Carbon dynamics in a biochar-amended loamy soil under switchgrass

Abstract

. 2015. Carbon dynamics in a biochar-amended loamy soil under switchgrass. Can. J. Soil Sci. 95: 1Á13. The environmental impacts of switchgrass production for bioenergy could be reduced through the use of biofertilizers rather than mineral fertilizers and through soil amendment with biochar. The objectives of this study were: (1) to assess the impact of biochar and biofertilizer on switchgrass (Panicum virgatum L.) yield and parameters related to carbon dynamics, (2) to correlate carbon parameters with soil physico-chemical properties over the first two growing seasons, and (3) to develop a C budget. A complete randomized block design was installed in a sandy loam with split plot treatment design, the main plots receiving 0 or 10 t ha(1 of biochar and the sub ( plots receiving no fertilization, mineral N fertilization, or biofertilizers. Biofertilizers had no significant impact on plant and soil. Biochar increased yield relative to the control treatment by about 10% during the first year and root biomass by up to 50% after 2 yr (P0.1). Mineral N fertilization also increased yield resulting in higher plant C sequestration after 2 yr. Biochar increased CO 2 soil concentration (CO 2-soil ) by up to 50% but its impact on CO 2 emission flux (CO 2-flux ) changed over time. The impact of mineral fertilization on CO 2-flux also varied with time. Soil CO 2 dynamics was mostly influenced by temperature, N and water content. Biochar and fertilization treatments showed interactions on some plant and soil parameters. The highest C sequestration budget was obtained with a combination of biochar and mineral N fertilization. The equivalent of about one-third of the increase in soil C content associated with biochar treatments was respired away by soil microorganisms. Nearly one-fourth of C sequestered by plants remained in or at the soil surface (root and crop residues).Key words: Panicum virgatum L., carbon sequestration, CO 2 emissions, soil carbon, soil gas concentration Allaire, S. E., Baril, B., Vanasse, A., Lange, S. F., MacKay, J. et Smith, D. L. 2015. Dynamique du carbone dans une production de panic e´rige´amende´e de biochar sur sol loameux. Can. J. Soil Sci. 95: 1Á13. Le biochar et les bioengrais pourraient aider ar e´duire les impacts environnementaux associe´s a`la production de panic e´rige´pour la bioe´nergie. Cette e´tude vise a`(1) quantifier l'impact du biochar et d'un bioengrais sur le rendement du panic e´rige´(Panicum virgatum L.), la se´questration de carbone, le CO 2 dans le sol (CO 2-soil ) et son e´mission (CO 2-flux ); (2) corre´ler les parame`tres de carbone avec les proprie´te´s du sol et (3) e´valuer le budget de carbone. Un plan expe´rimental en tiroirs a e´te´instaure´sur un loam. Les parcelles principales ont rec¸u 0 ou 10 t ha (1 de biochar, les parcelles secondaires ont rec¸u diffe´rents traitements d'engrais. Les bioengrais n'ont pas influence´les plantes et le sol. Le biochar a favorise´une augmentation de rendement de 10% a`la premie`re saison et la biomasse racinaire de 50% apre`s deux sais...

Greenhouse Gas Dynamics in a Tree-Based Intercropping System Compared to an Organic Conventional System

“…(Table 1). These values were comparable with those estimated in conventional agricultural studies for similar climates (Allaire et al 2012(Allaire et al , 2015 and in agroforestry systems . CO 2-soil was consistently (P < 0.0001) lower +10 m (East) than −10 m (West) from the tree row (Fig.…”

“…Negative fluxes were sporadically measured. These responses mainly occurred under cold soil conditions during fall, as observed in other studies under cold conditions (Allaire et al , 2015.…”

“…As described earlier and also explained in several gas flux studies (Allaire et al , 2012(Allaire et al , 2015Oishi et al 2013), CO 2-flux is inherently correlated with CO 2-soil , as a function of Fick's law. Because N cycling influences microbial activity (Thornton et al 2007), N 2 O -soil was negatively correlated with CO 2-flux (r = −0.376, 0.125 m; r = −0.397, 0.25 m).…”

“…Higher emissions occurred in May and June (Fig. 3), nearly 1 mo earlier than usually observed in Quebec (Allaire et al , 2012(Allaire et al , 2015, most likely because of earlier spring onset, a thinner snow cover in 2012 (Fig. 2), and new available C released by deep tillage.…”

“…Early in 2012, CO 2-soil was 10% higher under CM than under TBI, an effect that disappeared toward the end of the growing season. The difference may be attributed to the trees, which affected soil temperature and moisture content (correlated with CO 2-soil at P < 0.0001) that control CO 2 production in the soil (Allaire et al 2012(Allaire et al , 2015. Microbial processes are more efficient in using soil C (lower CO 2 emissions) in TBI than in CM systems, possibly because the microbial communities are more diverse (Lacombe et al 2009;Rivest et al 2013).…”