Sustainability & Energy Crops

Peter ScharfPeter Scharf

University of Missouri Plant SciencesUniversity of Missouri Plant Sciences

Argolis, Greece

• 7000 B.C.—Simple agriculture begins7000 B.C.—Simple agriculture begins• 4000 B.C.—Agriculture intensifies4000 B.C.—Agriculture intensifies• 3000 B.C.—Major civilization3000 B.C.—Major civilization• 2500 B.C.—Civilization collapses2500 B.C.—Civilization collapses• 1500 B.C.—New civilization1500 B.C.—New civilization• 200 B.C.—Civilization collapses200 B.C.—Civilization collapses• 900 A.D.—New civilization900 A.D.—New civilization• 1200 A.D.—Civilization collapses1200 A.D.—Civilization collapses

SOIL EROSIONSOIL EROSION

SOIL EROSIONSOIL EROSION

SOIL EROSIONSOIL EROSION

Importing half of their foodImporting half of their food

Argolis, Greece

• Q: How do they know that erosion occurred?Q: How do they know that erosion occurred?

• A: Find topsoil deposits ‘downstream’A: Find topsoil deposits ‘downstream’

• Q: How do they know it caused civilizations to fail?Q: How do they know it caused civilizations to fail?

• A: Erosion peaks = civilization peaksA: Erosion peaks = civilization peaks

• Q: How do they know it was caused by agriculture?Q: How do they know it was caused by agriculture?

• A: Written records: Plow 3 times/yearA: Written records: Plow 3 times/year

• Q: How do they know it wasn’t caused by weather?Q: How do they know it wasn’t caused by weather?

• A: Within-region differences in erosion/collapse A: Within-region differences in erosion/collapse schedulesschedules

What is ‘sustainability’?

• Can continue the same practices for a long period of time– Outputs stable– Inputs stable– Off-site effects acceptable

Closer to home

Piedmont, Virginia

Tell me what you seeTell me what you see

Closer to home• Used to be a

major ag region• “Soil erosion

was rampant from early times”

• “Most old agricultural fields are now in pine forests”

Div

erse

ag

Toba

cco

Cotton

Erosion: a familiar face in Missouri

Biofuels: potential impact on erosion

• Pressure to:– Put more land into crops (marginal)– Increase cropping intensity

• More continuous corn– Reduced erosion?

• Corn stover removal? (cellulosic ethanol)

• Continuous soybean? (biodiesel)

• Grass for cellulosic ethanol—thumbs up!

Biofuels: potential impact on erosion

• Pressure to:– Put more land into crops (marginal)Put more land into crops (marginal)– Increase cropping intensity

• More continuous corn– Reduced erosion?

• Corn stover removal? (cellulosic ethanol)Corn stover removal? (cellulosic ethanol)

• Continuous soybean? (biodiesel)Continuous soybean? (biodiesel)

Erosion and C

System C

No-till corn 0.03

No-till soybean 0.07

Corn silage 10% cover 0.22

Corn silage spring plow 0.43

CornStalkEthanol7-15XHigher

What is ‘sustainability’?

• Can continue the same practices for a long period of time– Outputs stable?

• Maintain topsoil• Maintain nutrients

– Inputs stable?• Continued availability of energy inputs?

– Off-site effects acceptable?• N, P, sediment, atrazine in water

Energy inputs & balance• Nitrogen fertilizer is by far the biggest

single energy input

• Efficient N use will be crucial to a positive energy balance– In-season N application timing– Diagnose correct rate (varies across the field)– Avoid streaky applications (equipment

problems)

Energy budget for corn productionEnergy budget for corn production

0

100

200

300

400

500

600

700

800

900

1000kJ

per

kg

gra

in (

dry

)

Data from Shapouri et al. 2002, nine state average

Energy inputs & balance• Nitrogen fertilizer is by far the biggest

single energy input

• Efficient N use will be crucial to a positive energy balance– In-season N application timing– Diagnose correct rate (varies across the field)– Avoid streaky applications (equipment

problems)

180 N 180 N at plantingat planting

153 N sidedress V7.5

Nitrogen timing in 2009:Nitrogen timing in 2009:in-season N kicks butt againin-season N kicks butt again

+ 68 bu/acre

Crop N need is variable Crop N need is variable within fieldswithin fields

What happens if you apply What happens if you apply 150 lb N/acre to this field?150 lb N/acre to this field?

Diagnosing where to put more NDiagnosing where to put more N

PredictorPredictor % of variability in N % of variability in N need explainedneed explained

Yield 2 to 20

Soil nitrate 17 to 25

Soil N quick tests 0 to 18

Soil conductivity 8

Corn color 53 to 77

Crop sensors for N rate diagnosisCrop sensors for N rate diagnosis

sensorssensors

Computer in cab reads sensors, calculates N rate, directs controller

Controller runs ball valve to change fertilizer rate

55 on-farm sensor N demonstrations 2004-2008

Sensor-N impact on energy balance of ethanol

Corn ethanol: energy net vs nitrogen fertilizer management

0

500

1000

1500

2000

2500

Shapouri et al. in-season sensor-based

ne

t k

J p

er

lite

r

Streaky N applications are very inefficient

SUMMARY: Sustainability & Energy Crops

• Soil erosion is the biggest threat to sustainability– Only major historical reason for agricultural

failure and collapse– Missouri is an erodibility champion– Grass fine, corn stalks maybe not

• Energy input is another major obstacle– Efficient N use is crucial (HIGH energy input)– Transport of low-density crops (hay)?

SUMMARY: Sustainability & Energy Crops

• Off-site effects and sustainability– Judgement call– N, P, sediment, atrazine– Much more of an issue with corn grain and

stover than with grass and wood