Composite System for Controlled Release Based on Glass-Alginate/CMC-Microorganisms as a Potential Multielement Fertilizer for Paspalum spp. Cultivation

• Grant number: 24/22346-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2025
• End date: August 31, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Danilo Manzani
• Grantee: Jose Hermeson da Silva Soares
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Fertilizers play a crucial role in global food production, especially in the context of population growth and inequality in the distribution of agricultural resources. Brazil stands out as the fourth largest consumer and importer of fertilizers in the world. This external dependency can be partly attributed to the inefficiency of traditional formulations, which have limitations both in the composition of macro- and micronutrients and in their high solubility, leading to significant losses through soil immobilization, leaching, and percolation, ultimately compromising plant growth.In this context, vitreous fertilizers, part of the oxide glass class, emerge as a promising alternative to conventional fertilizers. These materials are characterized as a condensed, non-crystalline state of matter and offer a highly versatile matrix that allows for the incorporation of nutrients with controlled release. An innovative approach proposed in this project involves combining glasses with microorganisms and alginate/CMC to form composites, broadening their functionality.Rhizospheric and endolithic microorganisms, known as plant growth promoters, can fix nitrogen, supply nutrients to plants, and address the challenge of incorporating nitrogen sources directly into the glass matrix. Additionally, these microorganisms help reduce phosphorus losses released into the soil and produce indoleacetic acid (IAA), which solubilizes inorganic/organic phosphorus and plays a key role in plant cell development. The use of alginate/CMC in the composite also provides the advantage of controlled nutrient release, along with protection against environmental variations.Thus, this project proposes the production of multielement vitreous fertilizers using the melt-quenching method, followed by the encapsulation of microorganisms in an alginate/CMC matrix via the gel-casting method to form composite spheres, acting as potential fertilizers. In vitro and in vivo tests will include material characterization techniques, spectroscopy, and assays for nutrient release, cell viability, IAA production, nitrogen fixation, and phosphorus solubilization. Finally, greenhouse experiments will be conducted with the forage plant Paspalum spp., using bromatological analyses. The choice of Paspalum is justified by its high genetic variability, providing greater adaptive potential compared to other species such as Brachiaria.