an environmental assessment of sensor-based variable-rate n management in corn darrin roberts dr....
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EONR Reflectance by Sensors Environmental Measurements 3 Steps to Accomplish ObjectivesTRANSCRIPT
An Environmental Assessment of Sensor-Based Variable-Rate
N Management in CornDarrin Roberts
Dr. Newell R. Kitchen, Advisor
Thesis Committee Members:Newell Kitchen, Peter Scharf, Ken Sudduth
Research Objectives
(I) Evaluate the relationship between EONR and active-light reflectance sensor readings
(II) Evaluate the relationship between environmental measurements and EONR
EONR
Reflectance bySensors
Environmental Measurements
3 Steps to Accomplish Objectives
3 Environmental Measurements(2004-2005 cropping seasons)
1. Yield Efficiency:(Yi - Ycheck plot)/Ni
2. N fertilizer recovery efficiency (NFRE):[(NRi – NRcheck plot)/Ni] * 100
3. Post-harvest soil sampling:Inorganic N levels were determined to a depth of 120cm
0
50
100
150
200
250
B04 CI04 CII04 D04 H04 P04 S04 W04
EON
R, k
g ha
-1
Min EONR Max EONR
Within-field EONR variability for 2004 fields
EONR related to Vis/NIR ratios for 2004 fields
y = -1463.2x2 + 2040.1x - 512R2 = 0.35
0
50
100
150
200
250
0.5 0.6 0.7 0.8 0.9 1.0VIS/NIR
EON
R(k
g N
/ha)
B04 CI04 CII04 D04H04 P04 S04 W04
00
5050
100 100
150 150
200 200
250 250
EO
NR
, kg
N/h
a
EO
NR
, kg
N/h
a
EONR = -794 + 2632.7087(index) + 1.3174(index)(EC) - 1798.747(index2)
R2 = 0.47
EONR related to Vis/NIR and soil EC for 2004 fields
0
25
50
75
100
-250 -200 -150 -100 -50 0 50 100 150 200Difference from EONR, kg ha-1
Yiel
d Ef
ficie
ncy,
kg
grai
n (k
g N
)-1 B04CI04CII04D04H04P04S04W04
Yield efficiency related to EONR for 2004 fields
0
25
50
75
100
-250 -200 -150 -100 -50 0 50 100 150
Difference from EONR, kg ha-1
NFR
E, %
B04D04S04
NFRE related to EONR for 2004 fields
0
50
100
150
200
-250 -200 -150 -100 -50 0 50 100 150
Difference from EONR, kg ha-1
Prof
ile In
orga
nic
N, k
g ha
-1 D04P04S04
Profile inorganic N related to EONR for 2004 fields
Research Conclusions EONR was highly variable within and between
corn fields EONR was greatly affected by yearly climate
conditions Because sensor indices, in conjunction with soil
EC, were able to separate low and high EONR values, further research might involve sensors in the development of N management zones within fields
Active-light reflectance sensors show promise to achieve EONR, increase Yield Efficiency and NFRE, and reduce N loss off fields
Thank you
