Abstract
Sugarcane straw is a crop residue known as the main input of carbon (C)
to the soil, but its removal represents a valuable asset for bioenergy
purposes, which may adversely affect soil organic C (SOC) stocks. Most
studies related to this issue is limited to site-specific conditions and
comprehensive studies in a wide range of soils and climate regions are
scarce. This study was designed to evaluate temporal SOC stocks changes
induced by sugarcane cultivation and straw management in the
southern-central of Brazil. Ten field experiments were arranged in a
randomized block design with four replications, including four straw
removal rates: total (TR), high (HR), low (LR) and no removal (NR). Soil
samples were collected to a 30-cm depth at the beginning of the trial
establishment and after four consecutive years. The dataset suggested
that 19% and 25% of the C added via straw were accumulated into the
soil of the sandy and clayey areas, respectively. This study showed
strong SOC depletion in sandy soils at rates of 1.4, 1.5, 1.9 and 2.3 Mg
ha-1 year-1 under NR, LR, HR and TR, respectively. In contrast, clayey
soils exhibited SOC accumulation over time, even removing all the straw
from the soil surface. Based on SOC changes, these findings provide a
robust scientific basis to support policy and management decisions for
straw-derived bioenergy, showing that the removal of sugarcane straw may
be potentially advantageous in clayey soils but should be avoided in
sandy soils of tropical regions in Brazil.