Slow-release Fertilizer Research Articles

Crushing Force Prediction Method of Controlled-Release Fertilizer Based on Particle Phenotype

This study proposed a method to predict the crushing force of controlled-release fertilizer granules based on their phenotypic characteristics to prevent coating damage during production, transport, and fertilization, which could affect nutrient diffusion rates. The phenotypic features, including sphericity, particle size, and texture, of three commonly used controlled-release fertilizers were obtained using machine vision, while the crushing force was measured using a universal testing machine. A principal component analysis was applied for data reduction, and the optimal parameters for the support vector machine (SVM) were selected using particle swarm optimization (PSO) combined with k-fold cross-validation. A particle swarm optimization–support vector machine (PSO-SVM) model was then developed to predict the crushing force based on fertilizer shape features. Compared with the traditional method, the innovation of this paper is that a non-destructive prediction method is proposed, which enables high-precision predictions of the crushing force by integrating multi-dimensional phenotypic features and an intelligent optimization algorithm. Comparative tests with a random forest regression, the K-nearest neighbor, a back propagation (BP) neural network, and a long short-term memory (LSTM) neural network have demonstrated that the PSO-SVM model outperforms these methods in terms of mean absolute error, root mean square error, and correlation coefficient, underscoring its effectiveness. The proportion of predictions within the −10% to +10% error range reached 0.82, 0.82, and 0.86 for the three fertilizers, confirming the high reliability and accuracy of the PSO-SVM method for non-destructive testing.

Productivity and Nutrition of Conilon Coffee (Coffea canephora) in Response to Slow-Realease Fertilizers

ABSTRACT The low availability of phosphorus (P) and nitrogen (N) in the soil is a determining factor in coffee plant productivity. To increase productivity technologies in fertilizers have been developed to improve the use of P and N by plants. Thus, the objective of this work was to evaluate the productivity and nutrition of the conilon coffee tree from the application of phosphate and nitrogen slow-release fertilizers. The experiment was conduced in the field and followed a randomized block design, with three replications, in a 3 × 2 × 3 factorial scheme, with three phosphate fertilizers (conventional monoammonium phosphate – CONV; conventional monoammonium phosphate coated with polymer – POL; and monoammonium phosphate conventional pelletized with filter cake – ORG); two amounts of phosphate fertilizers (Q100 = 100% of the amount of phosphate fertilizer; Q150 = 150% of the amount of phosphate fertilizer); and two nitrogen fertilizers (conventional urea – UC and conventional polymer-coated urea – UP). The experiment was conducted during two coffee harvests (2017/2018 and 2018/2019). Slow-release phosphate fertilizers (POL + ORG), when compared to CONV, showed higher productivity of processed coffee beans, representing an increase in productivity of 6.79% (5067,6 kg ha−1) and 11.62% (6048 kg ha−1) in the 2017/2018 and 2018/2019 harvests, respectively. The application of slow-release phosphate fertilizers (POL + ORG), in relation to CONV, also resulted in higher foliar P contents in some phenological stages of the coffee tree.

Influence of Biochar and Modified Polyglutamic Acid Co-Coated Urea on Crop Growth and Nitrogen Budget in Rice Fields

Natural superabsorbent polymers (SAPs) were essential coating materials for developing slow-release fertilizers (SRFs) due to low cost and biodegradability. However, conventional natural SAPs were unsuitable for rice systems due to low stability and short slow-release period. Herein, a natural SAP with a semi-interpenetrating polymer network was prepared by poly (γ-glutamic acid) (PGlu), diatomite, and pullulan polysaccharide and combined with biochar to develop double-layer co-coated slow-release urea for rice systems. The results indicated that diatomite and pullulan modification significantly improved the slow-release capacity of SAP, with a significant increase in the average fertilizer 15N content of the soil profile by 37.9 ± 7.4% in 14–56 days. The improved slow-release capacity had significant benefits for the sustainability of the rice system, which increased plant N uptake by 17.2 ± 4.8%, decreased fertilizer N losses by 30.4 ± 7.2%, and increased rice grain yield by 9.88 ± 3.6%. More importantly, this natural SAP was fully degradable and its decomposition products are large amounts of small-molecule nutrients that could provide additional C, N, and Si to rice. Therefore, novel co-coated SRF may emerge as a greatly promising candidate for future intensive paddies.

Morpho-Physiological Adjustment of Swietenia humilis Zucc. Plants to Varied Nutrient and Light Conditions and Their Performance in Nurseries and Fields Under Soils with Different Preparations

To enhance the plantation performance of Swietenia humilis Zucc., a threatened precious woody species from the dry tropics of Latin America, this study examined its morpho-physiological responses to variations in nutrient and light availability. We established a nursery trial with factorial treatments: three levels of fertilization (4, 6, and 8 g L−1 of substrate using a controlled-release fertilizer, CRF, 18-6-12) and two shade intensities (60% and 40%), alongside a full sun treatment. The field performance of nursery-raised plants was evaluated under two site conditions (with and without mechanical soil preparation) over 48 months. In the nursery, S. humilis exhibited diverse morpho-physiological characteristics influenced by the studied factors, with optimal growth observed at 6 g of the CRF and 40% shade. Mechanical soil preparation significantly improved plant survival, reducing mortality risk by 99.16% and increasing survival probability to nearly 75%. Height growth was also enhanced, being 2.5 times greater in the prepared site compared to that in the unprepared one. S. humilis showed acclimatization in the field, producing new foliage with high chlorophyll content. In conclusion, nursery management and soil site preparation influence the field performance of S. humilis. These findings have practical implications for improving the management of S. humilis in plantations across the dry tropics.

Immobilization of urea on beads based on OPEFB cellulose-alginate via blending to fabricate sustained release fertilizer

Transforming oil palm empty fruit bunches (OPEFB) waste into value-added cellulose as a reinforcement agent for eco-friendly slow-release fertilizer (SRF) composites is a strategy to achieve clean and sustainable production. OPEFB cellulose was isolated by alkalization (10 % w/v NaOH) for 1 h and bleaching (30 % v/v H2O2) for 1.5 h. The treatment increased the cellulose content to 80.88 %, reduced the non-cellulosic component, and improved the fiber crystallinity to 58.40 %. The hydrogel composite was cross-linked by blending urea in an OPEFB cellulose fiber (w/w) (0 %, 0.5 %, and 1 %) and sodium alginate (3 % w/w). Then, the wet beads were freeze-dried to fabricate SRF composites. Each material was evenly dispersed in the matrix, had a porous structure, and could bind total nitrogen up to 20.0 %, confirmed by the Kjeldahl method. Adding cellulose increased crystallinity (significant at 1 % w/w cellulose), decreased bulky density (significant at 0.5 % and 1 % w/w cellulose), increased swelling capacity (significant at 0.5 % w/w cellulose), and water-retention capacity. Reinforced composite with 0.5 % (w/w) cellulose released nitrogen into the soil (Fickian diffusion) following the Higuchi model (R2 = 0.957) with K = 0.0394 and equilibrium at around t1/2 = 1.8 h. Changing SRF composite properties are likely related to the porous structure loaded with urea crystals.

A novel agrosinters support growth, photosynthetic efficiency and reduce trace metal elements accumulation in oilseed rape growing on metalliferous soil

Soil conditioners to fertilize, improve soil structure and support the phytostabilization of trace metal elements (TMEs) are being used more and more frequently. One of the options are agrosinters – slow-release ceramic fertilizers consisting mainly of SiO2, CaO, P2O5 and K2O, with an alkaline pH and high impact strength. The effect of two different agrosinters, A1 and A2, on the growth and physiological condition of Brassica napus grown in uncontaminated and Pb-, Cd- and Zn-contaminated soil was investigated in a pot experiment. In vivo data were collected using an infrared gas analyzer, a fluorimeter, a pigment content meter and a thermal camera. Elemental composition of the biomass was also investigated. The tested agrosinters promote biomass yield and have an effect on improving leaf chlorophyll content, phenomenological energy fluxes and plant gas exchange. The effect of the agrosinters on the plants was dose- and amendment-specific. An immobilization effect was observed not only in the soil but also in the plants. A reduction in the Cd (22%) and Zn (40%) content in the biomass was measured. All this was related to the effect of increasing the available form of P (50%), K (300%) and Ca (50%) in the soil, which improves soil fertility and reduces the bioavailable forms of the studied TMEs, due to the increase in soil pH and/or the complexation of these with phosphate compounds. The multidimensional analysis of A2 agrosinter shows the most positive effects on plant conditions, indicating that fly ash as a mixed substrate benefits the plants.

Comparison of Automated Controller Settings for Irrigation and Fertilizer Needs of Potted Geranium

The future of agricultural water availability is threatened by climate change, population growth, and environmental regulations. Most of the global water is being used for crop irrigation. The objective of this research was to determine optimum timer-based controller settings and controlled-released fertilizer rates for ‘American Red’ (Pelargoium ×hortorum) potted geranium plants. Fertilizer was top-dressed at 3, 6, or 9 g. Plants were irrigated by a timer-based controller set to water at 11:00 AM every other day for 2 minutes, 9:00 AM and 2:00 PM for 1 minute per day, 11:00 AM for 1 minute per day, 11:00 AM for 2 minutes per day, and a control of manual hand watering. Data regarding plant growth, soil and leaf nutrients, and water use were collected. For geranium growth factors, the total flowers per plant was greatest for irrigation at 11:00 AM for 1 minute with 6 g fertilizer. Plant height and shoot dry weight were greatest for 6 and 9 g fertilizer. The number of umbels and soil plant analysis development (SPAD) chlorophyll meter readings were greatest for 9 g fertilizer. For geranium soil nutrient content, the pH was greatest for 3 g fertilizer, whereas the electrical conductivity, potassium, nitrate, sulfate, and boron were greatest for 6 and 9 g fertilizer. Regarding the nutrient content of the leaves, total nitrogen, boron, iron, and copper were greatest for 9 g fertilizer. Water use efficiency was greatest with 6 and 9 g fertilizer and irrigation 1 minute per day at 11:00 AM. The findings indicated that using timer-based controlled irrigation systems programmed to water for 1 minute during the morning with 6 g fertilizer resulted in plants that not only reduced water consumption but also enhanced water use efficiency and overall plant quality.

A comparative assesment of biostimulants in microbiome-based ecorestoration of polycyclic aromatic hydrocarbon polluted soil.

Polycyclic aromatic hydrocarbons (PAHs) pose severe environmental and public health risks due to their harmful and persistent nature. Therefore, developing sustainable and effective methods for PAH remediation is crucial. This study explores the biostimulation potential of various nutrient supplements in enhancing the metabolic activities of indigenous oleophilic bacteria to PAH degradation and removal. The physicochemical and microbiological characterization of the soil sample obtained from the aged crude oil spill site prior to bioremediation revealed the presence of PAH and other hydrocarbons, reduced nutrient availability as well as an appreciable population of PAH degrading bacteria such as strains of Pseudomonas, Enterobacter, Kosakonia and Staphylococcus. The polluted soil treatment was conducted in six microcosms representing each nutrient supplement: casmes-CM, cocodust-CCD and osmocote-OSM slow-release fertilizers, NPK 20:10:10, casmes + cow dung - CM + CD and a control (unamended soil). Each pot contained 4kg of soil spiked with 4% Escravos crude oil to a final concentration of 989mg/kg of PAH, respectively. All treatments enhanced the activity of the indigenous bacteria to promote PAH removal (> 50%) after 35days although CM + CD had the highest biostimulation effect (B. E.) of 56% with 71.77% PAH attenuation followed by NPK treatment with B. E. of 54.9% and 70.4% PAH removal, respectively. The order of degradation of PAHs from lowest to highest is: control > casmes > osmocote > cocodust > NPK > CM + CD. First-order kinetic model revealed soil microcosm amended with CM + CD had a higher k value (0.0342day-1) and lower t½ (18.48day) and this was relatively followed by NPK treated soil. Biostimulation is an effective bioremediation approach to PAH degradation, however, a combined nutrient regimen in the presence of PAH-degrading microbes is more potent and eco-friendly in driving this process.

Preparation of Lignin-Based Slow-Release Nitrogen Fertilizer

Slow-release nitrogen fertilizer technology is essential for sustainable agriculture, reducing field pollution and enhancing fertilizer efficiency. Lignin, a natural polymer derived from agricultural and forestry waste, offers unique benefits for slow-release fertilizers due to its biocompatibility, biodegradability and low cost. Unlike conventional biochar-based fertilizers that often rely on simple pyrolysis, this study employs hydrothermal activation to create a lignin-based slow-release nitrogen fertilizer (LSRF) with enhanced nutrient retention and controlled release capabilities. By incorporating porous carbon derived from industrial alkaline lignin, this LSRF not only improves soil fertility, but also reduces nitrogen loss and environmental contamination, addressing key limitations in existing fertilizer technologies. We studied the hydrothermal carbonization and chemical activation of IAL, optimizing the conditions for producing LSRF by adjusting the ratios of PC, IAL and urea. Using BET, SEM and FT-IR analyses, we characterized the PC, finding a high specific surface area of 1935.5 m2/g. A selected PC sample with 1923.51 m2/g surface area and 0.82 cm3/g pore volume and yield (37.59%) was combined with urea via extrusion granulation to create the LSRF product. Soil column leaching experiments showed that LSRF effectively controls nutrient release, reducing nitrogen loss and groundwater contamination, ensuring long-term crop nutrition. This research demonstrates LSRF’s potential in improving fertilizer efficiency and promoting sustainable agriculture globally.

Camellia oleifera Abel. shell based slow-release fertilizer: A new insights of urea store and release mechanism from cellular-structural-molecular level

The development of biodegradable slow-release fertilizers derived from lignocellulosic materials is essential for mitigating environmental pollution and ecological damage associated with petroleum-based components in conventional fertilizers, as well as for enhancing agricultural productivity. In this study, a Camellia oleifera Abel. shell based slow-release fertilizer (COSU) was prepared by molten urea impregnation method. FTIR NMR, SEM, EDX, BET and molecular dynamic simulation were used to reveal the urea storage and slow-release mechanisms of COSU at the cell wall and molecular level. These results indicated the role of the cellular tissue structure with its pore structure in the storage and slow release of urea and demonstrate the molecular behavior of urea adsorption and release on lignocellulosic chemical component. The maximum nitrogen loading rate of COSU was 36.58 % and the cumulative release rate over 28 days was 75.08 %, which met the GBT23348–2009 standard. The multiple coupling regulatory mechanism of the cell wall - lignocellulosic molecules of urea store and releasing were discussed and proposed. Pot experiments confirmed that the prepared slow-release fertilizer not only stimulated the growth of corn seedlings but also contributed to an increase in soil humus. The findings of this research provide a new insight and a solid theoretical foundation for the development of lignocellulose-based slow-release fertilizers, offering a sustainable alternative to traditional fertilizers and contributing to a greener agricultural future.

Logistic and Structural Equation Fitting Analyses of the Effect of Slow-Release Nitrogen Fertilizer Application Rates on the Nitrogen Accumulation and Yield Formation Mechanism in Maize

The purpose of this study is to clarify the differential effects of the application rate of slow-release nitrogen fertilizer (SRFN) on the nitrogen (N) accumulation dynamics, nutrient organ N distribution and transportation, yield, and N utilization efficiency of maize harvested using grain-type machines. This has significant implications for the scientific application of SRFN, as well as for reducing its application rate and improving its efficiency, in the agro-pastoral transitional zone of northern China. In a long-term positioning experiment that began in 2018, five treatments consisting of different SRFN application rates were set up, namely, N120 (120 kg ha−1), N180 (180 kg ha−1), N240 (240 kg ha−1), N300 (300 kg ha−1), and N360 (360 kg ha−1), with no fertilization during the growth period used as control (CK) treatment. To explore the characteristics of nitrogen accumulation dynamics in maize populations and the main factors affecting maize yield formation under the different SRFN application rate treatments, this study adopted a combination of quantitative analyses and model fitting, including logistic models, principal component analysis, and structural equation modeling. The research results show that SRFN application increased the aboveground N accumulation of the maize population, and the fitting effect of the logistic models was significant. The maximum rate of N accumulation in both years showed a trend of first increasing and then decreasing with the increase in the SRFN application rate. Compared with CK, SRFN application reduced the proportion of N distribution in the nutrient organs during the R6 stage, and it increased the N transport from the nutrient organs to the grains after the VT-R1 stage. With the increase in the SRFN application rate, both the economic yield and biological yield showed a single peak curve change and were maximized in the N240 treatment. The economic yield reached 15,342.07 kg ha−1 in 2020 and 16,323.51 kg ha−1 in 2021, increasing by 36.2% and 61.7% compared with CK, respectively. The apparent N fertilizer recovery rate, N uptake efficiency, N agronomic efficiency, and N fertilizer partial productivity all gradually decreased with the increase in the SRFN application rate. In maize populations, an appropriate SRFN application rate can adjust the characteristic parameters during the aboveground N accumulation rapid growth period, increase the N accumulation amount in aboveground parts, promote the transport of N from nutrient organs to grains, and improve yield. An application of 180–240 kg ha−1 SRFN is recommended for maize cultivation in the agro-pastoral transitional zone of northern China, as it is beneficial for stabilizing and increasing maize yield, as well as reducing the rate and improving the efficiency of N fertilizer.

Chitozan-zeolite Composite Fertilizer Formulations for Enhancing Nutrient Use Efficiency

The experiment was carried out in the Department of Soil Science and Agricultural Chemistry at the College of Agriculture, Vellayani, Kerala, from January to May 2024. Slow release fertilizer formulations (SRF) containing all the major (N, P,K), secondary (Ca, Mg, S) and micronutrients (Zn, B) were prepared using compatible fertilizer materials(urea, diammonium phosphate, muriate of potash, phosphogypsum, magnesium sulphate, zinc sulphate and borax), carrier materials (zeolite and chitosan) which are mixed in five ratios (1:1,1:2,1:3,2:1,3:1) and prepared by two methods namely solid impregnation and solute impregnation. Ten formulations were prepared with different combinations of fertilizer mix, carrier materials and impregnation methods. These formulations were prepared to meet the specific nutrient needs of solanaceous crops (75:40:25 N:P:K kgha-1) and the soil nutrient status. The formulations were characterized for their physical (hygroscopicity, moisture content and stability) and electro-chemical properties (pH, EC) and observed that they are non hygroscopic, non caking and are highly stable. The moisture content of formulations ranged from 2.57 % to 3.92 %, pH 6.30 to 6.81 and EC 10.06 to 16.29 dS m-1. The nutrient content in these formulations were 10.21 to 12.02 % nitrogen, 3.82 to 4.63 % phosphorus, 2.65 to 5.28 % potassium, 5.58 to 6.58 % calcium, 2.46 to 3.08% magnesium, 2.58 to 3.46% sulphur, 1.06 to 1.23% zinc and 0.15 to 0.24% boron. The highest nutrient content was obtained in formulation containing fertilizer mix + C-Z (1:1) prepared by solid impregnation method.

Slow-Release Nitrogen Fertilizer Promotes the Bacterial Diversity to Drive Soil Multifunctionality

The application of slow-release nitrogen fertilizer not only economizes labor input, but also decreases the frequency of use of mechanical intakes, with significant implications in advancing modern intensive agricultural production. Whether slow-release nitrogen fertilizer application can influence the association between microbial diversity and soil multifunctionality remains controversial. This study analyzed the spatial variances of soil environmental factors, soil multifunctionality, and their correlations with bacterial and fungal communities under five nitrogen application rates. The key factors influencing the dominant microbial species and community structures at different spatial locations were determined by the slow-release nitrogen fertilizer application rate, and the driving factors and dominant species of soil multifunctionality were identified. In contrast to the control group, moderate slow-release nitrogen fertilizer application enhanced soil multifunctionality and ameliorated the resilience of microbial diversity loss at diverse spatial locations resulting from irrational nitrogen fertilizer application. The resilience of the fungal community to disturbances caused by fertilization was lower than that of the bacterial community. Bacterial diversity exhibited a significant correlation with soil multifunctionality, and the soil multifunctionality intensity under 240 kg ha−1 treatment increased by 159.01% compared to the CK. The main dominant bacterial communities and the dominant fungal community Ascomycota affected soil multifunctionality through slow-release nitrogen fertilizer application. Structural equation modeling and random forest analysis demonstrated that bacterial community diversity, particularly in bulk soil and the rhizosphere, community composition, and soil nitrogen form are the primary driving factors of soil multifunctionality. Results indicated that the microbial niche alterations induced by slow-release nitrogen fertilizer application positively affect soil multifunctionality.

Concentration of Nutrients in Individual Organs of European Beech (Fagus sylvatica L.) Seedlings and Root System Development as a Result of Different Fertilization

The large-scale dieback of spruce monocultures, especially in the lower alpine, has become a significant problem and has necessitated the restoration of these areas, mainly using seedlings produced in forest nurseries. The primary source of nutrients for seedlings can be slow-release fertilizers and an appropriate dose of fertilizer improves the efficiency of its use and minimizes the negative environmental impact associated with the excessive use of mineral fertilizers. Aims: This study aimed to evaluate the effect of applying different fertilizer dose combinations on the accumulation of macronutrients in different parts of the seedlings (roots, shoots, and leaves) and on the morphology and development of fine roots. Methods: This research was carried out on producing beech seedlings with the application of starter soil fertilization with Yara Mila Complex (YMC) and Osmocote Exact Standard 3-4M (OES) fertilizers in four varying doses. Results: No deficiency of the analyzed macronutrients was noted in any of the tested fertilization variants. The highest content of all analyzed macronutrients was recorded in the leaves of beech seedlings, with values in roots and shoots being several times lower. The mixed fertilization variant OES 1.0 + YMC 1.0 shows a positive correlation with all analyzed elements and the parameters DQI (Dickson Quality Index), SA (Surface Area), RV (Root Volume), and mass. Conclusions: Results confirm the hypothesis that applying a mixture of fast-acting (YMC) and slow-acting (OES) fertilizer positively affects the nutrition and accumulation of macronutrients and the development of root systems in beech seedlings compared to fertilization with a single fertilizer.

Removal of Phosphate from Water by Iron/Calcium Oxide-Modified Biochar: Removal Mechanisms and Adsorption Modeling

Phosphorus (P) pollution is a leading cause of water eutrophication, and metal-modified biochar is an effective adsorbent with the ability to alter the migration capacity of phosphorus. This study uses bamboo as the raw material to prepare metal-modified biochar (ZFCO-BC) loaded with Fe and Ca under N2 conditions at 900 °C, and investigates its adsorption characteristics for phosphate. Batch experimental results show the adsorption capacity of the ZFCO-BC gradually increases (from 4.0 to 69.1 mg/g) as the initial phosphate concentration increases (from 2 to 900 mg/L), mainly through multilayer adsorption. Additionally, as the pH increases from 1 to 7, the adsorption capacity of the ZFCO-BC climbs to reach its maximum value of 48.4 mg/g with an initial phosphate concentration of 150 mg/L. At this pH, phosphate primarily exists as H2PO4− and HPO42−, which both readily react with Fe3+ and Ca2+ in the biochar. Furthermore, the addition of CO32−, HCO3−, NO3−, SO42−, F−, and Cl− each affect the removal rate of phosphate by less than 10%, indicating the ZFCO-BC has a highly efficient and selective phosphate adsorption capacity. A multi-column adsorption experiment designed to achieve long-term and efficient phosphorus removal treated 275.5 pore volumes (PVs) of water over 366 h. The cyclic adsorption–desorption experiment results show that 0.5 M NaOH can effectively leach phosphate from the ZFCO-BC. Observations at the molecular level from P K-edge XANES spectra confirm the removal of low-concentration phosphate is primarily dominated by electrostatic attraction, while the main removal mechanism for high-concentration phosphate is chemical precipitation. This study demonstrates that ZFCO-BC has broad application prospects for phosphate removal from wastewater and as a potential slow-release fertilizer in agriculture.

Cellulose-based controlled release fertilizers for sustainable agriculture: recent trends and future perspectives

Cellulose-based controlled release fertilizers for sustainable agriculture: recent trends and future perspectives

A Review on Nano Enabled Controlled Release Fertilizers and their Nutrient Release Mechanisms

The imbalance in nutrient release from conventional fertilizers and plant nutrient uptake leads to a surplus accumulation of nutrients in the soil. A key approach to tackle this issue involves the engineering of nano-enabled fertilizers for the controlled release of nutrients to crops. In this context, it is important to understand the strategies for designing and utilizing nano-enabled fertilizers that can effectively regulate nutrient release and enhance nutrient use efficiency (NUE). This review focuses on nano-structured materials that serve as nutrient carriers: nano-clays, hydroxyapatite (HA) nanoparticles, mesoporous silica, carbon-based nanomaterials, polymeric nanoparticles, and other nanomaterials. In addition, the nutrient release mechanisms in controlled release fertilizers (CRFs)/slow-release fertilizers (SRFs) are discussed. The discussion and perspectives presented emphasizes the need for standardized and comprehensive fertilizer evaluation systems, design of multifunctional nanomaterials, and the creation of stimuli-responsive nanocarriers to improve NUE.

Synthesis and mechanism of Mg/Al layered double oxides-silica nanocomposites for sustainable multi-nutrient delivery in agricultural applications

Potassium (K), urea (N), phosphate (P), and selenite (Se) are widely used in modern agriculture for improvement of crop yield and quality. However, traditional fertilizer suffers from poor fertilizer utilization efficiency and noncontrollable slow-release behavior. To improve nutrient utilization, we developed a layered double oxides-silica (LDO@Si) based on calcined Mg/Al layered double hydroxide-silica nanocomposites (LDH@Si), for slow release of K, N, P, and Se to crops. In this study, SEM, XRD, FT-IR, XPS, BET, and TGA were employed to analyze the structure, morphology, and microstructures of the samples. Results show that LDH@Si successfully transforms into LDO@Si after calcination, where LDO is mainly connected to silica via M-O-Si bonds. Furthermore, after K, P, and Se loading, the LDH@Si structure was successfully restored, indicating that phosphate and selenite ions have been effectively embedded in the inner layer of LDH. K ions are firmly fixed to the material surface via M-O-K bonds. After urea introducing, the pore structure of the material was completely filled, and excess urea formed a urea layer on the surface of the material. LDO@Si can continuously release nutrients into water through diffusion and LDO@Si dissolution for up to 240 h. Compared with chemical fertilizers, LDO@Si based slow-release fertilizer (CRSF2) significantly improves plant fresh weight, dry weight and chlorophyll content, increasing them by 13.91 %–23.13 %, 18.20 %–34.40 % and 2.24 %–14.81 %, respectively. Furthermore, a modest increase in the levels of nutrients N, P, and K is observed, while the Se concentration in plants treated with CRSF2 demonstrates significant enhancements of 9.57 %, 72.49 %, and 50.97 % compared to control treatments. These results illustrate the potential agricultural application of LDO@Si as a slow-release fertilizer for improving crop yields while minimizing the required amount of fertilizer.

Greener Production and Application of Slow-Release Nitrogen Fertilizer Using Plasma and Nanotechnology: A Review

The potential of both plasma and nanotechnology in producing slow-release fertilizer is immense. These technologies, when combined, may offer green and inexpensive nitrogen fertilizers, from rich renewable resources available in local areas. Together, these technologies may overcome some limitations of conventional synthetic fertilizers, which are currently expensive and associated with low nitrogen use efficiency and significant environmental concerns. This review explores the utilization of recent advances in plasma and nanotechnology, which can be leveraged to create new slow-release nitrogen fertilizers. It emphasizes their crucial role in addressing nitrogen depletion and improving crop production. Despite the lack of attempts to develop slow-release nanofertilizers from low-cost liquid nitrate generated by emission-free nonthermal plasma, the effectiveness of plasma nitrate matches that of conventional fertilizer for crop production. We propose a more efficient electrocatalytic conversion of plasma nitrate to ammonium salt, then coating it with plant-based cellulose nanoparticles to create a slow-release form. This set of processes would synchronize nutrient release with the dynamic N requirements of plants. Formulations using agro-based, low-cost cellulose nanomaterials could replace high-cost carrier hydrogels associated with low mechanical strength. This review also highlights the isolation of nanocellulose from various plant materials and its characterization in different formulations of slow-release nanoplasma N fertilizer. Additionally, we discuss mechanisms of N loss, slow-release, and retention in the soil that can contribute to the production and use of efficient, sustainable fertilizers to improve food security and, consequently, the health of our planet.

One-pot solvothermal synthesis of Ca-Fe-La composite for advanced removal of phosphate from aqueous solutions in a fixed-bed column: Modeling and resource utilization

The Ca-Fe-La composite was synthesized by the one-pot solvothermal method and applied to the advanced removal of phosphate from aqueous solutions in a fixed-bed column. The effects of some important process parameters on the phosphate adsorption were examined. It was found that the maximum equilibrium loading was 121.1 mg g−1 at an influent phosphorus concentration of 30 mg L−1, flow rate of 2.5 mL min−1, adsorbent mass of 0.5 g and pH of 5.14. The Thomas and fractal-like Thomas models were used to analyze the measured breakthrough curves. Their fitting quality was diagnosed by the adjusted coefficient of determination (Adj. R2), the root of mean squared error (RMSE) and the residual plot. According to the Thomas and fractal-like Thomas models, the breakthrough time and the saturation time were solved by the fzero command of MATLAB software. Akaike information criterion (AIC) and Bayesian information criterion (BIC) were adopted to further determine the optimal model. In all cases, the phosphate adsorption on the Ca-Fe-La composite followed the fractal-like Thomas model. The phosphate loaded Ca-Fe-La composite could be used as a slow-release fertilizer and promote tomato plant growth. This work aimed to provide reliable assessment methods for the modeling of the breakthrough curves and allow for waste management and resource utilization of the phosphate loaded Ca-Fe-La composite.