Effects of Biochar on the Emissions of Greenhouse Gases from Sugarcane Residues Applied to Soils

Abstract

The sugar and bioethanol industry generate large amounts of filter cake and vinasse, residues that are applied to sugarcane fields as conditioners and organic fertilizers. However, these may be significant sources of greenhouse gases emissions to the atmosphere. This study assessed the impact of sugarcane straw biochar on the emissions of CO 2 , CH 4 and N 2 O promoted by filter cake and vinasse applied to soil, and its effects on the chemical properties and bacterial communities of a Typic Hapludox and a Quartzipsamment. A laboratory incubation was conducted for 100 days with both soils under five treatments: vinasse and filter cake amendment (FV), plus biochar at 10 (FV + B10), 20 (FV + B20) and 50 (FV + B50) Mg•ha −1 , and a control. Soil pH, available P and exchangeable base contents increased with biochar added to sandy soil. Mineral N decreased with biochar addition to both soils. The FV treatment increased CO 2 emissions by 5-fold and 2.4-fold in sandy and clayey soils, respectively, compared to the control. Moreover, FV +B10 increased CO 2 emissions by 4% and 6.4% in sandy and clayey soils, respectively, compared to FV. Cumulative N 2 O emissions in FV were 537% and 125% higher in sandy and clayey soils, respectively, compared to the control. Nevertheless, increasing biochar amendment rates reduced N 2 O emissions from 24% to 34% in sandy soil, and from 14% to 56% in clayey soil. CH 4 emissions were negligible. The effects of filter, vinasse and biochar amendments on soil amelioration were closely related to its buffering capacity. Temporal changes on bacterial community structure were more pronounced in the sandy soil compared to clayey, and indicated that N 2 O emission mitigation in clayey soil was

Determining the Stability of Sugarcane Filtercake Biochar in Soils with Contrasting Levels of Organic Matter

“…While DOC and DON concentrations decreased, N mineralization increased in all treatments at the end of the experiment, mostly from nitrification of NH 4 + to NO 3 − (Tables 2 and 3). Other studies likewise observed lower NH 4 + and greater NO 3 − at the end of incubation experiments in which biochar was added to sandy [16] and sandy loam [37] soils. N mineralization increases were higher in the forest soil when compared with the field soil (Table 3), consistent with Ameloot et al [42], who observed that both N mineralization and immobilization with biochar additions were highest in an OM-rich soil when compared with an OM-poor soil.…”

“…This suggests greater N immobilization in the microbial biomass in the BC400 treatment than in BC600, perhaps contributing to its higher respiration rates ( Figure 3) and to priming of SOM pools in search of N in the N-poor field soil. A higher proportion of labile C in the BC400 treatment may have resulted in greater demand for inorganic N, thus leading to N immobilization [16]. The forest soil had higher cumulative CO 2 emissions from the BC400 treatment when compared with the BC600 (Figure 3), but its N mineralization rates did not vary significantly (p > 0.05), although BC400 had higher NH 4 + levels than BC600 ( Table 3).…”

“…It is high in nutrients and often applied directly on fields as fertilizer. However, it is rapidly mineralized and can potentially lead to nutrient runoff and eutrophication [15], as well as greenhouse gas emissions [16]. Transforming this nutrient-rich residue into biochar may increase its stability in the soil and slow down microbial activities.…”

Biochar impacts on nutrient dynamics in a subtropical grassland soil: 2. Greenhouse gas emissions

“…Land application of biochar as a soil amendment has recently drawn increased interest in the scientific community because of its perceived potential to reduce GHG emissions (Harter et al., 2014; Thers, Djomo, Elsgaard, & Knudsen, 2019). However, results among studies evaluating the effects of biochar on GHG emissions are inconsistent (Abbruzzini et al., 2017; Case, McNamara, Reay, & Whitaker, 2012; Case, McNamara, Reay, Stott, Grant, & Whitaker, 2015; Zhang et al., 2019). The apparent discrepancy is due to the highly variable chemical composition and properties of various biochar types and the environmental and management conditions in which biochar has been used (Artiola, Rasmussen, & Freitas, 2012; Lentz, Ippolito, & Spokas, 2014; Levesque et al., 2020; Maucieri, Zhang, McDaniel, Borin, & Adams, 2017).…”

Biochars in the mitigation of greenhouse gases and on phosphorus removal and reuse

“…Although a number of articles note that biochar's GHG mitigating ability has its potential expanded, not always proportionally, by increasing the applied dose (Abbruzzini et al, 2017; Deng et al, 2017), others, as was the case in this experiment Awasthi et al, 2017) report an increase in the applied dose, resulting in an increase in CO2 emissions.…”