Ethylcellulose as a coating material in controlled-release fertilizers

Review of current trends in chitosan based controlled and slow-release fertilizer: From green chemistry to circular economy

The demand for food is increasing rapidly with the growth of the global population. To ensure global food security, fertilizers are essential. Controlled-release fertilizers (CRFs) are a highly effective type of fertilizer that have been developed to meet this need. While CRFs offer significant advantages over traditional fertilizers, their use has been limited due to high production costs and negative impact on the environment. CRFs are manufactured and applied without considering the resource-use efficiency of the production process or the potential ecological consequences of fertilizer application. To tackle these issues, biopolymer-based CRFs have been developed. These innovative fertilizers are created by coating granules with biodegradable and eco-friendly biopolymers (chitosan, starch and cellulose). In addition, these groundbreaking fertilizers align with the tenets of the circular economy, which involve formulating products that enable a gradual and steady dispensation of nutrients over an extended period. Our objective in embracing these fertilizers is to transcend the traditional linear "take, make, dispose" approach and transition towards a more sustainable and circular model. This approach not only enhances nutrient delivery efficiency but also contributes significantly to reducing the environmental impact associated with conventional fertilizer use. Afterward, the research explored various aspects of controlled-release fertilizers (CRFs), including the mechanisms of nutrient release, the types of coating materials used, and the techniques employed for coating. The study also examined the benefits and challenges associated with CRFs and analyzed how specific parameters influence the nutrient release mechanisms.

Recent progress in the development of encapsulated fertilizers for time-controlled release

This review describes the latest achievements in the development of encapsulated controlled-release fertilizers, which encompasses sustainability issues in agriculture. The research community's interest in this particular area of science has doubled over the last couple of years due to the yearly increasing complexity of the food and supply situation, as well as maintaining the development of modern society in the era of population outbreak. This review covers demand in timely systematization and comprehensive analysis of emerging research in so-called "smart fertilizers" that release mineral components in accordance with the needs for nutrients classified into controlled- and slow-release fertilizers (CRFs and SRFs). Along with the thoroughly selected fundamental studies published in this area, the review specially focuses on the materials-based classification, emphasizing the importance of the host matrix in the time-controlled release of dopant. This substantially differentiates our review and renders scientific novelty and relevancy to it. The review is divided into sections, dealing with the types of slow- and controlled-release fertilizers each, and supplemented with the critical view on their usage. All data regarding encapsulated fertilizers in this review are systematized for the convenience of the readership when becoming familiarized with the latest achievements in this area. Perspectives and potential pathways are also described to recommend and guide researchers working on the related academic fields.

Nanocellulose: Structure, modification, biodegradation and applications in agriculture as slow/controlled release fertilizer, superabsorbent, and crop protection: A review

This review investigates the potential of nanocellulose in agriculture, encompassing its structure, synthesis, modification, and applications. Our investigation of the characteristics of nanocellulose includes a comprehensive classification of its structure. Various mechanical, chemical and enzymatic synthesis techniques are evaluated, each offering distinct possibilities. The central role of surface functionalization is thoroughly examined. In particular, we are evaluating the conventional production of nanocellulose, thus contributing to the novelty. This review is a pioneering effort to comprehensively explore the use of nanocellulose in slow and controlled release fertilizers, revolutionizing nutrient management and improving crop productivity with reduced environmental impact. Additionally, our work uniquely integrates diverse applications of nanocellulose in agriculture, ranging from slow-release fertilizers, superabsorbent cellulose hydrogels for drought stress mitigation, and long-lasting crop protection via nanocellulose-based seed coatings. The study ends by identifying challenges and unexplored opportunities in the use of nanocellulose in agriculture. This review makes an innovative contribution by being the first comprehensive study to examine the multiple applications of nanocellulose in agriculture, including slow-release and controlled-release fertilizers.

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.

Methylcellulose/lignin biocomposite as an eco-friendly and multifunctional coating material for slow-release fertilizers: Effect on nutrients management and wheat growth

To obviate adverse effects from the non-biodegradability of certain polymer-based slow-release fertilizers (SRFs) and to offset higher operational costs, the use of biopolymers as coating material has recently caught interest in the research circles. The present work aims to design a sustainable coating material based on biodegradable polymers. To this end, Alfa plant was initially exploited as a viable sustainable source for the extraction of lignin (LGe), which was in turn integrated into the development of a three-dimensional cross-linked network, including methylcellulose (MC) as a matrix and citric acid (CA) as a cross-linking agent. Then, the designed coating material was applied onto Di-ammonium Phosphate (DAP) and Triple Superphosphate (TSP) water-soluble fertilizers in a rotating pan machine. Chemical, physical, and biodegradation studies have confirmed that the coating material is environmentally-friendly. Nutrients release experiments in water as well as in soil environments have proved the effectiveness of the MC and MC/LGe coating layers in delaying the nutrients discharge. Besides, the nutrients release from coated DAP and TSP lasted longer than 30 days. Furthermore, the coating film enhanced the fertilizers mechanical resistance and boosted the soil water retention capacity. The agronomic evaluation has also confirmed their remarkable potential in enhancing wheat leaf area, chlorophyll content and biomass, in addition to the roots architecture and the final fruiting efficiency. These results showed that this hybrid composite could be used as an efficient coating material to produce slow-release fertilizers with multifunctional performances.

Controlled release fertilizers (CRFs) for climate-smart agriculture practices: a comprehensive review on release mechanism, materials, methods of preparation, and effect on environmental parameters

Fertilizers play an essential role in increasing crop yield, maintaining soil fertility, and provide a steady supply of nutrients for plant requirements. The excessive use of conventional fertilizers can cause environmental problems associated with nutrient loss through volatilization in the atmosphere, leaching to groundwater, surface run-off, and denitrification. To mitigate environmental issues and improve the longevity of fertilizer in soil, controlled release fertilizers (CRFs) have been developed. The application of CRFs can reduce the loss of nutrients, provide higher nutrient use efficiency, and improve soil health simultaneously to achieve the goals of climate-smart agricultural (CSA) practices. The major findings of this review paper are (1) CRFs can prevent direct exposure of fertilizer granule to soil and prevent loss of nutrients such as nitrate and nitrous oxide emissions; (2) CRFs are less affected by the change in environmental parameters, and that can increase longevity in soil compared to conventional fertilizers; and (3) CRFs can maintain required soil nitrogen levels, increase water retention, reduce GHG emissions, lead to optimum pH for plant growth, and increase soil organic matter content. This paper could give good insights into the ongoing development and future perspectives of CRFs for CSA practices.

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.