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Value of Functionalized Charcoal for Increasing the Efficiency of Urea N Uptake: Insights into the Functionalization Process and the Physicochemical Characteristics of Charcoal

Diogo Mendes de Paiva ORCID logo , Gelton Geraldo Fernandes Guimarães ORCID logo , Breno Cardoso Teixeira ORCID logo , Reinaldo Bertola Cantarutti ORCID logo

12/Aug/2019

DOI: 10.1590/18069657rbcs20180200

Graphical Abstract

Graphical Abstract

Highlights

Charcoal functionalized by HNO3 is similar to humic acids extracted from the soil.

The concentration of HNO3 has a greater effect on the capacity of the functionalized charcoal to adsorb NH3.

Urea mixed with functionalized charcoal facilitated a greater N uptake by corn plants.

Value of Functionalized Charcoal for Increasing the Efficiency of Urea N Uptake: Insights into the Functionalization Process and the Physicochemical Characteristics of Charcoal

ABSTRACT

Functionalized charcoal (CHox) incorporated into urea is known for its ability to reduce NH3 volatilization and increase agronomic efficiency. However, it is important to optimize the functionalization process and to elucidate its relationship with the physicochemical properties of CHox for N supply. Thus, charcoal obtained from eucalyptus wood was functionalized with different HNO3 concentrations and reaction times. Ammonia adsorption by CHox was evaluated in chambers with high NH3 concentrations. Dry matter yield, N uptake, and apparent N recovery efficiency of corn plants were evaluated after the application of the urea-CHox mixture to soil in a greenhouse experiment. The properties of CHox, such as pH, isoelectric point, and total acidity (carboxylic and phenolics groups) depended on the HNO3 concentration but were not influenced by the reaction time. The NH3 adsorption by the functionalized charcoal showed a positive correlation with the quantity of carboxylic and phenolic groups and a negative correlation with the pH value and the isoelectric point. The small differences observed in dry matter yield, N accumulation, and apparent N recovery efficiency among the corn plants from urea mixed with CHox or humic acids derived from charcoal (AHCH) are not sufficient to determine the higher efficiency of these sources.

Value of Functionalized Charcoal for Increasing the Efficiency of Urea N Uptake: Insights into the Functionalization Process and the Physicochemical Characteristics of Charcoal

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