Mycorrhizal Fungi in Nursery Production: Facts & Fiction
Carolyn Scagel, USDAi ARS, Horticultural Crops Research Laboratory, Corvallis, OR

See also:
Root Growth & Function--The Origin of All that is Green—

Bear Kaufmann. Initially posted April 7, 2008. Updated August 5, 2008.

Images showing trial preparation and radish germination
(Select image to enlarge in Gallery.)

Materials/Methods

Char was Lazzari Brand mesquite BBQ char (due to availability), crushed and screened to 1/8".
No nutrients were added to the char itself or to the soil.
Soil was FoxFarm OceanForest Potting Soil.
Sand used was horticultural sand.
No mycorrhizal fungi were added.
Mixtures range from 0-100% sand, soil, and char in ~16% increments by volume. 90 pots total. 28 combinations with 3 pots each + 6 additional pots at 33%/33%/33% composition. Pots were placed randomly within the tray. Tray was rotated 180° occasionally.
Plants were watered daily by a drip irrigation system.
Plants were removed from pots ~1 month after first watering. Soil was rinsed from roots and roots were patted dry with a towel. Wet weight of roots+shoots was measured (Acculab VI-3mg, 0.001 g precision).

Figure 1. Box Plots Showing Effect of Composition Across Three Transects

Figure 2. Pictures of Radishes at Important Compositions

Results

Plant growth was stunted even for the best preforming plants, likely due to the small pot size. Leaf color varied across different compositions.
A mixture of 33% charcoal and 67% soil had the best growth (176% of pure soil). Aside from mixtures around this level (Figure 1b), high levels of charcoal showed a generally negative effect on plant growth (Figure 1c).

Discussion

The positive interaction effects of charcoal and soil (Figure 1a,1b) are interesting. Assuming charcoal itself provides no integral nutrients to the soil (eg. nitrogen), increasing amounts of charcoal displace nutrients available from the soil mixture. The effects at 33% char/67% soil, however, show beneficial effects. This could be explained by increased mineralization rates caused by the charcoal causing soil nutrients to be more available to plants. Beyond 33%, the Cation Exchange Capacity of the charcoal may have held the nutrients produced by mineralization, making them less plant available. Since the charcoal was not amended/soaked in a nutrient bearing solution it likely had a low Base Saturationi leading to adsorption of nutrients as they became available. Other potential explanations for increased growth along the soil/char transect include alterations to pH or limiting nutrients (eg potassium(?)) provided by the charcoal. The speculative mineralization/CECii model could also explain the effects seen along the sand/char transect. Here, since the sand lacks organic materials and bound nutrients for soil microorganisms to make plant available, the increasing unsaturated CEC may have made any nutrients less plant available.

Author: Bear Kaufmann bear@ursine-design.com

Spreadsheet for Calculating Basic "New Terra Preta" Economics
Kevin Chisholm, May 13, 2008

This Spreadsheet should be helpful in getting a perspective on charcoal additions, to make a "New Terra Preta Soil.

Knowing soil density, the density of "loose charcoal" as it will be applied to the soil, the density of crushed charcoal, the depth to which the charcoal will be tilled in, and a proposed weight addition per square meter, we can then calculate the average depth of charcoal on the surface of the ground after spreading, and the weight percentage of charcoal that will exist, after the charcoal is tilled in to the desired depth.

1: If we know the cost of Charcoal: We can then calculate the cost per square meter for the charcoal, and the increased value of yield and other benefits that would be required for the charcoal addition to have the desired "Simple Payout Period."

2: If we know the value of the increase in yield and other benefits: We can then calculate the maximum permissible cost of the charcoal and its application cost per square meter, and the maximum we can afford to pay to attain our desired "Simple Payout Period."

This approach assumes that the charcoal addition simply allows the soil system to attain a higher potential, EITHER giving a Higher yield with the same level of nutrient additions and attention, OR the SAME yield, with a lower level level of nutrient additions and attention. Only the difference in the value of yield and attention is credited toward paying for the charcoal additions.

Note also that the charcoal additions are felt to provide nutrient retention, soil microbe habitat, and moisture retention advantages to the soil. If the soil was deficient in one or more of these requirements, then charcoal additions could be expected to be beneficial. On the other hand, if the soil was NOT deficient in these properties, then one would NOT expect a financial benefit to justify the cost of the charcoal additions.

Kevin Chisholm

Pyrolysis Reactor Tower Assembly
Sean Barry, April 21, 2008

I assembled the Pyrolysis Reactor Tower today. I had it fabricated over the winter.

Regards,

SKB

The Charcoal Vision: A Win–Win–Win Scenario for Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, while Improving Soil and Water Quality
David Laird, USDAi, ARS, National Soil Tilth Laboratoryi, April 12,2008
In, Agronomy Journal • Volume 100, Issue 1 • 2008

ABSTRACT
Processing biomass through a distributed network of fast pyrolyzers may be a sustainable platform for producing energy from biomass. Fast pyrolyzers thermally transform biomass into bio-oil, syngas, and charcoal. The syngas could provide the energy needs of the pyrolyzer. Bio-oil is an energy raw material (∼17 MJ kg−1) that can be burned to generate heat or shipped to a refinery for processing into transportation fuels. Charcoal could also be used to generate energy; however, application of the charcoal co-product to soils may be key to sustainability. Application of charcoal to soils is hypothesized to increase bio-available water, build soil organic matter, enhance nutrient cycling, lower bulk density, act as a liming agent, and reduce leaching of pesticides and nutrients to surface and ground water. Th e half-life of C in soil charcoal is in excess of 1000 yr. Hence, soil-applied charcoal will make both a lasting contribution to soil quality and C in the charcoal will be removed from the atmosphere and sequestered for millennia. Assuming the United States can annually produce 1.1 × 109 Mg of biomass from harvestable forest and crop lands, national implementation of Th e Charcoal Vision would generate enough bio-oil to displace 1.91 billion barrels
of fossil fuel oil per year or about 25% of the current U.S. annual oil consumption. Th e combined C credit for fossil fuel displacement and permanent sequestration, 363 Tg per year, is 10% of the average annual U.S. emissions of CO2–C.

Characterization and Thermal Conversion of Charcoal Derived from Fluidized-Bed Fast Pyrolysis Oil Production of Switchgrass
A. A. Boateng, Industrial Engineering Research, November 8, 2007

Abstract:

The charcoal coproduct associated with pyrolysis oil (bio-oil) production can add economic value to the process operation if it can be successfully employed as an activated biochar for soil amendment applications or can be used as a combustion fuel to power the pyrolysis process or as a gasifier feedstock. Although proposed, none of these have been extensively studied. In this submission, the surfaces and interfaces of the charcoal produced from making pyrolysis oil from switchgrass in a fluidized bed were characterized to establish its usefulness as an adsorbent material. Its reactivity in air and in CO2 were also determined to establish its potential as combustion fuel or gasification feedstock. It was found that the surface areas were low, typically 7.7 and 7.9 m2/g, 2 orders of magnitude of the areas encountered in activated charcoal. Compounding this was high surface crystallinity of the structure as measured by X-ray diffraction, thereby suggesting poor characteristics as a sorption agent without further activation. However, this does not preclude its use for other soil applications including carbon storage and as a nutrient delivery substrate. Upon further pyrolysis in helium, the charcoal yielded equal amounts of CO and CO2, exhibiting reaction kinetics similar to that of coal pyrolysis. Furthermore, reactivity in CO2 and in air atmosphere resulted in activation energies of 8 411 and 11 487 J/mol, respectively. It appears that the charcoal could be better used as combustion fuel or gasification feedstock than as an activated charcoal applied for metal sorption for the fact that the latter application will require higher surface and interfacial areas than measured.

Ind. Eng. Chem. Res., ASAP Article 10.1021/ie071054l S0888-5885(07)01054-8
Web Release Date: November 8, 2007

Growing plants with charcoal
Richard Haardi, Fourth Corner Nurseries, Bellingham, WA, June 27, 2007
[G2:709]
Select image to enlarge
This is an image of our charcoal as soil additive study at our nursery. Shown is one of our test subjects a local native shrub that we propagate and sell for riparian restoration projects. Black Twinberry, Lonicera involucratai. This plant was a 2 year old seedling, bareroot harvested and stems clipped to 6 inches before planting in the test bed 7 weeks ago.

Azotobacteri Question and Answer June 2007
Richard Haard, Four Courner Nursery, Bellingham, Washington, June 11, 2007

Question by Sean Barry:
RH ". . .Learning about potential for enrichment culture of Azotobacter and trying to measure available nitrogen in this situation."

Here you mention promoting the growth of nitrogen fixing Azotobacter. I have always been interested in the possibility of inoculating charcoal with mycorrhizal fungi.

Fourth USDA Greenhouse Gas Conference: Positioning Agriculture and Forestry to Meet the Challenges of Climate Change
February 6 - 8, 2007 - Baltimore Marriott Camden Yards, Baltimore, Maryland

Conference Program

13: Soil Carbon: Part I - Interactive Discussion

Charcoal from Comets, Asteroids and Wildfires
Tom Miles, May 28, 2007

There is speculation that pockets of charcoal that resulted in enriched soil came variously from comets and asteroids and resulting wildfires, as well as intentional burning. The latest comet event has been reported as 12,900 years ago in North America. See Science Daily:
Did A Comet Hit Great Lakes Region, Fragment Human Populations, 12,900 Years Ago? May 23, 2007

and National Geographic News:
Comet Wiped Out Early North American Culture, Animals, Study Says May 23,2007

Potential extraterrestrial causes of terra preta formation are discussed in the literature from Cornell University and elsewhere. It has also been debated on the Hypography Science Forumi.