Agronomic and Environmental Benefits of Recovered Gypsum for Sulfur Fertilization in Camelina for Biofuel Production

Camelina (Camelina sativa (L.) Crantz) is an underutilized oilseed crop proposed as low-input feedstock for biofuel production, such as sustainable aviation fuel, under Mediterranean climate. However, its productivity is lower than that of more commonly used biofuel crops. Among agronomic techniques, sulfur fertilization is an underrated practice that can positively affect crop seed yield. This study evaluated the agronomic and environmental performance of camelina under different sulfur fertilization strategies, using industrial gypsum as a recycled S source. Field trials were conducted in central Italy over two consecutive growing seasons (2023–2024), evaluating five N–S combinations on spring-sown camelina. Agronomic performance, seed quality, and Life Cycle Assessment (LCA) of camelina subjected to different fertilization strategies were evaluated. The combined application of 60 kg N ha−1 with 40 kg S ha−1 significantly increased seed (+39%) and straw (+33%) yields compared to N-only fertilization. Sulfur improved the agronomic efficiency of nitrogen fertilization by 78%, without negatively affecting seed quality (glucosinolates, oil and protein content). LCA revealed that the use of sulfur fertilizers reduced camelina's environmental impact compared to the typical fertilization strategy. This is mainly due to the reduction in land required to produce 1 Mg of seeds and to the process associated with land management (primarily tillage and N fertilizers). However, modeling choices such as the inclusion of indirect land use change can significantly affect the output assessment. Overall, moderate S fertilization optimized both productivity and environmental impact, supporting camelina's role as a promising alternative to be introduced in Mediterranean traditional cropping systems.