Biochar promotes the reduction of N2O to N2 and concurrently suppresses the production of N2O in calcareous soil

Effect of Biochar and Straw Application on Nitrous Oxide and Methane Emissions from Eutric Regosols with Different pH in Sichuan Basin: A Mesocosm Study

“…It is important to note that acidic soils, which are mostly distributed in the Sichuan region [99], are more prone to N 2 O emissions, yet the application of biochar seems not to only reduce these emissions, but also to correct the soil acidity. Therefore, the present study reports a significant decrease in N 2 O emissions following biochar application, as reported in previous studies [30,34,42,45,63] another important aspect is that soil pH is a crucial factor in the regulation of soil emissions, whereby acidic soil is more likely to increase N 2 O and CH 4 emissions than neutral and alkaline soils. Moreover, there seems to be a considerable interaction effect among soil WFPS, DOC, soil temperature, and soil nitrogen with biochar and straw, in addition to natural soil pH, on these two trace gases.…”

“…By increasing the C content in soil, the long-term application of charred plant straw could reduce both CH 4 and N 2 O fluxes [27], while enlarging pores size that are able to absorb soil C, decreasing complete biodegradation [28]. Recent indoor experiments involving biochar have been reported to minimize N 2 O emissions for neutral [29] and alkaline soils [30]. Conversely, Clough et al [31] observed the opposite findings in alkaline soil.…”

Biochar amendment alters the partitioning of nitrate reduction by significantly enhancing DNRA in a paddy field

“…Such an inhibitory effect has been well documented in previous studies (Borchard et al 2019;Cayuela et al 2014), which was attributed to either the suppressing effect of biochar on N 2 O production or the promoting effect of biochar on the reduction of N 2 O to N 2 in upland agricultural soils (Dong et al 2020;Yuan et al 2019). Several studies have reported that the decrease in apparent N 2 O emissions may be caused by either a direct decrease in the activities of nitrifiers and denitrifiers (Dong et al 2020;Song et al 2019) or an indirect decline in the availability of NH 4 + -N and NO 3 − -N substrates (for producing N 2 O) triggered by the entrapment of biochar (Hagemann et al 2017;Nguyen et al 2017). While in our study, experiments were performed under waterlogged conditions, where N 2 O emission is predominately produced by denitrification (Ishii et al 2011).…”

“…Biochar, as a carbonaceous material produced from the pyrolysis of different feedstocks (e.g., crop residues, woody biomass, and animal wastes), has been proposed as a useful soil amendment in terms of mitigating greenhouse gas emissions (Kuppusamy et al 2016;Lehmann et al 2021;Lévesque et al 2020;Wu et al 2021a) and improving soil fertility (Novak et al 2009) in agroecosystems. In most contexts of biochar research, biochar amendment can significantly reduce N 2 O emissions (Dong et al 2020;Wu et al 2021b;Zhang et al 2013). In upland soils, several mechanisms have been proposed for the reduced N 2 O emissions caused by biochar, showing that biochar may sorb N 2 O (Cornelissen et al 2013;Van Zwieten et al 2014), limit soil nitrification by binding NH 4 + (Yang et al 2015a), inhibit soil denitrification by enhancing soil aeration (Van Zwieten et al 2010), increase soil pH or act as an "electron shuttle'' facilitating the last step of denitrification (Cayuela et al 2013;Yanai et al 2007), as well as modify nitrifier and denitrifier communities (Dai et al 2021;Xu et al 2014).…”

Increased N2 emissions from an arable soil four years after biochar application#

“…Nitrogen losses as N 2 O can occur during the process of nitrification amounting to approximately 0.1% of N turnover, during nitrifier denitrification and denitrification (Wrage et al., 2005). In arable systems, in which often a reduction of emissions by BC application was observed (Edwards et al., 2018; Fungo, Chen et al., 2019; Dong et al., 2020), it is generally assumed that N 2 O is mainly produced by denitrification, especially in moist soils, that is, at a water‐filled pore space (WFPS) higher than 60% (Bateman and Baggs, 2005). Low temperatures also favor the release of N 2 O with maximum emissions around 2°C, since the activity of N 2 O reducing enzymes decreases with decreasing temperature leading to incomplete denitrification (Müller et al., 2003).…”