Effects of Flashed Carbonized©

Macadamia Nutshell Charcoal on Plant Growth and Soil Chemical Properties

Tai McClellan*, Jonathan Deenik1, GoroUehara1, Michael Antal2

1Department of Tropical Plants and Soil Science, 2Hawaii Natural Energy Institute

Picture source: http://www.gerhardbechtold.com/TP/gbtp.php

Terra Preta (Amazonian Dark Earths): Highly Fertile Anthropogenic Soils

Terra Preta Soil Typical Upland Amazonian Soil

Photo source: University of Bayreuth Photo source: University of Bayreuth

Charcoal Additions No Charcoal Additions

Effect of Charcoal on Plant Growth

Photo source: http://tinselwing.wordpress.com/tag/terra-preta/

Objective:

To demonstrate the effectiveness of charcoal additions on plant growth in two Hawaiian soils

Flash Carbonized©

Charcoal

Hawaii Natural Energy Institute

Materials and Methods• Cultivated fertile, volcanic ash soil (WaimeaSeries)• Flash Carbonized © macadamia nutshell charcoal • Lettuce • 4 treatments, 3 replicates

0% (w/w) 5% (w/w) 10% (w/w) 20% (w/w)

• With no charcoal additions • With 20% (w/w) charcoal addition

Results

Plant Effects

Lettuce Shoot Biomass

Increasing rate of charcoal0% 5% 10% 20%

Plan

t wei

ght (

gram

s/po

t)

0

20

40

60

80

100

120

140

160

a a

b

c

Lettuce Nitrogen Uptake

Increasing rate of charcoal0% 5% 10% 20%

Plan

t Upt

ake

(gra

ms/

pot)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

aa

b

c

Soil Effects

Soil Nitrogen Content

Increasing rate of charcoal0% 5% 10% 20%

Nitr

ogen

con

tent

(%)

0.0

0.1

0.2

0.3

0.4

0.5

c b ba

Soil Carbon Content

Increasing rate of charcoal0% 5% 10% 20%

Car

bon

cont

ent (

%)

0

5

10

15

20

25

d

cb

a

Corn Experiment

0% 5% 10% 20%

Corn Fresh Biomass

Increasing rate of charcoal

0% 5% 10% 20%

Plan

t wei

ght (

gram

s/po

t)

0

20

40

60

80

100

a

a

aa

Charcoal Effect in an Infertile Soil

0% 5% NPK + Lime

NPK + Lime

5% + NPK + Lime

Corn Fresh Biomass

Control

Control+5%

Control+ NPK+lime

Control+5%+NPK+lime

Plan

t wei

ght (

gram

s/po

t)

0

10

20

30

40

50

60

70

cc

a

b

Preliminary Conclusion:

Charcoal used in the experiment caused a negative effect on plant growth

But why?• Crop?• Soil??• Charcoal???

• Volatile Matter (VM) content: a measure of the susceptibility of charcoal to further decompose and form carbon when heated

Water Repellency Water Absorption

Charcoal Behavior Upon Wetting

22.5% VM Content 6.3% VM Content

Hypothesis:The volatile matter content of charcoal affects its value as a soil amendment

Soil with High VM Charcoal Soil with Low VM Charcoal

Uneven Infiltration Uniform Infiltration

Materials and Methods• More degraded tropical soil (Leilehua Series)• High (22.5%) and low (6.3%) volatile matter content charcoal• Corn• 5 treatments, 3 replicates

• control• control + 10% (w/w) high volatile matter charcoal • control + 10% (w/w) low volatile matter charcoal • control + lime + NPK• control + 10% (w/w) low volatile matter charcoal + lime + NPK

0% (w/w) 10% Low VM10% High VM

Effect of High Volatile Matter (22.5%) Charcoal on Plant Growth

0% 10% High VM

Effect of Low Volatile Matter (6.3%) Charcoal on Plant Growth

0% 10% Low VM

Low Volatile Matter Charcoal (6.3%) versus High Volatile Matter Charcoal (22.5%)

Low Volatile Matter

High Volatile Matter

Combined Effect of Low Volatile Matter Charcoal Plus Fertilizer

NPK + Lime

NPK + Lime + 10% Low VM

Corn Fresh Biomass

Control

10% High VM

10% Low VM

NPK+Lime

10% Low VM+NPK+Lime

Wei

ght (

gram

s/pl

ant)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

ab

c

A

A

Conclusions

High volatile matter content charcoal has a detrimentaleffect on plant growth

BUT!

Low volatile matter charcoal may have a beneficial effect on plant growth, especially when combined with fertilizer

What type of charcoal are you adding to your soil?

OR

Volatile Matter: < 4.5%Volatile Matter: 36.4%

Acknowledgments

Thank you to all who helped in this project:

• Dr. Paull and TPSS• Drs. Deenik, Uehara, Antal• Michael Lurvey, President of Carbon Diversion• Student help: Wade Nakagawa, Keawe Wright, Grace Asperin, Mike Ross, Sophie Sun