Application of bioenergy ash as a fertilizer for conifer seedlings in a sub-borial reforestation site in the central interior, British Columbia

In the Central Interior, British Columbia, two trials (in pots and in the field) examined conifer seedlings (lodgepole pine and hybrid spruce) subjected to treatments composed of two ash types (gasifier vs boiler), combined with nitrogen or alone. Two methods of placement, either broadcast spread or burying an ash-filled teabag, and two rates of application (2 tonnes ha-1 and 4 tonnes ha1) were other factors tested. Findings suggested ash fertilization success depended largely on tree species. The gasifier ash, high in mineral content compared to the charcoal-filled boiler ash, prompted the most growth, with and without nitrogen added, and also the highest soil pH increase. The low dose of ash was preferred by both species. Ash placement impacted belowground variables in the seedling pots and, in the field trial, positively influenced spruce growth. Broadcast ash induced the greatest soil pH change, compared to the teabag method.