Nitrogen losses from granulated urea with boron sources and effect on maize development

• Grant number: 23/10939-4
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2024
• End date: February 28, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Rafael Otto
• Grantee: Ingrid Martins Stelutti
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Nitrogen fertilizers are essential agricultural inputs in food production. Urea is the most consumed source of nitrogen (N) in the world. The hydrolysis of urea in the soil by the action of urease produces ammonia (NH3) which is volatilized to the atmosphere. N losses by volatilization represent an economic and nutritional problem of lower N use efficiency (NUE) by plants and, environmental by the transformation of N into more reactive species, such as nitrous oxide (N2O) and, eutrophication of water courses. The use of urease inhibitors is an alternative to reduce NH3 emissions and release N gradually into the soil. Some micronutrients have been shown to be efficient in inhibiting urease, such as boron (B), as a coating or incorporated into urea. The objective of this study is to develop a nitrogen fertilizer of increased efficiency from urea (with and without NBPT) and B sources of different solubility (boric acid, sodium tetraborate pentahydrate, sodium octaborate, ulexite and colemanite) in order to reduce N losses and make B available to maize plants (Zea mays). The fertilizers will be produced in a rotary dish granulator and characterized physically and chemically. Tests of urease activity, NH3 volatilization and N2O emission will be conducted under laboratory conditions, in addition to a greenhouse experiment with leaching columns grown with maize, in order to evaluate the gains in biomass production and, N and B absorption efficiency by maize plants.The results will be submitted to analysis of variance (ANOVA) and Tukey test (p < 0.05), if there is significance between the means of the treatments. The results will be adjusted by regression analysis as a function of N and B sources. It is expected that B inhibits urease in the soil and reduces ammonia volatilization and N2O emission, increasing NUE and making the micronutrient available to maize plants.