Slow Release Of Urea Research Articles

Preparation and characterization of starch carbamate modified natural sodium alginate composite hydrogel blend formulation and its application for slow-release fertilizer

The exploration of environmentally friendly slow-release fertilizer (SRF) based on natural bio-polymers is of great importance in the development of modern agriculture and horticulture. Herein, a novel starch carbamate (SC) modified sodium alginate (SA) hydrogel (SC/SAH) was prepared utilizing as-synthesized SC and natural SA through the cationic ions crosslinking method and ultimately the corresponding slow-release fertilizer (SC/SAH-SRF) was successfully developed by immersing the dried SC/SAH matrix into saturated urea solution. Due to the low gelation temperature and high viscosity of the synthesized SC, the formed SC/SAH exhibits significantly enhanced properties including excellent water absorbency up to 8.02 g/g with considerable repeatability, abundant pore structure and high hydrophilicity compared with the neat SAH and natural starch based hydrogel (NS/SAH). Accordingly, the SC/SAH leads to higher urea loading amount ∼ 1.28 g/g. Importantly, the resultant SC/SAH-SRF also shows superior slow-release performance, yielding a cumulative urea release of only 61.6 % within 10 h and almost completely release >16 h in water, what's more, only 58.5 % of the urea releases within 25 days and exceeding 50 days for complete release in soil column assays. The slow-release of urea from SC/SAH-SRF well complies for the first-order kinetics and accomplishes via a non-Fickian diffusion process. Moreover, the pot experiment demonstrates that the SC/SAH-SRF has higher growth promotion role for the maize seedlings than those of others. Consequently, this work provides a novel strategy for preparing environmentally friendly SRF by blending modified starch and hydrogel.

Syntheses and Characterization of Cephalexin-Chitosan/Natural Rubber network polymer for Slow-Release Fertilizer.

The increase in the world's population has forced the agricultural sector to increase the production of crops to meet food needs. The spread of nutrient deficiencies in the soil led to economic losses, a reduction in nutritional quality, and total grain quantity for humans and livestock. Coating fertilizers with polymers is one of the most important and effective aspects of slow-release fertilizers in the soil. aim this study, the reaction between chitosan and expired cephalexin as a grafted polymer was done and vulcanized with natural rubber in the presence of tetra methyl thiuram disulfide as catalyst to cover the urea fertilizer. The grafted polymer (chitosan/expired cephalexin compound) was prepared by the Schiff base method. The expired medicinal compound of cephalexin is rich in carbon, nitrogen, sulfur, and hydrogen atoms which improved the diffusion of the fertilizer .So the reaction of the validity of the reaction between chitosan and expired Cephalexin was confirmed by infrared (IR) and it was confirmed the presence of new absorption band due to the Azomethine group. The swelling, water retention, slow release of urea, and biodegradation of the NR/chitosan/expired cephalexin compounds were characterized. The rheometer test was carried out under the pressure of 250 bar and temperature of 170°C, The results showed that the Slow release of urea was increased with the increase in the concentration of cephalexin. The highest release percentage in soil media was 2.67 g/l for the C2 blend. The highest swelling ratio was 189.49 % for the C4 blend while the highest water retention was 75.67% for the C2 blend. It was also shown a good biodegradability, where the highest concentration of cephalexin with chitosan gave the highest rate of biodegradation to be 14.61% for C4. The homogeneity of the blends was studied by FE-SEM. It was concluded that the C1-C4 blends were the best for slow-release fertilizer application.

Biobased Materials as Promising Tools for the Slow-Release of Urea

Biobased Materials as Promising Tools for the Slow-Release of Urea

Structure and Properties of the Xerogels Based on Potassium Silicate Liquid Glass and Urea.

The xerogels based on the aqueous solutions of urea in potassium silicate liquid glass (PSLG) were produced by CO2 bubbling and investigated. The structure and chemical composition of the obtained materials were analyzed. Using the SEM, XRD, IR-FT, DSC, and low energy local EDS analysis, it was recognized that the dried gels (xerogels) contained three forms of urea: oval crystals of regular shape appeared onto the surface of xerogel particles; fibrous crystals were located in the silicate matrix; and molecules/ions were incorporated into the silicate matrix. It was shown that an increase in [(NH2)2CO] in the gel-forming system promoted increased contents in crystalline forms of urea as well as the diameter of the fiber-shaped urea crystals. A rate of the urea release in water from the granulated xerogels containing 5.8, 12.6, and 17.9 wt.% of urea was determined by the photometric method. It was determined that the obtained urea-containing xerogels were characterized with a slow release of urea, which continued up to 120 days, and could be used as controlled release fertilizers containing useful nutrients (N, K).

High-Strength, High-Water-Retention Hemicellulose-Based Hydrogel and Its Application in Urea Slow Release.

The use of fertilizer is closely related to crop growth and environmental protection in agricultural production. It is of great significance to develop environmentally friendly and biodegradable bio-based slow-release fertilizers. In this work, porous hemicellulose-based hydrogels were created, which had excellent mechanical properties, water retention properties (the water retention ratio in soil was 93.8% after 5 d), antioxidant properties (76.76%), and UV resistance (92.2%). This improves the efficiency and potential of its application in soil. In addition, electrostatic interaction and coating with sodium alginate produced a stable core-shell structure. The slow release of urea was realized. The cumulative release ratio of urea after 12 h was 27.42% and 11.38%, and the release kinetic constants were 0.0973 and 0.0288, in aqueous solution and soil, respectively. The sustained release results demonstrated that urea diffusion in aqueous solution followed the Korsmeyer-Peppas model, indicating the Fick diffusion mechanism, whereas diffusion in soil adhered to the Higuchi model. The outcomes show that urea release ratio may be successfully slowed down by hemicellulose hydrogels with high water retention ability. This provides a new method for the application of lignocellulosic biomass in agricultural slow-release fertilizer.

Syntheses and Characterization of Chitosan-Expired Amoxicillin/Natural Rubber Copolymers for Slow-Release Fertilizer

As the global population rises, so does the urgency with which the agricultural sector must increase crop output to keep up with demand. The spread of nutrient deficiencies in the soil led to economic losses and a significant decrease in nutritional quality and total quantity of grains for humans and livestock. Fertilizers can increase nutrient use efficiency through the slow release mechanism and targeted or controlled delivery. Coating fertilizers with polymers is one of the most important and effective aspects of slow-release fertilizers in the soil. In this study, urea fertilizer was coated with a grafted polymer prepared from chitosan and expired amoxicillin using condensation reaction and vulcanized with natural rubber using tetramethyl thiuram disulfide (TMTD) as catalyst. The expired amoxicillin improved the diffusion of the fertilizer. The FTIR results confirmed the presence of azomethine group in chitosan/expired amoxicillin. The swelling, water retention, slow release of urea, biodegradation and remoter tests of the chitosan/NR/expired amoxicillin compounds were characterized. The slow release rate of urea was decreased with the increase in the concentration of amoxicillin. The highest release percentage in soil media was 2.69 g/L for the B2 blend. The highest swelling ratio was 189.482 % for the C4 blend while the highest water retention was 75.69% for the B2 blend. It was also shown a good biodegradability, where the highest concentration of amoxicillin with chitosan gave the highest rate of biodegradation to be 14.63% for C4. The homogeneity of the mixtures was studied by FE-SEM technique. It was concluded that the C1-4 blends were the best for slow-release fertilizer application.

Physiological and Molecular Investigation of Urea Uptake Dynamics in Cucumis sativus L. Plants Fertilized With Urea-Doped Amorphous Calcium Phosphate Nanoparticles.

At present, the quest for innovative and sustainable fertilization approaches aiming to improve agricultural productivity represents one of the major challenges for research. In this context, nanoparticle-based fertilizers can indeed offer an interesting alternative with respect to traditional bulk fertilizers. Several pieces of evidence have already addressed the effectiveness of amorphous calcium phosphate-based nanoparticles as carriers for macronutrients, such as nitrogen (N), demonstrating increase in crop productivity and improvement in quality. Nevertheless, despite N being a fundamental nutrient for crop growth and productivity, very little research has been carried out to understand the physiological and molecular mechanisms underpinning N-based fertilizers supplied to plants via nanocarriers. For these reasons, this study aimed to investigate the responses of Cucumis sativus L. to amorphous calcium phosphate nanoparticles doped with urea (U-ACP). Urea uptake dynamics at root level have been investigated by monitoring both the urea acquisition rates and the modulation of urea transporter CsDUR3, whereas growth parameters, the accumulation of N in both root and shoots, and the general ionomic profile of both tissues have been determined to assess the potentiality of U-ACP as innovative fertilizers. The slow release of urea from nanoparticles and/or their chemical composition contributed to the upregulation of the urea uptake system for a longer period (up to 24 h after treatment) as compared to plants treated with bulk urea. This prolonged activation was mirrored by a higher accumulation of N in nanoparticle-treated plants (approximately threefold increase in the shoot of NP-treated plants compared to controls), even when the concentration of urea conveyed through nanoparticles was halved. In addition, besides impacting N nutrition, U-ACP also enhanced Ca and P concentration in cucumber tissues, thus having possible effects on plant growth and yield, and on the nutritional value of agricultural products.

Uji Pupuk Slow Release Urea Dirakit dari Berbagai Bahan Polimer terhadap Pertumbuhan dan Hasil Bawang Merah Tiron pada Tanah Sawah Purwosari

This research aims to determine 1) the effect of four formulas on slow release urea on the growth and yield of shallot plant at Purwosari village and 2) formula of slow release urea that have the best growth and yield of shallot plant at Purwosari village. The research was conducted in November 2019 untill Maret 2020 The research was conducted at the ex-paddy fields of Purwosari village, Baturraden District, Banyumas Regency and Research Laboratory, Jenderal Soedirman University. Research in the form of non-factorial field experiments using RAKL with five treatments repeated five times. The formula of each treatment includes: F0 = NPK (Urea, SP-36, and KCl), F1 = 70% urea + 6% chitosan + 24% humic acid, F2 = 70% urea + 10% Azolla microphylla + 10% gondorukem + 10% humic acid , F3 = 60% urea + 10% Azolla microphylla + 10% montmorillonite + 10% gondorukem + 10% humic acid, and F4 = 56% urea + 3% humic acid + 24% zeolite + 11% tapioca flour + 6% gondorukem. The observed variable including growth and yield components of shallot. The variable of growth including the height of plant, the number of leaves, the weight of fresh plant of clump-1, the weight of fresh plant of effective plot, the weight of dry plant of clump-1, the weight of dry plant of effective plot, and the number of clump-1 bulbs. The yield components of shallot is a bulbs. Result of the research showed that the best formula for plant growth and yield of shallot plant is F2. The growth and yield of shallot produced by F4 is always lower than in the control treatment (F0). Farmers can fertilize less and optimize nitrogen uptake by plants with application of slow release of urea.

Synthesis of bio-based MIL-100(Fe)@CNF-SA composite hydrogel and its application in slow-release N-fertilizer

With the severe shortage of water resources and the low utilization efficiency of fertilizer, slow-release fertilizer equipped with water-absorbing and water-retaining capacity has captured much attention. Herein, by integrating metal-organic frameworks (MOFs) with cellulose nanofibres (CNFs) and sodium alginate (SA), a novel cellulose-based hydrogel (MIL-100(Fe)@CNF-SA) was fabricated that acted as a carrier for urea. The resultant hydrogel was not only qualified with a high surface area of 129.17 m2/g but also affluent in the hydrophilic groups. In parallel with the good water-holding capacity of 55% when the loading of the resultant hydrogel was only 0.5 g, the complete loss of the water in the treated soil was successfully slowed down by nearly 20 d compared with the soil without treatment. Urea (1.47 g/g) could be captured in the composite hydrogel, wherein the slow release of urea was achieved due to the synergism of the highly porous structure of the hydrogel and the crystals with a high specific surface area. Moreover, the positive effect of the resultant hydrogel on the growth of wheat was indexed to the germination rate, number of tillers, photosynthetic rate and chlorophyll content of the crop, which verified their further application in irrigating farming.

Development of Urea Uptake and Release Studies Using N, N-Dimethylacrylamide/Maleic Acid/Citric Acid Based Macrogel

Recently, the use of polymers in agricultural and horticultural applications has been seen as a solution to reduce water consumption and excess fertilizer use in particularly. In this study, macrogels were synthesized to allow fertilizer species and water to be controlled and released in the soil. A natural macrogel derived from N,N-Dimethylacrylamide (DMAAm), Maleic Acid (MA) and Citric Acid (CA) was selected because of its ability to absorb/release a large amount of water and to have modifiable functional groups. Urea, which is an abundant source of nitrogen, was chosen to model the fertilizer. The macrogel was prepared using easily available, low-cost, modifiable starting materials by redox polymerization technique. p(DMAAm-co-MA-co-CA) (DMC1) surface was modified by hydrochloric acid (HCl) and sodium hydroxide (NaOH) to obtain p(DMAAm-co-MA-co-CA)/HCl (DMC2) and p(DMAAm-co-MA-co-CA)/NaOH (DMC3), which have positively and negatively charged, respectively. After being analyzed for intermolecular interactions (Fourier-Transform Infrared Spectroscopy,FT-IR) and thermal properties (Thermogravimetric Analysis,TGA), the macrogels were tested in terms of sorption isotherms and thermodynamic parameters. However, in order to examine the urea release mechanism, the macrogels were tested using four release models such as Zero Order Kinetic Model(Z-O), First Order Kinetic Model(F-O), Higuchi(H) and the Korsmeyer-Peppas(K-P) power law. Cumulative urea release values for DMC1, DMC2 and DMC3 macrogels were calculated as 100% at pH 4 and 10, 100% at pH 6, 8 and 10, 100% at pH 4, 6, 8 and 10, respectively. Analyzes confirmed that synthesized macrogels can be good water holder for soil and can be a slow release of urea.

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

ABSTRACT: Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.

Slow Release of Urea Encapsulated by Starch PVA Matrix

The hydrophobicity of starch/PVA blend was improved by crosslinking with boric acid. It was found that the swelling ratio of the boric acid modified starch/PVA matrix decreased as function of boric acid concentration. FTIR spectra and SEM images demonstrated that the urea had been encapsulated in polymer matrix successfully. The urea release characteristic was explained with respect to the swelling ratio and crosslinking density of polymer matrix. In addition, the matrix displayed a good barrier for controlling the release rate of urea from pellet.

Frontal polymerization of superabsorbent polymers based on vermiculite with slow release of urea

Poly(acrylic acid‐co‐acrylamide)/sodium carboxymethyl cellulose/vermiculite (VMT) superabsorbent polymers (SAPs) were prepared by frontal polymerization (FP), a kind of polymerization model characterized by short reaction times and low‐energy consumption. The effects of VMT content and monomer ratios on frontal parameters and water absorbency were investigated. Due to the good heat insulation property of VMT, the propagating front still sustained at high VMT concentrations (over 30%). The preparation of SAPs with high VMT‐loading via FP has advantages of low energy consumption and low materials prices, decreasing the cost of SAPs effectively. SAPs with slow‐release fertilizer (SSRF) were obtained by embedding urea into their networks during the FP process. The addition of urea not only endows SAPs with slow release function of urea (more than 30 days in soil), but also increases their water absorbency (by 17.4%). The effects of obtained SSRF on tall fescue seeds germination and growth were studied. Compared with the control group, the germination rate and vigor index of tall fescue seeds applied SSRF with 10% urea increased by 17.5 and 80.2%, respectively. POLYM. ENG. SCI., 57:69–77, 2017. © 2016 Society of Plastics Engineers

Slow Release of Urea as a Source of Nitrogen from Some Acrylamide and Acrylic Acid Hydrogels

: Some hydrogels based on acrylamide and acrylic acid were synthesized by γ radiation using N,N methylenebisacrylamide as cross-linker. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) were used for the characterization of the prepared hydrogels. Thermal gravimetric analysis (TGA) was used to investigate the thermal stability. The water uptake, % of these hydrogels depends on acrylamide/maleic acid (AAm/MA) and acrylic acid/maleic acid (AAc/MA) comonomers ratio. The highest water uptake was found at 10/40, wt% and 20 KGy radiation dose in both cases. Hydrogels based on the acrylamide and acrylic acid and containing urea as fertilizer were used as a slow-releasing source of nitrogen in water at 25°C. We found that the release of urea from the prepared hydrogels was prolonged to four months and was faster in the case of AAm/MA, which exhibited a higher diffusion coefficient, 6.10−6, in comparison with that of AAc/MA, 4.10−6.

Slow release of urea through latex film

A systematic analytical and experimental investigation on the slow release of urea from a latex coated urea ball of about 15 mm in diameter into a finite amount of water has been conducted. Seven samples with coating thickness from 0.226 to 0.434 mm were investigated for release time up to 200 days. Experimental results are very well represented by the analytical equations. Diffusivities of latex coated urea balls are found to range between 0.257 × 10 −8 and 2.47 × 10 −8 cm 2/s.