Advanced search
Start date
Betweenand

Development and evaluation of acidity buffering systems for the volatilization control of ammonia from urea

Grant number: 17/18673-2
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): December 01, 2017
Effective date (End): November 30, 2019
Field of knowledge:Engineering - Materials and Metallurgical Engineering
Principal Investigator:Cauê Ribeiro de Oliveira
Grantee:Vinicius Ferraz Majaron
Home Institution: Embrapa Instrumentação Agropecuária. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil

Abstract

Urea is the most commonly nitrogen fertilizer used in Brazilian agriculture due to its high concentration of N (~ 45%) and lower cost per unit of nutrient. However, due to the significant N losses by the volatilization of ammonia (NH3), this fertilizer, when applied to the soil surface, shows low agronomic efficiency. The high rates of NH3volatilization may be related to rapid hydrolysis of urea, which provides favorable conditions for NH3 gas formation and intensifies its loss to atmosphere, resulting in economic and environmental impacts. In this way, efforts are dedicated to the development of new strategies to reduce these losses and increase the efficiency of urea. An alternative studied is the urea coating with elemental sulfur (S°), which presents as a principle the stabilization of N in the soil due to the acidity generated during the oxidation of S° to sulfate (SO42- ). However, due to the low oxidation rate of S° in the soil and, on the other hand, the rapid hydrolysis of urea, these two processes occur at different moments reducing the efficiency of this interaction. To overcome this problem, it is necessary to delay the hydrolysis of the urea, controlling its release to the medium, and at the same time to accelerate and intensify the oxidation of the S°, a goal that can be achieved with the inoculation of efficient microorganisms in this process. Recent studies have shown that the fungus Aspergillus niger is an efficient producer of organic acid, besides promoting the oxidation of the S°. The aim of the project is to produce and evaluate a coating capable of promoting natural acidification on the surface of the urea granules, in order to buffer the alkalinization provided by the hydrolysis of urea and thus reduce the volatilization of ammonia and increase the availability of the N in the soil. In addition to reducing the economic and environmental impacts provided by the control of ammonia volatilization, it is expected that this new coating system will be able to adequately supply SO42- to plants. Thus, coatings systems will be produced and characterized in order to study the dispersion of S and spores of A. niger in the coating matrix as well as their interaction with the urea granule. Urea incubation assays (with or without coating) will also be conducted in culture medium and in solid medium to evaluate the bioactivation of the spores, the potential of the acidification of the medium and the profile of the oxidation of S° and the release of N-urea. The granules will also be incubated to the soil, to evaluate the release of N-urea, the volatilization of NH3 and oxidation of the S°. (AU)