In this paper, a screening‐level life cycle assessment (LCA) approach is used to compare the potential environmental benefits and tradeoffs of different management options for wood ash, namely, agricultural land application, forest soil amendment, use in forest roads, use in concrete and mortar, and landfilling. Uncertainty analyses are used to evaluate the generalizability of the results obtained. Although decisions regarding the selection of a beneficial use option are site‐specific and depend on available local markets and wood ash characteristics, this study shows that it is possible to draw a few general conclusions from the application of LCA. All beneficial use (BU) options showed lower environmental indicator scores than those associated with landfilling, in addition to net potential environmental benefits. From an environmental perspective, results suggest that, only in a few situations, beneficially using wood ash might not produce potential net environmental benefits but would still be preferred over landfilling, and in a very few cases, landfilling would be preferred over a BU option. For instance, net environmental benefits may be compromised if wood ash needs to be transported over long distances before it can be beneficially used. Out of the four BU options evaluated, the use of wood ash in concrete to replace Portland cement showed the greatest potential environmental benefits. However, the application of wood ash on agricultural or forest land showed greater environmental benefits than the use in concrete in cases where both its liming and fertilizing potentials are assumed to be achieved at the same time.

Several regulatory agencies and universities have published guidelines addressing the use of wood ash as liming material for agricultural land and as a soil amendment and fertilizer. This paper summarizes the experiences collected from several forest products facility-sponsored agricultural application programs across North America. These case studies are characterized in terms of the quality of the wood ash involved in the agricultural application, approval requirements, recommended management practices, agricultural benefits of wood ash, and challenges confronted by ash generators and farmers during storage, handling, and land application of wood ash. Reported benefits associated with land-applying wood ash include increasing the pH of acidic soils, improving soil quality, and increasing crop yields. Farmers apply wood ash on their land because in addition to its liming value, it has been shown to effectively fertilize the soil while maintaining soil pH at a level that is optimal for plant growth. Given the content of calcium, potassium, and magnesium that wood ash supplies to the soil, wood ash also improves soil tilth. Wood ash has also proven to be a cost-effective alternative to agricultural lime, especially in rural areas where access to commercial agricultural lime is limited. Some of the challenges identified in the review of case studies include lengthy application approvals in some jurisdictions; weather-related issues associated with delivery, storage, and application of wood ash; maintaining consistent ash quality; inaccurate assessment of required ash testing; potential increased equipment maintenance; and misconceptions on the part of some farmers and government agencies regarding the effect and efficacy of wood ash on soil quality and crop productivity.