Biochar adsorbed ammonia is bioavailable

Abstract

Biochar is produced as a by-product of the low temperature pyrolysis of biomass during bioenergy extraction and its incorporation into soil is of global interest as a potential carbon sequestration tool. Biochar influences soil nitrogen transformations and its capacity to take up ammonia is well recognized. Anthropogenic emissions of ammonia need to be mitigated due to negative environmental impacts and economic losses. Here we use an isotope of nitrogen to show that ammonia-N adsorbed by biochar is stable in ambient air, but readily bioavailable when placed in the soil. When biochars, containing adsorbed 15 N labelled ammonia, were incorporated into soil the 15 N recovery by roots averaged 6.8% but ranged from 26.1% to 10.9% in leaf tissue due to differing biochar properties with plant 15 N recovery greater when acidic biochars were used to capture ammonia. Recovery of 15 N as total soil nitrogen (organic+inorganic) ranged from 45% to 29% of 15 N applied. We provide a proof of concept for a synergistic mitigation option where anthropogenic ammonia emissions could be captured using biochar, and made bioavailable in soils, thus leading to nitrogen capture by crops, while simultaneously sequestering carbon in soils.

Removal of nitrate, ammonia and phosphate from aqueous solutions in packed bed filter using biochar augmented sand media

“…Hale, et al [10] who studied the adsorption of ammonium by biochars prepared from corn cob and cacao shell suggested that ammonium is weakly adsorbed on the surface of the biochar through electrostatic exchanges with other cationic species. This is consistent with the findings of Taghizadeh-Toosi, et al [11] who reported that ammonium adsorbed by biochar was readily available to plants. Upon close inspection of the results, a trend was observed which indicated that the addition of biochar may enhance the NH4 + removal efficiency overtime.…”

Application of Two Bioenergy Byproducts with Contrasting Carbon Availability to a Prairie Soil: Three-Year Crop Response and Changes in Soil Biological and Chemical Properties

“…The treatment of 50 kg N¨ha´1 combined with BC benefited the crop yield similar to that in 100 kg N¨ha´1 applied alone treatment. This could be due to the ability of BC to reduce urea N losses through reduction of leaching or gaseous losses [36].…”

Biochar can restrict N2O emissions and the risk of nitrogen leaching from an agricultural soil during the freeze-thaw period

“…Presumably, biochar in the soil can retain N which is released from microbes (Müller et al 2002, Groffman et al 2006) and/or roots (Fitzhugh et al 2001) dying due to the frost and, thus, inhibit the formation of N 2 O. Taghizadeh-Toosi et al (2011) stated that N adsorbed by biochar is bioavailable, but the results of this study do not fully support the statement. Our results indicate that biochar retains, at least temporarily, both NH 4 + and NO 3 -in the soil (Fig.…”

“…In this study, the used biochar was made from spruce chips under rather low temperatures (400-450°C). Some earlier studies have found that wood-originated biochar can absorb N (Taghizadeh-Toosi et al 2011, Dempster et al 2012) and increase the amounts of inorganic and organic N in the soil (Clough et al 2010, Biederman and Harpole 2013, Güereña et al 2013 but N is available for plants (Taghizadeh-Toosi et al 2011) and microbes (Dempster et al 2012). Our results, however, show that the wood-originated aged biochar characterized by a moderate specific surface area (209.7 m 2 g -1 ) can retain N and thus diminish N 2 O flux and leaching of NH 4 + and NO 3 -during FT. Our results are supported by Singh et al (2010), who stated that according to their experiment, which lasted over 5 months, the effectiveness of biochar in reducing N 2 O emissions and NH 4 + leaching increased with the ageing of biochar in the soil.…”