South W est,Iowa w ell draining soil SIde-dressed U AN (lbs N ac -1 ) 0 50 100 150 200 250 C orn Yield (bu ac -1 ) 0 50 100 150 200 250 SIde-dressed U AN (lbs N ac -1 ) 0 50 100 150 200 250 2010 N orth C entral,Iowa poorly draining soil C orn Yield (bu ac -1 ) 0 50 100 150 200 250 300 0 % rem oval 50 % rem oval 100 % rem oval 2009 2009 2010 * * * * * * * * * * * Figure 1. Residue removal effects on corn yields as affected by N rate in 2009 and 2010 for poorly and well-drained soils. Asterisk indicates significant difference between residue removal within each N rate at p=0.05.
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Figure 8. Potential sink or source for Atmospheric CO 2 -C .
Figure 1. Residue removal effects on corn yields as affected by N rate in 2009 and 2010 for poorly and well-drained soils. Asterisk indicates significant difference between residue removal within each N rate at p=0.05. - PowerPoint PPT Presentation
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South West, Iowawell draining soil
SIde-dressed UAN (lbs N ac-1)
0 50 100 150 200 250
Cor
n Y
ield
(bu
ac-1
)
0
50
100
150
200
250
SIde-dressed UAN (lbs N ac-1)
0 50 100 150 200 250
2010
North Central, Iowapoorly draining soil
Cor
n Y
ield
(bu
ac-1
)
0
50
100
150
200
250
300
0 % removal50 % removal100 % removal
2009 2009
2010
*
*
*
**
*
*
**
**
Figure 1. Residue removal effects on corn yields as affected by N rate in 2009 and 2010 for poorly and well-drained soils. Asterisk indicates significant difference between residue removal within each N rate at p=0.05.
North Central, Iowapoorly draining soil
Residue Removal (%)
0 50 100
Co
rn Y
ield
(b
u a
c-1)
0
20
40
60
80
100
120
140
160Chisel plowNo-till
South West, Iowawell draining soil
Residue Removal (%)
0 50 100
bab
a
c
b b
c
ba
d
b b
Figure 2. Residue removal effects on corn yields as affected by tillage in 2010 for poorly and well-drained soils. Different letters indicate significant difference between residue removal and tillage at p=0.05.
North Central, Iowapoorly draining soil
Corn Residue Removal (%)
0 50 100
Soi
l Org
anic
Car
bon
(%)
0
1
2
3
4
5
6Chisel plowNo-till
Baseline = 4.46
South West, Iowawell draining soil
Corn Residue Removal (%)
0 5 10
Baseline= 2.39
aa a
aa
aa a a a
a
a
Figure 3. Total soil carbon as affected by two years of residue removal for poorly and well-drained soils. Different letters indicate significant difference between residue removal at p=0.05.
Corn Residue Removal (%)
0 20 40 60 80 100
Corn Residue Removal (%)
0 20 40 60 80 100
Corn Residue Removal (%)
0 20 40 60 80 100
SW
Iow
a, w
ell d
rain
ing
soi
lN
et S
OC
Seq
uest
ratio
n (t
on C
ac-1
)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
0 lbs N ac-1
NC
Iow
a, p
oorly
dra
inin
g s
oil
Net
SO
C S
eque
stra
tion
(ton
C a
c-1)
-2.0
-1.5
-1.0
-0.5
0.0
0.5Chisel plowNo-till
150 lbs N ac-1 250 lbs N ac-1
y = -0.6228 - 0.0036x, R2 = 0.72, CPy = -0.5281 - 0.0038x, R2 = 0.97, NT
y = -0.3059 - 0.0090x, R2 = 0.90, CPy = -2049 - 0.0083x, R2 = 0.98, NT
y = -0.1397 - 0.0089x, R2 = 0.85, CPy = 0.0584 - 0.0068x, R2 = 0.92, NT
Figure 4. Potential changes to net soil organic carbon from carbon input from above- and below-ground biomass minus losses from microbial respiration to a depth of 15 cm. Carbon budget was conducted in 2010 in a well-drained soil and poorly-drained soil under different tillage and N fertilization regimes.
North Central, Iowapoorly draining soil
Residue Removal (%)
0 50 100
Bu
lk D
en
sity
(g
cm
-3)
1.0
1.1
1.2
1.3
1.4
1.5
1.6Chisel plowNo-till
South West, Iowawell draining soil
Residue Removal (%)
0 50 100
bb
a
b b
a
a
bb b
a a
Baseline: 1.25Baseline: 1.28
Figure 5. Soil bulk density as affected by two years of residue removal and tillage systems for poorly and well-drained soils. Different letters indicate significant difference between residue removal and tillage at p=0.05.
North Central, Iowapoorly draining soil
Residue Removal (%)
0 50 100
Ag
gre
ga
te M
ea
n W
eig
ht D
iam
ete
r
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8Chisel plowNo-till
North Central, Iowapoorly draining soil
SIde-dressed UAN (kg N ha-1)
0 170 280
bbc
c
a
c c b
aa
Figure 6. Aggregate mean weight diameter as affected by two years of residue removal, tillage and nitrogen rate systems for a poorly-drained soil site. Different letters indicate significant difference between residue removal, tillage and nitrogen rate at p=0.05.
North Central, Iowapoorly draining soil
Residue Removal (%)
0 50 100
Ste
ad
y In
filtr
atio
n R
ate
(cm
min
-1)
0.0
0.1
0.2
0.3
Chisel plowNo-till
South West, Iowawell draining soil
Residue Removal (%)
0 50 100
aa a a a a
a
ab
c
a
aba
Figure 7. Steady water infiltration rates as affected by residue removal and tillage for poorly and well-drained soil sites. Different letters indicate significant difference between residue removal and tillage at p=0.05.
0% Removal
Side-dressed UAN (N lbs ac-1)
0 150 250
Net
Gai
n o
r L
oss
of
CO
2 (l
bs
CO
2-C
ac-1
)
-1
0
1
2
3
4
5Chisel PlowNo-till
50% Removal
Side-dressed UAN (N lbs ac-1)
0 150 250
100% Removal
Side-dressed UAN (N lbs ac-1)
0 150 250
aa
a
b
c c
abab abab
c
c
b
abb
bc
cc
Figure 8. Potential sink or source for Atmospheric CO2-C .1. Include above ground biomass, grain, and root biomass for ANPP2. (ANPP + BNPP) – Rh 3. Positive values indicate a sink for atmospheric CO2