Carbon-based pelleting, soil ripping and herbicide application can be used to overcome plant recruitment barriers in Grey Stinkwood (Jacksonia furcellata)

Seed-based restoration efforts frequently experience limited success due to competition from invasive plant species and poor soil conditions. We aimed to alleviate these plant recruitment barriers through a combination of carbon-based seed enhancement technologies and commonly applied restoration management practices. Compared to non-pelleted (control) seeds, we tested seven seed enhancement technologies on Grey Stinkwood (Jacksonia furcellata), a perennial shrub common within the Banksia Woodlands of Western Australia, which included extruded pellets, coating and coins (a novel extrusion method), incorporated with activated carbon or biochar. We tested five management practices including combinations of herbicide and soil ripping at two locations (post-sand mine and Post-pine plantation). At the Post-pine site, coins incorporating biochar had the highest overall mean emergence (53%), and at the Post-mine site, extruded pellets containing activated carbon had the highest mean emergence (58%). In comparison, emergence was significantly lower from the non-pelleted seeds (44% and 45% respectively). Survival at the Post-mine site was also higher from biochar coins (31%) compared to the non-pelleted seeds (22%), and highest in plots with herbicide application followed by soil ripping (36%), compared to the control, in which no management practice was applied (16%). At the Post-pine site, survival was poor (<10%), and seed treatment and management practice did not significantly affect seedling survival. Using carbon-based seed treatments and management practices, such as herbicide application followed by soil ripping, may help to overcome seedling emergence bottlenecks in direct seeding programmes. However, further examination into seedling survival is required, particularly within highly degraded settings, before seed enhancement technologies are used in large-scale seeding programmes.