Aged biochar affects gross nitrogen mineralization and recovery: a ¹⁵N study in two contrasting soils

Abstract

Biochar is a pyrolysed biomass and largely consists of pyrogenic carbon (C), which takes much longer to decompose compared to the biomass it is made from. When applied to soil, it could increase agricultural productivity through nutrient retention and changing soil properties. The biochar-mediated nutrient retention capacity depends on the biochar properties, which change with time, and on soil properties. Here, we examined the effects of a wood biochar (20 t ha À1 ), that has aged (21 months) in a grassland field, on gross nitrogen (N) mineralization (GNM) and 15 N recovery using a 15 N tracer. A field experiment was conducted in two soil types, that is a Tenosol and a Dermosol, and also included a phosphorus (P) addition treatment (1 kg ha À1). Compared to the control, biochar with P addition significantly increased GNM in the Tenosol. Possibly, biochar and P addition enhanced nutrient availability in this nutrient-limited soil, thereby stimulating microbial activity. In contrast, biochar addition reduced GNM in the Dermosol, possibly by protecting soil organic matter (SOM) from decomposition through sorption onto biochar surfaces and enhanced formation of organo-mineral complexes in this soil that had a higher clay content (29% vs. 8% in the Tenosol). Compared to the control, biochar significantly increased total 15 N recovery in the Tenosol (on average by 12%) and reduced leaching to subsurface soil layers (on average by 52%). Overall, 15N recovery was greater in the Dermosol (83%) than the Tenosol (63%), but was not affected by biochar or P. The increased N recovery with biochar addition in the sandy Tenosol may be due to NH þ 4 -N retention at exchange sites on aged biochar, while such beneficial effects may not be visible in soils with higher clay content. Our results suggest that aged biochar may increase N use efficiency through reduced leaching or gaseous losses in sandy soils.

Biochar physicochemical properties: pyrolysis temperature and feedstock kind effects

“…The heating to temperatures of 350-650°C breaks and rearranges the chemical bonds in the biomass, forming new functional groups (e.g. carboxyl, lactone, lactol, quinine, chromene, anhydride, phenol, ether, pyrone, pyridine, pyridone, and pyrrole) (Mia et al 2017). Figures 1 and 2 shows example structures on the outer surface of the graphene sheets (Harris 1997;Harris and Tsang 1997) and pores (Van Zwieten et al 2010;Zheng et al 2010).…”

Impact of Pyrolysis Temperature and Feedstock on Surface Charge and Functional Group Chemistry of Biochars

“…The negative charge sites on biochar surfaces responsible for CEC are attributed to carboxylate and phenolate functional groups (Mia et al, 2017). Properties of these functional groups can be estimated by reference to the properties of reference compounds.…”

“…Cheng et al (2008), for example, reported CECs increasing from ~5 to 25 cmol c kg −1 as pH increased from 4 to 8 for a series of weathered biochars recovered from historic charcoal kiln sites. The CEC is also reported to increase due to oxidation of biochar surfaces both under natural weathering conditions in soils and accelerated chemical weathering under laboratory conditions (Cheng et al, 2008; Mia et al, 2017). …”

Influencia del biocarbón aplicado al suelo sobre atributos de rendimiento y calidad de avena forrajera

“…Cuando el BC ha sido incorporado al suelo puede mejorar su calidad (Ajayi et al, 2016;Ye et al, 2016;Biederman et al, 2017), puesto que ha influido positivamente sobre sus propiedades físicas, químicas y bióticas (Mukherjee y Lal, 2014;Coumaravel et al, 2015;Subedi et al, 2016;Mia et al, 2017), mejorando los contenidos de materia orgánica, aireación, textura (Ajayi et al, 2016), retención de humedad, y disponibilidad de elementos químicos nutritivos para las plantas (Aker et al, 2013;Kanthle et al, 2016;Kim et al, 2016;Biederman et al, 2017;Esfadbod et al, 2017). El BC ha llegado a actuar como inmovilizador de oligoelementos contaminantes (Jones et al, 2016) y también ha mejorado aspectos relacionados con la actividad enzimática (Wang et al, 2015).…”

“…Por consiguiente, impactos positivos sobre la germinación (Clay et al, 2016), crecimiento y desarrollo de los cultivos (Pérez- Salas et al, 2013;Fawad et al, 2017;Liu et al, 2017a), y producción de biomasa pueden ser generados (Lou et al, 2016). Esto podría traducirse en mejores rendimientos de los cultivos (Mackie et al, 2015;Dai et al, 2016;Plaza et al, 2016;Zhang et al, 2016b;Mia et al, 2017;Trupiano et al, 2017). Además, cabe mencionar que el origen de la materia prima del BC coadyuva en la mitigación de efectos adversos sobre el ambiente (Escalante-Rebolledo et al, 2016).…”