integrating soil carbon stabilization concepts and nitrogen cycling
TRANSCRIPT
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
Bord
er
101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121
20'
CC SC CS
120
240 80 200
160 40 0 40 0
120
200
160 80 240
201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221
CS SC CC
160
200
120 80 0 40 240 80 240
200 0 40 160
120
301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321
SC CS CC12
0 0 80 240
200
160 40 200
120 40 240
160 80 0
401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421
60' CS CC SC
40 160 80 0
240
120
200
160 40 200 0 80 120
240
15' 40' Border
40' Alley
20' B
orde
r
20' B
orde
r
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
