Toward Carbon Mitigation Resiliency in the Agriculture Sector: An Integrated Lca-Ghg Protocol-Ipcc Guidelines Framework for Biofertilizer Application in Paddy Field

Abstract

Agriculture contributes 22% of global greenhouse gas emissions, with fertilizers accounting for 10.6% portion. Biofertilizers are a potential alternative to chemical fertilizers, emitting lower emissions during their production and application. Past studies have quantified either the upstream or downstream emissions of biofertilizers, yet the direct and indirect emissions from a life cycle perspective remain unclear. Additionally, most studies did not consider local conditions such as soil organic carbon and soil nitrogen content, leading to inaccuracies. This study solves this gap by developing a new integrated methodology of life cycle assessment, IPCC guidelines, and GHG Protocol to quantify the life cycle greenhouse gases (GHG) of a paddy biofertilizer product from Malaysia. Most GHG emissions are derived from methane under Scope 3 emissions, contributing to 87.33% of the life cycle emissions. Scope 1 and Scope 2 emissions amount to 12.67% of the life cycle emissions. Since the fertilizer ratios contain 70% chemical fertilizer and 30% biofertilizer, the upstream emissions of biofertilizers only contribute 0.69% of the life cycle emissions. The sensitivity analysis revealed that fluctuations in soil organic carbon have the most significant impact on GHG emissions, potentially causing fluctuations of 100 t CO2eq/ha/yr. A scenario analysis suggests that a nationwide phase-out of chemical fertilizers could lead to a maximum 10.12% reduction in agricultural GHG by 2030. This study contributes to SDG 13 by providing a comprehensive assessment of biofertilizer life cycle emissions, highlighting their potential to reduce GHG emissions and supporting the development of low-carbon national policies.

Keywords: life cycle assessment, carbon accounting, biofertilizer, paddy, agricultural climate policy