Assessing the environmental sustainability of Portuguese olive growing practices from a life cycle assessment perspective

The olive value chain represents one of the most important bioeconomic sectors for Portugal, having this country the opportunity to emerge as the third-largest worldwide olive oil producer in the upcoming decade due to the modernization of its olive groves. Traditional rainfed production systems have been replaced by new intensive olive systems, with high-density, irrigated and mechanically harvested, which are leading to significant changes in the Portuguese olive sector. A very limited number of studies are available aiming at a deeper understanding of the consequences of these modifications, especially focused on the environmental dimension. Considering this gap of knowledge, this work aims the comparative analysis of the environmental impacts caused by three different Portuguese olive production systems: traditional rainfed (T), intensive (I) and super-intensive (SI) systems, during their entire life cycle in a reference period of 50 years, using a life cycle assessment methodology. The different agricultural practices used in the systems were grouped in six categories such as fertilization, harvesting, irrigation, phytosanitary control, pruning and soil management. Biomass valorization (resulting from pruning and plant removal) to produce electricity was assessed. Two strategies for dealing with multifunctionality in olive groves were analyzed: i) allocation based on economic criteria (market prices) and ii) substitution (“avoided burden approach”) of biomass valorization. Seven impact categories were selected and 1 hectare (ha) of cultivated olive growing area was adopted as functional unit. Super-intensive production systems resulted in higher environmental impacts for all categories (from 2.1 to 135.6 times higher when comparing with traditional rainfed systems and 1.2 to 2.8 times higher when comparing with intensive systems) and fertilization was the agricultural practice with the highest contributions for the environmental impacts in most of the categories, in the three systems under study. The multifunctionality approaches adopted significantly influenced the results, minimizing the environmental impacts of the olive production systems. This work highlights the importance of optimize agricultural practices during the entire life cycle of an olive grove, proposing measures to overcome and minimize environmental impacts, and suggesting the valorization of traditional varieties (namely ‘Galega vulgar’) in intensive systems, as a way of combining better productivity with less environmental impacts.