Total Rainfall

1

• Environmental Impacts of Conversion of Cropland

• to Short-Rotation Woody Crops

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Monthly Rainfall
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Total Rainfall
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Runoff Totals
Runoff Fraction
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Short Rotation Woody CropSycamore Height
4 ft
5 ft
8 ft
8 ft
8 ft
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Short Rotation Woody Crop
Sycamore DBH and Volume
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SRWC Fertilization
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No-till Corn Fertilization
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Runoff Nitrate
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Leaf Litter Analysis
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Runoff Ammonium
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Runoff Phosphorous
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Percolation Totals
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Lysimeter Nitrate
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Sedimentation in Flumes

• 220 lbs/ac/yr

• 4 lbs/ac/yr

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Double Ring Infiltration
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Double Ring Infiltration

• a

• b

• b

• c

• c

• c

• c

• c

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Average Green Weights
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Biomass - Dry WeightEnd of 5th Growing Season

• 28,572 kg/ha
• (12.7 tons/ac)
• aboveground

• 11,519 kg/ha
• (5.1 tons/ac)
• belowground

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Coppice versus Seedlings

• 6-year-old Sycamore

• 1st year Coppice

• 1st year Seedlings

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Coppice versus Seedlings
150 lb/acre NH4NO3
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Comparison of Root Systems
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Woody Crops as an Energy Source

• Biofuels
• Agricultural and mill residues
• Switchgrass (Panicum virgatum L.) and
  short-rotation woody crops
• Woody bioenergy crops
• Poplar (Populus), willow (Salix), American
  sycamore (Platanus occidentalis L.)
• Two- to twelve-year rotation lengths
• Co-fired with coal in power plants

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Bioenergy Crops and Row Crops

• Bioenergy crops on agricultural land
• Diversified income for farmers (Walsh et al.,
  1998)
• Soils improved under bioenergy crops (Tolbert et
  al., 2000)
• Woody crop / row crop rotation

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Objectives

• Determine the feasibility of following a woody
  crop with a row crop
• Measure the effect of a woody crop on subsequent
  row crop yields and responses to N fertilizer
• Document the effects of a woody crop rotation on
  soil C and N

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Study Site

• Ames Plantation
• Loess belt
• 137 cm precipitation
• Soils
• Memphis-Loring silt
• loam intergrade
• Fine-silty, mixed, active, thermic Typic
  Hapludalf Fine-silty, mixed, active, thermic
  Oxyaquic Fragiudalf

from www.amesplantation.org
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Treatments

• Cropping sequence
• Soybean gt 4-yr sycamore gt corn
• Soybean gt 5-yr sycamore gt corn
• Soybean gt corn
• Rate of N fertilizer applied to corn
• Broadcast ammonium nitrate
• 0, 73, 146, 219 kg N ha-1
• Soil depth (0 to 30 cm)
• Distance from stump (5 to 150 cm)
• Time

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Plot Layout
5-yr sycamore (1995-1999)
15 m
4-yr sycamore (1995-1998)
12 m
Road
Continuous row crops (Soybean through 1998)
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Dependent Variables

• Sycamore dry biomass yield
• Sycamore stump C, N, density
• Corn (Zea mays L.) grain yield
• Soil total C, N, and inorganic N
• LECO CNS-2000 (LECO Corp., St. Joseph, MI)
• Modified indophenol blue method (Sims et al.,
  1995)

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Experimental Design

• Completely-randomized design
• Cropping treatment and N rate analyzed as
  factorial
• Analysis of Variance
• Fishers Least Significant Difference
• Single degree-of-freedom contrasts
• P lt 0.05
• Regression
• Linear and quadratic responses

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Sycamore Biomass Yield
30
25
20
15
Dry biomass (Mg ha-1)
10
A
A
5
0
4-year
4-year
5-year
5-year
Annual mean
Entire rotation
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Stump Wood Density
1.0
0.8
0.6
A
A
Density (g cm-3)
0.4
B
0.2
0.0
0
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104
Weeks After Harvest
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Stump C and N Concentrations
10
600
A
A
B
500
B
8
B
400
6
Total C (g kg-1)
Total N (g kg-1)
300
4
200
C
2
100
0
0
0
104
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52
104
0
Weeks After Harvest
Weeks After Harvest
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Corn Grain Yield
2000
1999
4.0
7
3.5
6
A
A
3.0
5
A
2.5
AB
4
Yield (Mg ha-1)
Yield (Mg ha-1)
2.0
B
3
1.5
2
1.0
1
0.5
0.0
0
Corn after soybean
1st-yr corn after sycamore
2nd-yr corn after sycamore
1st-yr corn after sycamore
Corn after soybean
Note Fertilizer applied at 146 kg N ha-1.
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Corn Grain Yield, 1999
8
1st-yr corn after soybean
7
1st-yr corn after sycamore
6
2
R
0.90
2
5

R
0.57
Yield (Mg ha-1)
4
3
2
1
0
0
219
73
146
N fertilizer (kg N ha-1)
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Corn Grain Yield, 2000
4
3
2
Yield (Mg ha-1)
1
0
0
219
73
146
N fertilizer (kg N ha-1)
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Corn Grain Yield, 2001
12
10
8
Yield (Mg ha-1)
6
4
2
0
0
219
73
146
N fertilizer (kg N ha-1)
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Soil Total C Concentration, 1999

0-2.5

2.5-7.5
Soil depth (cm)
7.5-15

5 cm from stump
15-30

0
2
4
6
8
10
12
14
16
18
Total C (g kg-1)
Note Contrasts compare stump to row crop
treatments.
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Soil Total C Concentration (0-30 cm)
10


8


6
Total C (g kg-1)
4
37.5 cm from stump
2
5 cm from stump
Continuous row crops
0
0
20
40
60
80
100
120
140
Weeks after sycamore harvest
Note Contrasts compare soil 5 and 37.5 cm from
stumps to soil under continuous row crops.
Fertilizer applied at 146 kg N ha-1.
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Soil C Concentration (0-30 cm)
134 Weeks After Sycamore Harvest
8

6
4
Total C (g kg-1)
2
0
150
5
37.5
75
Continuous row crops
Distance from stump (cm)
Note Contrast compares soil at four distances
from stumps to soil under continuous row
crops. Fertilizer applied at 146 kg N ha-1.
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Soil Total N Concentration, 1999

0-2.5
2.5-7.5
NS
Soil depth (cm)
7.5-15

5 cm from stump
15-30
NS
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Total N (g kg-1)
Note Contrasts compare stump to row crop
treatments.
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Soil Inorganic N Concentration (0 to 30 cm) in
June, 1999
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Continuous row crops
5 cm from stump
NS
40
37.5 cm from stump
NS
30
NO3- and NH4 (mg kg-1)
NS
20
NS
10
0
219
0
146
73
-1
N fertilizer (kg N ha
)
Note Contrasts compare stump to row crop
treatments at each N rate.
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Conclusions

• No mechanical limitations
• Nitrogen immobilized in stumps
• Nitrogen fertilization may need to be increased
  for corn following a woody crop
• Soil C concentration increased by sycamore