Long-term study on crambe (Crambe abyssinica) grown on marginal land

Sloping land represents one of the major biophysical constraints limiting agricultural productivity in Mediterranean Europe, particularly in Italy. According to European Union (EU) legislation, non-food crops, like crambe ( Crambe abyssinica Hochst. ex R.E. Fr.), should be cultivated on marginal lands. Crambe emerged as a promising industrial oilseed crop for sloping marginal areas due to its rustic nature, low input requirements, and resilience to several biotic and abiotic stresses. This study provides a six-year evaluation of crambe under favorable conditions (0% slope) and marginal sites with 15% and 25% slopes in northern Italy. The aim was to assess the effects of slope on crop productivity and quality, evaluating the suitability of crambe for marginal land valorization. Cultivation on a 15% slope resulted in a 27% reduction in seed yield. Despite the decline in seed yield, seed oil content increased significantly under marginal conditions, indicating a compensatory response to reduced stand density and productivity. As a result, oil yield was not significantly affected at the 15% slope. This suggests that the increase in oil concentration offset the reduction in seed yield. In contrast, under steep slope condition (25%), this compensatory mechanism was insufficient, and oil yield showed a marked decline (approximately −60%) compared with the flat site. Erucic acid concentration showed minor variations across slope, resulting in a stable parameter. These findings demonstrate that crambe maintains good productivity (∼1.5 Mg DM ha⁻¹) and stable oil quality on 15% slope sites, highlighting its potential for the valorization of Italian sloping marginal lands.