A comparative life cycle assessment between conventional and organic chickpea cultivation in southern Italy

Legumes combine a high protein intake with reduced environmental impact and are suitable for application in rotational cropping systems, with the twofold function of producing grains and fixing N into the soil. By doing so, whether put in combination with low-input systems, they can contribute to implementing sustainable agriculture paths. Chickpea is the third most consumed grain legume in the world, and its nitrogen-fixing capacity can be beneficial for the next crops for improving soil fertility, structure, and water retention capacity and for reducing chemical fertilizer production and application. Despite the benefits, it is however needed to explore the relevant environmental sustainability issues associated with chickpea cultivation. To that end, Life Cycle Assessment (LCA) is proven valid methodology to compare cropping system alternatives, to support decision making. In this study, LCA was used in fact to compare conventional vs. organic cultivation of chickpea grains in Southern Italy in the period 2020–2022, through LCA application with a cradle-to-gate approach, using the EF 3.1 method. For the assessment, following previously published LCAs,1 kg asported N was chosen as the functional unit (FU), to make allocation possible between the harvested chickpea grains (modelled as kg eq of asported N), and the N leftover, thereby best representing the twofold function of the investigated system to produce legumes and fix N into the soil. From a review of the literature, the authors found that only a few LCAs have been developed that dealt with chickpea cultivation, which highlights the relevant contribution that this article is expected to make to specialized literature. This study represents one of the few LCAs focused exclusively on chickpea cultivation, providing a comparative analysis of conventional and organic systems, using an innovative N-based functional unit and an allocation between grain yield and nitrogen fixation. With such a FU, organic cultivation resulted to be more environmentally damaging (7.81 mPt vs. 3.40 mPt) than the conventional one, due to its lower yields that amplify the environmental impacts per unit of product. Moreover, a sensitivity analysis was incorporated in the study to explore the extent to which the choice of other FUs influence results from the assessment. The study highlighted, in particular, that results change in favour of the organic system in the case of a surface-based FU, thanks to the reduced agricultural activities and inputs per unit of ha (252 mPt for organic farming, and 279 mPt for conventional farming). These findings suggest that, while organic cultivation performs better from an environmental sustainability perspective, conventional farming is more efficient in terms of productivity. The study contributed to understanding the importance of FU selection in LCAs and provided valuable insights that can be useful to farmers for improving the sustainability of chickpea production systems and to practitioners to improve LCA applications in this research content area. • Conventional vs. organic chickpea cultivation was investigated. • Life cycle assessment (LCA) was applied for the purpose. • A nitrogen-based allocation and a multifunctional approach were used. • Results were found as changing with the functional unit. • Improvements can be made for enhanced sustainability of organic farming.