Sustainable coating material based on chitosan-clay composite and paraffin wax for slow-release DAP fertilizer

Graphene oxide-based nanocomposites for outstanding eco-friendly antifungal potential against tomato phytopathogens

To obtain the collaborative antifungal potential of nanocomposites conjugated with graphene oxide (GO), a combination of GO with chitosan (CS/GO) and GO with chitosan (CS) and polyaniline (PANI/CS/GO) was carried out. The synthesized GO-nanocomposites were recognized by several techniques. Vanillin (Van.) and cinnamaldehyde (Cinn.) were loaded on the prepared nanocomposites as antioxidants through a batch adsorption process. In vitro release study of Van. and Cinn. from the nanocomposites was accomplished at pH 7 and 25°C. The antimicrobial activity of GO, CS/GO, and PANI/CS/GO was studied against tomato Fusarium oxysporum (FOL) and Pythium debaryanum (PYD) pathogens. The loaded ternary composite PANI/CS/GO exhibited the best percent of reduction against the two pathogens in vitro studies. The Greenhouse experiment revealed that seedlings' treatment by CS/GO/Van. and PANI/CS/GO/Van significantly lowered both disease index and disease incidence. The loaded CS/GO and PANI/CS/GO nanocomposites had a positive effect on lengthening shoots. Additionally, when CS/GO/Cinn., CS/GO/Van. and PANI/CS/GO/Van. were used, tomato seedlings' photosynthetic pigments dramatically increased as compared to infected control. The results show that these bio-nanocomposites can be an efficient, sustainable, nontoxic, eco-friendly, and residue-free approach for fighting fungal pathogens and improving plant growth.

Functionally responsive hydrogels with salt-alkali sensitivity effectively target soil amelioration

The long-standing crisis of soil salinization and alkalization poses a significant challenge to global agricultural development. High soil salinity-alkalinity, water dispersion, and nutrient loss present major hurdles to soil improvement. Novel environmentally friendly gels have demonstrated excellent water retention and slow-release capabilities in agricultural enhancement. However, their application for improving saline-alkali soil is both scarce and competitive. This study proposes a new strategy for regulating saline-alkali soil using gel-coated controlled-release soil modifiers (CWR-SRMs), where radical-polymerized gels are embedded on the surface of composite gel beads through spray coating. Characterization and performance analysis reveal that the three-dimensional spatial network structure rich in hydrophilic groups exhibits good thermal stability (first-stage weight loss temperature of 257.7 °C in thermogravimetric analysis) and encapsulation efficiency for fulvic acid‑potassium (FA-K), which can enhance soil quality in saline-alkali environments. The molecular chain relaxation under saline-alkali conditions promotes a synergistic effect of swelling and slow release, endowing it with qualifications as a water reservoir, Ca2+ source unit, and slow-release body. The results of a 6 weeks incubation experiment on 0-20 cm saline-alkaline soil with different application gradients showed that the gradient content had a significant effect on the soil improvement effect. Specifically, the T2 (the dosage accounted for 1 % of soil mass) treatment significantly increases water retention (30 % ~ 90 %), and nutrient levels (30 % ~ 50 %), while significantly decreasing soil sodium colloid content (30 % ~ 60 %) and soil pH (10 % ~ 15 %). Furthermore, PCA analysis indicates that the addition of 1 % CWR-SRMs as amendments can significantly adjust the negative aspects of soil salinity and alkalinity. This highlights the excellent applicability of CWR-SRMs in improving saline-alkali agricultural ecosystems, demonstrating the potential value of novel environmentally friendly gels as an alternative solution for soil challenges persistently affected by adverse salinity and alkalinity.

Water-resistant and pyknotic recyclable waste-cotton-derived bio-polyurethane-coated controlled-release fertilizer: Improved longevity, mechanism and application

Reasonably utilize the recyclable waste-cotton resource to develop the bio-polyurethane coatings had aroused more and more environmental interests recently. However, the terrible water resistance and porousness of the waste-cotton-derived bio-polyurethane coating caused the rapid nutrients release. In this work, the water-resistant and pyknotic cotton-fibre-derived coated-ureas (WPCUs) were fabricated with the recyclable low-cost waste-cotton-derived materials. The dramatically enhanced pyknotic and water-resistant characteristics of the WPCUs coatings can be obtained by the three-dimensional computerized tomography (2.33 to 1.19 %) and the water contact angle. The enhanced elasticity and the decreased water absorption were also vital to enhance the controlled-release performance. The accompanying controlled-release performance of the WPCUs was obviously improved (<2 h to 58.43 days). The modified WPCU75-10 with 4.0 % coating content exhibits the excellent controlled-release performance compared to the unmodified WPCU0-0. The controlled release mechanism can be clarified: The air column inside of the "small and few" micropores in the WPCUs coating only allow the gaseous water molecules to slowly penetrate and dissolve the inner urea cores (rather than liquid water). The obviously increased oilseed rape yield (128.75 %) showed the dependable agricultural application of the WPCUs. This work provides the resultful approach to develop the eco-friendly recyclable waste-plant-derived controlled-release fertilizers.

The application of chitosan as a carrier for fertilizer: A review

The smart combination of agriculture and other sciences can greatly reduce the limits of fertilizer use. Chitosan is a linear amino polysaccharide with a rigid structure which has hydrophilic and crystal properties. The formation of intermolecular hydrogen bonds the presence of reactive groups and cross-linking, the formation of salts with organic and inorganic acids with complexing and chelating properties ionic conductivity, film formation are the characteristics of chitosan. With the presence of amino groups, chitosan can form a complex with other compounds and also enter the vascular system of plants and lead to the activation of metabolic-physiological pathways of plants. This polymeric compound can bond with other natural polymers and in combination with fertilizers and nutritional elements, on the one hand, it can provide the nutritional needs of the plant and on the other hand, it also helps to improve the soil texture. Chitosan nanomaterials as a Next-generation fertilizers act as plant immune system enhancers through slow, controlled, and targeted delivery of nutrients to plants. Chitosan can assist agricultural researchers and has become an ideal and effective option with its many applications in various fields.

Recent advances in green technology and Industrial Revolution 4.0 for a sustainable future

This review gives concise information on green technology (GT) and Industrial Revolution 4.0 (IR 4.0). Climate change has begun showing its impacts on the environment, and the change is real. The devastating COVID-19 pandemic has negatively affected lives and the world from the deadly consequences at a social, economic, and environmental level. In order to balance this crisis, there is a need to transition toward green, sustainable forms of living and practices. We need green innovative technologies (GTI) and Internet of Things (IoT) technologies to develop green, durable, biodegradable, and eco-friendly products for a sustainable future. GTI encompasses all innovations that contribute to developing significant products, services, or processes that lower environmental harm, impact, and worsening while augmenting natural resource utilization. Sensors are typically used in IoT environmental monitoring applications to aid ecological safety by nursing air or water quality, atmospheric or soil conditions, and even monitoring species' movements and habitats. The industries and the governments are working together, have come up with solutions-the Green New Deal, carbon pricing, use of bio-based products as biopesticides, in biopharmaceuticals, green building materials, bio-based membrane filters for removing pollutants, bioenergy, biofuels and are essential for the green recovery of world economies. Environmental biotechnology, Green Chemical Engineering, more bio-based materials to separate pollutants, and product engineering of advanced materials and environmental economies are discussed here to pave the way toward the Sustainable Development Goals (SDGs) set by the UN and achieve the much-needed IR 4.0 for a greener-balanced environment and a sustainable future.

Dynamic Release Characteristics and Kinetics of a Persulfate Sustained-Release Material

Sustained-release materials are increasingly being used in the delivery of oxidants for in situ chemical oxidation (ISCO) for groundwater remediation. Successful implementation of sustained-release materials depends on a clear understanding of the mechanism and kinetics of sustained release. In this research, a columnar sustained-release material (PS@PW) was prepared with paraffin wax and sodium persulfate (PS), and column experiments were performed to investigate the impacts of the PS@PW diameter and PS/PW mass ratio on PS release. The results demonstrated that a reduction in diameter led to an increase in both the rate and proportion of PS release, as well as a diminished lifespan of release. The release process followed the second-order kinetics, and the release rate constant was positively correlated with the PS@PW diameter. A matrix boundary diffusion model was utilized to determine the PS@PW diffusion coefficient of the PS release process, and the release lifespan of a material with a length of 500 mm and a diameter of 80 mm was predicted to be more than 280 days. In general, this research provided a better understanding of the release characteristics and kinetics of persulfate from a sustained-release system and could lead to the development of columnar PS@PW as a practical oxidant for in situ chemical oxidation of contaminated aquifers.

Chitosan/kaolinite clay biocomposite as a sustainable and environmentally eco-friendly coating material for slow release NPK fertilizers: Effect on soil nutrients and tomato growth

Soil nutrient availability and non-biodegradation of some polymer-based slow-release fertilizers (SRFs) have a direct impact on crop production and soil ecological quality. Proper fertilization practices can lead to obviating adverse effects of over-fertilization on soil nutrients and, consequently, on crop yields. This work aims to assess the effect of a durable liner material based on biodegradable polymers on soil nutrient availability and tomato growth. For this purpose, Chitosan composite (CsGC) was adopted as a durable coating material, including clay as a reinforcing coating material. The influence of chitosan composite coating (CsGC) on the sustained nutrient release of coated NPK fertilizer (NPK/CsGC) was studied. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDX) were used to examine the coated NPK granules. Results revealed that the proposed coating film improved the mechanical strength of the NPK fertilizer and enhanced water retention capacity of the soil. The agronomic investigation has also proved their outstanding potential to boost chlorophyll content, biomass, and tomato metabolism. Furthermore, the surface response study confirmed a strong correlation between tomato quality and representative soil nutrients. Therefore, kaolinite clay, as part of the coating system, can be an effective way to improve tomato quality and maintain soil nutrients during tomato ripening.

Starch-based controlled release fertilizers: A review

Starch, as a widely available renewable resource, has the potential to be used in the production of controlled-release fertilizers (CRFs) that support sustainable agriculture. These CRFs can be formed by incorporating nutrients through coating or absorption, or by chemically modifying the starch to enhance its ability to carry and interact with nutrients. This review examines the various methods of creating starch-based CRFs, including coating, chemical modification, and grafting with other polymers. In addition, the mechanisms of controlled release in starch-based CRFs are discussed. Overall, the potential benefits of using starch-based CRFs in terms of resource efficiency and environmental protection are highlighted.

Development of Hybrid Materials Based on Chitosan, Poly(Ethylene Glycol) and Laponite® RD: Effect of Clay Concentration

In the context of increasing interest in biomaterials with applicability in cosmetics and medicine, this research aims to obtain and characterize some hybrid materials based on chitosan (CS) (antibacterial, biocompatible, and biodegradable), poly(ethylene glycol) (PEG) (non-toxic and prevents the adsorption of protein and cell) and Laponite^® RD (Lap) (bioactive). The rheological properties of the starting dispersions were investigated and discussed related to the interactions developed between components. All samples exhibited gel-like properties, and the storage modulus of CS/PEG dispersion increased from 6.6 Pa to 657.7 Pa by adding 2.5% Lap. Structural and morphological characterization of the films, prepared by solution casting method, was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and polarized light microscopy (POM). These analyses proved the incorporation of Lap into CS/PEG films and revealed the morphological changes of the films by the addition of clay. Thereby, at the highest Lap concentration (43.8%), the "house of cards" structure formed by Lap platelets, which incorporate chitosan chains, as evidenced by SEM and POM. Two stages of degradation between 200 °C and 410 °C were evidenced for the films with Lap concentration higher than 38.5%, explained by the existence of a clay-rich phase (given by the clay network) and chitosan-rich one (due to the intercalation of chitosan in the clay network). CS/PEG film with 43.8% Lap showed the highest swelling degree of 240.7%. The analysis of the obtained results led to the conclusion that the addition of clay to the CS/PEG films increases their stability in water and gives them greater thermal stability.

Innovative bio-waste-based multilayer hydrogel fertilizers as a new solution for precision agriculture

The aim of the research work was to present a multilayer hydrogel capsule with controlled nutrient release properties as an innovative fertilizer designed for sustainable agriculture. Preparation of the capsules included the following steps: sorption of micronutrients (Cu, Mn, Zn) on eggshells (1) and their immobilization in sodium alginate, with the crosslinking agent being the NPK solution (2). The capsules were coated with an additional layer of a mixture of biopolymers (0.79% alginate, 0.24% carboxymethylcellulose and 8.07% starch)by means of dipping and spraying techniques. The biocomposites were characterized by limited (<10% within 100 h for the structures encapsulated by the dipping method) release of fertilizer ions (except for small K⁺ ions). The hydrogel fertilizer formulations were analyzed for physicochemical properties such as macro- and micronutrient content, surface morphology analysis, coating structure evaluation, mechanical properties, swelling and drying kinetics. High nutrient bioavailability was confirmed in vitro (extraction in water and neutral ammonium citrate). Germination and pot tests have revealed that the application of multicomponent hydrogel fertilizers increases the length of cucumber roots by 20%, compared to the commercial product.

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.

Biomimetic Modification of Water-Borne Polymer Coating with Carnauba Wax for Controlled Release of Urea

Benefitting from the special structure of the leaf cuticle layer, plants have natural hydrophobicity and anti-fouling abilities. Inspired by the leaf surface structure, a biomimetic modification strategy was raised to improve the surface hydrophobicity of polyacrylate coating for controlled release fertilizer. Double-layer (polyacrylate and carnauba wax) coated fertilizer was obtained after biomimetic modification. The quality of controlled release fertilizer modified with the carnauba wax was greatly enhanced, and the coating material was effectively saved. The surface appearance of polyacrylate-coated fertilizer was improved for the surface blemish was repaired by the loaded carnauba wax. The characterizations by Fourier transform infrared spectroscopy indicated that the hydrogen bonds were formed between the water-based polyacrylate membrane and the carnauba wax layers. By optimizing the content of polyacrylate and carnauba wax, the release duration of the fertilizer was effectively prolonged, which was improved from 1 month to more than 2 months after the biomimetic modification. Therefore, biological wax as an environmentally-friendly natural material that has showed a broad potential in the application of coated controlled release fertilizer.

Abandoned agriculture soil can be recultivated by promoting biological phosphorus fertility when amended with nano-rock phosphate and suitable bacterial inoculant

In semi-arid regions, post-restoration vegetation recovery on abandoned agricultural lands often fails due to inherently low organic matter content and poor soil fertility conditions, including phosphorus (P). As such, amending these soils with controlled release P fertilizer, especially with suitable P solubilizing bacteria (PSB) may promote plant growth and productivity by stimulating biological P fertility. To this aim, a pot study was performed to evaluate the agronomic potential of maize and soil biological P pools, using encapsulated (ENRP) and non-encapsulated (NRP) nano-rock phosphate as the P fertilizer source, on reclaimed agricultural soil in the presence and absence of PSB inoculant. The experiment was setup following a 3 × 2 factorial arrangement with four replicates. Without PSB, NRP treatment showed marginal positive effects on plant growth, P nutrition and P use efficiency (PUE) compared to control treatment. Although larger gains with NRP treatment were more noticeable under PSB inoculation, ENRP was the most convenient slow-release P fertilizer, increasing plant growth, P nutrition and grain yield compared to all treatments. Importantly, PSB inoculation with ENRP resulted in significantly higher increase in soil CaCl2-P (8.91 mg P kg soil-1), citrate-P (26.98 mg P kg soil-1), enzyme-P (18.98 mg P kg soil-1), resin-P (11.41 mg P kg soil-1), and microbial-P (18.94 mg P kg soil-1), when compared to all treatment combinations. Although a decrease in soil HCl-P content was observed with both types of P fertilizer, significant differences were found only with PSB inoculation. A significant increase in soil biological P pools could be due to the higher specific area and crystalline structure of nano materials, providing increased number of active sites for PSB activity in the presence of biobased encapsulated shell. Furthermore, the increase in PSB abundance, higher root carboxylate secretions, and decreased rhizosphere pH in response to nano-structured P fertilizer, implies greater extension of rhizosphere promoting greater P mobilization and/or solubilization, particularly under PSB inoculated conditions. We conclude that cropping potential of abandoned agricultural lands can be enhanced by the use of nano-rock phosphate in combination with PSB inoculant, establishing a favorable micro-environment for higher plant growth and biochemical P fertility.

Chitosan-kaolinite clay composite as durable coating material for slow release NPK fertilizer

Durable chitosan-based coating material used as a barrier for slow-release fertilizers in the agricultural soil. This approach decreases the intense usage of fertilizer and works on their accessibility for the plants' necessities. In present paper, the proposed coating material was prepared on the basis of chitosan-kaolinite composite (CS-Gl-K). Fourier transform infrared spectroscopy analysis (FTIR), Scanning Electron Microscopy (SEM), thermogravimetric analysis (ATG), XRD, swelling degree and biodegradability studies were used to analyze the influence of the kaolinite clay incorporation in chitosan film properties. The characterization of the chitosan composites has been thoroughly studied. The NPK mineral fertilizer was coated according to the dip-immersing process of chitosan-kaolinite composites. Slow-release efficiency was evaluated by determining the rate of phosphorus release from the covered granules into water and soil. Moreover, phosphorus release from coated NPK/CS-Gl-K granules was generally delayed contrasted with NPK/uncoated. In addition, the biodegradation investigation of the composite material (CS-Gl-K) in soil was affirmed its durability. The proposed coating material has good slow-release properties, low cost and is environmentally friendly. The FTIR, ATG and XRD spectra revealed a good intercalation between the kaolinite-clay pores and chitosan chains.

Synthesis and Characterization of Slow-Release Fertilizer Hydrogel Based on Hydroxy Propyl Methyl Cellulose, Polyvinyl Alcohol, Glycerol and Blended Paper

In this study, biodegradable slow-release fertilizer (SRF) hydrogels were synthesized from hydroxyl propyl methyl cellulose (HPMC), polyvinyl alcohol (PVA), glycerol and urea (SRF1) and HPMC, PVA, glycerol, urea and blended paper (SRF2). The fertilizer hydrogels were characterized by SEM, XRD and FTIR. The swelling capacity of the hydrogels in both distilled and tap water as well as their water retention capacity in sandy soil were evaluated. The hydrogels had good swelling capacity with maximum swelling ratio of 17.2 g/g and 15.6 g/g for SRF1 and SRF2 in distilled, and 14.4 g/g and 15.2 g/g in tap water, respectively. The water retention capacity of the hydrogels in sandy soil exhibited higher water retention when compared with soil without the (SRFs). The soil with the hydrogels was found to have higher water retention than the soil without the hydrogels. The slow-release profile of the hydrogels was also evaluated. The result suggested that the prepared fertilizer hydrogels has a good controlled release capacity. The blended paper component in SRF2 was observed to aid effective release of urea, with about 87.01% release in soil at 44 days compared to the pure urea which was about 97% release within 4 days. The addition of blended paper as a second layer matrix was found to help improve the release properties of the fertilizer. The swelling kinetic of the hydrogel followed Schott's second order model. The release kinetics of urea in water was best described by Kormeye Peppas, suggesting urea release to be by diffusion via the pores and channels of the SRF, which can be controlled by changing the swelling of the SRF. However, the release mechanism in soil is best described by first order kinetic model, suggesting that the release rate in soil is depended on concentration and probably on diffusion rate via the pores and channels of the SRF.

Microfluidic encapsulation for controlled release and its potential for nanofertilisers

Nanotechnology is increasingly being utilized to create advanced materials with improved or new functional attributes. Converting fertilizers into a nanoparticle-form has been shown to improve their efficacy but the current procedures used to fabricate nanofertilisers often have poor reproducibility and flexibility. Microfluidic systems, on the other hand, have advantages over traditional nanoparticle fabrication methods in terms of energy and materials consumption, versatility, and controllability. The increased controllability can result in the formation of nanoparticles with precise and complex morphologies (e.g., tuneable sizes, low polydispersity, and multi-core structures). As a result, their functional performance can be tailored to specific applications. This paper reviews the principles, formation, and applications of nano-enabled delivery systems fabricated using microfluidic approaches for the encapsulation, protection, and release of fertilizers. Controlled release can be achieved using two main routes: (i) nutrients adsorbed on nanosupports and (ii) nutrients encapsulated inside nanostructures. We aim to highlight the opportunities for preparing a new generation of highly versatile nanofertilisers using microfluidic systems. We will explore several main characteristics of microfluidically prepared nanofertilisers, including droplet formation, shell fine-tuning, adsorbate fine-tuning, and sustained/triggered release behavior.

Cellulose nanocrystals-filled poly (vinyl alcohol) nanocomposites as waterborne coating materials of NPK fertilizer with slow release and water retention properties

Effective fertilizers management is essential for sustainable agricultural practices. One way to improve agronomic practices is by using slow-release fertilizers (SRF) that have shown interesting role in optimizing nutrients availability for plants growth. Considering the current ecological concerns, coated SRF using ecofriendly materials continue to attract great attention. In this context, novel waterborne and biodegradable coating nanocomposite formulations were elaborated from cellulose nanocrystals (CNC)-filled poly (vinyl alcohol) (PVA) for slow release NPK fertilizer with water retention property. CNC were extracted from hemp stalks using sulfuric acid hydrolysis process and their physico-chemical characteristics were investigated. CNC with various weight loadings (6, 10, 14.5 wt%) were incorporated into PVA polymer via solvent mixing method to produce viscous coating nanocomposite formulations with moderated shear viscosity. Uniform PVA@CNC coating microlayer was applied on the surface of NPK fertilizer granules in Wurster chamber of a fluidized bed dryer at controlled spraying and drying parameters. The nitrogen, phosphorus and potassium release profiles from coated NPK fertilizer were determined in water and soil. It was found that the coating materials extended the N-P-K nutrients release time from 3 days for uncoated fertilizer to 10 and 30 days for neat PVA- and CNC/PVA-coated fertilizer in soil medium, indicating the positive role of the presence of CNC in the PVA-based coatings. The morphology, coating rate and crushing strength of the as-prepared coated products were investigated in addition to their effect on water holding capacity and water retention of the soil. Enhanced crushing strength and water retention with a positive effect on the soil moisture were observed after coating NPK fertilizer, mainly with high CNC content (14.5 wt%). Therefore, these proposed nanocomposite coating materials showed a great potential for producing a new class of SRF with high nutrients use efficiency and water retention capacity, which could be beneficial to sustainable crop production.

Biodegradation and viability of chitosan-based microencapsulated fertilizers

Enhanced efficiency fertilizers (EEF) are an important subject for sustainable materials. It is fundamental for the released nutrient and biodegradation in the soil to have synergy to ensure material harmlessness. Chitosan, montmorillonite, and KNO₃ were considered to develop the EEF because of the high biodegradation potential of the final product. We correlated the material biodegradability and release in water and soil to their formulation. We assume the materials are biodegradable since the biodegradation efficiency achieved over 30 %. As the nutrient diffusion and matrix degradation happen concomitantly, we also observed that the clay delays degradation and the KNO₃ improved it. Likewise, the storage period can change the biodegradability properties once the material started to degrade. Hereupon, the amount of nutrient delivered will match the amount consumed by the plant, the matrix will degrade and no residue will be left in the soil.