Impact of different water and nitrogen inputs on the eco-efficiency of durum wheat cultivation in Mediterranean environments

Abstract The present study addresses the eco-efficiency (environmental and economic trade-offs) of durum wheat cultivation practices adopted at field level under typical Mediterranean conditions of Southern Italy. This study is based on three years of experimental data of durum wheat cultivation under three water supply regimes (full irrigation, 50% of full irrigation and rainfed) coupled with two nitrogen (N) fertilizer levels (high N, HN: 120 kg/ha, and low N, LN: not fertilized). The environmental impact assessment was based on a novel life cycle impact assessment method which quantifies seventeen midpoints (problems-oriented) and three endpoints (damage-oriented) indicators using ReCiPe 2016 model. The economic performance was evaluated using the total value added to the system’s final products due to water and N use and applied management practices. Eco-efficiency was assessed as a ratio of the total value added to the environmental impact categories. The water consumption impacts were estimated in addition to the typical environmental impact categories. The high input (irrigation and fertilization) intensity systems resulted in higher agricultural production, however, produced greater impacts on water consumption, global warming, and energy-related indicators. In turn, these impact categories generated the damages to human health, ecosystem quality, and resource scarcity. The analysis demonstrated that eco-efficiency cannot be always compensated by higher yield and corresponding economic total value added. The eco-efficiency assessment indicated that agronomic practices with the low use of resources (e.g., deficit irrigation with low N) tend to have higher eco-efficiency than more intensive cultivation strategies. Hence, the sustainable crop production strategies should evolve towards the adoption of precision agriculture and optimization of water and fertilization inputs (in space, timing, and quantities) that can improve yield response to resources, environmental and economic performance. In this sense, life cycle thinking and assessment considering multiple impact categories are essential to support decision-making processes towards sustainability.