Double cropping autumn-sown camelina with food crops and pelargonic acid application

Double-cropping systems represent a sustainable strategy to produce feedstock for the biobased industry without reducing food security, while simultaneously improving farmer profitability. Camelina [Camelina sativa (L.) Crantz], given its adaptability and short growth cycle, can serve as a winter intermediate crop, replacing fallow periods and preceding the establishment of typical summer food crops of the Mediterranean cropping systems. A two-year study (2022–2024) was conducted at the Experimental Farm of the University of Bologna to evaluate the agronomic performance, resource use efficiency, and economic profitability of two camelina varieties (CCE117 and CCE44, Camelina Company Spain) double-cropped with grain sorghum (Sorghum bicolor L.) and sunflower (Helianthus annus L.). Pelargonic acid was for the first time applied to camelina to accelerate camelina desiccation and advance harvest maturity, thereby enabling earlier establishment of the following crop. The application of 14.5 L ha-1 pelargonic acid bioherbicide on half of camelina strips (Cam-PA) allowed for an earlier harvest (7–15 d,) when compared to harvesting camelina at physiological maturity (Cam-FM). Cam-PA achieved the highest seed yield (Cam-PA:1.26 Mg DM ha- 1 vs. Cam-FM: 0.91 Mg DM ha-1), but had a lower seed oil content (Cam-PA: 26.1% vs. Cam-FM: 30.4%). Sunflower following Cam-PA achieved an average seed yield of 1.83 Mg DM ha-1, resulting in 47% higher total seed production of the double-cropping system than of a sole sunflower system; this double-cropping system also yielded the highest system gross revenue, €1675 ha-1. By contrast, the camelina-sorghum sequence produced nearly 90% less seed yield than sole-sorghum system, which highlights the need for earlier-maturing hybrids and suggests that double-cropping with sorghum may be feasible when implemented in silage or biogas production.