title: Chitosan-Montmorillonite microspheres: A sustainable fertilizer delivery system.
abstract: Controlled release fertilizers are efficient tools that increase the sustainability of agricultural practices. However, the biodegradability of the matrices and the determination of the release into soil still require some investigation. This paper describes the preparation of potassium-containing microspheres based on chitosan and montmorillonite clay and the in situ soil release. The chitosan-montmorillonite microspheres were prepared using a coagulation method and different proportions of montmorillonite. The structural, thermal and morphological properties as well the water swelling and fertilizer sorption capacity were evaluated. The best formulations were applied in soil, and the fertilizer release was monitored using time-domain reflectometry (TDR). Montmorillonite clay provides better sorption properties than the chitosan microspheres because of the rough and porous surface. Due to these properties, high levels of fertilizer were sorbed onto the material. ChMMT33-containing potassium shows two specific periods of fertilizer release: the first one lasted approximately three days and was assigned to the external fertilizer on the microspheres. The second was assigned to the internal fertilizer. TDR is an important and fast tool and was used to determine the fertilizer release and the ion movement in the soil.
authors.affiliation: Laboratório de Materiais Poliméricos e Biossorventes, Universidade Federal de São Carlos, Campus Araras, Araras, Brazil.
authors.forename: Bruna Rodrigues
authors.initials: BR
authors.lastname: dos Santos
authors.affiliation: Departamento de Recursos Naturais e Proteção Ambiental, Universidade Federal de São Carlos, Campus Araras, Araras, Brazil.
authors.forename: Fabiana Britti
authors.initials: FB
authors.lastname: Bacalhau
authors.affiliation: Laboratório de Materiais Poliméricos e Biossorventes, Universidade Federal de São Carlos, Campus Araras, Araras, Brazil.
authors.forename: Tamires dos Santos
authors.initials: Tdos S
authors.lastname: Pereira
authors.affiliation: Departamento de Recursos Naturais e Proteção Ambiental, Universidade Federal de São Carlos, Campus Araras, Araras, Brazil.
authors.forename: Claudinei Fonseca
authors.initials: CF
authors.lastname: Souza
authors.affiliation: Laboratório de Materiais Poliméricos e Biossorventes, Universidade Federal de São Carlos, Campus Araras, Araras, Brazil. Electronic address: faez@cca.ufscar.br.
authors.forename: Roselena
authors.initials: R
authors.lastname: Faez
mesh_terms: D065966:Absorption, Physicochemical; D001546:Bentonite / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D065546:Drug Liberation; D005308:Fertilizers; D008863:Microspheres; D011188:Potassium / Q000737:chemistry; D012987:Soil / Q000737:chemistry
chemical_list: D005308:Fertilizers; D012987:Soil; D001546:Bentonite; D048271:Chitosan; D011188:Potassium
keywords: Chitosan; TDR technique; agricultural practices; controlled release