Journal Articles

See the latest peer-reviewed journal articles published in partnership with the Utah Biomass Resources Group.

Use of Biochar By Sheep: Impacts On Diet Selection, Digestibility, and Performance

McAvoy, D.J, Burritt B., & Villalba, J.J. 2020. Use of biochar by sheep: impacts on diet selection, digestibility, and performance. Journal of Animal Science, December, 2020, Volume 98, Issue 12, skaa380.


The objective of this study was to determine the influence of biochar obtained from exothermic production of lodgepole pine (Pinus contorta) and quaking aspen (Populus tremuloides) on sheep performance and diet digestibility and on preference for a ration enriched with this carbon-based material. Twenty-four lambs were housed in individual pens and assigned to one of three treatment groups (eight animals per group), where they received: 1) a 60:40 ration of alfalfa:barley (Control), 2) an isoenergetic and isonitrogenous ration with alfalfa, barley, and 2% biochar (BC), and 3) a simultaneous offer of the Control and BC rations (Choice). Lambs were exposed to two consecutive feeding periods (Period 1: 13 d and Period 2: 21 d), representing time intervals where the evolution of intake, animal performance, and rumen parameters were assessed; in vivo digestibility was determined during the last 5 d of the study. Ration intake did not differ among groups of lambs (P > 0.10), although during some days in Period 2, intake was greater for the BC and Choice groups than for the Control group (P < 0.05). Lambs in Choice had a lower preference for BC than for the Control ration (Period 1: P < 0.05; Period 2: P < 0.10), although they incorporated a substantial amount of BC (39 and 40%, for Periods 1 and 2, respectively) into their diets. No differences in body weight gains (ADG) or gain-to-feed ratios were found among groups of animals (P > 0.10), although dry matter digestibility and digestible dry matter intake was greater for lambs in the BC group than for lambs in Control group (P < 0.05). The ruminal concentration of the volatile acid acetate in Period 2 was greater for BC than for Choice (P < 0.05). During the same period, the concentration of valerate and ruminal pH values were greater in BC than in Control (P < 0.05). Thus, the addition of biochar to grain-based diets enhanced diet digestibility and influenced some ruminal parameters in lambs. Nevertheless, these positive effects were not reflected in significant improvements on ADG or feed conversion efficiencies. Lambs offered choices between Control and BC rations formed a diet with concentrations of biochar of ~1.2%, suggesting that these animals would tolerate such levels without reductions in ration palatability.

Read the Use of Biochar by Sheep Article

Mobile Pyrolysis for Hazardous Fuels Reduction and Biochar Production in Western Forests

McAvoy, D.J., Dettenmaier, M., and Kuhns, M.R. 2018. Mobile pyrolysis for hazardous fuels reduction and biochar production in western forests, Journal of Extension, February, 2018, Vol 56/No. 1/Ideas at Work/ 1IAW3.


Mobile pyrolysis is a novel approach to fuels reduction. In this article, we address the experiences of the Utah Biomass Resources Group in developing mobile pyrolysis technologies and generating the products derived from pyrolysis of woody biomass—biochar, bio-oil, and syngas. We describe development of a mobile pyrolysis platform for biomass conversion demonstration, its use in a series of demonstrations conducted in several western states, and the usefulness of the resulting products. Additionally, we discuss our outreach and communication efforts to date and speculate on the future of the technology.

Read the Mobile Pyrolysis for Hazardous Fuels Article

Methods to reduce forest residue volume after timber harvesting and produce black carbon

Page-Dumroese, D., Busse, M.D., Archuleta, J.G., McAvoy, D.J., and Roussel, E. 2017. Methods to reduce forest residue volume after timber harvesting and produce black carbon. Scientifica. 2017: Article ID 2745764. 


Forest restoration often includes thinning to reduce tree density and improve ecosystem processes and function while also reducing the risk of wildfire or insect and disease outbreaks. However, one drawback of these restoration treatments is that slash is often burned in piles that may damage the soil and require further restoration activities. Pile burning is currently used on many forest sites as the preferred method for residue disposal because piles can be burned at various times of the year and are usually more controlled than broadcast burns. In many cases, fire can be beneficial to site conditions and soil properties, but slash piles, with a large concentration of wood, needles, forest floor, and sometimes mineral soil, can cause long-term damage. We describe several alternative methods for reducing nonmerchantable forest residues that will help remove excess woody biomass, minimize detrimental soil impacts, and create charcoal for improving soil organic matter and carbon sequestration.

Read the Methods to Reduce Forest Residue Article

Preliminary Screening of the Effect of Biochar Properties and Soil Incorporation Rate on Lettuce Growth to Guide Research and Educate the Public Through Extension

Hunter, B., Cardon, G.E., Olsen, S., Alston, D.G., and McAvoy D.J. 2017. Preliminary screening of the effect of biochar properties and soil incorporation rate on lettuce growth to guide research and educate the public through Extension. Journal of Agricultural Extension and Rural Development, Vol.9 (1), pp. 1-4, January 2017.


Extension service of the land grant university system is often the first source of public information for emerging soil amendments such as biochar. Biochar is a charcoal product made by heating plant biomass via pyrolysis and is increasingly marketed as an organic soil amendment. As energy producing pyrolysis industries expand, there is increasing opportunity to utilize locally produced biochar for its potential value in sustainable agriculture. However, the highly variable properties of biochar materials and their effects on plant growth and soil nutrient supply make it difficult to objectively study the effect of this soil amendment and provide guidance to users of locally sourced biochar materials. Therefore, preliminary screening studies are needed to identify potentially beneficial ranges of biochar properties and their effects on soils and plants that can then be rigorously tested in field research. The role of extension in conducting such screening studies is invaluable to providing both guidance to researchers in developing sound study methods, and in educating the public on biochar and the myriad of uncertainties surrounding its use; thereby establishing the need for rigorous research on its properties. In 2014, a simple, yet informative screening trial was performed to identify optimal biochar pyrolysis production temperature, conditioning (that is, degree of crushing) and soil application rate for future field experiments. Lettuce (Lactuca sativa, var. Parris Island Cos) chosen for its short growth period and rapid biomass development, was grown in 9-L pots filled with silt loam field soil amended with biochar and/or fertilizer (or none) made from Utah-sourced cherry wood. The pots were uniformly drip irrigated once daily to keep them near field capacity throughout the study period, thereby eliminating any influence of differential soil-plant-water relations. Three biochar products created from the same cherry wood source, but resulting from three different pyrolysis temperatures (375, 475 and 575°C) and either powder ground (P) or masticated (M) texture were applied to soil at three application rates (1, 2 and 3% by weight). Variation in plant dry weight at harvest within and among treatments was high. Lettuce growth with the addition of biochar was decreased as compared to control treatments in all cases, except for biochar produced at the lowest temperature, 375°C. Results indicate that masticated biochar produced at 375°C and applied to soil at the rate of 2% by mass offers the best combination of beneficial response and ease of handling for future field evaluations. This case study’s benefit for demonstrating the value of preliminary screening trials to inform both future research and public outreach education is discussed.

Read the Preliminary Screening of the Effect of Biochar Article

Co-firing of pulverized coal with pinion pine/juniper wood in raw, torrified and pyrolyzed forms

Nelson, M. & McAvoy, D.J. 2013. Exploring solutions to pinyon and juniper expansion and densification through Biomass Field Days. Journal of National Association of County Agriculture Agents.


A program was funded by the U.S. Forest Service to perform pilot-scale co-firing studies at the University of Utah in a 1.5 MW pulverized-coal test facility, to examine the emissions, deposition behavior and ash characteristics, when co-firing pulverized coal with wood culled from pinion–juniper (P–J) forests in Utah.

The woody material was evaluated in each of three forms: 1) raw, untreated material; 2) torrefied material, and 3) biochar from the pyrolysis of the P–J material. The different types of the thermally processed P–J material were produced by Amaron Energy in a 1/2 t per day prototype pyrolysis facility prior to the testing at the University of Utah. 

Results of the pilot-scale co-firing trials indicated essentially no major differences in gaseous emissions or unburned carbon in flyash or baghouse ash when co-firing pulverized coal with any of the 3 biomass fuels for the conditions investigated. In addition, no significant deposition problems would be anticipated using 5–10% biomass on a thermal input basis. Operation with 10% or greater percentage of raw or torrefied wood resulted in feeding problems at this scale; however, the bio-char could be fed with no problems for levels as high as 20% (the highest percentage tested).

Read The Co-firing of Pulverized Coal Article

Exploring Solutions to Pinyon and Juniper Expansion and Densification Through Biomass Field Days

Nelson, M. & McAvoy, D.J. 2013. Exploring solutions to pinyon and juniper expansion and densification through Biomass Field Days. Journal of National Association of County Agriculture Agents.


Pinyon and Juniper (PJ) trees are taking over rangelands in the western U.S. Currently there are nearly 50 million acres of PJ woodlands and more acres are being expanded into each year. Utilization of woody biomass generated from forest treatments can provide jobs, stimulate the local economy and ultimately reduce the cost of forest treatments. Southern Utah Woody Biomass, a loosely knit organization of private individuals and government personnel has come together to promote the development of harvesting techniques and the utilization potential of PJ biomass. Since October 2010 three field days have been hosted in southern Utah. Over $7.5 million in equipment has been demonstrated and exhibited. Field day attendees include 715 people from 18 states, Canada, and China. The field days demonstrated different methods of harvesting in PJ woodlands and looked at ways of adding value to the harvested trees. Leading experts in the woody biomass and forestry industry addressed the importance of restoring woodlands and ways for industry and government to partner to address the problem.

Read the Exploring Solutions to Pinyon and Juniper Expansion Article

The Impact of Wood Biochar on the Plant Uptake of Pharmaceuticals and Personal Care Products from Reclaimed Wastewater

Flashinski, Jeffrey, "The Impact of Wood Biochar on the Plant Uptake of Pharmaceuticals and Personal Care Products from Reclaimed Wastewater" (2019). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 7464.


Reclaimed water (treated water discharged from wastewater treatment plants (WWTPs)) is increasingly used in drier regions for irrigation purposes. This effectively increases the water supply and reduces the amount of WWTP discharge into surface waters but it creates the potential for contaminants in the reclaimed water, such as pharmaceuticals and personal care products (PPCPs), to accumulate in exposed crops. The US Environmental Protection Agency (US EPA) considers PPCPs contaminants of emerging concern due to their near universal presence in the environment and their potential for endocrine disruption. Biochar is gaining attention as a soil amendment and could potentially be used to sequester contaminants in the soil thereby reducing the contaminant uptake in crops.

The main objective of this study was to investigate the impact of wood biochar on the corn uptake of PPCPs originating from reclaimed water. Biochars derived from regional trees were chosen because they are rapidly expanding and represent a source of forest fire fuel (pinyon and juniper trees) or because they are frequently attacked by insects (lodgepole pine). The impact of biochar on contaminant uptake was tested by growing corn in non-amended soil and soil amended with biochar while being watered with reclaimed water supplemented with PPCPs (1 mg/L). Sand was also used for comparison since it is a less sorptive growth media. After a 28- day growing period, the corn leaves were dried, extracted, and analyzed for PPCPs.

Read the Impact of Wood Biochar Article

Innovative Water Management Using Advanced Irrigation Systems and Biochar

Holt, Jonathan A., "Innovative Water Management Using Advanced Irrigation Systems and Biochar" (2021). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 8075.


Two approaches to water optimization in agriculture are to increase soil water retention and improve the efficiency of irrigation. A soil amendment that has received attention for its ability to increase soil water retention is biochar, the remaining biomass after high C materials have been pyrolyzed (burned with limited oxygen and heat). Two studies were conducted at a total of 10 site-years in Utah from 2018 to 2020 to evaluate how wood biochar influences the productivity and crop quality of irrigated alfalfa (Medicago Sativa L.), corn (Zea mays L.), and wheat (Triticum L.), along with soil water tension. One study included a single biochar rate of 22 Mg ha-1 at two irrigation levels (full vs. partial), where soil-incorporated biochar increased silage corn yield by 12% in 2018 and reduced yield by 10% in 2019. Top-dressed biochar had no impact on alfalfa yield from 2018-2020, in either irrigation rate. The other trial had six to seven biochar rates (0 – 67 Mg ha-1), plus the addition of wood chips at a single rate (22 Mg ha-1) at one site. This trial displayed a yield decrease of 0.01 Mg ha-1 of wheat grain for each additional Mg ha-1 of biochar applied, however there were no impacts on silage corn production. Data obtained over ten site years showed minimal impacts from biochar on crop yield, quality, or soil water tension, leading us to conclude that wood biochar was not an effective tool for enhancing crop production or conserving irrigation water in arid agriculture.

Most pivot sprinkler package in the Intermountain West are classified as mid-elevation sprinkler application (MESA). Several studies of low elevation spray application (LESA), low energy precision application (LEPA), and mobile drip irrigation (MDI) have demonstrated greater efficiency than MESA, due to less loss between the time that the irrigation water leaves the nozzle and enters the rootzone. However, these advanced sprinkler packages have rarely been tested at a reduced application rate. Eight site-years of data were collected at four Utah farms from 2018 to 2020, to evaluate crop yield and quality responses to full and reduced rates of each system in alfalfa, corn, and small grains. Soil water tension was also measured. Data showed that the advanced systems were sometimes able to maintain yield and quality while applying 15 to 25% less water, yet there were situations where MESA outperformed the advanced systems. This led us to conclude that there is not one style that will have the best results all the time, but that tailoring the package to the field characteristics is where the optimization with these packages can occur. Therefore, this chapter is being published as an Extension Guidebook for farmers.


Read the Innovative Water Management Article