Slow-release Fertilizer Formulations Research Articles

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.

Carbon and Zeolite Based Slow Release Fertilizer Formulations Enhances Nutrient Use Efficiency and Yield in Chilli

Aims: To develop slow release fertilizer formulations using humic acid, charcoal and zeolite and to evaluate nutrient availability, nutrient use efficiency and yield in chilli.
 Study Design: This experiment was conducted through completely randomized design with 14 treatments and 3 replications.
 Place and Duration of Study: The research was appraised at the Department of Soil Science, College of Agriculture, Vellayani between September 2022- December 2022.
 Methods: Carbon and zeolite based slow release fertilizer formulations (SRF) containing all the major, secondary and micronutrients were prepared using compatible fertilizer materials (urea, rajphos, muriate of potash, phosphogypsum, magnesium sulphate, zinc sulphate and borax), carrier materials (zeolite, humic acid and charcoal) and the binding agent (carboxy methyl cellulose) in the ratio of 1:1 and 1: 0.5 in the form of pellets. These formulations were applied to chilli and evaluated nutrient use efficiency and yield.
 Results: The pellets were highly stable and weight ranged between 4.0 and 4.5 g. The highest fruit yield of chilli observed was 581.2 g/ plant. The available nitrogen (320.86 kg ha-1), phosphorus (87.15 kg ha-1), potassium (214.35 kg ha-1), calcium (351.13 mg kg-1), magnesium (106.54 mg kg-1), sulphur (9.32 mg kg- 1), boron (0.46 mg kg-1) and zinc (4.25 mg kg-1) was found to be highest in treatment receiving 75% recommended dose of fertilizers (RDF) as humic acid based slow release formulation applied in two splits (basal and 1 MAP). The apparent recovery percentage of nitrogen 78.2%, phosphorus 86.33% and potassium 98.70% and partial factor productivity of 25.98 g g-1 were recorded due to the application of pellets.
 Conclusion: Carbon and zeolite based slow release fertilizer formulations in the form of pellets are very effective compared to conventional fertilizers due to their gradual pattern of nutrient release which better meets plant demand, minimizes leaching and therefore nutrient use efficiency and ultimately crop yield. Application of slow release formulations significantly increases the nutrient availability in soil, nutrient use efficiency, growth and yield of chilli.

Evaluation of Fertilizer-manure Blocks as a Slow Release Fertilizer Formulation for Okra [Abelmoschus esculentus (L.) Moench

Background: Fertilizer use efficiency is the output of any crop per unit of the nutrient applied under a specified set of soil and climatic conditions and slow/ ccontrolled release fertilizer formulations offer agricultural producers the opportunity to increase fertilizer/nutrient use efficiency, especially in soils with very low cation exchange capacity. Methods: In pot culture study, fertilizer-manure blocks consisting of selected proportions of different organic manures and fertilizers were prepared in two dimensions (100 g and 25 g) with three different dosages of fertilizers (100% POP, 50% POP, 25% POP) and were evaluated in a pot culture experiment using Okra variety Arka Anamika. Result: Fertilizer-manure blocks showed significant effect on growth and yield of okra. The use of fertilizer-manure blocks of proportion; Coirpith-35%, Cowdung-25%, Vermicompost-13%, Groundnutcake-10%, Neem cake 10%, Zeolite-2%, Humic acid-5%, 100 g size containing 25% of the recommended dose of nutrients placed 5cm below the level of planting and top dressing of 50% of KAU POP recommendation was identified as the best treatment (B:C ratio-1.26 and nutrient use efficiency-28.12) for enhancing the productivity of okra in grow bags. Days to flowering, number of fruits per plant, fruit yield per plant, length of fruits, girth of fruits and number of seeds per fruit were significantly influenced by the treatments. The selected treatment had recorded highest value for number of fruits per plant (20.70), fruit yield per plant (457.9 g), fruit length(17.90 cm), fruit girth (6.326 cm) as well as number of seeds per fruit (58.67). The general application of the recommended fertilizers and soil test based recommendation were found to be on par with the placement of slow release fertilizer- manure blocks with respect to fruit yield per plant.

The utilization of activated carbon as micronutrients carrier in slow release fertilizer formulation

In many plantations, fertilizers were often added in high dosage and applied several times to get maximum productivity. But processes in soil caused not all nutrients in fertilizer could be uptaken by plants. Besides, the high dosage can be toxic to plants. The use of slow release fertilizer can overcome this case. This research was aimed to obtain the data of adsorptive capacity of activated charcoal to the nutrients mixed and gathering the information about nutrients release rate of fertilizer produced. The study was conducted by converting materials into activated charcoal. SRF was formulated by soaking fine activated charcoal CuSO4, FeSO4 or ZnSO4 solution for 24 hours. Analysis conducted were the observation of surface topography, qualitative analysis using EDX, and determination of total Cu, Fe and Zn in SRF. The optimal treatment was chosen to determine its release rate by extracting fertilizer with distilled water and 2% citric acid. The results showed the activated charcoal could be used to adsorb nutrients mixed as shown by SEM and EDX results. Nutrients in the charcoal could be released slowly and could not be easily leached out.

Preparation and characterization of biogenic CaCO3-reinforced polyvinyl alcohol–alginate hydrogel as controlled-release urea formulation

A slow-release fertilizer formulation was prepared by incorporation of urea in polyvinyl alcohol–alginate hydrogel core followed by deposition of calcium carbonate coating using HCO3−/CO32−-rich alkaline cell-free ureolytic culture broth. High urea encapsulation efficiencies were evident in both CaCO3-reinforced (23.48% w/w) and regular (38.71% w/w) hydrogel matrices. Deposition of carbonate over the matrix surface in the reinforced hydrogel was evident from scanning electron microscopy and typical FTIR band near 1465 cm−1 due to C–O stretch of carbonate ion. Aqueous phase release behaviour was not significantly different between the two hydrogel variants. In the soil column, two-stage urea release pattern (i.e. a slow followed by a fast) was eminent that can extend into hours. Therefore, the modified hydrogel for controlled release could be expected to have wide potential application as slow-release fertilizer in agriculture.

Zeolite reinforced carboxymethyl cellulose‐Na+‐g‐cl‐poly(AAm) hydrogel composites with pH responsive phosphate release behavior

ABSTRACTPhosphate fixation in soils is a matter of concern in agriculture. Conventional application of phosphorus fertilizer suffers from low P use constraint, particularly in acidic soils. Rhizosphere centric slow release strategy bears tremendous prospects. In the present study, monocalcium phosphate (MCP) was impregnated in zeolite reinforced CMC‐Na+‐g‐cl‐Poly(Aam) hydrogel composites with aim to develop slow phosphate release device for soil application. X‐ray diffraction, scanning electron microscopy, and Fourier transform‐infrared spectroscopy confirmed the successful synthesis of slow release fertilizer formulations. Presence of zeolite in composite matrix during polymerization resulted in higher MCP loading. The “burst release” phenomena under neutral aqueous environment as compared to diffusion led slow release mechanism under acidic condition suggesting that phosphate release from developed composite matrix was pH responsive. The developed materials possess potential to serve as tool for improving phosphate use efficiency under resource stress agriculture. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47332.

Constructing Slow-Release Formulations of Ammonium Nitrate Fertilizer Based on Degradable Poly(3-hydroxybutyrate).

The present study describes construction and investigation of experimental formulations of ammonium nitrate embedded in a matrix of degradable natural polymer poly-3-hydroxybutyrate [P(3HB)] and P(3HB) blended with wood flour shaped as tablets, some of them coated with P(3HB). Kinetics of ammonium release into soil as dependent on the composition of the polymer matrix was investigated in laboratory experiments. The rates of fertilizer release from formulations coated with a biopolymer layer were considerably (two months or longer) slower than the rates of fertilizer release from uncoated formulations, while release from polymer and composite (polymer/wood flour) formulations occurred with comparable rates. The use of the experimental formulations in laboratory ecosystems with wheat (Triticum aestivum L.) was more effective than application of free ammonium nitrate. The advantage of the slow-release fertilizer formulations is that they are buried in soil together with the seeds, and the fertilizer remains effective over the first three months of plant growth. The use of such slow-release formulations will reduce the amounts of chemicals released into the environment, which will curb their accumulation in food chains of ecosystems and mitigate their adverse effects on the biosphere.

FERTILIZANTE DE LIBERAÇÃO LENTA NO DESENVOLVIMENTO DE MUDAS DE <i> Anadenanthera peregrina </i> (L.) Speg. (ANGICO-VERMELHO) E <i> Schinus terebinthifolius </i> Raddi (AROEIRA-VERMELHA)

http://dx.doi.org/10.5902/1980509820582Com o objetivo de avaliar o desenvolvimento de duas espécies arbóreas nativas - Anadenanthera peregrina (angico-vermelho) e Schinus terebinthifolius (aroeira-vermelha) - submetidas a doses de fertilizante de liberação lenta na formulação 13-06-16, conduziu-se um experimento em viveiro utilizando uma mistura de matérias-primas com composto orgânico, vermiculita e Plantmax® para compor substrato base. O experimento foi conduzido no delineamento experimental inteiramente casualizado com seis tratamentos em quatro repetições. Os tratamentos foram: T1–0 kg (testemunha); T2–2 kg; T3–4 kg; T4–6 kg; T5–8 kg e T6–10 kg de fertilizante de liberação lenta por metro cúbico de substrato base. Avaliou-se aos 189 dias após a semeadura a altura total, diâmetro do colo, biomassa fresca da parte aérea, biomassa seca da parte aérea, biomassa seca da raiz, biomassa seca total, relação entre altura e diâmetro do colo e o índice de qualidade de Dickson. Os resultados evidenciam que a aplicação de fertilizante de liberação lenta leva a ganhos significativos de crescimento em ambas as espécies, sendo as melhores doses 6,68 a 5,54 kg m-3 para a espécie Anadenanthera peregrina, e 8,38 a 14,42 kg m-3 para Schinus terebinthifolius.

Hydrogel/clinoptilolite nanocomposite-coated fertilizer: swelling, water-retention and slow-release fertilizer properties

Preparation of a new core–shell slow-release fertilizer formulation was conducted through the coating of commercial NPK fertilizer with hydrogel/clinoptilolite (Hyd/CL) nanocomposite. The Hyd/CL nanocomposite was prepared from free radical polymerization of sodium alginate, acrylic acid, acrylamide, and clinoptilolite zeolite. The uniform coating on the surface of the fertilizer granules was verified by scanning electron microscopy. The swelling kinetics as well as the water-retention property and water absorption rate of the prepared samples was studied. Furthermore, the release of fertilizer from Hyd/CL nanocomposite-coated fertilizer granules into soil showed that the Hyd/CL nanocomposite layer around the fertilizer granules caused the system to liberate the nutrient in a more controlled manner (lower than 57 % of loaded fertilizer on the 30 days) than that with the uncoated fertilizer. The overall results eventually suggested that the hydrogel nanocomposite designed in this work can be used as a coating on granular fertilizer compounds for application in agriculture due to its water-retention and slow-release properties.

New Environment-Friendly Use of Wheat Straw in Slow-Release Fertilizer Formulations with the Function of Superabsorbent

With the aim of improving fertilizer use efficiency and minimizing the negative impact on the environment, a new double-coated slow-release nitrogen and phosphorus fertilizer with water retention was prepared. Wheat straw was introduced into the formulations as the basic coating material. Specifically, poly(acrylic acid-co-N-hydroxymethyl acrylamide)/wheat straw superabsorbent composite was used as the outer coating, and wheat straw/sodium alginate blends was used as the inner coating. The degradation of the superabsorbent composite in the soil solution was studied. The impact of the content of wheat straw on the extent of degradation in cellulase solution was also examined. The superabsorbent composite synthesized under the optimal conditions showed super water absorbency and excellent degradability. The water-retention property and the nutrient slow-release behavior of the product were investigated. The results revealed that the product with water-retention and slow-release capacity, being economical, n...

EFFECTS OF CONTROLLED-RELEASE FERTILIZER ON FRUIT YIELD AND QUALITY OF CLEMENTINE CITRUS TREES

A field experiment was carried out in a commercial citrus orchard on mature Clementine trees (Citrus reticulata Swingle). The trees received the same fertilization amount but by two different fertilization methods. On one plot of one-half an hectare, the trees were fertilized with a slow-release fertilizer (17N-12P-18K +2Mg) buried 10 cm deep under drip emitters at the beginning of the spring tree flush growth (first week of April). A second application was made at the beginning of the autumn tree flush growth (end of August) with another slow-release fertilizer formulation (13N-5P-27K +2Mg). On the other half a hectare plot, the trees were fertigated with the same quantity of nutrients as the first plot but distributed throughout the growing season. The results showed no differential treatment effect on yield. Fruit weight was higher with the controlled-release fertilizer producing more fruit as Extra Class Size. The fruit quality was similar between the two fertilizer methods.

Slow-release Fertilizer Source and Rate Affects Fall Garden Mum Vegetative Growth

Three slow-release fertilizer formulations (Osmocote 14–14–14, 18–6–12, and Nutricote 17–6–10) at three rates (1, 2, and 3 lb/yd3) were incorporated into 4 pine bark: 1 sand (by volume) media filling 1-gal nursery containers. Additional treatments included slow-release fertilizer formulations at 1 lb/yd3 fertigated with 100 ppm N 20–10–20 fertilizer. As fertilizer rates increased, vegetative height, width, and dry-weight accumulation generally increased for both pinched and no-pinch mum crops. Fertigated pinch and no-pinch mums were the largest plants with the greatest dry-weight accumulation for each fertilizer formulation. The high rate for all slow-release fertilizers produced the greatest vegetative growth for nonfertigated treatments. This research suggest that higher rates for incorporated slow-release fertilizers and/or fertigation are required to produce maximum vegetative growth.

Effect of Slow Release Fertilizers on Formation of Mycorrhizae and Growth of Container Grown Pine Seedlings

Slow-release fertilizer formulations at various NPK analyses, release rates, and application rates were evaluated for their effects on seedling growth and mycorrhizal development of container-grown seedlings of Pinus echinata (Mill.) inoculated with Pisolithus tinctorius (Pers.) Coker and Couch. Fertilizer release rate and application rate affected formation of mycorrhizae. At 9.0 kg/m3 (15.0 lb/yd3), greater numbers of seedlings formed mycorrhizae and a greater portion of the root system was mycorrhizal with the 8 to 9 month release fertilizer, regardless of formulation, than with the 1 to 2 or 3 to 4 month release fertilizers. Best seedling growth and mycorrhizae formation was obtained with the 21N-3.OP-11.6K (21-7-14) 8 to 9 month release fertilizer at the 4.5 kg/m3 (7.5 lb/yd3) application rate. Because fertilizer release is temperature dependent, deleterious effects of over fertilization may be greater with higher greenhouse temperatures. The low benefits of fertilization rates higher than 4.5 kg/m3 (7.5 lb/yd3) do not warrant the risk of interference with formation of mycorrhizae.

Slow-release 15N fertilizer formulations to measure N 2-fixation by isotope dilution

Pot experiments were carried out to examine the effects of slow-release fertilizer formulations on estimates of N 2-fixation determined by the isotope dilution method. Soybeans were used as the N 2-fixing plants, with non-nodulated soybeans and maize as the non-fixing controls. The 15N-fertilizer formulations used were ( 15NH 4)SO 4, K 15NO 3, gypsum-pelleted K 15NO 3, ( 15NH 4) 2SO 4 + glucose, ground plant material enriched with 15N or 15N-oxamide. The estimate of the amount of N 2 fixed by the nodulated soybean plants depended upon both the control plant and the fertilizer formulation used. Maize took up N later than non-nodulated soybean and estimates of soil N-pool (soil “A” value + fertilizer N added) calculated from the enrichment of this control were about twice as large as those calculated from the enrichment of non-nodulated soybean receiving the same fertilizer treatment. As a consequence, estimates of N 2-fixation relative to this control were lower than those relative to non-nodulating soybean (mean 140 mg N per pot compared with 292 mg N per pot). With unstablilized 15N salts errors were sufficient to produce negative estimates of fixation relative to maize. Even with a “well-matched” control (non-nodulated soybean) estimates of fixation varied with fertilizer formulation.

Slow-release Fertilizers Optimize Mycorrhizal Development in Container-grown Pine Seedlings Inoculated with Pisolithus tinctorius1

Abstract Seedlings of pitch pine (Pinus rigida mill.) and Virginia pine (P. virginiana mill.) were grown with and without inoculum of the ectomycorrhizal fungus Pisolithus tinctorius [(Pers.) Coker & Couch] in a sphagnum peatmossperlite medium supplemented with various rates of the slow-release fertilizer (18N–2.5P–10K Osmocote or single rates of 14N–6P–11.6K Osmocote and 19N–3P–8.3K Sierrablen plus ON–19.8P–OK superphosphate) or a soluble 20N–8.6P–16.4K fertilizer treatment. Mycorrhizal development was evaluated after 5 months of growth and then after a 3-month cold storage period. Seedlings heavily mycorrhizal with P. tinctorius and of acceptable planting size were produced with 2.3 to 4.5 kg 18N–2.5P–10K Osmocote/m3 medium. Higher fertilizer rates reduced or eliminated mycorrhizal development and reduced plant growth. Seedlings grown with soluble fertilizer were comparable in size to those produced with slow-release fertilizers, but mycorrhizal development was eliminated. The 3 slow-release fertilizer formulations produced seedlings of comparable size and mycorrhizal development. Superphosphate with or without slow-release or soluble fertilizer did not influence seedling growth or mycorrhizal development. Mycorrhizae continued to develop while plants were in cold storage. The ITW One-Way tube produced seedlings equal in size to those produced in the Leach Pine Cell, but mycorrhizal development appeared to be more sensitive to high fertilizer rates with the ITW tube. Mycorrhizal development did not affect seedling size.