Increasing biochar use and production for abandoned mine land restoration: Development of a management tool to select biochar types and rates across diverse soils and ecosystems

Biochar-based soil amendments can combat land degradation and improve soil health, reduce nutrient leaching, and increase water storage. There are hundreds of thousands of non-contaminated (i.e., non- productive with no heavy metal contaminants) abandoned mine land sites across the U.S. that need to be restored to reduce wind and water erosion, provide wildlife forage, shade streams, and improve soil productivity. Biochar has the potential to remediate these negative environmental consequences and restore vegetation, while simultaneously providing a use for forest waste residues and an opportunity to sequester carbon. Creating biochar from non-merchantable forest slash that would otherwise be burned serves to reduce fire risk and safeguard soil health and air quality. However, the use of biochar for mine site and ecological restoration remains rare in forested regions of the U.S. Recent biochar-themed workshops involving public land managers and private stakeholders revealed that the primary issue preventing greater use of biochar is a lack of research and information regarding biochar types, application methods and expected benefits for specific soils and climates. 

Science-based information is needed to encourage land managers to use biochar. A standardized and coordinated research approach is necessary to unravel the complex interactions between different biochar types and site-specific responses. Currently, there is little cohesive data about various types of biochar, made in various ways, and how respective soil- climate interactions may alter benefits for mine site remediation. Similarly, few studies have followed ecosystem responses in biochar amended mine sites beyond ~3 years. These knowledge gaps limit land managers’ ability to select optimal biochar feedstocks and characteristics, as well as to predict expected benefits and timescales for complete site recovery. At the national scale, these unknowns present a pervasive barrier for scaling up production and use of biochar in forest and mine site remediation activities, despite ongoing needs for viable opportunities to utilize forest waste residues, improve forest health and increase land management-based pathways for carbon sequestration. 

Photo Credit

USDA photo by Jessica Brewen

We propose to address these pervasive issues with the following set of research activities:

1. We will apply a single, standardized biochar type (i.e., from Restoration Fuels LLC, John Day, OR) on many (>10) different soils, under different climates, to determine site level controls on rehabilitation success associated with biochar amendment. In addition, we will also vary biochar application rates to better define optimal methods.
2. Using a variety of biochar types (i.e., from different feedstocks and production methods), we will determine relationships between specific biochar properties (i.e., pH, CEC, water retention,) and the soil (i.e., chemical/physical/microbial properties) and vegetation response at two sites with contrasting soils and climate.
3. Across a series of previously established biochar research sites in the eastern and western U.S., which span unique combinations of soils, vegetation and climate, we will analyze and contrast the intermediate term (3-8 years post application) of soil, microbial (e.g., fungi and bacteria), and vegetation response to biochar amendments relative to adjacent, undisturbed analogs.
4. Leveraging the data and iterative opportunities of the proposed field studies, we will build, calibrate and validate a model of ecosystem responses to biochar applications across edaphic and climatic gradients. This model will be built into an interactive land management tool for public use. 

This experimental work is coordinated with our partners from Regions 4, 6, 8, and 9, Pacific Northwest and Northern Research Stations, and with Restoration Fuels, LLC (U.S. Endowment and Forest Service partners). In-woods biochar production will be done with previously purchased Air Curtain, Inc., CharBoss. The project will support a post-doc and a PhD student to lead/assist with field work, data management, tool development and publishing results (i.e., datasets, manager’s guide and peer- reviewed papers).

Objectives 

1. Using standard woody residue feedstocks and biochar created by different thermochemical methods, we will identify optimal biochar characteristics (e.g., porosity, cation exchange capacity, etc.) and application rates for remediation of mine sites across the U.S., with attention towards response contrasts between areas with distinct soils, vegetation, and climate combinations.
2. Use field study data to develop, calibrate, and validate a model of soil-vegetation responses to biochar amendment, and an associated tool for land managers.
3. Evaluate the intermediate term (3-10 years) success of soil and vegetation recovery across mine sites amended with biochar across the U.S., to validate often theorized, yet rarely confirmed, timescales and pathways for complete site recovery.

Expected Project Results 

A. Outputs:

We will provide land managers with needed information and a tool to select appropriate biochar types and application rates for remediation of disturbed areas and to better predict associated soil and vegetation responses. We will deliver webinars/workshops and share findings at regional and national mine restoration meetings. We will publish our data, a manager’s guide, and at least two or three peer-reviewed journal papers.

B. Expected Outcomes:

We expect this work to fulfill manager needs, at the national scale, for defining appropriate biochar characteristics, application methods and the expected benefits for rehabilitating abandoned mine soils and other disturbed areas with biochar. This project will support and promote national emphases for the production and use of biochar, mine land remediation, fostering climate-smart land practices, and fire risk reduction. Work also establishes a long-term monitoring network with opportunities to further study mine land treatment responses and environmental conditions.

C. Metrics of Success:

Success will be the provision of our multi-faceted study data and the dissemination of our findings through presentations, online tools and information, and a variety of publications. These products will provide specific tools and guidelines for land managers to confidently select an appropriate biochar and application method to remediate abandoned mine soils across the U.S., and a foundation to predict outcomes related to vegetation, erosion, and soil health.

Geographies and High-Risk Landscapes to be Addressed 

This project will address several high-risk landscapes on National Forests by addressing the need to dispose of ‘waste’ woody residues to reduce a risk of wildfire. Our work will be located primarily on the Payette, Boise, Umatilla, Superior, Daniel Boone, and Arapahoe-Roosevelt National Forests where abandoned mine sites are located. Potential exists to expand further as opportunities arise on other high-risk landscapes (e.g., Grand Mesa, Uncompahgre, and Gunnison National Forest).