of photosynthesis into grains. Nanofertilizers improve plant growth due to their large surface area, slow nutrient release, and increased uptake efficiency, helping the plant gradually secure nutrients over the period of growth. The small particle size ensures improved penetration into plant tissues, which helps improve photosynthetic output, root activity, and reproduction.

The increase in grain number and weight under the influence of nanofertilizers as an alternative source of fertilization is not only due to increased availability of nutrients but also from improvements in nutrient use efficiency that occur with the sustained release of nutrients through ion exchange and diffusion. Additionally, the use of the nanofertilizer provides a constant source of essential elements during important growth phases in the crop cycle (particularly at the stages of flowering and grain filling). This improvement in nutrient use efficiency contributes positively to the photosynthesis process and, thus, to the production of assimilates and the better formation and filling of kernels. However, yield components are also influenced by a variety of environmental factors, including soil moisture, genetics of the plant, root development, etc. As such, the increase in grain number and weight is due to the combined positive effects of being provided with adequate nutrients and having ideal growth conditions.

In general, maize plants without a fertilizer (zero fertilizer) performed relatively poorly due to nutrient stress and low fertility of the soil, and maize with a common fertilizer experienced large yield increases in the short term but could pose long-term degradation to soil fertility and the environment. Nanofertilizers have been found to produce the highest and most balanced improvement in productivity while also increasing nutrient-use efficiency and minimizing nutrient loss. Therefore, it could be argued that all types of fertilizer have varying effects on the growth of maize, but the best way toward the goal of sustainability is to apply combinations of integrated nano- and organic nutrient management systems that improve soil health and environmental impact while improving long-term agricultural productivity.

The advantages of higher grain yields seen with the application of the nanofertilizer versus that of a conventional fertilizer can be explained by improved availability of nutrients, greater reactivity, and improved delivery of nutrients to the plant because of their smaller particle size and greater surface area than that of conventional fertilizers. These particle size characteristics also serve to facilitate nutrient dissolution, mobility, and uptake by the plant’s roots while minimizing losses through leaching, volatilization and through fixation in the soil. The characteristics of many nanofertilizers also allow for a controlled or slow release of nutrients, which helps to ensure a steady and synchronized supply of nutrients that meet the demands of the plant at various stages of growth. Subsequently, the enhanced nutrient use efficiencies, augmented root growth, increased photosynthetic activity, and finally, increased biomass and grain yields obtained from the application of nanofertilizers as compared to the conventional fertilizer application are attributable to the rapid nutrient release associated with conventional fertilizers, which results in high levels of nutrient loss before plants can fully utilize them.

Among the treatments tested, the nanofertilizer treatment showed the largest mean grain yield at 8.10 t ha^–1 and a harvest index of 34.84%. Its efficacy implies an improved nutrient use and more effective biomass allocation. In an explicit manner, SDG 2 (Zero Hunger) resolution positively affects productivity of a sustainable yield. Nanofertilizers incorporate cutting-edge formulations that encapsulate nutrients within the nanostructured carrier (zeolite nanoparticles) in a controlled manner. Nanofertilizers in the form of nanoparticles allow for controlled release and targeted delivery. Controlled release of nutrients within nanostructured nanoparticles retains nutrients as availability is more precise to the growing season and less is lost. Subsequently, nanofertilizers exhibit principles from SDG 9 (Industry, Innovation, and Infrastructure) and SDG 12 (Responsible Consumption and Production), as these treatment modes foster technology advancement and minimize waste in agricultural production systems.

Nanofertilizers also show efficacy and relevance to SDG 13 (Climate Action) and SDG 14 (Life Below Water) viability as they reduce nutrient leaching and runoff. Low nutrient leaching (NO³ and PO4^–3) and subsequent low risk of aquatic ecosystem degradation due to eutrophication conserve marine and freshwater biodiversity. Greater nutrient use efficiency (subsequent to nanofertilizer applications) also reduces the need for repeated applications and reduces fertilizer-related emissions to climate. Therefore, it is possible that nanofertilizers increase climate resilience of agricultural systems while preventing the potential contamination of water bodies.

The nanofertilizer is applied in low to medium quantities and gives higher yields because it has a good retention of nutrients due to its controlled release characteristics while also having a very low environmental risk. A coated urea fertilizer requires high application rates and provides a medium yield gain and moderate retention of nutrients because its coating reduces nitrogen loss but still has a moderate environmental risk, because it could potentially leach into the groundwater. A zeolite-based fertilizer additionally has an application rate that is medium in quantity but provides either low or moderate yield gain while also having good retention of nutrients due to its slow-release characteristics and having virtually no environmental risk.

Table indicates that using a nanofertilizer at low to moderate levels gives the highest possible yield due to their improved and slower controlled release of nutrients and very little environmental risk. In comparison, coated urea is only applied in high quantities, giving a moderate increase in yield because although the coating does reduce nitrogen loss somewhat, it does not stop all leaching from happening. Zeolite carriers function at a normal to moderate rate of application, which produces a low to moderate increase in crop yield due to their longer nutrient release period and their ability to retain nutrients. Both nanofertilizers and zeolite carriers were shown to have a much greater nutrient retention than coated urea. Therefore, nanofertilizers demonstrate the greatest overall combination of efficiency, yield performance (production), and environmental safety when compared with the other options available to farmers.

7. Comparison Table of Yield Gains, Dosing, and Safety Different Carrier Fertilizers.

fertilizer type	application rate ()	yield gain	nutrient retention/release	safety/environmental impact	reference
nanofertilizer	low–medium	high	high (controlled release)	low environmental risk	this study
coated urea	high	medium	medium (coating reduces N loss)	medium risk (some leaching)
zeolite-based carrier	medium	low–medium	high (slow release)	low environmental risk

The various treatments produced different results regarding the properties of the soil, as indicated in Table , however, the soil in the nonfertilized control group (no fertilizers added) had the lowest levels of soil pH (6.29), organic carbon % (OC = 1.64%), organic matter % (OM = 2.82%), and cation exchange capacity (CEC = 3.40 mequiv/100 g) compared to all other treatments. The use of chemical fertilizers increased these same properties, resulting in a soil pH of 6.50, OC of 1.84%, OM of 3.16%, and CEC of 9.74 mequiv/100 g on average. The use of nanofertilizers produced the highest soil pH (6.61), OC of (2.18%), OM of (3.74%), and CEC of (10.00 meq/100 g). In conclusion, the use of nanofertilizers produced a greater increase in the chemical properties of the soil than did the use of chemical fertilizers and the nonfertilized control.

8. Major Soil Characteristics of the Experimental Site after Harvesting.

treatments	pH	OC (%)	OM (%)	CEC (meq/100 g soil)
without fertilizers	6.29	1.64	2.82	3.40
chemical fertilizers	6.50	1.84	3.16	9.74
nanofertilizers	6.61	2.18	3.74	10.00

4. Conclusions

This research successfully produced a sustainable nanofertilizer created from zeolite nanostructures that were extracted from industrial sludge and enriched with bovine nutritional inputs, with the goal of utilizing waste products to develop high-value agricultural products. The physicochemical and structural characterization strain was realized through the analysis of X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to confirm the effective synthesis of a high-crystalline, highly compositional, and morphologically stable nanofertilizers. XRD analysis demonstrated peaks that are characteristic of zeolitic frameworks to verify the sludge was converted to an ordered aluminosilicate phase. The XRF findings show evidence of macro- and micronutrients that are crucial to the plant structure, as they contain calcium, phosphorus, potassium, iron, silicon, nitrogen, and aluminum found in its industrial and bovine origins. The FTIR spectra present discrete absorption bands that signify the hydroxyl, phosphate, and aluminosilicate groups to signify the functional components needed for plant nutritional inputs. SEM images exhibit a very porous and irregular surface morphology that increases nutrient adsorption and nutrient release rate; furthermore, TEM images elucidate nanoscale lattice fringes (0.276 nm) consistent with zeolitic crystallinity to confirm the material’s nascent dimensional stability. The field study on maize production indicated that the utilization of the nanofertilizer resulted in a significant improvement in plant growth, phenological stages and yield components when compared to both conventional and control treatments. The inoculated maize plants exhibited a mean hundred-kernel weight of 33.9 g and a grain yield of 8.10 t ha^–1, both of which exceed the conventional fertilizer values of 32.8 g and 7.84 t ha^–1, respectively. Maize treated with the nanofertilizer also demonstrated a harvest index of 34.84% which indicate a more efficient use of nutrients and a better partitioning of photosynthesis to grain. It concludes that the zeolite-based nanofertilizer improves nutrient availability, retains nutrients, and has better release kinetics than conventional fertilizers, improves sustainable maize production, and valorizes industrial and animal wastes to improve environmental protection as all positioned within a circular economy.

All data generated or analyzed during this study are included in this published article.

The study was conceived and designed with input from all authors. Eyasu Derbew Demeke handled the material preparation, experimental labor, data gathering, and analysis. Wondimagegn Mamo Mengistu was responsible for the original concept, supervision, and funding of the resources. Teshome Tayye took part in sample selection and preparatory investigations. Desta Abaychew took part in field design and preparation. Dessie Belay actively engaged in laboratory works. Kingsley and Genene actively involved in characterization of the samples, supervision and funding of resources. Yedilfana Setarge Mekonnen was responsible for the study’s conceptualization, planning, supervision, and funding of resources. All writers provided feedback on the initial draft of the text, which was written by Eyasu Derbew Demeke. The final manuscript was read and approved by all writers.

This work was supported by the African Centre for Technology Studies (ACTS) and the Ministry of Innovation and Technology (MInT) project (Project No. ACTS/RIMP/RGC-MinT/AAU/2023).

The authors declare no competing financial interest.

Co-author Abdela Befa Kinki was inadvertently omitted in the version published June 25, 2026; the corrected version reposted September 8, 2026.