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Thinning woody biomass to reduce wildfire risk has become a common forest management prescription throughout the Intermountain West. Converting the resulting slash into biochar, a carbon-rich soil amendment, could help mitigate some of the shortcomings of other fuel treatments, but land managers in the western United States have not widely adopted biochar, despite its potential benefits and new government incentives. Thus, we investigated the often under-studied sociocultural, economic, and biophysical barriers to biochar production and identified important factors to inform future outreach efforts that will help to expand biochar production from thinning slash in northern New Mexico. We distributed surveys and conducted interviews with land managers and personnel working in environment conservation organizations who work with land managers throughout northern New Mexico. We found that 65% of participants (n = 60) were familiar with biochar, and 13% already produced biochar. Participants identified improving soil and reducing forest fuel loads as the main benefits of biochar. The most prevalent barriers to adopting biochar were insufficient knowledge about biochar production and its application and concerns about production costs. Given land manager preferences, outreach efforts to encourage biochar adoption should focus on hands-on informational activities. Barriers and preferred outreach methods varied by participant race and familiarity with biochar. With appropriate training to empower land managers, biochar can provide environmental and community benefits by the sustainable conversion of forest residues into a soil enhancement product that would be beneficial to northern New Mexico's dry, high wildfire risk context., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

For millennia, Maya farmers (i.e., milperos) throughout Mesoamerica have managed milpa: sequential agroforests initiated by slashing and burning patches of secondary forest and then cultivating a diverse polyculture of trees and annual crops. To reduce greenhouse gas emissions associated with deforestation, the Mexican government and non-governmental organizations have urged milperos to cease burning. We collaborated with Maya milperos in several communities in the Montes Azules Biosphere Reserve region in Chiapas, Mexico to determine carbon retained as char in traditional milpas, carbon loss associated with burning, and effects of burning on soil quality. We found the carbon retention of char in Maya milpas (24 ± 6.5% of C in vegetation) is 4-1400% higher than other slash-and-burn agroecosystems reported in the literature. Burning resulted in significant carbon loss of 12.6 (±3.6) t C ha -1 yr -1 , but this was partially mitigated by char production (3.0 [±0.6] t C ha -1 yr -1 ) and incomplete combustion of woody biomass. The effects of burning on soil were minimal, with the only significant changes observed being increases in pH, potassium availability, and cation exchange capacity (2, 100, and 7%, respectively). The mean residence times of charred materials were at least double that of uncharred biomass. While there is a risk that shortening fallow periods would undermine the sustainability of Maya swidden agroecology, proper management and secure land tenure can help maintain intensive production without enduring environmental degradation. The char produced in these swiddens and successional management could allow this agroforestry system to be a long-term carbon sink., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tomasz B Falkowski reports financial support was provided by Cornell Atkinson Center for Sustainability. Ronald Nigh reports a relationship with Dana A.C. that includes: non-financial support., (Copyright © 2023 Elsevier Ltd. All rights reserved.)