Nitrogen rates (15N) and co-inoculation with beneficial bacteria in maize and common bean in the Cerrado

• Grant number: 24/10425-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2025
• End date: February 29, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Marcelo Carvalho Minhoto Teixeira Filho
• Grantee: Karina da Silva Souza
• Host Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

Nitrogen is the nutrient required in the largest quantity and constitutes one of the highest costs in the production systems of crops like corn (Zea mays L.) and common beans (Phaseolus vulgaris L.), being essential for achieving high yields. Management practices that reduce the need for fertilizers are fundamental for food security and environmental sustainability. Research shows the potential of using plant growth-promoting bacteria (PGPB) to improve plant development. However, knowledge about the responses of grasses and legumes grown in succession, associated with the use of more than one PGPB combined with nitrogen fertilization, is insufficient. Therefore, the objectives will be to evaluate the effects of inoculation in corn and common beans, grown in succession, combined with N doses (15N-urea). The experiments will be conducted in the experimental area of the School of Engineering at Ilha Solteira, with a randomized block design in a 4x5 factorial scheme, with four replications. The treatments for corn will be: 1) Azospirillum brasilense; 2) A. brasilense + Pseudomonas fluorescens; 3) A. brasilense + Bacillus subtilis; and 4) Control, combined with five N doses: 0, 50, 100, 150, and 200 kg ha-1. For the common bean in the subsequent cultivation, the inoculations will be: 1) Rhizobium tropici; 2) R. tropici + A. brasilense; 3) R. tropici + P. fluorescens; and 4) Control, combined with doses of 0, 20, 40, 80, and 120 kg ha-1 of N, in the form of urea (15N) applied as topdressing. Soil and plant chemical analyses, microbiological analyses, 15N isotopic determinations, evaluations of soil chemical attributes, biometric analyses of crop growth, prolificacy (corn), nutritional status at flowering, leaf chlorophyll index, production components, grain yield, total extraction, export, and return of macro and micronutrients to the soil will be carried out.