Updates from the Turf Farm: Soil C quality and soil respiration rates

Paul J. Lilly, Jennifer C. JenkinsThe Rubenstein School of Environment

and Natural Resources,University of Vermont

BES Annual Meeting16 October, 2008

The Residential Carbon Project

- Soil type

- Previous land use

- Vegetation density

- Structure density

- Age of housing

- Management??

What do we know about management?

- Everybody mows

- Mowing heights between 5 and 15cm (Residential Carbon Project sites)

- Lots of people fertilize

- 70% in Glyndon, 50% in Baisman Run (Law et al. 2004)

- self-application ~100 kgN/ha/yr, range ~10 - 400; lawn services ~100-150 kgN/ha/yr (Law et al. 2004); UMD extension says 125-150 kgN/ha/yr

- Some people water

-~60% of residential water use is outdoor (Mayer et al. 1999)

-~10% of households in Law et al. survey

-~55% of households in Syracuse, NY survey (Lilly unpublished)

- Everything else is minor

40 ft.

5 ft.

Rep

3

Rep

1

Rep

2

40 ft.

5 ft.

Rep

3

Rep

1

Rep

2

40 ft.

5 ft.

Rep

3

Rep

1

Rep

2

40 ft.

N1

N2

N0

N0

N1

N2

N0

N2

N1

N1

N2

N0

N0

N2

N1

N0

N2

N2

N0

N2

N1

N1

N0

N1

N1

N0

N2

N0

N2

N1

N1

N0

N2

N1

N2

N0

5 ft.

Rep

3

Rep

1

Rep

2

Belowground respiration (soil only collar)

aboveground respiration = respiration on (soil + veg) collar – respiration on (soil only) collar

C uptake =Δ standing stock C +Δ total soil C +Clippings C +Δ Microbial biomass C +(Soil + veg) respiration +DOC export

C Cycling at the Turf Farm

Total soil C

DOC export in soil water

Aboveground (stubble/thatch) C

Belowground(root) C

Rootturnover

Clippings C

Fast pool

Passive pool = Total soil C – (fast pool+slow pool)

Slow pool

PotentialC min

Microbial Biomass C

Standing Biomass C

- Labile C pool changes seasonally

0

10

20

30

40

50

60

70

80

July '07 November '07 April '08 July '08

C m

iner

aliz

atio

n (

ug

C/d

ry g

so

il/d

ay)

W1 MT F0

W0 MT F0

W1 MS F0

W0 MS F0

0

10

20

30

40

50

60

70

80

July '07 November '07 April '08 July '08

C m

iner

aliz

atio

n (

ug

C/d

ry g

so

il/d

ay)

W1 MT F1

W0 MT F1

W1 MS F1

W0 MS F1

0

10

20

30

40

50

60

70

80

July '07 November '07 April '08 July '08

C m

iner

aliz

atio

n (

ug

C/d

ry g

so

il/d

ay)

W1 MT F2

W0 MT F2

W1 MS F2

W0 MS F2

- Net gain over the last year

C mineralization(OM to CO2)

Belowground respiration (soil only collar)

aboveground respiration = respiration on (soil + veg) collar – respiration on (soil only) collar

C uptake =Δ standing stock C +Δ total soil C +Clippings C +Δ Microbial biomass C +(Soil + veg) respiration +DOC export

C Cycling at the Turf Farm

Total soil C

DOC export in soil water

Aboveground (stubble/thatch) C

Belowground(root) C

Rootturnover

Clippings C

Fast pool

Passive pool = Total soil C – (fast pool+slow pool)

Slow pool

PotentialC min

Microbial Biomass C

Standing Biomass C

0

200

400

600

800

1000

1200

0 20 40 60 80 100 120 140 160 180

Time since start of incubation (days)

CO

2-C

evo

lved

(u

g C

per

g s

oil

)

July 07 Core

Nov 07 Core

April 08 Core

July 08 Core

Fast and slow(er) soil C

Belowground respiration (soil only collar)

aboveground respiration = respiration on (soil + veg) collar – respiration on (soil only) collar

C uptake =Δ standing stock C +Δ total soil C +Clippings C +Δ Microbial biomass C +(Soil + veg) respiration +DOC export

C Cycling at the Turf Farm

Total soil C

DOC export in soil water

Aboveground (stubble/thatch) C

Belowground(root) C

Rootturnover

Clippings C

Fast pool

Passive pool = Total soil C – (fast pool+slow pool)

Slow pool

PotentialC min

Microbial Biomass C

Standing Biomass C

Clippings Production

-Mowing matters!

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

No fertilizer Med. fertilizer High fertilizer

bio

mas

s p

rod

uce

d,

Oct

'07-

Oct

'08

(Mg

/ha

dry

wei

gh

t)

Low Mow, No Water

Low Mow, Watered

High Mow, No Water

High Mow, Watered

Belowground respiration (soil only collar)

aboveground respiration = respiration on (soil + veg) collar – respiration on (soil only) collar

C uptake =Δ standing stock C +Δ total soil C +Clippings C +Δ Microbial biomass C +(Soil + veg) respiration +DOC export

C Cycling at the Turf Farm

Total soil C

DOC export in soil water

Aboveground (stubble/thatch) C

Belowground(root) C

Rootturnover

Clippings C

Fast pool

Passive pool = Total soil C – (fast pool+slow pool)

Slow pool

PotentialC min

Microbial Biomass C

Standing Biomass C

Soil (and plant) respiration

0

2

4

6

8

10

12

14

NS NT WS WT

Oct ‘07

0

1

2

3

4

5

6

7

8

9

NS NT WS WT

Sept ‘080

2

4

6

8

10

12

14

16

18

NS NT WS WT

Sept ‘08

To sum up:

- For clippings, mowing matters most, then fertilizing; watering doesn’t.

-Labile C pool indicator changes (a lot) seasonally; not related to treatments; some indication pool might be increasing under most treatments

- Microbial biomass doesn’t change seasonally; no obvious treatment effects

-Control of respiration is dominated by watering; in a wet year like this year, treatment differences are swamped

- Some indication soil C quality (lability) may be changing

Acknowledgements

-Jen Jenkins, Peter Groffman-Mark Carroll, Dave, Matt, Joe-Gio McClenachan-Dan Dillon-Lisa Martel and David Lewis-NSF-UMBC and CUERE