1
An Integrated System for Mapping An Integrated System for Mapping Soil Physical Properties OnSoil Physical Properties On--thethe--GoGo
(the Mechanical Sensing Component)(the Mechanical Sensing Component)
Viacheslav AdamchukViacheslav AdamchukPhilip ChristensonPhilip Christenson
Biological Systems EngineeringBiological Systems EngineeringUniversity of Nebraska University of Nebraska -- LincolnLincoln
Presentation OutlinePresentation Outline• Background
– Problem statement and history of sensor development
– Overview of integrated mapping of soil physical attributes
• Materials and Methods– Vertical blade with an array of strain gage bridges– Ling-term tillage plots experiment
• Results and Discussion– Comparison of tillage practices using on-the-go
measurements of soil mechanical resistance– Field mapping– Overview of the latest prototype system– Summary
Problem Statement Problem Statement
• The assessment of soil variability is one of the most important steps in site-specific management
• Conventional means to attain soil variability data are incapable of accurately identifying spatial inconsistency within a production field at an economically feasible cost
• There is a need to develop equipment for mapping soil attributes on-the-go
• On-the-go sensing technology must be reliable, rapid, simple, inexpensive, repeatable
OnOn--thethe--go Soil Sensorsgo Soil Sensors
Electrical and Electromagnetic
Acoustic
Mechanical Electrochemical
H+
H+ H+H+
H+
Pneumatic
Optical and Radiometric
Applicability of OnApplicability of On--thethe--Go Soil SensorsGo Soil Sensors
OKSomeSomeResidual nitrate (total nitrogen)
OKOKCEC (other buffer indicators)
OKSomeOther nutrients (potassium)
GoodSomeSoil pH
SomeOKSomeDepth variability (hard pan)
SomeGoodSoil compaction (bulk density)
SomeOKSoil salinity (sodium)
GoodGoodSoil water (moisture)
GoodSomeSoil organic matter or total carbon
SomeOKGoodSoil texture (clay, silt and sand)
Soil property H+
H+ H+H+
H+
Integrated Mapping ApproachIntegrated Mapping Approach• Instrumented blade
– Compacted field areas– Soil mechanical resistance profile– Blade with an array of strain gage bridges– Sensing depth down to 30 cm– Minimum soil disturbance
• Capacitor-type sensor– Volumetric water content– Dielectric soil properties measurement
• Optical sensor– Organic matter content– Soil reflectance at 470 and 660 nm– Direct soil contact through a sapphire window
2
Vertical Blade Mapping ApproachVertical Blade Mapping Approach
Strain Gages
Tool Bar
Travel Direction
Purdue University (West Lafayette, Indiana)
1998
< 2.892.89 – 3.113.11 – 3.333.33 – 3.55> 3.55
Soil Mechanical Resistance, kN
1998 Farm Progress Show Site
Corn Yield
20 cm __20 cm __
Vertical Smooth Blade with an Array Vertical Smooth Blade with an Array of Strain Gagesof Strain Gages
Purdue University (West Lafayette, Indiana) – UNL
(Lincoln, Nebraska)1999 - 2001
Strain Gage Array
Three Independent Blade SystemThree Independent Blade System
UNL (Lincoln, Nebraska) –University of Sao Paulo
(Piracicaba, Brazil)2002 - 2004
Three blades• 0 – 10 cm• 10 – 20 cm• 20 – 30 cm
Soil-metal friction compensation
sensor
Soil Mechanical Resistance (Three Blade System)Soil Mechanical Resistance (Three Blade System)
Soil Mechanical Resistance (Three Blade System)Soil Mechanical Resistance (Three Blade System)
Soil Mechanical Resistance, MPa
ARDC (Mead, Nebraska)
Field 1.10December 2002
0 – 10 cm depth 10 – 20 cm depth
20 – 30 cm depth
Example of Spatial Resemblance Example of Spatial Resemblance between Different Data Layersbetween Different Data Layers
bu./acre
Soybean Yield, 2000
Soil Mechanical Resistance, 20-30 cm
Soybean Yield, 2002
Soil Electrical Conductivity, 0-30 cm
bu./acre
MPa
mS/m
3
Integrated Soil Physical Properties Integrated Soil Physical Properties Mapping System (ISPPMS)Mapping System (ISPPMS)
Two wavelengths soil reflectance sensor
Soil mechanical resistance profiler with an array of
strain gage bridgesCapacitor-based
sensor
UNL (Lincoln, Nebraska) 2004
““Organic Matter” SensorOrganic Matter” Sensor
Shank
Cross-sectionof the sensor
660 nm LEDs
Photodiode
Purdue University (West Lafayette, Indiana)
1988 - 1992
UNL (Nebraska, Lincoln)
2004 - 2005
CapacitorCapacitor--Based SensorBased SensorUNL (Lincoln, Nebraska) –
Retrokool (Berkeley, California)2001-2003
• Silty clay loam soil• Triple replicates• Two tests
2.0
2.2
2.4
2.6
2.8
3.0
3.2
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
Gravimetric Soil Moisture, g/g
Sens
or O
utpu
t, V
Test 1Test 2Average
Instrumented Blade with a Instrumented Blade with a HalfHalf--Split Cutting EdgeSplit Cutting Edge
Gage 1
Gage 2
Gage 3
Gage 4
Boss A
Boss B
Boss C
Vertical location:
Cutting edge
Blade
Discrete reaction forces
Apparent soil surface
Direction of travel
Second order polynomial
model
Actual soil surface
5 – 30 cm measurement depth
Tillage Treatment Experimental PlotsTillage Treatment Experimental Plots
0.25 - 0.290no-till w/o cultivationF0.24 - 0.2513double diskedE0.23 - 0.2630chiselled and diskedD0.24 - 0.275no-till with cultivationC0.24 - 0.2613diskedB0.26 - 0.2820plowed and double diskedA
Gravimetric moisture content, g/g
Maximum depth of tillage, cmTillage treatmentPlot
• Twenty years history• Controlled wheel traffic• Five cone penetrometer profiles• Five on-the-go measurements (1 Hz)
Apparent Soil ProfilesApparent Soil Profiles
Plot B (disked)
0
5
10
15
20
25
-0.8 -0.4 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8
Soil mechanical resistance, MPa
Rela
tive
dept
h, c
m
ISPPMS - pass 1Cone - pass 1ISPPMS - pass 2Cone - pass 2
Plot D (chiselled and disked)
0
5
10
15
20
25
-0.8 -0.4 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8
Soil mechanical resistance, MPa
Rela
tive
dept
h, c
m
ISPPMS - pass 1Cone - pass 1ISPPMS - pass 2Cone - pass 2
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Integrated Load IndicesIntegrated Load Indices
0
2000
4000
6000
8000
-2000 0 2000 4000 6000 8000 10000
Cone penetrometer index estimate, N
ISPP
MS
inde
x es
timat
e, N
Overall integrated loadDifference between lower and upper integrated loadsLower integrated loadUpper integrated load
r2 = 0.24
r2 = 0.56
r2 = 0.55
r2 = 0.03
Overall Integrated Load ComparisonOverall Integrated Load Comparison
1
3
5
7
9
1 1
1 3
0 2000 4000 6000 8000 10000
Overall integrated load (ISPPMS), N
Tilla
ge p
lot
Center rowWheel row
A
F
E
D
C
B
pass
1
2
1
2
1
2
1
2
1
2
1
2
1
3
5
7
9
1 1
1 3
0 2000 4000 6000 8000 10000
Overall integrated load (cone penetrometer), N
Tilla
ge p
lot
Center rowWheel row
A
F
E
D
C
B
pass
1
2
1
2
1
2
1
2
1
2
1
2
Cone PenetrometerInstrumented Blade
double diskedEdiskedBno-till w/o cultivationFno-till with cultivationC
chiselled and diskedDplowed and double diskedATreatmentTillage PlotTreatmentTillage Plot
b) Wheat yield, 2002
a) Total force estimate from instrumented blade, 2004 Overall Resistance Load
Wheat Yield
Mg/kg
N
Maps of Soil Mechanical Resistance Maps of Soil Mechanical Resistance (Instrumented Blade) and Wheat Yield(Instrumented Blade) and Wheat Yield
Rogers Memorial Farm(Eagles, Nebraska) Field R-9, July 2004
Relatively high water holding
capacity
The Latest PrototypeThe Latest Prototype
Replaceable cutting edge
Array of strain gage bridges
SummarySummary• On-the-go mapping of soil mechanical
resistance allows delineation of field areas with relatively hard or soft cultivated layer of soil
• High-order polynomial representation of topsoil profile is not beneficial
• Estimates of soil mechanical resistance attained using cone penetrometer and on-the-go sensing approaches have different nature
• Integration of sensing systems with alternative measurement concepts is critical
• Maps of physical soil properties can be used to prescribe spatially differentiated field management
http://bse.unl.edu/adamchukE:mail: [email protected]