Given the growing importance of organic food production, there is a pressing need to understand the relative environmental impacts of organic and conventional farming methods. This study applied standards-based life cycle assessment (LCA) to compare the cradle-to-farm gate greenhouse gas emissions of 12 crop products grown in California using both organic and conventional methods.
Systems modeled in the study
We modeled 12 different crops produced using both organic and conventional methods in California. The system boundary was defined as cradle-to-farmgate. In addition to analyzing steady-state scenarios in which the soil organic carbon stocks are at equilibrium, this study modeled a hypothetical scenario of converting each conventional farming system to a corresponding organic system and examined the impact of soil carbon sequestration during the transition.
LCA tool and LCI database
The results showed that steady-state organic production has higher emissions per kilogram than conventional production in seven out of the 12 cases (10.6% higher overall, excluding one outlier). Transitional organic production performed better, generating lower emissions than conventional production in seven cases (17.7% lower overall) and 22.3% lower emissions than steady-state organic. The results demonstrated that converting additional cropland to organic production may offer significant GHG reduction opportunities over the next few decades by way of increasing the soil organic carbon stocks during the transition. Non-organic systems could also improve their environmental performance by adopting management practices to increase soil organic carbon stocks.
Detailed LCA reports available here as “supplemental”: https://www.tandfonline.com/doi/abs/10.1080/10440046.2012.672378