Delivery of Agrochemicals Using Nanocomposites

Abstract

Excessive fertilizer use degrades soil health, decreases the efficiency with which plants absorb nutrients, and pollutes the environment. As a response to the problem, the use of controlled-release fertilizer is gaining popularity. The delivery of agrochemicals (macro- and micronutrients, insecticides, and other agrochemicals) to the appropriate locations has shown significant promise for engineered nanocomposites (ENCs). With an emphasis on their usefulness in plant production and protection, this study discusses the synthesis of nanocomposites, as well as their physical and chemical characterization and methodologies for ensuring continuous release and tailored distribution to crops. The practicality of the use, the commercial viability of nanoformulations, and biosafety issues are also covered.  The development of a critical understanding of the state of the art in nanocomposites for the controlled release of agrochemicals will be facilitated by this. Critical topics like manufacturing scaling up, economic assessments, field-based trials, and environmental safety considerations should receive more emphasis in the future study.

Introduction 

Agrochemicals, specialized nanocomposites, targeted distribution, and controlled release The global grain output would need to increase by 70% in order to meet the food demands of the rapidly expanding population, which is expected to reach 9.6 billion by 2050. On the other hand, a decrease in the supply of food is anticipated as a result of decreased agricultural output, limited land availability, and other factors. Recent research on the long-term effects of such agrochemicals suggest a deterioration in soil health, despite the fact that fertilizer application has been crucial in raising agricultural productivity in recent decades. To increase agricultural productivity, however, farmers frequently use excessive amounts of fertilizers, pesticides, and herbicides. Such agrochemicals shouldn't be used carelessly due to their cancer- and mutagenic-causing properties. Conventional agrochemicals also have substantial drawbacks: after being applied to the soil, the concentration of these fertilizers initially rises, but soon falls to ineffective levels over time due to the compound's breakdown, leaching, or volatilization. This propensity encourages the frequent application of conventional fertilizers, which degrades soil quality and eutrophicates nearby water sources. The application of numerous fertilizers, such as ammonium salts, urea, nitrate, or phosphate compounds, to fields for the purpose of enhancing soil nutrients, causes unusually high local concentrations that seriously harm crops. The majority of the urea applied is also lost by volatilization, leaching, and other processes, and the buildup of NH4+ causes the pH of the soil to rise. Volatilization can cause a loss of nitrogen from surface soil of up to 70%. Because they typically result in insoluble inorganic compounds, mostly Fe- and Al-based oxides, lower soil phosphate levels by 0.01 ppm to 1.00 ppm, and because 80 to 90% of applied phosphate fertilizers are lost to the environment, phosphate fertilizers are also inaccessible to plants. Furthermore, extremely low (18) potassium levels could be caused by excessive levels of ammonia and salt blocking potassium absorption. Fertilizers containing potassium have a 20% utilization efficiency. Agriculture yield is also impacted by micronutrient deficiency. Major micronutrients like iron are mostly unavailable to plants in calcareous soil due to the limited solubility of the oxidized ferric form in an aerobic environment. Zinc and manganese shortages are common in soil that has a pH between neutral and alkaline, as well as soil that is rich in calcium. The definition of controlled release is the permeation-controlled transfer of active substances from a modified reservoir to a particular target area while keeping the concentration of the active ingredient at a predetermined level for a lengthy period of time. Due to their high robustness and prolonged shelf life, several nanocomposites have been created for the slow release of agrochemicals, making them perfect for usage in agricultural fields. The majority of reports on nanocomposites concentrate on the creation, description, and kinetics of their release in soil and water. Only a few studies have examined the effects of nanocomposites on plants. Recently, agrochemicals have been supplied utilizing nano-encapsulated products, which secure the delivery payload at its core while still allowing for progressive release. A hydrophilic coating on the delivery payload actively absorbs water, generating swelling, followed by disintegration and diffusion of the cargo. Additionally, a number of polymer-based nanocomposites are used to make pesticide-delivery nanocomposites. A popular bottom-up method for making nanoparticles is the sol-gel method. Some of the processes include hydrolysis, polycondensation, gelation, aging, drying densification, and crystallization. The most popular technique for creating zeolites and hybrid nanomaterials based on silica is called sol-gel. Polymer silicate nanocomposites can be made using a variety of techniques, including melt intercalation, in situ intercalative polymerization, exfoliation adsorption, and template synthesis. The melt intercalation synthesis method is the most straightforward, economical, and ecologically friendly method available. It is therefore well acknowledged as a synthesis method for producing polymer silicate nanocomposite. This process involves melting the polymer and mixing it with the appropriate quantity of intercalated clay. Based on the compatibility of the silica layers and the polymer, molten or intercalated nanocomposite can be produced. Since the entire procedure is carried out in an inert atmosphere, an organic solvent is not necessary. Due to their distinct characteristics, such as agrochemicals' slow release and customized delivery, nanocomposites can be significantly more beneficial than bulk chemical fertilizers and pesticides. The growth and maintenance of plants require the macronutrients potassium, phosphorus, and nitrogen. In addition to being necessary for the production of proteins, nucleic acids, and other macromolecules, nitrogen and phosphorus are also important for the growth of plant structures. Potassium is also crucial for maintaining osmotic potential and ion balance. To make sure that these macronutrients are distributed properly in agricultural fields, a number of nanocomposites have been created.

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