influence of biochar and diversified cropping systems on soil physical and chemical properties -...

Influence of Biochar and Diversified Cropping Systems on Soil Physical and Chemical

Properties

Debbie Aller, David Laird, Ross Mazur, Ken Moore, Roger Hintz

SWCS conference- July 28th 2015

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• Increasing energy demands

• Bioenergy production impacts on soil and water quality (Hatfield, 2015)

• Alternative cropping systems • small grains• perennial grasses• biochar amendments

Rationale

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Biochar

Carbon sequestration

Plant pathogens

Crop yields

GHG emissions

Microbial activity

Soil fertility

Nutrient retention

Soil moisture

Photo credit: http://biochar.ucdavis.edu

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• Long-Term Rotation Plots

• Sorenson Farm- Boone County, IA

Study Site

• Established in 2006• CRBD with split plots• Biochar – 10 tons/ac• 2 biochar ages (2012, 2013)• Biomass, yield, and soil data

• 5 cropping rotations • Continuous corn• Corn, soy, corn, soy, corn, soy• Corn, soy, triticale/soy, corn,

soy, triticale/soy• Corn, corn, corn/SG, SG, SG, SG• Continuous switchgrass

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Background

Goal Hypotheses

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• Determine the effect of biochar, biochar age, and cropping system on soil physical and chemical properties.

• Crop rotations that include triticale, switchgrass, and biochar additions will impact soil quality

• Biochar age will impact soil quality

Lab AnalysisPhysical Properties

• Saturated hydraulic conductivity• Solute transport• Gravimetric water content • Bulk density• Porosity

Chemical Properties• pH and EC • Total C/Total N • C/N ratio

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Results

• Biochar decreased soil ρb compared with no biochar controls. • No effect of biochar age• Continuous switchgrass had a decreased ρb similar to biochar

amended plots

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Cont Corn Corn-Soy Corn-Soy-Tricale Corn-Swg Cont Swg

Rotation

Bul

k D

ensi

ty (g

/cm

3)

1.2

1.3

1.4

1.5

1.6No biocharBiochar 1 yearBiochar 2 year

No biocharBiochar 1 yearBiochar 2 year

A B AB A B No biocharBiochar 1 yearBiochar 2 yeara

b b

a

b b

a

bb

a

b b

Cont Corn Corn-Soy Corn-Soy-Triticale Corn-Swg Cont Swg

Rotation

Bul

k D

ensi

ty (g

/cm

3 )

1.2

1.3

1.4

1.5

1.6

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Rotation

Gra

vity

Dra

ined

Wat

er C

onte

nt (g

/g)

0.20

0.25

0.30

0.35


ResultsB A B B B No biochar

Biochar 1 yearBiochar 2 year

b

aa

a a a

a

a a

b

bb


Rotation

Gra

vim

etric

Wat

er C

onte

nt (g

/g)

0.20

0.25

0.30

0.35

• Gravimetric water content was greater for treatments with biochar compared to no biochar.

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Rotation

C:N

Rat

io (%

/%)

8

10

12

14

16

18No biocharBiochar 1 yearBiochar 2 year


NSResults

b

a

a aa

a

bb b

a

a

a


Rotation

C:N

Rat

io (%

/%)

8

10

12

14

16

18

• Soil C/N ratio increased with biochar amendment compared to no biochar controls

• No effect of biochar age

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Rotation

pH

5.0

5.5

6.0

6.5

7.0No biocharBiochar 1 yearBiochar 2 year

A A A B B No biocharBiochar 1 yearBiochar 2 year

a a aa

a

a a

ab

b

b b


Rotation

pH

5.0

5.5

6.0

6.5

7.0

• Soil pH increased with biochar addition compared with no biochar controls

• Soil pH lower in switchgrass rotations compared to other rotations

Results

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Results

• Cropping rotation, biochar presence, and age of biochar appear to have minimal effects on solute transport

• Saturated hydraulic conductivity was highly variable; no differences among treatments

• Biochar • Decreased soil bulk density• Increased gravimetric water content, porosity, soil C/N ratio, and

pH• No effect on EC

• No effect of cropping rotation, biochar presence, and age of biochar on solute transport

• Continuous switchgrass rotation had a similar impact as biochar on soil bulk density and pH

• No difference of biochar age on soil physical and chemical properties 13

Conclusions

Thank you and Questions?

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