Soil respiration and cropping system diversity

Jed Eberly Central Ag Research Center

December 10, 2019

What is soil respiration?

• Emission of carbon dioxide (CO2) from the soil • Due to activity of macro- and microorganisms

in the soil

Why is it important?

http://earthobservatory.nasa.gov/Features/CarbonCycle/

http://changingclimate.osu.edu/features/accounting-for-carbon

Nitrogen Cycle

Biomass nitrogen

Plant available nitrogen

Mineralization

N-mineralization

Nitrogen Management• Maximize return• Minimize cost

http://www.smart-fertilizer.com/articles/nitrogenHawkesford (2014) J Cereal Science. 59(3): 276-283

What controls soil respiration rates?

• Temperature• Moisture• Soil physical properties• Nutrient availability (e.g. N, P, Ca)• Availability and quality of soil carbon• Type and abundance of soil microorganisms

What controls soil respiration rates?

• Temperature• Moisture• Soil physical properties• Nutrient availability (e.g. N, P, Ca)• Availability and quality of soil carbon• Type and abundance of soil microorganisms

Project Objectives

• Determine the impact of increased cropping system diversity on respiration

• Measure the contribution of N mineralization to the N budget

Rotation And Tillage Study

Rotation And Tillage Study

• Microbial activity• Nitrogen

mineralization• Microbial community– Structure– Function

Winter wheat Fallow

Winter wheat

Spring wheat

Winter wheat Barley Winter

lentil

Winter wheat Barley Spring

pea

Spring wheat

Spring pea

Prosomillet Safflower

Methods

• Soil sampling– Total N– Nitrate N

• Soil respiration• N mineralization

0.0

0.1

0.2

Nov 01 Nov 15 Dec 01 Dec 15Date

Prec

ipita

tion

(inch

es)

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0.5

1.0

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2.0

10/31

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12/20

Date

Aver

age

Res

pira

tion (u

mol

m−2

s−1 )

Treatment SP−MIL−SAF−SW WW−SW

Methods

+ ATP Luciferase

LuciferinLight

Soil core

Resin

Mineralization

Biomass

Soil Respiration

Fall 20180.0

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Nov 01 Nov 15 Dec 01 Dec 15Date

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age

Res

pira

tion (u

mol

m−2

s−1 )

Treatment SP−MIL−SAF−SW WW−SW

Spring 20190.00

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0.75

Apr 01 Apr 08 Apr 15 Apr 22Date

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ipita

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es)

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pira

tion (u

mol

m−2

s−1 )

Treatment SP−MIL−SAF−SW WW−SW

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Jun Jul Aug Sep OctDate

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ipita

tion

(inch

es)

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10/11

Date

Aver

age

Res

pira

tion (u

mol

m−2

s−1 )

Treatment SP−MIL−SAF−SW WW−SW

Respiration rate of changeRain event WW-SW SP-MIL-SAF-SW

5/16/19 0.42 0.225/27/19 0.44 0.316/11/19 0.16 0.246/22/19 0.37 0.279/24/19 0.20 0.18

Fall 2018 Spring 2019

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1

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SW-WW SP-MIL-SAF-SW

Aver

age

Resp

iratio

n Ra

te (μ

mol

CO

2m

-2s-1

)***

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1

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1.4

SW-WW SP-MIL-SAF-SW

Aver

age

Resp

iratio

n Ra

te (μ

mol

CO

2m

-2s-1

)0.0

0.5

1.0

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2.5

SW-WW SP-MIL-SAF-SW

Aver

age

Resp

iratio

n Ra

te (μ

mol

CO

2m

-2s-

1 )

Summer 2019

Factor Rs (2018) Rs (2019)

Cropping system (CS) <0.001 0.192

Soil Temperature <0.001 <0.001

Soil Moisture 0.899 <0.001

Air Temperature <0.001 0.010

CS*Soil Temperature 0.333 0.391

CS*Soil Moisture 0.732 0.088

CS*Air Temperature 0.001 0.042

Soil temp*Soil moisture 0.038 <0.001

CS*Soil temp*Soil moisture <0.001 0.667

ANOVA

Results

SW-WW

SP-MIL-

SAF-SW

0

1

2

3

4

Nitr

ate-

N (p

pm)

SW-W

W

SP-MIL-

SAF-SW

1000

1500

2000

2500

Tota

l N (p

pm)

**

Expected OutcomesTemperature & Precipitation effects on activity

Determine differences in N-mineralization in diversified cropping systems

• Provide guidance for fertilizer application

• Leaching risk

Acknowledgements

Project Personnel• Pat Carr• Clain Jones• Simon Fordyce

CARC Staff• Eva Magnuson• Jenni Hammontree

FundingMontana Fertilizer Advisory Committee

Questions

Jed EberlyAssistant ProfessorMSU Central Ag Research Center52583 US Hwy 87Moccasin, MT 59462Phone: 406.423.5421Email: jed.eberly@montana.edu