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-~55% of households in Syracuse, NY survey (Lilly unpublished)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