Slow-release Urea Fertilizer Research Articles

Development and Characterization of a Chitosan and Polyvinyl Alcohol (CS/PVP)-Based Slow-Release Urea Fertilizer Membrane

A slow-release test of urea fertilizer was conducted using chitosan-urea (CS-U) and chitosan/polyvinyl pyrrolidone K30-urea (CS/PVP-U) membranes. The urea membrane synthesis involved a blending method, with PVP K30 added as a component. The slow-release capabilities of CS-U, CS/PVP1-U, CS/PVP2-U, CS/PVP3-U, and CS/PVP4-U membranes were compared. FTIR results showed an increased intensity of the primary NH double peak at 1587 cm-1 and 1640 cm-1, while the C=O spectrum shifted from 1640 to 1647 cm-1 and the -OH group from 3354 cm-1 to 3362 cm-1, indicating hydrogen bond formation in CS/PVP-U. XRD analysis confirmed the membrane’s amorphous structure, and FE-SEM and AFM studies revealed morphology and roughness differences, with CS/PVP4-U having the largest cross-sectional diameter. The release study showed that PVP-modified chitosan membranes increased urea release, achieving 60 ppm/2 days for the first 16 days, then decreasing to about 55 ppm through day 30, with partial urea release controlled over time. This suggests that SRF fertilizer can effectively control urea release into the environment.

Modified Slow-Release Urea Fertilizers on Yield and Nitrogen Use Efficiency of Wheat Crop (Triticum aestivum L) for Safe and Sustainable Agricultural System

ABSTRACT Safeguarding the agricultural environment from pollution is one of the most critical challenges facing the world in the context of climate change. The loss of nitrogen fertilizers through agricultural runoff or volatilization in the form of nitrate or ammonia emissions is a significant contributor to pollution. This loss also represents an economic waste that may lead to increased prices of agricultural products. Therefore, finding a solution to this problem has become imperative. An experiment was conducted on wheat plants using various rates of urea coated with slow-release materials. The study aimed to assess the impact of these fertilizers on wheat growth and yield, nutrient uptake, and nitrogen utilization efficiency (NUtE). Results demonstrated that urea fertilizers coated with slow-release materials outperformed conventional fertilizers in terms of wheat growth and yield, uptake of nitrogen, phosphorus, and potassium, as well as NUtE. The most favorable outcomes were achieved using urea-formaldehyde, urea-humic, and urea-biochar fertilizers at 100% of the recommended nitrogen application rate. This resulted in economically viable grain production with high fertilizer efficiency. Based on these findings, we recommend applying either urea-formaldehyde or urea-humic at a rate of 107 kg N ha−1 to produce wheat grain and straw with enhanced NUtE. This approach can help reduce environmental pollution caused by nitrogen losses.

Environmentally friendly slow-release urea fertilizer based on modified chitosan membrane

The inefficient use of conventional fertilizers has prompted the exploration of slow-release fertilizer (SRF) systems to enhance plant nutrient delivery and uptake. This study investigates the potential of the chitosan (CS) membrane modified with succinic acid (SA) and calcium ions (Ca2+) as an effective SRF system. The CS/SA-U/Ca-coated membrane can extend the release period of urea, thereby optimizing fertilizer efficiency and promoting plant growth. The structural and chemical features of the CS/SA-U/Ca membrane were comprehensively analyzed. The modification with Ca2+ increased the membrane’s thickness, decreased its swelling degree, and resulted in a rougher, more porous surface, all of which contributed to a more controlled release of urea. Urea release profiles were evaluated in both water and soil, demonstrating that the CS/SA-U/Ca coating extended the release period to 20 days in water and over 30 days in soil. Quantitative UV–Vis spectrophotometry and qualitative assessments were used to measure the urea release and evaluate the impact of the SRF on vegetable plant growth. Experimental results demonstrated a significant enhancement in plant growth, with a 46 % increase in stem growth and a doubling of leaf count compared to control plants without the SRF membrane. These findings suggest that the CS/SA-U/Ca-coated SRF system holds promise for optimizing fertilizer use and promoting plant growth by providing a more controlled nutrient release.

Optimizing neem oil coating thickness for the development of slow-release urea fertilizer to enhance wheat growth and yield

Optimizing neem oil coating thickness for the development of slow-release urea fertilizer to enhance wheat growth and yield

Synthesis and characterization of chitosan-modified membrane for urea slow-release fertilizers

BackgroundUrea is a fertilizer widely used by farmers, especially vegetable farmers, due to its high nitrogen content, around 46 %. However, plants only use a small amount of nitrogen, a maximum of 35 %, while the remaining nitrogen is wasted and released into the environment. Undeniably, it causes increases production costs and environmental problems. A slow-release urea fertilizer (SRF) has been formulated to resolve these issues. MethodsIn this study, the membrane was made of chitosan with several crosslinking agents such as Tripolyphosphate (TPP). In addition, calcium ion bonds are expected to increase the interaction with urea fertilizer through the encapsulation process. The resultsOur data showed that urea slow-release fertilizer (SRF) with the chitosan/TPP/Ca membrane, was successfully synthesized. This membrane has the characteristics of a thin white layer that is transparent. The physical and chemical characterization of SRF membranes with various coating membrane variations showed that the chitosan/TPP/Ca-urea membrane has Young's modulus of 7.75–22.05 N/mm2, swelling of 109.52–132.62 % and porosity of 0.756–1.06 %. Functional group analysis shows that several spectral changes indicate the presence of crosslinking process between the chitosan functional groups and TPP. The urea release results show that the membrane is released through a diffusion mechanism. Furthermore, SEM results show that these membranes have pores with various shapes and sizes. ConclusionBased on the result, it can be concluded that chitosan membrane modification with the addition of TPP and calcium oxide provides improved membrane characteristic cs including degree of development, hydrophobicity, membrane stress, and nitrogen release on the membrane. This membrane shows is indicating suitability as a slow-release fertilizer.

The Development of Environmental Friendly Biological Sulfur Recovery Unit (BSRU) For Sulfur Coated Urea with Slow Release Fertilizer Method: A Case Study in Field X

The absorption of nitrogen from urea fertilizer is significantly inefficient. Due to its solubility in water. This problem can be overcome by producing slow-release fertilizer (SRF) that inhibits urea from being dissolved in water. Sulfur-coated urea (SCU) is one of the SRF methods. Therefore, this study aimed sulfur-coated slow-release urea fertilizer using sulfur waste from the Biological Sulfur Recovery Unit (BSRU) in Field X. A total of 14 tons of sulfur cake was produced daily by BSRU in Field X and sent to the laboratory for composition analysis, followed by drying. Subsequently, the dried sulfur was into a powder using a hammer and sieved to achieve a size of 200 mesh. Based on the results, SCU with the sulfur to urea ratio of 1:1 and mixing time of 15 minutes exhibited the best performance in dissolution tests with the longest dissolution time of 5 minutes which was better compared to the uncoated urea. After 7 days of observation, spinach that received SCU was more fertile and greener. The calculated NPV and payout time were 88712 million IDR and 1.76 years, respectively. This indicated that the development of this study was economically attractive. In conclusion, the value of sulfur waste from gas processing was increased by using sulfur waste from BSRU as a coating of urea while reducing related environmental effects.

Valorization of lignin by crosslinking for slow-release urea fertilizer systems: A promising approach for agricultural applications

Slow-release fertilizers hold promise for their extensive use in agriculture. Urea, a commonly employed fertilizer, poses the risk of elevated nitrogen levels in soil due to its water solubility when used improperly. To address this issue, the development of a cost-effective and biodegradable urea slow-release matrix was pursued by crosslinking wheat straw-derived lignin with epichlorohydrin at varying ratios (1:1, 1:2, and 2:1) and subsequently impregnating it with urea. The crosslinked lignin matrices exhibited superior properties compared to unmodified lignin. After 8 days of immersion in water, the percentage release of urea from the crosslinked lignin matrices reached 48%, whereas it was 95% for unmodified lignin. Characterization techniques such as Fourier transform infrared spectroscopy, 13C nuclear magnetic resonance, and thermogravimetry analysis were employed to gain insights into the structural and functional aspects of the crosslinked lignin. The results revealed that the crosslinked lignin possessed a higher surface area and exhibited more suitable functional groups for urea impregnation. The controlled hydrophilic-lipophilic balance of the crosslinked lignin matrices offers significant advantages in fertilizer systems, enabling a controlled and gradual release of urea. This innovative approach not only offers enhanced control over nutrient delivery but also demonstrates the potential of lignin as a sustainable and cost-effective alternative for slow-release fertilizer formulations. This development provides an effective solution to address the issue of excessive nitrogen levels and opens up new avenues in material development, holds promise for sustainable agriculture and paves the way for further advancements in the field.

Preparation and characterization of slow-release urea fertilizer encapsulated by a blend of starch derivative and polyvinyl alcohol with desirable biodegradability and availability

In this study, a novel double-layer slow-release fertilizer (SRF) was developed utilizing stearic acid (SA) as a hydrophobic inner coating and a blend of starch phosphate carbamate (abbreviated as SPC) and polyvinyl alcohol (PVA) as a hydrophilic outer coating (designated as SPCP). The mass ratios of SPC and PVA in the SPCP matrices were systematically optimized by comprehensively checking the water absorbency, water contact angle (WCA), water retention property (WR), and mechanical properties such as percentage elongation at break and tensile strength with FTIR, XRD, EDS, and XPS techniques, etc. Moreover, the optimal SPCP/5:5 demonstrated superior water absorbency with an 80.2 % increase for the total mass compared to natural starch/PVA(NSP), along with desirable water retention capacity in the soil, exhibiting a weight loss of only 48 % over 13 d. Relative to pure urea and SA/NSPU/5:5, SA/SPCPU/5:5 released 50.3 % of its nutrient within 15 h, leading to nearly complete release over 25 h in the aqueous phase, while only 46.6 % of urea was released within 20 d in soil, extending to approximately 30 d. The slow release performance of urea reveals that the diffusion rate of urea release shows a significant decrease with an increase in coating layers. Consequently, this work demonstrated a prospective technology for the exploration of environmentally friendly SRF by integrating biodegradable starch derivatives with other polymers.

Enhancing the use of coated urea fertilizer and assessing its effect on growth and yield performance in grain corn

Use of urea fertilizer is currently increasing to meet the agricultural demand. However, the efficiency and optimization of urea application in agriculture is uncertain. Therefore, this study was conducted to compare the efficacy of slow-release urea and standard urea fertilizer. Reductions in the N rate of the slow release was assessed by measuring the different growth performance and yield at the field. A 25% reduction in N content using coated urea gave similar growth performance and yield compared to standard practice The findings indicated that there was no significant difference in stem diameter, number of leaves and chlorophyll content between the control treatment and slow-release urea. Grain yield and yield components like cob length, number of grains per cob, weight of grain per cob and 1000 grain weight obtained in the field was similar when applying the slow-release urea with the yield and yield components obtained from standard practice as a control. We conclude that this slow-release urea can be used in extensive cropping of corn while promising at least the same yields than standard practices with reducing impact on environment and nitrogen losses in the soil.

Hydrogel Nanocomposite Based Slow-Release Urea Fertilizer: Formulation, Structure, and Release Behavior

To enhance the nitrogen utilization efficiency of fertilizers, we developed a novel slow-release fertilizer hydrogel through free radical polymerization, incorporating lignin-containing cellulose nanofiber (LCNF), clinoptilolite (CL), urea, and acrylic acid (AA)-co-acrylamide (AAm) polymer. Various analytical techniques were utilized to examine the structure, swelling, and release behaviors of the fabricated hydrogels with varying LCNF concentrations. The results indicated that the addition of 10% LCNF led to a decrease in water absorption from 72.44 g g−1 to 24.04 g g−1. However, re-swelling was significantly enhanced, with a reduction in re-swelling capacity loss from 32.91% to 23.52%. Concurrently, water retention capacity notably increased from 18.03% to 39.20%. The hydrogel containing 10% LCNF exhibited a slower urea release over 30 days. The kinetic studies revealed that the swelling and urea release behaviors align well with the second-order kinetics model and the Peppas-Sahlin model, respectively. In summary, the developed LCNF/CL/(AA-co-AAm)/urea hydrogel nanocomposites present a novel strategy for the future production and utilization of slow-release fertilizers in agricultural and horticultural fields.

Slow-Release Urea Fertilizer with Water Retention and Photosensitivity Properties Based on Sodium Alginate/Carboxymethyl Starch Sodium/Polydopamine

Using slow-release fertilizer is one of the sustainable strategies to improve the effectiveness of fertilizers and mitigate the environmental pollution caused by excess usage of fertilizer. In this study, a slow-release urea fertilizer with water retention and photosensitivity properties was prepared by a two-step method. It was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and an infrared camera. This fertilizer can prolong the release period of urea, improve water-retention capacity of soil, and carry out photothermal conversion under illumination. Comparing four release kinetics models, the Ritger–Peppas model was the best fitting model for releasing behavior in soil, and diffusion followed the Fickian mechanism. The application of fertilizer on winter wheat was carried out to intuitively evaluate the fertilizer’s effects on promoting plant growth and resisting water stress. Thus, this study provides a new strategy for improving fertilizer utilization rate and maintaining soil moisture, which will be beneficial for sustainable agriculture.

Optimized carbonization of coffee shell via response surface methodology: A circular economy approach for environmental remediation

The disposal of coffee shell waste on farmland, is a common practice that can causing the environmental and waste valuable resources. Carbonization has been identified as an effective method for transforming coffee shells into useful products that mitigate environmental pollution. Through the response surface methodology, the carbonization conditions of the coffee shells were optimized and its potential as a biochar-based slow-release urea fertilizer was explored. Experiments were conducted on coffee shell performance under varying carbonization conditions such as temperature (600–1000 °C), time (1–5 h), and heating rate (5–20 °C/min). The results indicated that the ideal urea adsorption was 56.3 mg/g, achieved under carbonization conditions of 2.83 h, 809 °C, and 15.3 °C/min. The optimal nutrient release rate within seven days was 45.4% under carbonization conditions of 3.19 h, 813 °C, and 15.0 °C/min. The infrared spectroscopy analysis indicates that carbonization conditions influenced the absorption peak intensity of coffee shell biochar, while the functional group types remain unchanged. The biochar exhibits diverse functional groups and abundant pores, making it a promising candidate for use as a biochar-based fertilizer material. Overall, the findings demonstrate an effective waste management approach that significantly reduces environmental pollutants while remediating pollution.

New Slow-Release Urea Fertilizer Fortified with Zinc for Improving Zinc Availability and Nitrogen Use Efficiency in Maize

New Slow-Release Urea Fertilizer Fortified with Zinc for Improving Zinc Availability and Nitrogen Use Efficiency in Maize

Experimental investigations on PVA/chitosan and PVA/chitin films for active food packaging using Oxytenanthera abyssinica lignin nanoparticles and its UV-shielding, antimicrobial, and antiradical effects

This study investigated the effect of adding lignin nanoparticles (LNPs) derived from Oxytenanthera abyssinica via alkali-acid nanoprecipitation method to polyvinyl alcohol/chitosan (PVA/CI) and polyvinyl alcohol/chitin (PVA/CH) films for the active food packaging applications. Adding LNPs at concentrations of 1 % and 3 % improved the films' thermal stability and mechanical properties. The lowest water solubility and moisture content were observed in PVA/CI/LNPs films. LNPs exhibited effective 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, with the highest values observed in PVA/CH/LNPS and PVA/CI/LNPS films with values of 87.47 and 88.74 % respectively. The addition of LNPs also improved the UV-blocking abilities of the films. PVA/CH/LNP3 and PVA/CI/LNP3 have the smallest percentage transmission values of 3.34 % and 0.86 % in the UV range. The overall migration of dietary stimulants was lower in PVA/CI/LNPS and PVA/CH/LNPS films compared to PVA film. Antibacterial tests demonstrated the inhibitory capacity of the synthesized biofilms against both gram-positive and negative bacterial species, with the highest inhibitory value of 26 mm. The study suggests that PVA/CH/LNPS and PVA/CI/LNPS films have potential applications as active food packaging materials and can be explored in other potential applications such as drug delivery, tissue engineering, wound healing, and slow-release urea fertilizer development.

Effect of Varying Levels and Source of Slow-release Urea Fertilizers on Yield, Post Harvest Soil Nutrient Status and Economics of Wet Direct Seeded Rice (Oryza sativa L.)

A field experiment was conducted at the research farm of ICAR-Indian Institute of Rice Research (IIRR), Hyderabad, Rajendranagar in kharif, 2022 to study the effect of varying levels and source of slow-release urea fertilizers on yield, post harvest soil nutrient status and economics of wet direct seeded rice. The experiment was laid out in a randomized block design with ten treatments consisting of nitrogen management practices and replicated thrice. The results revealed that 100% RDN (Recommended Dose of Nitrogen) (120 kg/ha) applied through silicon coated urea resulted in the highest grain yield (6249 kg/ha) and straw yield (7114 kg/ha). Post harvest soil nutrient status revealed that 125% recommended dose nitrogen (150 kg/ha) applied through silicon coated urea resulted in the highest soil available nitrogen. Similarly, the highest soil available nitrogen gain was recorded in the plots that received 125% silicon coated urea. Silicon coated urea applied @ 120 kg/ha ulimately fetched higher gross return of ₹. 1,42,964/ha, net returns ₹. 1,03,793 and benefit-cost ratio of 2.65. It can be concluded that RDN applied through silicon coated urea @ 120 kg/ha found to be a suitable alternative to neem coated urea in increasing the grain yield, soil fertility and profitability.

Preparation and properties of multifunctional eco-friendly slow-release urea fertilizer encapsulated by diatomite filter aid waste-based superabsorbent

Due to the high cost, incomplete degradation, and limited raw material sources of traditional slow-release fertilizers, the development of environmentally friendly slow-release urea based on waste filter aids is of great significance in modern agriculture. In this study, beer diatomite filter aid waste-based superabsorbent resin (BDWSA)11beer diatomite filter aid waste (BDW), beer diatomite filter aid waste-based superabsorbent resin (BDWSA), acrylic acid (AA),N, N-methylenebisacrylamide (MBA), potassium persulfate (KPS), ethyl cellulose (EC), monolayer-coated slow-release urea (MSRU), double-coated slow-release urea (DSRU). was synthesized by free radical grafting copolymerization through microwave radiation heating with beer diatomite filter aid waste (BDW), acrylic acid (AA), N, N-methylenebisacrylamide (MBA), and potassium persulfate (KPS). Then, BDWSA was used as the outer coating material, along with ethyl cellulose (EC) and Kaolin as the inner coating, urea and Phellinus igniarius biochar as the fertilizer core, to form a multifunctional eco-friendly double-coated slow-release urea (DSRU) for water-retaining and slow-release functionalities. The performance of slow release behavior of nitrogen was investigated, and showed that urea in soil released 86.02 % of nitrogen during 3 days, monolayer-coated slow-release urea (MSRU) released 94.02 % of nitrogen in 30 days, and DSRU released a total of 74.66 % of nitrogen in 30 days, indicating that DSRU can improve fertilizer utilization by delaying nutrient release. The biodegradation experiment showed that DSRU degraded 86.65 % wt% in 90 days, not only indicating a good biodegradation effect but also beneficial to the growth of soybeans under drought conditions in growth experiments. Therefore, the eco-friendly DSRU product with excellent slow-release capacity has broad application prospects in agriculture.

Slow-release urea fertilizer fabrication through the incorporation of raw bentonite and gelatin binder

Slow-release urea fertilizer fabrication through the incorporation of raw bentonite and gelatin binder

Wood Ash Additive for Performance Improvement of Gelatin-Based Slow-Release Urea Fertilizer

Urea is a crucial nutrient for plant growth, but because of its substantial losses due to nitrification, ammonification, and subsurface leaching, there is currently a push to reduce these losses. Urea is frequently uploaded and trapped in gelatin. In this research, the improvement of urea uploading and encapsulation efficiency is investigated using wood ash made from plant biomass (Pinus roxburghii). The 8 g w/v of gelatin was mixed with various concentrations of wood ash (from 4 to 16 g w/w), urea (from 4 to 24 g w/w), and glutaraldehyde (from 0.5 to 3 mL g−1) to prepare various formulations of slow-release fertilizer (SRF). According to this study, adding wood ash to gelatin increases its ability to upload and encapsulate urea. The urea on its surface and the metal in wood ash both considerably contribute to the compositional alterations in gelatin in SRFs, which were demonstrated by IR spectroscopy. Visualization from photographs revealed that the homogenous dispersion of wood ash improved structural compatibility. The water content of the SRF formulation showed that wood ash can reduce water absorption by changing how hydrophobic gelatin is. Wood ash improves the gelatin’s ability to reduce the rapid release of urea over time, according to testing of cumulative urea release from SRF. The optimal combinations for achieving the maximum 53.43% of urea uploading were 2.44 g of urea, 2.47 mL of glutaraldehyde, and 1.50 g of wood ash, according to the Box–Behnken model. The gelatin-based SRF that had been amended with wood ash was applied to the Mentha spicata plant, and the plant’s healthy development and higher chlorophyll content revealed its agronomic potential. This study has a significant contribution to the development of an affordable and more effective wood ash-modified gelatin-based SRF.

Multicomponent biodegradable hydrogels based on natural biopolymers as environmentally coating membrane for slow-release fertilizers: Effect of crosslinker type

This work aims to explore the suitable crosslinker type for synthesizing multicomponent biodegradable hydrogels of cassava starch (CSt) grafted with acrylic acid (AA) semi-interpenetrated by natural rubber (NR)/polyvinyl alcohol (PVA) blend (CSt-g-PAA/NR/PVA, CSB semi-IPN hydrogel) as coating membranes for slow-release urea fertilizers. Three crosslinker types (ethylene glycol dimethacrylate (EGDMA), glutaraldehyde (GA) and N,N′- methylene-bis-acrylamide (MBA)) were employed to investigate their influences on the properties of CSB semi-IPN hydrogels. The results revealed that the different crosslinkers clearly exhibited different water-retention capacity, biodegradation, slow release and plant growth performance of the CSB semi-IPN hydrogels. The CSB-G2 hydrogel (crosslinked with GA at 2 wt%) remained higher water-retention at 30 days (20.2 %), greater rate of degradation (1.37 %/day) and better biosafety (OD600 = 2.26) compared to CSB-M2 and CSB-E2 hydrogels. After urea pellets were coated by CSB hydrogels and wax layers (UCSBw formulation), the urea release rates from the UCSBw-M2, UCSBw-E2 and UCSBw-G2 formulations in 30 days were 67.7 %, 68.7 % and 78.3 %, respectively, corresponding well with swelling ratio and pore size. Besides, the UCSBw-G2 formulation yielded the greater plant growth performance (height, leaf length and product weight) than other two formulations and commercial fertilizer. In conclusion, GA is the suitable crosslinker for synthesizing the CSB-g-PAA/NR/PVA hydrogels with high water-retention, excellent biodegradation, less negative impact on environments, acceptable slow-release rate, good biosafety and reasonable price for slow-release fertilizers.

Modifikasi Lumpur PDAM-Alginat Sebagai Peng-Enkapsulasi Urea dan Aplikasinya Sebagai Pupuk Lepas Lambat

Modification of sludge solid waste regional water company (PDAM) Pontianak with alginate for the application of slow-release urea fertilizer. Characterization of materials was performed with Fourier-Transform Infra-Red (FTIR) spectroscopy and scanning electron microscopy (SEM). Analysis of the FTIR spectrum obtained showed that the characteristics of the absorption band at wavelengths of 3639.89 cm-1 and 3690.9 cm-1 are characteristic of the vibration of NH2 stretching asymmetric and symmetric derived from the presence of urea. Nitrogen release tests on mud PDAM-alginate composites with concentrations of 10%, 20%, 30%, 40% and 50% for 72 consecutive hours of 12,80%, 19,33%, 4,00%, 8,39% and 6,20%. This shows that urea encapsulated mud PDAM-alginate at a concentration of 30% is the composition with the best results in holding urea encapsulated.