Abstract:
Sugarcane is the feedstock for raw sugar manufacturing in Sri Lanka where the existing
cultivation occupies 30,000 hectares that is around 35% of the arable land area for sugarcane. Future
improvements in the local cane sugar industry require expansion of cultivation in the full capacity.
The conventional rain-fed sugarcane cultivation method in Sri Lanka utilizes diesel-operated
tractors/equipment and manual agricultural operations in land preparation, crop establishment, crop
maintenance and harvesting activities with open burning of crop residues. Since these agricultural
operations contribute many airborne emissions (CO2, SO2, NOx, CH4, NH3, N2O, particulates, etc.), a
quantitative assessment of life cycle climate change impacts is required for future policy decision
making towards sustainable expansion of sugarcane cultivation. A published life cycle impact
assessment on cradle-to-gate life cycle of sugarcane cultivation in Sri Lanka has not been reported.
Hence, the novelty of this study is the evaluation of four major climate change impacts (global
warming potential, terrestrial acidification, photochemical oxidant formation, and particulate matter
formation) and associated airborne emissions. Inventory data on materials/resources utilization
and energy consumption are collected from a data survey through interviewing sugarcane
farmers and industry statistics, which are applied to estimate emissions from individual
operations: agrochemical manufacturing/transportation/application, agricultural machinery
operations, seed cane transportation, crop residues burning, etc. The corresponding climate
change impacts were quantified using the ReCiPe midpoint (H) V1.12 impact assessment method
in SimaPro Life Cycle Assessment (LCA) software. The results indicate the contributions from
agricultural operations in the conventional cultivation practice for all climate change impacts.
Global warming potential impact result is 3,120 CO2 eq where the major contributors are
chemical fertilizers application (45%) and open burning of crop residues (40%). More than 50%
of terrestrial acidification and particulate matter formation impact results are also represented
by chemical fertilizers application while open burning of crop residues is responsible for almost
95% of the photochemical oxidant formation impact result. Therefore, the study compares
impact results with a scenario for effective crop residues utilization (zero crop residues burning
with 50% utilized as organic manure in the same cultivation field) and the respective climate
change impact mitigation potentials are quantified.
