Lignocellulosic materials as anchoring and reinforcing matrices in the enhanced efficiency fertilizers production

Abstract

World population growth has driven demand for food, resulting in the intensive use of fertilizers in agricultural production. However, a substantial portion of the nutrients found in conventional fertilizers, intended to fulfill the plant's nutritional requirements, is lost, primarily through volatilization and leaching. Then, optimizing agricultural production techniques is imperative to achieve sustainable fulfillment of food demand, as proposed by objectives 2 and 12 of the Sustainable Development Goals (SDGs). An alternative is the use of enhanced efficiency fertilizers (EEF). EEF are materials composed of one or more nutrients (usually in salt form) and a matrix (polymeric, inorganic, or composite material) that anchors or encapsulates these nutrients. For this, it is crucial to use biologically-based, biodegradable, and low-cost matrices that help to delay nutrient release. The distinctiveness stems of this study derived from using two abundant and nutrient-compatible natural polymer matrices: cellulose nanofibrils (CNF) and lignin. Combining the CNF and lignin properties in the same material presents a potential for innovation because it uses two compounds from the same raw material and generates a different EEF. While the chemically modified CNF will anchor the nutrient ions, the lignin, with its hydrophobic character, will help delay the release of these ions. Nitrogen, phosphorus, and potassium will be the macronutrients anchored or encapsulated by CNF/lignin through spray drying. The microspheres and microcapsules obtained will be covered by another polymer matrix through processing in a Haake rheometer and extruder to produce EEF in the form of pellets or similar. To carry out this last stage, there is the intention of collaborating with the University of Pisa (UNIPI), in Italy (IT). All materials obtained will be thermally, structurally, and morphologically characterized. Evaluating the mechanisms and kinetics governing nutrient release will be conducted in aqueous solutions and soil environments, utilizing time domain reflectometry (TDR). Moreover, the biodegradation behavior of the polymer matrices will be investigated using the Bartha respirometer. Anticipated outcomes encompass the roles of modified CNF and lignin as biodegradable carriers, effectively retarding nutrient solubility in the context of EEF production.