Impact of plant growth-promoting bacteria on reducing greenhouse gases in tropical pastures

• Grant number: 24/22677-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Production
• Principal Investigator: Ricardo Andrade Reis
• Grantee: Marcelo Augusto Oliveira Castro
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil
• Associated research grant: 22/15974-0 - Strategic grazing management and supplementation towards sustainable intensification at tropical pasture-based beef cattle production systems, AP.TEM

Abstract

Brazilian livestock plays a central role in beef production but still faces challenges related to productivity and sustainability, such as pasture degradation and greenhouse gas (GHG) emissions. Plant growth-promoting bacteria (PGPB) may be an alternative to mitigate these issues. This study aims to investigate the effects of nitrogen fertilization combined with inoculation with Biopasto®, a product containing PGPB (Azospirillum brasilense and Pseudomonas fluorescens), on GHG emissions in soil cultivated with Urochloa brizantha cv. Marandu, as well as key environmental variables involved. The study will be conducted during the rainy season (December 2024 to April 2025) at the Forage Sector of UNESP, Jaboticabal campus - SP. Standardized static chambers will collect gas samples and evaluate N¿O and CH¿ emissions. The experiment will consist of four treatments: control (no nitrogen application); application of 150 kg N ha¿¹ via urea; application of 100 kg N ha¿¹ via urea + Biopasto®; and application of 75 kg N ha¿¹ via urea + Biopasto®. The experimental design will be completely randomized (CRD) with four treatments and five replications (chambers), totaling 20 experimental units. Evaluations will be performed in three periods, each starting after nitrogen fertilization. A total of 48 tester animals (4 animals per paddock), uncastrated Nelore (Bos taurus indicus) males with an initial average body weight of approximately 240 kg, will be used to maintain pasture height between 25 and 30 cm under a continuous stocking system with variable stocking rates (put-and-take). Additional animals, referred to as regulators, will also be used. The hypotheses of this study are that inoculation with Biopasto® will mitigate nitrous oxide (N¿O) and methane (CH¿) emissions from the soil compared to the treatment fertilized only with urea.