Source: UNIVERSITY OF ARIZONA submitted to
CHARACTERIZATION AND USE OF BIO-CHAR AS A SOIL AMENDMENT, AND FERTILITY IMPLICATIONS FOR SEMI-ARID SOILS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0218159
Grant No.
(N/A)
Project No.
ARZT-1365570-H21-159
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2009
Project End Date
Sep 30, 2014
Grant Year
(N/A)
Project Director
Artiola, J.
Recipient Organization
UNIVERSITY OF ARIZONA
888 N EUCLID AVE
TUCSON,AZ 85719-4824
Performing Department
Soil, Water & Environmental Science
Non Technical Summary
Bio-fuels derived from bio-char (pyrolysis of organic residues) are considered viable forms of carbon-negative energy production. Bio-chars, while producing bio-fuels, retain one-half of original carbon in their structures in the form of lightweight, highly porous particles that sorb water, pollutants, and nutrients. In addition, these materials are considered stable in the soil environment for hundreds to thousands of years. Numerous sources of organic residues, amenable for bio-char production, are available to produce bio-fuels and bio-chars, including forest and agriculture residues and animal wastes. These renewable organic materials are often incorporated into the soil where they degrade quickly, or are burned, releasing carbon dioxide into the atmosphere. Bio-char production may soon become viable for energy production in rural, agricultural areas with the use of transportable pyrolysis units that produce bio-fuel and bio-char materials in-situ (farms, orchards, forests) that can be readily incorporated into nearby agricultural soils. Besides storing carbon and generating carbon credits, users of bio-char may realize additional benefits, since these materials improve the structure and water holding capacities of soils and may increase soil fertility by providing a reservoir of nutrients (ammonia, nitrate, phosphate) for plants. The least researched part of this process is the nutrient management capabilities of bio-char materials in the soil environment. There is a need to quantify the beneficial aspects of bio-char added to the soil environment as a potential storage/release vessel for fertilizers. Adopters of bio-fuel production should know the full range of benefits related to the production and use of bio-char for land application. Farmers in particular, must be persuaded at multiple fronts about the benefits of recycling organic wastes if they are to embrace this sustainable approach to energy production. Defining the cost-saving nutrient management benefits of bio-char soil amendments, will help increase bio-char (and energy) production from renewable organic residues and animal wastes.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
10201102000100%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
0110 - Soil;

Field Of Science
2000 - Chemistry;
Goals / Objectives
This research will focus on the following objectives: 1) Help develop bio-char materials by working closely with the University of Arizona Bio-Fuel and Bio-char Research Group (see cooperation section) to produce cost-effective bio-chars, beneficial as soil amendments for Arizona semi-arid soils. 2) Characterize new bio-char products as they are produced by the UA Bio-fuel and Bio-char Research group using laboratory standards chemical characterization methods, including bio-char sorption capacities, and batch equilibrium studies. 3) Characterize the nutrient sorption and release properties of bio-char products, produced by the University of Arizona bio-char research group, using laboratory soil-bio-char column studies. 4) Use greenhouse studies to determine nutrient storage, leaching, and plant nutrient uptake of Arizona vegetable crops grown in bio-char-amended Arizona soils.
Project Methods
Procedure/Benefits/Audience. The success of this research is tied to other activities of the University of Arizona Bio-fuel and Bio-char Research Group. However, commercially available bio-char materials may be used initially (example, mesquite bio-char) to conduct laboratory and greenhouse studies. Nonetheless, the principal goal of the group is to generate and test bio-fuels AND bio-chars, derived from locally (Arizona) produced organic residues and wastes from agriculture and forestry. This will be accomplished with a pilot scale pyrolysis unit being installed at the University of Arizona Red Rock Agricultural Research Center. The bio-chars will be tested for their general and specific macro and micro-nutrients sorption/release characteristics under laboratory batch conditions. Selected bio-chars will also be tested in the laboratory for total carbon, nitrogen, and sulfur and total ash content. The mineral composition of these materials will also be determined. All nutrient sorption/release studies will have controls to establish the contributions (if any) that these materials can add (nutrients, salinity, alkalinity) to the soil/water environment. All characterizations will be done on representative samples of bio-char newly produced materials obtained from composited sub-samples (n>6) and analyzed in triplicate. Selected bio-char materials, based on the results of step 2, will be tested under simulated field conditions, to determine the specific macro and micro nutrients sorption/release properties, using columns packed with soil-bio-char mixtures. The column eluents will be analyzed to quantify the sorption/desorption properties of these mixes under dynamic (flow) conditions. See step 2 for the list of ions that will be monitored in the eluting soil pore volume fractions. The best-performing bio-chars, based on the results of steps 2 and 3, will be tested in greenhouse conditions to evaluate nutrient leaching losses and plant nutrient status during a plant growth cycle. This will be done using pots with soil-bio-char mixtures (to be determined) seeded with plants (crops) grown in Arizona (alfalfa, lettuce, sorghum, cotton). A completely randomized block design will be used with multiple replicates (n>4). Volumes and major chemical characteristics (pH, salinity) of the pot leachates will be measured after each irrigation. Samples of these leachates will be preserved and analyzed for nutrients at the end of the plant growth cycle. Rural Arizona farmers could benefit from this bio-char energy production approach by: reducing their dependency on fossil fuels, recycling agriculture wastes, storing carbon credits in the soil, saving irrigation water and fertilizer costs, and increasing plant yields and biomass production. The benefits to the public in general include, nationally lowering our dependency on imported liquid fossils for energy production, increasing carbon storage, rather than releasing it into the atmosphere, reducing the rate of global warming, saving valuable local water resources, and increasing food production locally, thereby reducing food costs and imports.

Progress 07/01/09 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Two MS and one Ph.D. student have benefitted from this project through external funding obtained to support biochar-related research on the use of biochar as a soil amendment. In addition several part-time laboratory students have participated in the analysis and characterization experiments of biochar materials. How have the results been disseminated to communities of interest? An Extension publication related to the preparation and use of biochar in urban landscaping and home gardening is in its planning stages. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The original goals were met as follows: Biochar derived from Arizona pine forest waste woodchips was produced using forest waste provided by the U.S. Forest Service through Bio-fuel Biochar research group. Bio-fuel derived from forest green waste was not found to be technically achievable using fast pyrolysis gasifier. Slow pyrolysis batch methods were used to convert pine forest waste and other green wastes into biochar. Pine forest waste derived biochar was selected because of the ready availability and consistency of green waste, relatively low alkalinity (compared to other biochar materials such as mulberry, mesquite, and sorghum bagasse) and the physical stability and high porosity of its particles. The second goal was met with the full characterization of the PFW biochar using traditional and adapted chemical and physical methods, including: Alkalinity, pH, soluble and total salts, nutrients such as N, P, and K, porosity, particle size distribution and moisture release curve. Pine forest waste derived biochar was found to have a very heterogeneous particle size distribution ranging from less than 1mm to over 2cm in length, which difficulted the use of this material in small scale laboratory characterization efforts such as porosity and moisture release/retention studies. Overall, this biochar was found to have an exceptional porosity (80%) and therefore particle bulk density. However, laboratory studies simulated field conditions showed that the pore space of this biochar could only be partially filled with water at 50% capacity even after prolonged periods of submersion. The third goal was partially met initially with laboratory studies showed that this material could retain significant amounts of ammonia but negligible amounts of nitrate ions under laboratory batch conditions. Under laboratory column flow conditions significant amounts of ammonia gas were also retained in biochar, suggesting that this material can storethis gaseous form of N that may otherwise escape from alkaline soils during periods of drought. Other nutrients such as K, Ca, Mg, P were found to be present at concentrations or chemical forms not significant to the fertility of alkaline soils or not chemically unavailable in alkaline pH soils. The fourth goal was met with the use of several greenhouse studies, summarized as follows: These studies were carried out using a light-textured (loamy sand), alkaline soil common in semi-arid climates that contained only 0.2% organic carbon. The addition of up to 4% by weight PFW biochar significantly increased the soil's water holding capacity and extended to survival of a turfgrass by up to two weeks under drought conditions in warm season grasses such as bermudagrass. Other grasses of the desert southwest responded similarly under drought conditions in biochar amended soil nearly doubling their survival period over the controls. The grasses tested under greenhouse conditions included: needle brama grass and Cane beargrass) . Nonetheless, in the biochar amended soils there was an initial period of stunted growth on salt-sensitive plant (romaine lettuce), which did not extend beyond the first planting cycle. Thereafter, the repeated use of the same biochar-soil mixes seeded again produced plant yields at the 2-4% biochar application rates significantly above those of the controls. This suggests that biochar not only retains water but also nutrients such as nitrogen that are released back into the soil solution and sustain plant growth when no new fertilizer is applied.

Publications

  • Type: Journal Articles Status: Published Year Published: 2012 Citation: Artiola, J.F., C. Rasmussen, and R. Freitas. 2012. Effects of a Biochar-Amended Alkaline Soil of he Growth of Romaine Lettuce and Bermudagrass. Soil Science. 177:9, 561-570.
  • Type: Other Status: Published Year Published: 2009 Citation: Villareal-Manzo L. Water conservation in biofuels development: greenhouse and field crop production with biochar. (Ph.D. dissertation. The University of Arizona)
  • Type: Journal Articles Status: Other Year Published: 2012 Citation: Villarreal-Manzo, L., P. Waller, R.J. Freitas, R. Ryan, J.F. Artiola, C. Rasmussen, T. McDonald, M. Tuller, M. Meding. Assessment of crop drought tolerance in biochar amended soils. Submitted to Irrigation Science. Not accepted. In Revision
  • Type: Theses/Dissertations Status: Accepted Year Published: 2014 Citation: Kazumasa Yamafuji. Studies of biochar and manure to mitigate carbon dioxide release and nitrogen deficiency in semi-arid soils. Masters Thesis. The University of Arizona.


Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? New collaborations are being established with other faculty to continue studying biochar-animal waste interactions and biochar-stormwater contaminants interactions. Potential collaborations with producers of composts to develop value-added compost materials with biochar. How have the results been disseminated to communities of interest? Peer reviewed publication in Soil Science (see 2012) reports. An Extension publication is in the planning stages What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Pine forest waste biochar is relatively low in alkalinity (~1-5%), a desired trait for AZ soils, which are normally alkaline. The PFW biochar can hold up to 4 times its weight in water due to its high porosity (~86%). However, under field or submerged conditions, up to 50% of the biochar pores remain empty. This unique property of biochar may contribute to the refractive nature and therefore longevity of this carbon-based material in biologically active, oxidative natural systems like soils. PFW biochar can be used to reduce water stress in Bermuda grass (commonly used in water thirsty golf courses) and can also be used in revegetation projects that directly seed native grass species. Thus, native grasses, and possibly other native plant species tolerant to extreme pH-salinity soil conditions, may adapt quickly to a soil amended with PFW biochar, becoming more drought-resistant. However, the addition of PFW biochar to alkaline soils may require a period of "aging" before pH-salinity sensitive vegetables can benefit. Biochar previously exposed to fertilizers may trap and release them subsequently when plants are not fertilized externally. Biochar may also reduce fertilizer leaching in light textured soils by slowing the release of chemicals during periods of excess soil water application. Dry Pine forest waste biochar may sorb significant amounts of ammonia gas sort-term. This may be advantageous during periods of drought and to control ammonia emissions from semi-desert soils.

Publications


    Progress 01/01/12 to 12/31/12

    Outputs
    OUTPUTS: Arizona pine forest waste woodchips, obtained from the Forest Service, were used to produce biochar (PFW) using slow pyrolysis (batch mode) with a biochar temperature of 450-500 degrees C. Our green house (GH) studies (reference below) have shown that pine PFW biochar can be used as a soil amendment in AZ soils that are typically alkaline, moderate to high pH, and well-drained. Although biochar amended soil needs a period of acclamation, lettuce seed germination rates are no different in the biochar-treated soil than in the controls and wet plant matter yields were higher (at the 95%CI) in the 4% and the 2% biochar higher than the control. Thus, any deleterious effects of fresh biochar may have had to lettuce plants initially, dissipated in subsequent GH trials using the same biochar-amended soils. New GH studies this year showed that lettuce plant growth was significantly higher than the controls because biochar acted as a slow release fertilizer source. This was demonstrated using soil-biochar mixes pretreated with a fertilizer solution as sole source of nutrients during the entire plant growth cycle. Previous research, now also published, showed that Bermuda grass may have benefited from the presence of biochar, which increased the water holding capacity of the loamy sand soil as demonstrated by laboratory soil, biochar, and soil biochar-amended moisture release data. New GH experiments using a plant mix of 9 native grasses commonly used in the Southwest to revegetate disturbed lands, have also shown positive plant responses to biochar soil additions. In these GH experiments the seeded grasses were allowed to grown during 6 months. Two sets of grass clippings (collected after 3 and 6 months of plant growth) showed now statistical differences in dry matter production between the control, 2%, and 4% biochar amendments. These results were expected, since all pots were regularly watered and fertilized equality. After the last clipping, watering to the pots was stopped for three weeks, exposing the plants to day-time temperatures exceeding 95-100 degrees F. Glass clippings were again collected at the end of the three week period and, as in the previous Bermuda grass study, the 2 and 4% biochar-amended soils exhibited significantly higher biomass production than the controls during this drought period. Watering was restarted on the 4th week of drought and after 3months, only the 4% biochar amended pots showed vigorous grass growth, with limited or no growth at all observed in the 2% biochar and control pots. A plant species survey identified only 4 of the 9 species of grasses initially planted growing back during the first 3 months period of recovery. Further studies using barrel size mesocosms are planned with future funding AFRI funding (proposal in review) to explore the nexus between biochar and manure applications in semi-arid alkaline soils. We propose to study the biochar-manure interactions in the soil focusing on nitrogen, in particular ammonia and ammonium species, which (based preliminary laboratory data) are significantly sorbed by PFW biochar. PARTICIPANTS: Craig Rasmussen, Associate Professor, Soil, Water & Environmental Science, University of Arizona Robert Freitas, Research Scientist, Agricultural and Biosystems Engineering, University of Arizona TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    Pine forest waste biochar is relatively low in alkalinity (~1-5%), a desired trait for AZ soils, which are normally alkaline. The PFW biochar can hold up to 4 times its weight in water due to its high porosity (~86%). However, under field or submerged conditions, up to 50% of the biochar pores remain empty. This unique property of biochar may contribute to the refractive nature and therefore longevity of this carbon-based material in biologically active, oxidative natural systems like soils. PFW biochar can be used to reduce water stress in Bermuda grass (commonly used in water thirsty golf courses) and can also be used in revegetation projects that directly seed native grass species. Thus, native grasses, and possibly other native plant species tolerant to extreme pH-salinity soil conditions, may adapt quickly to a soil amended with PFW biochar, becoming more drought-resistant. However, the addition of PFW biochar to alkaline soils may require a period of "aging" before pH-salinity sensitive vegetables can benefit. Biochar previously exposed to fertilizers may trap and release them subsequently when plants are not fertilized externally. Biochar may also reduce fertilizer leaching in light textured soils by slowing the release of chemicals during periods of excess soil water application.

    Publications

    • Artiola, J.F., Rasmussen, C., Freitas, R., 2012. Effects of a Biochar-Amended Alkaline Soil on the Growth of Romaine Lettuce and Bermudagrass. Soil Science 177(9), 561-570.


    Progress 01/01/11 to 12/31/11

    Outputs
    OUTPUTS: Arizona pine forest waste woodchips, obtained from the Forest Service via Arizona Power Service (APS), were used to produced biochar using slow pyrolysis (batch mode) with a biochar temperature of 450-500 degrees C and a yield of 20% by mass. Several Greenhouse (GH) studies were undertaken to test the viability of biochar as a soil amendment in AZ soils that are typically alkaline, moderate to high pH, and well-drained. A well-characterized loamy sand soil from the Red Rock(RR), AZ, Agricultural Experiment Station was selected. The GH experiments were conducted using 3-gallon pots with 8 replications and a randomized block design using drip irrigation. Two plants were selected, romaine lettuce, a C3 (cool season) vegetable, Bermuda grass a C4 (warm season) grass, and a mix of nine native grasses. Given the low particle bulk density of PFW biochar, measured at 0.22 g per cubic cm, two application rates were selected: 2% and 4% by weight biochar to RR soil - being equivalent to 40 and 80 tons of biochar per hectare (to a 15cm depth), respectively. During this year second lettuce GH Study was undertaken using the same pots and biochar treatments, but no fertilizer was added during the growth cycle. Again, no significant differences in germination rates were observed in any of the treatments or control, all exhibiting a 95% success. During this second trial no stunted plant growth was observed in the biochar-amended pots. All plants were harvested after three months and wet plant matter yields were measured. An ANOVA analysis (n=8) of the data ranked (at the 95%CI) the 4% and the 2% biochar higher than the control. It its theorized that any deleterious effects of fresh biochar may have had to lettuce plants in the first trial dissipated by the second GH trial. It is also possible that the aged biochar may have advantaged lettuce plant growth in pots with biochar that may have acted as a slow release fertilizer source. Further research is needed to demonstrate whether this biochar can act as a slow released fertilizer. A new lettuce GH experiment is underway using soil and soil-biochar(aged) mixes pretreated with a fertilizer solution as sole source of nutrients during the plant growth cycle. Preliminary data suggests that the biochar-amended soils produce larger lettuce heads than soil without biochar. Previous research showed that Bermuda grass may have benefited by the presence of biochar, which increased the water holding capacity of the loamy sand soil. Therefore, a new GH experiment has been started using a plant mix of 9 native grasses commonly used in the Southwest to revegetate disturbed lands. Upon full establishment of the grasses and initial biomass production measurements, the plants will be subjected to water stress for at least one month. During this time biomass production will be measured and at the end of the period individual plant species survivability will be documented. PARTICIPANTS: Craig, Rasmussen, Soil, Water & Environmental Science. Robert Freitas, Arid Land Studies. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    Pine forest waste biochar is relatively low in alkalinity (~1-5%), a desired trait for AZ soils, and has an extreme porosity (measured at ~86%). Pine forest waste biochar has a low bulk density and, based or preliminary laboratory experiments and porosity data, it can sorb up to twice its weight in water under field conditions. A previous water stress test on Bermuda grass suggests that biochar-amended soils may prevent severe damage to turf grass, extending its survivability for up to two weeks. It is hoped that the benefits of biochar amendments may be extended to native grass species used in revegetation projects. Additional GH experiments with Romaine lettuce indicate that the observed deleterious effects of fresh biochar may be short-term. Newly planted lettuce in pots with aged biochar did no exhibit stunted plant growth. Additionally, preliminary results indicate that biochar may act as a slow release of fertilizer to plants significantly increasing leaf yields over the controls. We can cautiously conclude that the addition of PFW biochar to alkaline soils may require a period of "aging" before pH-salinity sensitive vegetables can benefit. Biochar previously exposed to fertilizers may trap and release them subsequently when plants are not fertilized externally. Native grasses, and possibly other native species tolerant to extreme pH-salinity soil conditions, may adapt quickly to a soil amended with PFW biochar, becoming more drought-resistant.

    Publications

    • Artiola, J.F. C. Rasmussen, and R. Freitas. 2011. Effect of a biochar-amended desert, alkaline soil on the growth of Romane Lettuce and Bermuda Grass. Soil Science (in review).


    Progress 01/01/10 to 12/31/10

    Outputs
    OUTPUTS: During the second year we focused on the production of sufficient biochar material to conduct greenhouse experiments and its characterization. Arizona pine forest waste woodchips, obtained from the Forest Service via Arizona Power Service (APS), was used to produce biochar using a 50,000BTU woodgas stove. Biochar was produced using slow pyrolysis (batch mode) with a biochar internal temperature of 450-500 degrees C and a yield of 20% by mass. Two Greenhouse (GH) studies were undertaken to test the viability of biochar as a soil amendment in AZ soils that are typically alkaline, moderate to high pH, and well-drained. A well-characterized loamy sand soil from the Red Rock(RR), AZ, Agricultural Experiment Station was selected. The GH experiments were conducted using 3-gallon pots with 8 replications and a randomized block design using drip irrigation. Two plants were selected, romaine lettuce, a C3 (cool season) vegetable, and Bermuda grass a C4 (warm season) grass. Given the low particle bulk density of PFW biochar, measured at 0.22 g per cubic cm, two application rates were selected: 2% and 4% by weight biochar to RR soil - being equivalent to 40 and 80 tons of biochar per hectare (to a 15cm depth), respectively. Lettuce results: No significant differences in germination rates were observed in any of the treatments or control, all exhibiting a 95% success. However, during the first month of growth biochar treated lettuce pots displayed significant stunted growth, particularly in the 4% treatment pots (compared to controls),but plant in the biochar treatments began to recover during the second month. All plants where harvested after 2.5 months of growth and fresh weight plant matter yields were measured. An ANOVA analysis (n=8) of the data ranked (at the 95%CI) the 2% biochar higher than the control and significantly higher than the 4% biochar treated soil. At the 99%CI the 2% biochar treatment was only marginally higher than the control. Bermuda grass results: Germination proceeded normally in all pots. Clippings were collected from pots, as soon growth exceeded 2.5-3", once a week for two months. Statistical analysis of dry biomass again placed the 2% biochar treatment above the other two treatments at the 95%CI, but not at the 99%CI. Pots were water -stressed for one month and grass clippings where collected every week for 4 weeks. Biomass dry weight yields increased as a function of biochar treatment, these being significantly higher above the control at the 99%CI at the 4% and 2% biochar application rates. During this period the grass in the control pots died or went dormant after 14-16 days. Seven days later most of the grass in 2% biochar pots had similar symptoms. And about 6 days later most of the 4% biochar pots looked gray and showed no growth. Irrigation was restarted but after two weeks none of the control pots showed signs of life, about 50% for 2% pots had marginal/spotty growth(in the form of runners) and all of the 4% biochar pots showed growth considered normal, having recovered from the water stress period with no apparent ill effects PARTICIPANTS: Craig Rassmussen, Soil, Water & Environmental Science, University of Arizona Robert Freitas, Arid Land Studies, University of Arizona TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    We have demonstrated that biochar can be produced from several sources of organic residues, including forest and woodland pine forest waste, produced in large quantities (more than 4 million tons per year in AZ) from normal silvicultural practices and drought-related changes AZ forests. Pine forest waste biochar is relatively low in alkalinity (~1-5%), a desired trait for AZ soils, and has an extreme porosity (measured at ~86%). Pine forest waste biochar has a low bulk density and, based or preliminary laboratory experiments and porosity data, it can sorb twice its weight in water under field conditions. A water stress test on Bermuda grass suggests that biochar-amended soils may prevent severe damage to turf grass, extending its survivability for up to two weeks. Greenhouse growth experiments have also shown benefits in the form of increased biomass production may be had when Bermuda grass is planted in a light sandy soil amended with 2% biochar. Romaine lettuce, which is sensitive to soil salinity changes, benefited from biochar applications at the 2% rate compared to the control. But at the 4% biochar rate stunted plant growth was observed. Although eluent salinity did not change significantly across treatments, there was a measurable increase in the eluent pH of pots with biochar amendments (up to 0.3 units), perhaps affecting plant growth at the early stages, despite normal germination rates. Preliminary observations on an ongoing greenhouse study using the same pots reseeded with lettuce, suggest that poor plant growth responses observed in the first study may be temporary. As the biochar "ages" in the soil, the equilibration of alkaline species with carbon dioxide lowers its solution pH (after several wet/dry/leaching cycles). In this second trial we have thus far observed again, no changes in germination rates (~95% across all treatments), and very similar plant growth rates in all the pots, including those amended with 4% biochar. We can cautiously conclude that the addition of PFW biochar to alkaline soils may require a period of "aging" before pH-salinity sensitive vegetables can benefit. Conversely, warm season grasses, and possibly other species tolerant to extreme pH-salinity soil conditions, may adapt quickly to a soil amended with PFW biochar, becoming more drought-resistant.

    Publications

    • No publications reported this period


    Progress 01/01/09 to 12/31/09

    Outputs
    OUTPUTS: This first year of research focused on the selection, development and production of biochar materials in cooperation with the University of Arizona Biochar Research Group and a Public Utilities Company. In collaboration with groups, I participated in the in the analysis and interpretation of data from two experiments, a greenhouse and field plot experiments using a commercial biochar produced from mesquite, completed in 2009, see citation below. We also continued collaboration in the use of biochar generated from the production of wood-derived bio-oil, which proved unfeasible, despite a large investment (by APS) pilot scale equipment. Biochar produced during this process (bio-oil recovery) had the consistency of fine dust. Chemical characterization indicated that this "biochar" retained a significant amount of soluble organic constituents, was very difficult to handle (produce a lot of dust), and would measurably lower the albedo of semi-arid soils. In addition, at least initially, the amended soils (a clay loam and a loamy sand lost some of their aggregate structure. Nonetheless the significant increases in soil water holding capacities (~25%) were measured with the addition of up to 10% w/w biochar in a loamy sand soil from Red Rock, AZ. PARTICIPANTS: The University of Arizona Biochar Research Group composed of researchers from: College of Agriculture and Life Sciences: Soil, Water & Environmental Sciences and Agricultural Biosystems Engineering Departments. Arizona Public Utilities (APS) TARGET AUDIENCES: These include: Agriculture: Farmers Forestry: Forest Management AZ Public: Home Owners/gardeners PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    Following more research on the production of biochar materials, it was concluded that biochar materials should be produced using equipment (still under research/development in the US) that does not pulverize/grind biochar and combusts the wood (feedstock) more efficiently. Presently, the only methods available to produce biochar are with downdraft and/or updraft gasifiers, which usually do not recover bio-oils but combust them. A 50,000 BTU stove was obtained and various AZ woody residues (feedstocks) were tested, these include: mesquite, mulberry, white pine wood, sweet sorghum and sweet sorghum bagasse, and AZ pine forest waste. In addition, three commercially available "biochar" materials (used in energy production) were also obtained for comparison purposes. We produced biochars from these six agricultural/forest wastes and observed that their bulk densities are <0.2g/cm3, compared to a processed (palletized) biochar sold for energy production that approaches 0.5g/cm3. However, the water holding capacities of the six biochars we produced (and two of the commercial biochars) ranged from ~1.8 to 4+ times their weight in water. Additional funding (104b) was obtained ($10K, J.Artiola, R. Freitas, C. Rasmussen, PIs) to conduct greenhouse experiments on the efficacy of these biochars to improve plant drought tolerance in AZ soils. This research is presently focusing on one biochar in particular, AZ pine forest waste biochar, which can retain up to 4 times its weight in water, a loamy sand soil and two or more crops. To date, our research into the production and characterization of biochars as soil amendments suggests that these materials may improve soil water holding capacity in sandy soils, and may increase soil pH (due to biochar alkalinity) temporary. Further research in these areas continues. Initial physical and chemical characterization and energy balance estimates of pyrolyzed agricultural/forest wastes suggests that biochars will likely have to be produced and disposed of (incorporated into soils) in-situ, using excess energy produced during pyrolysis, to retain their negative carbon footprint and long-term soil carbon storage benefits.

    Publications

    • Villareal-Manzo, L., P. Waller, R. J. Freitas, R. Ryan, J. F. Artiola, C.Rasmussen, T. McDonald, M. Tuller, M. Meding. 2010. Assessment of crop drought tolerance in biochar amended soils. submitted to: Irrigation Science.