8/14/2019 SAT biochar ethylene Poster 10_10b.pdf

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Controlling unwanted ethylene emissions from biochar potting

mixtures for horticultural applicationsWill Fulton1, Myles Gray1, John Miedema2, Fred Prahl3, Markus Kleber1

1 Department of Crop and Soil Science, Oregon State University, Corvallis, OR

2 Director of Biomass Energy for Thompson Timber and Starker Forests, Philomath, OR

3 College of Oceanic and Atmospheric Sciences, Oregon State University

Vermiculite is mined, imported (40% off-shore), and then expanded at

1000Ctemperatures for use as a potting soil amendment in American

horticulture. Pyrolysis of locally available carbon waste streams

produces both heat to warm greenhouses and biochars, which have

been suggested as a substitute for expanded vermiculite in potting soils.

However, Spokas et al. (2010) reported observing ethylene emissions

from some biochars[1]. Ethylene is a hormone that affects plants in a

variety of ways (Fig. 1), some of which have the potential to interfere

with the expected developmental patterns of nursery crops [2,3,4].

The chemical and physical characteristics of biochars are subject to

variations (Fig. 2) which appear to derive from differences of feedstock,or pyrolysis, or post-pyrolysis handling. We hypothesize that nurseries

could manage production and handling of biochars such that they

would become ethylene neutral.

Fig. 2:(A) Physical and chemical phases of plant biomass components over a

range of temperatures.(B) Gravimetric analysis for the same range.[5].

Image courtesy of Roland Leatherwood, Cornell University

2. Objectives

The central goal of this project is to develop the technology for the

production of ethylene neutral biochars usable as substitutes for

vermiculite as a potting medium amendment. We have established

two objectives for this first phase.

1. To measure changes in ethylene evolution from biochar basedpotting mixtures over time.

2. To test the effects of post-production handling on the ability of

biochars to stimulate ethylene emissions.

Fig. 1: Effects of Ethylene on Nursery Plants

4. Methods Mixtures (50/50 by volume) of peat moss and each biochar were prepared in 250 mL serum bottles.

Moisture content was adjusted to field capacity (treatment 1) and saturation (treatment 2).

Vermiculite/peat moss mixtures were prepared for comparison, and all samples were stored at 21.6.

Ethylene was measured using a gas chromatograph with flame ionization detection on the 1st, 2 nd, 4 th,

7th, 14th, 28th, 42nd, 56th, and 70thdays of incubation. Additional quantities of the four biochars were stored in the open to assess the effect of post production

handling. After storage for 90 days, the agedchars were then analyzed by the same protocols.

6. Discussion

8. Conclusions

1. Feedstocks: the hazelnut shell biochars emitted ethylene from the start, while

the Douglas fir biochars emitted small amounts on the second and fourth days

only (Fig. 5).

References:[1] Spokas, K., Baker, J. & Reicosky, D., 2010. Ethylene: potential key for biochar amendmentimpacts. Plant and Soil, 333, 443-452.

[2] Primrose, 1979. A review, ethylene and agriculture: The role of microbes. Journal of

Applied Bacteriology, 46, 1-25.

[3] Arshad, M. & Frankenberger, W.T., 2002. Ethylene: agricultural sources and applications,

Springer.

[4] Argueso, C.T., Hansen, M. & Kieber, J.J., 2007. Regulation of Ethylene Biosynthesis. Journal

of Plant Growth Regulation, 26, 92-105.

[5] Keiluweit, M., Nico, P.S., Johnson, M.G. & Kleber, M., 2010. Dynamic Molecular Structure

of Plant Biomass-Derived Black Carbon (Biochar). Envir. Sci. & Tech, 44, 1247-1253.

.

Acknowledgement: This research is being funded by the

Agricultural Research Foundation (ARF) at Oregon State University.

3. Materials

Two feedstocks, Douglas fir (Pseudotsuga menziesii) chips and hazelnut (Corylus

avellana) shells, were each pyrolyzed to two peak temperatures (370Cand 620C)

to make biochars (Table 1, Fig. 3 & 4).

The absence of ethylene emissions does not, in itself, make all biochars

suitable substitutes for expanded vermiculite in potting media mixtures.

Differences in density, which is a function of feedstock, may govern

biochar water retention. Water retention is a key attribute of expanded

vermiculite.

Fig. 5: Ethylene emissions from four biochars incubated for 70 days

Fig. 3: Magnified images of the four biochars used in our mixtures

1. Feedstocks yielding biochars that stimulate ethylene accumulation in

potting media mixtures will do so to a lesser degree, if they are

pyrolyzed at higher temperatures (above 550C).

2. Biochars stored in the open (or aged)for 90 days following pyrolysis

do not stimulate ethylene emission.

7. Summary

Synopsis: Ethylene emissions from biochars are controllable - biochars can be safely used as potting media in nursery applications

Hazelnut shell 370C Hazelnut shell 620C Douglas fir 370C Douglas fir 620C

We are evaluating the feasibility of using waste stream feedstock

biochars in potting mixtures as substitutes for environmentally

expensive expanded vermiculite. Our initial objective was to determine

if any post pyrolysis handling techniques might eliminate biochar

stimulated ethylene accumulations. Our testing has demonstrated that

simple open air storage for 90 days is an effective solution.

5. Results

2. Heat Treatment Temperature (HTT): 370hazelnut shell biochars emitted 2-3x

more ethylene than the 620 samples, while the 620 and 370 Douglas fir

biochars emitted equivalent amounts of ethylene (Fig. 5).

3. Moisture: Ethylene emissions from the saturated samples (sat) tended to be

initially lower, but were not significantly different from the unsaturated (FC)

(Fig. 5).

4. Storage: None of the biochars agedfor 90 days emitted ethylene (Fig. 6).

Fig. 4: The retort at Starker Forest/Thompson Timber , Philomath, OR,where the biochars were made

Fig.6: Zero ethylene emissionsafterbiochars were stored in theopen (or aged) for 90 days

HeatTreatmentTemp

erature

370C

620

C

Feedstock

Hazelnut shell Douglas fir wood

1. Introduction