Crop Residue as Feedstock for the New Bioeconomy:

Opportunities and Roadblocks

W. W. Wilhelm USDA-ARS, Lincoln, NebraskaG. E. Varvel USDA-ARS, Lincoln, NebraskaD. L. Karlen USDA-ARS, Ames, IowaJ. M.-F. Johnson USDA-ARS, Morris, MinnesotaJ. M. Baker USDA-ARS, St. Paul, Minnesota

CSSA Symposium – Feedstock Production for the New Bioeconomy: Opportunities and RoadblocksCrop Science Society of American Annual Meeting, Indianapolis, Indiana November 14, 2006

Billion Ton Report

Biomass production – 1366 million ton Forestry – 368 million tons Agriculture – 998 million tons

Perennial energy crops – 377 million tons Wastes – 87 million tons Grain – 87 million tons Crop residues – 428 million tons

Corn stover – 256 million ton

Billion Ton Report

Biomass production – 1366 million ton Forestry – 368 million tons Agriculture – 998 million tons

Perennial energy crops – 377 million tons Wastes – 87 million tons Grain – 87 million tons Crop residues – 428 million tons

Corn stover – 256 million ton

Bold, optimistic projectionsBasis for discussionLofty target

What is a ONE BILLION?

If one ton = 1 sq in 1 billion tons = 145 football fields

What is a ONE BILLION?

If one ton = 1 sq in 1 billion tons = 145 football fields

Agricultural land (cropland plus hay and pasture)

5 ton ac-1 200 x 106 acres

56% of North Central Region agricultural land Iowa, Illinois, Nebraska, Minnesota, Indiana, and

South Dakota (Total = 195.5 x 106 ac)

Billion Ton ReportAgriculture Assumptions

Yield increase 50% by 2030 Corn and small grains

Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1

Machine to recover 75% stover No tillage adopted universally

Corn yield Nebraska contest winners and averages

Duvick and Cassman. 1999. Crop Sci. 39:1622-1630.Cassman et al. 2003. Ann. Rev. Envir. Res. 28:-315-356.

1965 1975 1985 1995 2005

Co

rn y

ield

(M

g h

a-1)

0

5

10

15

20

25

Co

rn y

ield

(b

u a

c-1)

0

50

100

150

200

250

300

350

Irrigated average114 kg ha-1 yr-1

(1.81 bu ac-1 yr-1)

Irrigated contest winnersRainfed contest winners208 kg ha-1 yr-1

(3.31 bu ac-1 yr-1)

Rainfed average89 kg ha-1 yr-1 (1.42 bu ac-1 yr-1)

Cassman et al. 2006. CAST Report (release Nov. 16, 2006)

Double-X to single-X hybrids

Expansion of irrigated area, increased N

fertilizer rates

Conservation tillage, soil testing, NPK

fertilization

Transgenic (Bt) insect resistance

Reduced N fertilizer & irrigation?

(embodied technological innovation)

Integrated pest management

USA Corn Yield Trends, 1966-2005

y = 112.4 kg ha-1 yr-1

(1.79 bu ac-1 yr-1)

r2 = 0.80

2000

4000

6000

8000

10000

12000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Gra

in y

ield

(kg

ha-1

)

Billion Ton ReportAgriculture Assumptions

Yield increase 50% by 2030 Corn and small grains

Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1

Machine to recover 75% stover No tillage adopted universally

Residue:grain in soybean

Low residue production Longevity of residue Accelerates decay of SOM

Greater N content of leaves and roots Rhizodeposits

Large biomass soybean (LBS) Forage-type soybean Grain yield not proven Grain harvest efficiency

Billion Ton ReportAgriculture Assumptions

Yield increase 50% by 2030 Corn and small grains

Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1

Machine to recover 75% stover No tillage adopted universally

Fractional stover harvestISU proto-type harvester

Hoskinson et al. 2006. Biomass and Bioenergy (in press).

Harvest scenario Stover collected(Mg ha-1)

Percentharvested*

(%)

High cut (at ear height) 4.9 46

Low cut (header on soil) 6.7 64

Normal cut 5.1 49

* Total residue produced, 10.5 Mg ha-1

Billion Ton ReportAgriculture Assumptions

Yield increase 50% by 2030 Corn and small grains

Residue/grain ratio for soybean increase from 1.5:1 to 2.0:1

Machine to recover 75% stover No tillage adopted universally

No tillage adoption(Conservation Tillage Information Center-National Crop Residue Management Survey, 1994-2004, http://lanshark.ctic.purdue.edu/CTIC/CRM.html)

30

90

150

210

270

330

Millions o

f pla

nte

d a

cre

s

Conservation tillageNo tillageTotal cropland

0

10

20

30

40

50

Perc

ent

of to

tal pla

nte

d a

cres

(%)

Conservation tillageNo tillage

No till with no residue

Runoff occurred sooner

Significant carryover effect of residue removal

Runoff initiated 35% sooner in subsequent year

Sediment concentrations increasing by > 100%.

Wilson et al. 2004. Trans. ASAE 47:119-128.

Billion Ton ReportAgriculture Assumptions

Assumption Assessment

Yield increase 50% by 2030 Doubtful

Residue:grain ratio for soybean increase from 1.5:1 to 2.0:1

Achievable, but of doubtful use

Machine to recover 75% stover Very achievable

No tillage adopted universally Doubtful

Erosion control

Traditional uses of crop residues

Feed and bedding Soil amendment

Soil carbon Plant nutrients

andStover harvest

Soil C changeS

oil

carb

on

Time

Managementchange

Cultivation

Pre-cultivation steady-state

No tillageCover cropsGreen manure

REAP

Residue needed to maintain SOC

Crop rotation

Tillage Mg ha-

1

n

Corn mbp 7.5±1.0

6

Wheat mbp 5.5±1.1

5

All mbp 6.3±1.0

13

All Chisel/nt

4.5±0.4

5

Johnson et al. 2006. Agron. J. 98:622-636.

-10

-5

0

5

10

15

20

0 5 10 15 20 25

Grian yield (Mg ha-1)

Ha

rve

sta

ble

sto

ve

r (M

g h

a-1

)

Stover produced

CT-CC

MBP-CC

CT-CS

MBP-CS

REAP

Change allocation of biomass

Soil carbon

Food

Feed

Fiber

Fuel

REAP

Change allocation of biomass

Soil carbon

Food

Feed

Fiber

Fuel

REAP

Soil carbon

Food

Feed

Fiber

Fuel

Change allocation of biomass vs. increase total biomass production

Soil carbon

Food

Feed

Fiber

Fuel

Increase photosynthetic efficiency 25%, from 4% 5%

Fuel

Fiber

Feed

Food

Soil carbon

REAPLong et al. 2006. Plant Cell Envir. 29:315-330.

Multiple biomassMany technologiesConservationReduced expectationsAsking and answering the right question