Contribution of above- and belowground bioenergy crop residues to soil carbon

Autor(es)

Carvalho, Joao L. N. ; Hudiburg, Tara W. ; Franco, Henrique C. J. ; DeLucia, Evan H.

• Tipo de documento: Artigo Científico
• Fonte: Global Change Biology Bioenergy; v. 9, n. 8, p. 1333-1343, AUG 2017.
• Citações Web of Science: 31

Resumo

GHG mitigation by bioenergy crops depends on crop type, management practices, and the input of residue carbon (C) to the soil. Perennial grasses may increase soil C compared to annual crops because of more extensive root systems, but it is less clear how much soil C is derived from above-vs. belowground inputs. The objective of this study was to synthesize the existing knowledge regarding soil C inputs from above-and belowground crop residues in regions cultivated with sugarcane, corn, and miscanthus, and to predict the impact of residue removal and tillage on soil C stocks. The literature review showed that aboveground inputs to soil C (to 1-m depth) ranged from 70% to 81% for sugarcane and corn vs. 40% for miscanthus. Modeled aboveground C inputs (to 30 cm depth) ranged from 54% to 82% for sugarcane, but were 67% for miscanthus. Because 50% of observed miscanthus belowground biomass is below 30 cm depth, it may be necessary to increase the depth of modeled soil C dynamics to reconcile modeled belowground C inputs with measured. Modeled removal of aboveground corn residue (25-100%) resulted in C stock reduction in areas of corn-corn-soybean rotation under conventional tillage, while no-till management lessoned this impact. In sugarcane, soil C stocks were reduced when total aboveground residue was removed at one site, while partial removal of sugarcane residue did not reduce soil C stocks in either area. This study suggests that aboveground crop residues were the main C-residue source to the soil in the current bioethanol sector (corn and sugarcane) and the indiscriminate removal of crop residues to produce cellulosic biofuels can reduce soil C stocks and reduce the environmental benefits of bioenergy. Moreover, a switch to feedstocks such as miscanthus with more allocation to belowground C could increase soil C stocks at a much faster rate. (AU)

• Processo FAPESP: 13/13451-0 - Uso da discriminação isotópica para avaliar a contribuição da parte área e das raízes em aportar carbono para o solo
• Beneficiário: João Luís Nunes Carvalho
• Modalidade de apoio: Bolsas no Exterior - Pesquisa
• Processo FAPESP: 02/10534-8 - Rendimento da cana-de-açúcar em ciclos consecutivos associado ao efeito residual e as transformações de N e S no solo, em sistema conservacionista
• Beneficiário: Paulo Cesar Ocheuze Trivelin
• Modalidade de apoio: Auxílio à Pesquisa - Temático