Use of Biomass Crops As Alternatives to Pine Bark

James Altland

Pine and Douglas fir bark

• Primary component of nursery crops in U.S.– 60% to 80% of substrate

• Excellent substrate

• Used for many years

Pine and Douglas fir bark

• Decreasing availability, increasing price– More bark diverted for fuel in mills– Less forestry activity

• Energy Independence Security Act of 2007– Goal of 36 billion gal. ethanol by 2022– Pres. Obama elevated goal to 60 billion gal. by

2030– Wood, from southern pine, is viewed as the most

likely source of ethanol.

Pine bark

• Minor portion used for horticulture.– Most used for fuel.– Fuel fraction has increased.

• Decreasing availability

• Little softwood bark production in north

• Increasing shipping costs

Fate of bark in U.S.

Fuel

Misc.

Fiber

Not used

Timber harvests

0100020003000400050006000700080009000

10000

NorthCentral

Southeast West Rockies

1,0

00

,00

0 c

u. f

t.

Hardwood

Softwood

Bark generation over time

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

1986 1991 1996 2001

1000

dry

to

ns North Central

Northeast

PNW

Southwest

South Central

Southeast

Lu et al. 2006. J. Environ. Hort.

New substrate

• Regionally abundant/available

• Affordable

• Effective

• Manageable with current technology

• Inventory is controlled by nursery producer.

Pine based alternatives

• Various wood products have been researched in the Southeast– Clean Chip Residual– WoodGro®– WholeTree™

Courtesy of C. Boyer

•Switchgrass (Panicum virgatum)

•Native perennial grass.

•Technical resources.

•2 to 6 ton/acre

•$4 to $6 per yd3

Giant miscanthus

Sterile hybrid

10 to 15 ton/acre

Not as widely grown…yet

Corn stover

2 to 4 tons/acre

80 million acres in U.S.

Hasn’t worked well yet.

Bamboo (Phyllostachys)

•Grows in Ohio

•grows better further south

•Yield is unknown

•Trials just started

•Invasive?

•Gregarious flowering

Hybrid poplar

• Prevalent in PNW

• 5 to 10 ton/acre/year

• SRIC– Short rotation intensive

culture.– 2 year rotation

Willow

•Biofuel crop in NY.

•5 to 10 ton/acre/year

•3 year rotation cycle

•Technical resources.

Ideal substrate

• Locally available

• Effective– Using current production techniques and

standards.

• Not dependent on whim of others.– Not dependent on fiscal viability of others.– Not dependent on external forces.

Overall approach

• Compare alternative substrates to bark standards

• Observe and measure properties

• Understand materials empirically

• Engineer substrates to meet varied needs

pH management

• All biomass substrates have high pH– 6.5 to 7.5

• Amendment with lime not advised

• Ca and Mg supplements will be necessary.– Studying sulfates and oxides of Ca and Mg

• Fe levels are also low

Substrate pH – 8 weeks

L***

L***

LSD = 0.3

Physical properties

• Air space, container capacity, bulk density• Matric and hydraulic properties

• Chipped materials– Coarse (0.25 to 1.5 in)– Filler

• Hammermill– Particle size distribution similar to pine bark– Requires only small levels of amendment

Physical properties

• Hammermilled biofuel substrates have:– High air space– Low water capacity

• Processing through 3/16” hammermill

• Amendment with:– 15% peat + 10% compost

PB:SG + 15% peat + 10% compost

Plant growth

• Broad spectrum of plant species– Unique substrate requirements

• Difficult to provide a substrate ‘recipe’

• Substrate empirical properties– Allows substrate tailoring.

Rose shoot weight – 9 weeks

LSD = 1.0

Q***

Q***

Joe-pye weed growth

Nitrogen

• N dynamics in switchgrass substrates differ from pine bark.

• Develop N application methods to capitalize on differences.

Nitrogen leaching from PB or SG substrates

Cultural practices - fertilization

• Fertilizer placement affects weed growth.– Topdress– Dibble– Incorporate

Current work

• Long-term stability.

• Conduciveness/supressiveness of pathogens.

Biomass substrates

• Pros– Inexpensive– Local– Available

• Cons– Herbicide residues– Long-term stability– Fertility

Questions