Dr Ricardo Bordonal1, Dr Dener Oliveira2, Dr Douglas Weiler3, Dra Eleanor Campbell4, Dr Maurício Cherubin5, MSc Sarah Tenelli1, Dra Simone Correa1, Dr Carlos Eduardo Cerri5, Dr João Luís Carvalho1
1CTBE/CNPEM – Brazilian Bioethanol Science and Technology Laboratory, National Center for Research in Energy and Materials, Campinas, Brazil, 2Instituto Federal Goiano, Campus Posse, Posse, Brazil, 3Instituto Federal Farroupilha, Campus Panambi, Panambi, Brazil, 4University of New Hampshire, Durham, United States, 5ESALQ/USP – Universidade de São Paulo, Escola Superior de Agricultura “Luiz de Queiroz”, Piracicaba, Brazil
Brazil is the major producer of sugarcane (Saccharum spp.) with a production of 615-million-ton from a cultivated area of 9 million hectares, accounting for 40% of global sugarcane production. Large-scale energy demand has triggered new approaches to sugarcane straw as a promising solution to increase bioenergy production (bioelectricity and cellulosic ethanol) in Brazil. However, the maintenance of straw in the fields ensures the continued provision of ecosystem services such as soil organic carbon (SOC) accumulation, which plays a critical role to maintaining soil quality and increasing the resilience of agroecosystems to extreme climatic events. The approach taken in this work was to simulate the temporal dynamics of SOC to a 0.3-m depth, validating the DayCent model through field experiment data, and finally to make predictions of the effects of straw removal scenarios (TR–total removal; MR–moderate removal; and NR–no removal) on long-term SOC changes in sugarcane areas under contrasting edaphoclimatic conditions in south-central Brazil. The DayCent model estimates were consistent (r = 0,99; P < 0.05) with the field-observed SOC changes in clayey and sandy soils. The DayCent simulations from 2014 to 2050 showed that TR depleted SOC at a rate of -0.39 and -0.21 Mg ha-1 year-1 in clayey and sandy soils, respectively. While MR did not modify SOC at any soil types, the long-term data indicated that NR resulted in SOC accretion of 0.35 and 0.29 Mg ha-1 year-1 in clayey and sandy soils, respectively. By 2050, SOC stocks under TR and MR in clayey soil were predicted to be 70% and 85% of those observed in NR, while in sandy soil TR and MR were 48% and 72% relative to NR. This study provides new insights to stakeholders for developing improved straw management strategies towards greater sustainability for bioenergy production in Brazil.
Ricardo is researcher at the Brazilian Bioethanol Science and Technology Laboratory, based in Campinas, Sao Paulo, Brazil. His research is focused on climate-smart agriculture with emphasis on soil quality assessment under different agricultural and land management practices in sugarcane cropping systems, with emphasis on SOM dynamics. Ricardo is engaged in research projects whose main objective is to reduce greenhouse gas emissions in the sugarcane industry by increasing the use of solid residues from the agroindustry (bagasse and sugarcane straw) to generate surplus eletricity.