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Sensors for Crop Management Conference Stillwater OK January 17, 2008. Sensors for Mapping Soil pH. Eric Lund, Veris Technologies, Salina, KS. On-the-go pH mapping. How does it work? How accurate is on-the-go pH mapping? Does managing pH pay?. On-the-go pH mapping is here. - PowerPoint PPT Presentation
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Sensors for Mapping Soil pH
Eric Lund, Veris Technologies, Salina, KS
Sensors for Crop Management ConferenceStillwater OK January 17, 2008
• How does it work?
• How accurate is on-the-go pH mapping?
• Does managing pH pay?
On-the-go pH mapping
On-the-go pH mapping is here...
HERE’S HOW IT WORKS:
A sampler shank is lowered into the soil
A soil core flows through the sampler trough
The soil core is raised
against two pH
electrodes
The geo-referenced pH and EC data are recorded
The entire process is automated
Automated pH Mapping How Does It Work?
How accurate is on-the-go pH mapping from Veris Technologies?
• Statistical analysis
• Visual comparisons
• Repeatability
Statistical analysis2002-2004 Field Trials: 328 validation samples...15 fields...4 states...
r2 = 0.81
3.0
4.0
5.0
6.0
7.0
8.0
9.0
3.0 4.0 5.0 6.0 7.0 8.0 9.0
328 Lab Samples
On
-th
e-G
o p
H M
app
ing
Lab vs. Veris pHOSU lime trials--Enid R2 = 0.9051
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
4 4.5 5 5.5 6 6.5 7 7.5 8 8.5
Lab pH
Ver
is p
H
Statistical analysis
Visual comparisons
Lab samples overlaid on Veris pH sensor data
Visual comparisons
Lab samples overlaid on Veris pH sensor data
Visual comparisons
Repeatability
Significantly more accurate liming than other methods.
How do the results compare? 2.5 acre grids, zones, blanket rate
Improvement over blanket rate lime
0
500
1000
1500
2000
2500
2.5 acre grids soil type Veris sensors
lim
e (
lbs
/ac
re)
Does managing pH pay?
Does managing pH pay?
4
4.5
5
5.5
6
6.5
7
7.5
8
Enid fields
lab
pH
Does managing pH pay?
Does managing pH pay?
Does managing pH pay?
Cumulative gross income
Cumulative net income
Cumulative expense (7 yr proration)
Soybean yield increase
Corn yield increase
1995 0 -6.29 6.29 01996 5.5 -7.08 12.58 11997 13.5 -5.37 18.87 41998 57.5 32.34 25.16 81999 65.5 34.05 31.45 42000 98.5 60.76 37.74 62001 102.5 58.47 44.03 22002 141 96.97 44.03 72003 163 118.97 44.03 112004 185 140.97 44.03 42005 189 144.97 44.03 22006 211 166.97 44.03 4
Does managing pH pay?
University of Nebraska studyLime vs. no limeCorn-bean rotation7 yr study (but data still being collected)Corn $2/bu Soybeans $5.50/bu
Soil EC zones
Soil EC zones
Take-home messages• pH varies widely within most fields• On-the-go pH sensing can accurately map pH
variability• Soil EC zones are another alternative—not as
precise as on-the-go sensing, but typically better than blanket rate
• Lime economics vary by field, but:-low pH levels in OK fields call for lime-since many fields have areas that need zero or a reduced lime amount, precision lime should pay
