Short-term changes in spruce foliar nutrients and soil properties in response to wood ash application in the sub-boreal climate zone of British Columbia

Abstract

Utilization of wood ash as a forest soil amendment in British Columbia could have numerous benefits, including potentially increasing tree growth. Two wood-derived bottom ashes (low-carbon gasifier ash and high-carbon boiler ash) were applied at 5000 kg ha −1 (dry weight equivalent) with urea (100 kg N ha −1 ), in a twoway factorial randomized block design across two (18-and 24-yr-old) hybrid spruce (Picea glauca × engelmannii Parry × Engelm.) plantations in interior British Columbia. Changes in spruce foliar nutrients and selected soil properties were evaluated. After one growing season, foliar Ca and S significantly increased in plots treated with ash, and foliar N significantly increased while foliar Mg and P significantly decreased in spruce treated with urea. In LFH horizons, soil pH, exchangeable base cations (Ca, Mg, and K), strong acid-extractable B, and Ca significantly increased (p < 0.05) with ash addition; soil pH was greatest in plots treated with urea plus gasifier ash. No significant treatment effects were observed in underlying mineral soil. We conclude that gasifier and boiler ash derived from clean wood applied at 5000 kg ha −1 are effective soil amendments as expressed within 1 yr by changes in nutrient status of LFH horizons and spruce foliage.Résumé : Employer les cendres de bois comme amendement forestier présenterait de nombreux avantages en Colombie-Britannique, notamment celui de faire croître les arbres plus vite. Les auteurs ont répandu 5000 kg par hectare (équivalent en poids sec) de deux sortes de cendres (celle d'un gazogène libérant peu de carbone et celle d'une chaudière en dégageant une grande quantité). Les cendres ont été appliquées avec de l'urée (100 kg de N par hectare) sur le sol de deux peuplements (18 et 24 ans) d'épinettes hybrides (Picea glauca × engelmannii Parry × Engelm.) dans le cadre d'une expérience bifactorielle par blocs aléatoires, dans le centre de la Colombie-Britannique. Ensuite, ils ont évalué comment variaient la concentration d'oligoéléments dans les feuilles et certaines propriétés du sol. Après une seule période végétative, la teneur en Ca et en S des feuilles avait sensiblement augmenté sur les parcelles amendées avec la cendre. La concentration foliaire de N avait sensiblement augmenté et celle de Mg et de P, sensiblement diminué chez les épinettes des parcelles bonifiées avec de l'urée. Dans l'horizon LFH, l'addition de cendres avait significativement (p < 0,05) accru le pH du sol, la concentration des cations de bases échangeables (Ca, Mg, K) ainsi que la concentration de B et de Ca extractibles à l'acide fort. Le pH du sol le plus élevé a été relevé dans les parcelles amendées avec de l'urée et les cendres du gazogène. Aucun effet important dû au traitement n'a été observé dans la couche sous-jacente de sol minéral. Les auteurs en concluent que l'application de 5000 kg par hectare de cendres de bois propre venant d'un gazogène ou d'une chaudière est un amendement efficace, comme l'illustrent les changements notés un an plus tard avec le bilan nutrit...

Wood ash as a soil amendment in Canadian forests: what are the barriers to utilization?

“…1 site; Table 4), forest floor pH increased in the first year following application of 2 Mg•ha −1 or 8 Mg•ha −1 of wood ash, and treatment effects remained constant at years 2 and 5 (Brais et al 2015). In a white spruce (Picea glauca (Moench) Voss) plantation in northcentral British Columbia, forest floor pH had increased five months after the application of 5 Mg•ha −1 low-carbon gasifier ash or highcarbon boiler ash; treatment effects were strongest following the application of gasifer ash, particularly when applied in combination with 100 kg•ha −1 urea (Domes et al 2018). In all of the above studies, wood ash application had no significant effect on the pH of the surface (0-10 cm) mineral soil.…”

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

“…Similar to Domes et al (2018), increased soil pH was observed where a lowcarbon ash (similar to the UNBC ash type in this trial), was applied to young, 18 and 25-year old spruce stands. Our results suggested the N addition stabilized the pH somewhat.…”

“…These two kinds of ash placements were integrated into the study to determine whether the location of the ash would impact the seedlings during a vital establishment phase, particularly where a slump in nutrients can occur post-harvest (Olsson et al, 1996;Thiffault et al, 2010) Depending on the mineral content and texture of the ash, UNBC ash being finetextured compared to the chunkier CPLP ash, a type of ash stabilization prior to land application might be recommended (Jacobson, 2003). The ashes used in this study were very similar to the gasifier (UNBC) and boiler (CPLP) ashes reported by Domes et al (2018). The gasifier ash is a high mineral, low carbon ash with a greater calcium carbonate equivalence (i.e.…”

“…greater neutralizing capacity) and base cation content than the high carbon (mainly charcoal) boiler ash (CPLP). Domes et al (2018) found that the low carbon gasifier ash was more reactive, increasing soil pH and exchangeable base cations than the higher carbon boiler ash.…”

Forest soil biotic communities show few responses to wood ash applications at multiple sites across Canada

“…There are reports of changes to soil functional and community composition due to the addition of ash throughout the literature. However these lack consistency in the amount of amendment required to elicit a response and the direction of response 19 , 22 , 48 – 50 . Comparing the results of these studies is further complicated by methodological differences between them.…”