Evaluate of potential of nitrogen-fixing bacteria to replace nitrogen fertilization in the production and quality of Urochloa brizantha cv. Marandu

• Grant number: 24/17460-9
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2025
• End date: February 28, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Pastures and Forage Crops
• Principal Investigator: Ricardo Andrade Reis
• Grantee: Isadora Menezes Costa Tarôco
• 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

A recurring problem in pasture based livestock farming in Brazil is the presence ofvarious degraded pasture areas or those in some stage of degradation. To reverse this scenario,management strategies are needed to help recover these areas, such as pasture fertilization.Among the various essential nutrients, nitrogen (N) is one of the most required by forageplants, impacting the increase in forage supply and quality and, consequently, leading to ahigher stocking rate and weight gain of the animals. Synthetic nitrogen fertilizers, in general,can suffer losses in the form of gas or leaching. In the search for sustainability in cattleproduction systems on pastures formed by tropical grasses, there are strategies to minimizeenvironmental impacts, such as the use of plant growth-promoting bacteria (PGPB).Therefore, the objective of this study is to evaluate the effects of using conventional nitrogenfertilizer combined with the nitrogen-fixing bacteria inoculation on Urochloa brizantha (Syn.Brachiaria brizantha) cv. Marandu grass. The study will be conducted during the rainyseason (December 2024 to April 2025). The experimental design will be a randomizedcomplete block (RCB) design consisting of 4 treatments and 3 replications (paddocks),totaling 12 experimental units. A total of 48 tester animals (4 animals/paddock), male Nellorecattle (Bos taurus indicus) with an initial average body weight of approximately 240 kg, willbe used for performance evaluation. The field experiment will evaluate four differenttreatments: control (no N application); application of 150 kg N ha¿¹ via urea; application of100 kg N ha¿¹ via urea + BioPasto; application of 75 kg N ha¿¹ via urea + BioPasto. Animalperformance will be evaluated using the continuous stocking method, with stocking rateadjustment to maintain a 95% light interception of incident radiation. The pasture will bemanaged to a height of 25 to 30 cm in a continuous stocking system with stocking rateadjustment (put-and-take) using additional animals referred to as regulators. Greenhouse gas(GHG) emissions will be measured using 5 replicates (chambers) per treatment, distributedrandomly within each paddock, totaling 20 chambers, with each chamber considered anexperimental unit. The studied variables related to animal performance will include stockingrate, average daily gain, weight gain per area, forage chemical composition, forage intake,diet digestibility, and enteric methane emissions, as well as environmental variables (N¿Oemissions, soil CH¿ emissions, NH¿ volatilization, and explanatory variables such astemperature, rainfall, and soil moisture)