Biochar-mediated reductions in greenhouse gas emissions from soil amended with anaerobic digestates

Abstract

Available online xxxKeywords: Nitrous oxide Anaerobic digestate Biochar Nitrification Denitrification a b s t r a c t This investigation examines nitrous oxide (N 2 O) fluxes from soil with simultaneous amendments of anaerobic digestates and biochar. The main source of anthropogenic emissions of N 2 O is agriculture and in particular, manure and slurry application to fields. Anaerobic digestates are increasingly used as a fertiliser and interest is growing in their potential as sources of N 2 O via nitrification and denitrification. Biochar is a stable product of pyrolysis and may affect soil properties such as cation exchange capacity and water holding capacity. Whilst work has been conducted on the effects of biochar amendment on N 2 O emissions in soils fertilised with mineral fertilisers and raw animal manures, little work to date has focused on the effects of biochar on nitrogen transformations within soil amended with anaerobic digestates. The aim of the current investigation was to quantify the effects of biochar application on ammonification, nitrification and N 2 O fluxes within soil amended with three anaerobic digestates derived from different feedstocks. A factorial experiment was undertaken in which a sandy loam soil (Dunnington Heath series) was either left untreated, or amended with three different anaerobic digestates and one of three biochar treatments; 0%, 1% or 3%. Nitrous oxide emissions were greatest from soil amended with anaerobic digestate originating from a maize feedstock. Biochar amendment reduced N 2 O emissions from all treatments, with the greatest effect observed in treatments with maximum emissions. The degree of N 2 O production and efficacy of biochar amelioration of gas emissions is discussed in context of soil microbial biomass and soil available carbon.

Standard Extraction Methods May Underestimate Nitrate Stocks Captured by Field‐Aged Biochar

“…Ventura et al (2013) also reported significantly reduced cumulative NO 3 − leaching by 75% in an apple orchard, quantified using ion exchange resins over 1 yr. Rizhiya et al (2015) reported higher NO 3 − concentrations in the BC‐amended topsoil, accompanied by reduced N 2 O emissions. A number of laboratory studies have also frequently reported reduced NO 3 − leaching (Lehmann et al, 2003; Laird et al, 2010; Yao et al, 2012; Zheng et al, 2013; Jassal et al, 2015), sometimes accompanied by reports of reduced amounts of extractable NH 4 + and particularly NO 3 − (Sika and Hardie, 2014) and sometimes accompanied by reports of increased amounts of extractable NO 3 − (Van Zwieten et al, 2010; Cayuela et al, 2013; Martin et al, 2015). However, some field studies show no reduction in NO 3 − leaching (Castaldi et al, 2011; Eykelbosh et al, 2015) or even greater NO 3 − leaching than NH 4 + due to BC addition (Güereña et al, 2013).…”

Research and Application of Biochar in Soil CO2 Emission, Fertility, and Microorganisms: A Sustainable Solution to Solve China’s Agricultural Straw Burning Problem

“…This table shows the amount of CO 2 produced by the production of 1 kg of biochar. According to the research conclusion of Zhang [35], the production of 1 kWh electricity can emit 860 g of CO 2 , and from the conclusion of Toyama's research [36], the production of 1 L N 2 can emit 0.12 g of CO 2 .…”

Biochar production and applications in soil fertility and carbon sequestration – a sustainable solution to crop-residue burning in India

“…Similar CO 2 emission trends were reported for other biochars. 98,99 The cumulative CO 2 emissions were highest in the soil amended with 0.5 (wt%) followed by 1.0 (wt%) and 3.0 (wt%) CSBC, respectively [ Fig. 8(A)].…”