Influence of biochars on flux of N2O and CO2 from Ferrosol

Abstract

Biochars produced by slow pyrolysis of greenwaste (GW), poultry litter (PL), papermill waste (PS), and biosolids (BS) were shown to reduce N2O emissions from an acidic Ferrosol. Similar reductions were observed for the untreated GW feedstock. Soil was amended with biochar or feedstock giving application rates of 1 and 5%. Following an initial incubation, nitrogen (N) was added at 165 kg/ha as urea. Microcosms were again incubated before being brought to 100% water-filled porosity and held at this water content for a further 47 days. The flooding phase accounted for the majority (<80%) of total N2O emissions. The control soil released 3165 mg N2O-N/m2, or 15.1% of the available N as N2O. Amendment with 1 and 5% GW feedstock significantly reduced emissions to 1470 and 636 mg N2O-N/m2, respectively. This was equivalent to 8.6 and 3.8% of applied N. The GW biochar produced at 350°C was least effective in reducing emissions, resulting in 1625 and 1705 mg N2O-N/m2 for 1 and 5% amendments. Amendment with BS biochar at 5% had the greatest impact, reducing emissions to 518 mg N2O-N/m2, or 2.2% of the applied N over the incubation period. Metabolic activity as measured by CO2 production could not explain the differences in N2O emissions between controls and amendments, nor could NH4+ or NO3– concentrations in biochar-amended soils. A decrease in NH4+ and NO3– following GW feedstock application is likely to have been responsible for reducing N2O emissions from this amendment. Reduction in N2O emissions from the biochar-amended soils was attributed to increased adsorption of NO3–. Small reductions are possible due to improved aeration and porosity leading to lower levels of denitrification and N2O emissions. Alternatively, increased pH was observed, which can drive denitrification through to dinitrogen during soil flooding.

Biochar Impacts Soil Microbial Community Composition and Nitrogen Cycling in an Acidic Soil Planted with Rape

“…Although the ways to decrease nitrification N 2 O have not been well characterized, it has been shown that the decreases of soil N 2 O emissions were often accompanied by lower nitrification rates. 16 Several hypotheses have been proposed for N 2 O decreases by biochar, including: (i) biochar reduces levels of denitrification via improving soil aeration; 17 (ii) biochar increases the adsorption of NO 3 − , thus decreasing substrate availability for denitrification; 18 (iii) biochar increases soil pH therefore driving denitrification thorough to N 2 ; 18 (iv) biochar sorbs N 2 O; 19 and (v) biochar contains ethylene which could inhibit nitrification and thus the formation of NO 3 − and N 2 O. 20 More studies are needed to clarify the effect of biochar, especially when it is used as a soil amendment in agricultural production.…”

Benchmarking nitrous oxide emissions in deciduous tree cropping systems

“…Relative standard deviation (based on seven replicate injections) for N 2 O was <2%. For each batch of samples, a range of standards, controls and blanks were included for quality control purposes (van Zwieten et al 2010).…”

Increase in soil carbon sequestration using rice husk charcoal without stimulating CH4and N2O emissions in an Andosol paddy field in Japan

“…The effects of biochar use on GHG emissions have been reported in many agricultural fields, but most of these studies were conducted in aerobic incubations or upland fields amended with wood-derived biochar (Rondon et al 2006;Spokas and Reicosky 2009;Singh et al 2010;Van Zwieten et al 2010;Scheer et al 2011;Wang et al 2012). Only a few studies have been conducted in anaerobic conditions or paddy fields Liu et al 2011;Feng et al 2012;Zhang et al 2012).…”

“…Only a few studies have been conducted in anaerobic conditions or paddy fields Liu et al 2011;Feng et al 2012;Zhang et al 2012). The results of previous studies on biochar effects on GHG emissions varied and depended on experimental conditions such as soil type, water and fertilizer management, biochar feedstock and the pyrolysis temperature for producing biochar (Singh et al 2010;Van Zwieten et al 2010;Zhang et al 2010;Liu et al 2011;Li et al 2013). To quantify GHG emissions in rice (Oryza sativa L.) production, field studies on site are suitable because the actual field condition during cultivation is repeatedly changing between aerobic and anaerobic status, and because a large part of CH 4 emissions occurs via rice plants (Inubushi et al 1989;Yu et al 1997).…”