figure 1. residue removal effects on corn yields as affected by n rate in 2009 and 2010 for poorly...

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 = -0.1649 - 0.0086x, R2 = 0.91, CP

y = 0.1377 - 0.0092x, R2 = 0.82, NT

y = -0.8993 - 0.0006x, R2 = 0.61, CP

y = -0.6428 - 0.0016x, R2 = 0.54, NTy = -0.5230 - 0.0036x, R2 = 0.54, CP

y = -0.2915 - 0.0080x, R2 = 0.90, 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

2010

Day of Year

50 100 150 200 250 300

2009

Day of Year

50 100 150 200 250 300

So

il S

urf

ace

CO

2 E

fflu

x (l

bs

ac-1

day

-1)

0

100

200

300

Chisel Plow, 0 % removedChisel Plow, 50 % removedChisel Plow, 100 % removedNo-tillage, 0 % removedNo-tillage, 50 % removedNo-tillage, 100 % removed

Figure 9. Seasonal CO2 emissions under different residue removal and tillage management in 2009 and 2010 for the poorly drained soil site in Ames.

2009

Day of Year

100 150 200 250

So

il S

urf

ace

N2O

Eff

lux

(g N

ha-1

day

-1)

0

50

100

150

200

250Chisel PlowNo-tillage

2010

Day of Year

100 150 200 250

So

il Mo

isture (cm

3 cm-3 vo

l %)

0

5

10

15

20

25

30

35

40

45

50

Chisel Plow moistureNo-till moisture

*

***

*

*

*

*

Figure 10. Seasonal N2O emissions under different tillage management in 2009 and 2010 for the poorly drained soil site in Ames.

2009 2010

Ave

rag

e S

oil

Su

rfa

ce

N2O

Eff

lux

(g N

ha-1

da

y-1)

0

10

20

30

40

50

600 % Residue Removed50 % Residue Removed100 % Residue Removed

a

bb

a

a

a

Figure 11. Mean annual N2O emissions under different corn residue removal management in 2009 and 2010 for the poorly drained soil site in Ames.

Table 1. Effect of N fertilizer Rate on Corn Biomass N and C Content at Plant Maturity Across Sites, 2009-2010 (John Sawyer and Jose Pantoja).

N Rate Veg. Cob Grain Total   Veg. Cob Grain Total

lb N/acre - - - - - - - - - -lb N/acre - - - - - - - - - - - - - - - - - - - - - -lb C/acre - - - - - - - - - - - - - -

0 28 (43%) 3 (4.6%) 34 (52%) 651,770 (50%) 230 (5.5%) 1,555 (44%) 3,550

150 59 (38%) 6 (4.0%) 89 (58%) 1543,140 (43%) 510 (7%) 3,670 (50%) 7,320

250 73 (40%) 7 (3.8%) 103 (56%) 183  3,375 (42%) 555 (7%) 4,080 (51%) 8,010

Only the main effect of N rate was statistically significant for N and C (p<0.001).

Veg., vegetative material.