Integrating Soil Carbon Stabilization Concepts and Nitrogen Cycling
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Transcript of Integrating Soil Carbon Stabilization Concepts and Nitrogen Cycling
Is Soil Organic Matter Important for Corn Yield?
Integrating Soil Carbon Stabilization Concepts and the Nitrogen Cycle
Hanna Poffenbarger (PhD student)Mike Castellano, Dan Olk, John Sawyer, Johan Six
40' Border
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CC SC CS
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CS SC CC
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SC CS CC12
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60' CS CC SC
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15' 40' Border
40' Alley
20' B
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40' Alley
40' Alley
After 15 years, how does historical N rate affect yield and N use efficiency when fertilized at the optimum rate?
After 15 years, how does historical N rate affect yield and N use efficiency when fertilized at the optimum rate?
Historical Nitrogen Rate and Extant Soil Organic Carbon
Yiel
d w
hen
ferti
lized
at
the
optim
um ra
te
After 15 years, how does historical N rate affect yield and N use efficiency when fertilized at the optimum rate?
Historical Nitrogen Rate and Extant Soil Organic Carbon
Yiel
d w
hen
ferti
lized
at
the
optim
um ra
te
Nitrogen Retention, Saturation & the Carbon Saturation Concept
Linking C Saturation & N Dynamics
0%
100%
Maximum Capacity (Saturation)
Carbon Inputs at Steady State
POM C/N Ratio
N inputs
transferred to SOM
Net NitrificationR
elat
ive
Uni
ts
0%
After 15 years, how does historical N rate affect yield and N use efficiency when fertilized at the optimum rate?
Zero-N subplot
Optimum N subplot (15N)
Mainplots with different historical N rate for the last 15 years (0-270 kg N ha-1 y-1)
Central Iowa AONR = 202 kg N ha-1
~70 kg N ha-1 unrecovered
South Iowa AONR > 269 kg N ha-1
~180 kg N ha-1 unrecovered