Search

N 2 O emissions resulting from the application of nitrogen (N) fertilizers and vinasse represent the main sources of greenhouse gases (GHG) emissions in sugar-energy sector. Conversely, the application of biochar in soils has been worldwide recognized as an strategy to mitigate N 2 O emissions, although little is known about their effects on soils under energy cane production. The study aimed to evaluate the effects of biochar addition as a strategy to mitigate soil N 2 O emissions in soil under energy cane cultivation, as well as to quantify the abundance of N 2 O-producing and N 2 O-reducing microbial guilds. A greenhouse experiment was conducted in a completely randomized design, with five treatments and four replications. The treatments were: i) no N fertilization (control); ii) N fertilization; iii) N fertilization plus vinasse; iv) N fertilization plus biochar; v) N fertilization plus vinasse plus biochar. All treatments (except control) were balanced to receive the same amount of nutrients. Biochar was added at a rate of 5 g kg−1 of soil. Soil N 2 O emissions were quantified by static chambers for 78 days, and soil sampling were performed to determine chemical and microbiological attributes, including functional genes of the nitrogen cycle (AOA, AOB, nir K, nir S, nos ZI and nos ZII) by real-time PCR. Results indicated that vinasse addition increased N 2 O emissions. Conversely, the application of biochar reduced N 2 O emissions associated with the application of N fertilizer (56 %) and N fertilizer + vinasse (41 %). The high N 2 O emissions observed in vinasse treatment were directly correlated with nitrifier microorganisms (AOB and AOA), indicating that nitrification should be the main pathway of N 2 O emissions in this treatment. The production of energy cane biomass was similar between N fertilizer treatments. High N 2 O emission intensities (mg N 2 O g biomass−1) were obtained in treatments with vinasse application. This study concluded that biochar is an effficient strategy to mitigate N 2 O emissions, providing the first insights into how biochar affects the microbial community associated with N 2 O emissions from soil under energy cane cultivation. [Display omitted] • Organic residues are important drivers of N 2 O emissions in agricultural soils. • The application of vinasse increased N 2 O emissions by 86 %. • Highest N 2 O emissions correlated with nitrifier microorganisms (AOB, and AOA). • The addition of biochar reduced N 2 O emissions by rates ranging from 41 % to 54 %. • Energy cane biomass was not affected by N fertilization methods. [ABSTRACT FROM AUTHOR]

This paper explores the viability of producing energy and agricultural soil conditioners with biochars and bio-oils from the pyrolysis of biomasses that in some cases are potential environmental pollutants. This approach addresses the need to develop sustainable production systems that minimize pollution and soil degradation, and meet the demand for renewable fuels. Large volumes of biomass from different sources are available in Brazil, including Eucalyptus crop residues (CE), castor meal (CM), coconut pericarp (CP), sugarcane bagasse (SB), and water hyacinth (WH). CM char and SB bio-oil are good prospects for energy generation. Characterization using DRIFT, 13 C NMR, and van Krevelen diagrams indicated that after carbonization, aromatic structures were predominant in the biochars produced from the CP, CE, and SB biomasses, while aliphatic groups were abundant in the biochars from CM and WH. Analysis using EPR showed that unpaired electrons were preferentially located on carbon atoms in the case of the CP, CE, and SB biochars, with EPR g values around 2.0030, while the CM and WH biochars presented g values around 2.0035, indicating that the unpaired electrons were closer to oxygen atoms. In terms of bio-oil chemical composition, the most abundant compounds were 3-pyridinol and furans (WH), phenols (CP), and hexadecanoic, octadecanoic, 9,12-octadecenoic (z,z), 3-docosenoic, and 5-docosenoic acids (present only in the CM bio-oil). The bio-oils from SB and CE were quite similar and the main compound was 1,2,6-hexanetriol. The biomass sources studied produced reasonable amounts of bio-oil, and could compete as suitable raw materials for biofuel production. [ABSTRACT FROM AUTHOR]

The objective of this study was the full characterization of pruning residue from macrophyte Cyperus giganteus from tertiary wastewater treatment plant (WTP), Ponte dos Leites, located in Araruama, RJ, Brazil. Analyses aimed to systematically assess the feasibility of using the pruning residues as an energy resource. To do so, macrophytes were submitted to experimental analyses of their physical properties (real density: 0.44–0.77 g cm−3, bulk density: 0.08–0.09 g cm−3, among other characteristics), chemical and proximate analyses, and thermal analysis. Results of thermal behavior characterized the biomass as a viable energy source (high heat value, 14–16 MJ kg−1). C. giganteus different samples fractions analyses confirmed that molecular structures of the macrophyte (lignin: 17.3–26.8 wt %, cellulose: 27.8–32.6 wt %, hemicellulose: 30.1–31.5 wt %; depending on the plant part) affect thermal decomposition behavior. Maximum mass losses ranged from 83.43 to 75.91%. Energy production potential from biomass pruning residues generated at Ponte dos Leites was estimated to be around 92,400 MJ mês−1. This shows the effectiveness of using pruning residues biomass from macrophyte Cyperus giganteus for energy production, highlighting its energy potential, and support its use as inputs in thermal conversion processes. [Display omitted] • Physical-chemical characterization of Cyperus giganteus pruning residues from CW. • Assessment of C. giganteus biomass thermal properties (TGA, LHV, HHV and UHV). • Potential use of C. giganteus biomass for bioenergy production (biochar). • Potential use of biochar from C. giganteus biomass for agricultural purposes. [ABSTRACT FROM AUTHOR]