In-situ evaluation of chitosan-based materials containing fertilizer by time-domain reflectometry (TDR) technique

•TDR efficiently monitored the fertilizer ions released in the soil.•The fertilizer release depends on the shape and size particle.•Microcapsules slowly deliver the nutrient for longer than 45 days•The fertilizer disposal is water-dependent. Population growth and resource reduction have created tremendous pressure on the current world scenario to meet the increasing food demands. To face this challenge, strategies are needed to promote the rational use of natural resources since overusing agricultural inputs such as chemical fertilizers may lead to severe environmental problems. In the present work, we evaluated (i) the nutrient release profile of macrospheres, microspheres, and microcapsules based on chitosan, montmorillonite clay, and KNO3 by TDR technique and (ii) the influence of controlled water replacement on the nutrient release in soil. TDR probes inserted in containers with sandy soil evaluated the nutrient release from materials, with and without tracking of field capacity, obtaining results for soil moisture and electrical conductivity. The nutrient release was dependent on soil water management, improving fertilization oversight. Microcapsules released the nutrient slower and for longer periods (higher than 46 days). Also, the water content corroborated the swell ability of materials, which affected and controlled the release of nutrients. These findings validate that chitosan-based materials matched the requirements for a more efficient and sustainable fertilizer, and the TDR technique effectively determined the release of nutrients. [Display omitted]