Decomposition dynamics altered by straw removal management in the sugarcane-expansion regions in Brazil

作者：Letícia L. Varanda, Maurício Roberto Cherubin, Carlos Eduardo Pellegrino Cerri · 发表于：Soil Research · 年份：2018 · DOI：10.1071/sr17298 · 被引用次数：21 · 研究领域：Sugarcane Cultivation and Processing、Biofuel production and bioconversion、Soil Management and Crop Yield

Brazilian bioenergy production based on sugarcane is globally known as a sustainable energy matrix. In order to supply the growing demand for biofuels, the sugarcane area expanded by 46% in the last decade in Brazil. In addition, the industry’s interest in using sugarcane straw as raw material for bioenergy production has recently increased. Thus, understanding the straw decomposition dynamics in these new frontiers is imperative to support decision-making that will define a sustainable straw removal rate. A field experiment was conducted in three sites under a climate and soil gradient (from central to south) within the sugarcane-expansion region (i.e. Goiás, Mato Grosso do Sul and Paraná states) to evaluate the straw decomposition. The amounts of 3, 6 and 12 Mg ha–1 of straw (dry mass, DM) were left on the soil surface after harvesting, representing the straw removal rates of about 75, 50 and 0% respectively. We quantified DM loss, carbon (C) and nitrogen (N) contents and biochemical composition of the straw throughout a crop cycle (300 days). In addition, visual changes in the decomposing straw were evaluated through scanning electron microscopy. An exponential model was efficiently fitted to data of DM loss, describing the pattern of straw decomposition over time. The DM, C losses and cellulose and hemicellulose contents of straw changed over time among sites, reflecting the local edaphoclimatic conditions favourable for decomposition. The C : N ratio decreased from 106 :...