Yield Monitors and Maps BAE 4213 April 12, 2007 Randy Taylor Biosystems and Ag Engineering.
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Transcript of Yield Monitors and Maps BAE 4213 April 12, 2007 Randy Taylor Biosystems and Ag Engineering.
Yield Monitors and Maps
BAE 4213April 12, 2007Randy TaylorBiosystems and Ag Engineering
What Are the Tasks? Measure grain flow
Mass or Volume Flow Sensor
Measure ground speed Existing ground speed
sensor or position sensor signal
Program harvest width Programmed as a
constant value or changed on-the-go
Combine position GPS Position Sensor
Flow Sensors
Yield Monitor Errors How do we calculate yield
Yield errors must be related to one of these 3 measurements: mass, length, width
For a yield monitor Mass is determined from the flow sensor Width is a programmed constant Length is determined from speed
widthlength
mass
area
massYield
Width When do errors occur?
header not full (i.e. harvest width does not match header width)
How do we fix it? Adjust on the go => bad idea
How much error are we really talking about? U of Missouri research found it was 8-12%
in drilled beans if they assumed constant full header
How much do you have to reduce harvest width to get area (field) to be accurate?
Distance Errors UNL Research harvesting up & down slope
found no significant difference in mass accumulation.
However they found a 42’ difference going uphill verses down on a 6% slope
Though GPS was the intended speed signal, differences in end points was not observed in a GIS
The greater distance measurements going uphill cause a reduction in calculated yield
Mass Flow Measurement Errors
Combine Dynamics Calibration
Combine Dynamics Crop is cut or removed from plant Conveyed to feeder house in the header Conveyed to threshing unit (cylinder or rotor) ~80% of separation should occur during threshing ~20% of grain goes on to separation (rotor or straw
walkers) Grain that falls on the cleaning shoe should pass through
near the front of the shoe Grain that goes through the returns
All of these affect the grain flow relative to its former location in the field
Mass Flow Sensors
Lag/Resonance Time
Sensor Calibration
Response to mass flow is non linear Diaphragm vs Triangular Can get a very good fit with linear Operating at points away from one
calibration can cause errors Where do we see these?
Start and stop grain flow
Transitional Mass Flow
What Causes Error?
R2 = 0.53
R2 = 0.86
R2 = 0.61
R2 = 0.78
-40
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0
10
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0 10 20 30 40 50
Average Mass Flow, lbs/s
Err
or,
%
Ranking Plots
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5
10
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20
25
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0 10 20 30 40
Actual Rank
Yie
ld M
on
ito
r R
ank
Project 2
Project 3
Project 4
Project 5
Project 6
Ideal
Using YM for OFR 50% of the error between weigh wagon and
yield monitor weights was due to mass flow Correlation between yield monitor and
weigh wagon weights was 0.97 Regression results lead to the same
conclusions regarding the treatments Challenging to rank treatments with YM
data
What Can a Yield Map Tell Us?
Soil fertility, type, etc. Disease or insect pressure Variety differences Poorly drained areas Compacted areas Does not point out the yield limiting
variable, it only indicates the response to it
Using YM Data
1. Diagnosing Crop Production2. Estimating Nutrient Removal3. On-Farm Research4. Establishing Yield Potential (Goals)
1. Diagnosing Crop Production
Probably the most widespread use for yield maps today
Print maps to keep records on Select appropriate ranges
Number of ranges Spread (don’t create or exaggerate
variability) Color scheme
Problem Diagnoses
Wire worm infestation
Crop drowned
Presenting Yield Maps
5 – 6 ranges or groups maximum Based on
Natural Break Even Intervals Predefined Crop Standard Deviation Percent of Average
Color Scheme
Dryland Wheat Even Intervals
1996 1997
Dryland Wheat Predefined Crop
1996 1997
Dryland Wheat Percent of Average
1996 1997
Normalized Yield (96-97)
Data Aggregation
Point data Contouring
Some type of interpolation Likely have minimal or confusing choices
Grid Interpolated Averaged Summed
Points versus Interpolation
How many of the dark blue points are zero yield?
Header Status
Raised the mean yield about 5 bu/ac, but did it really make a difference?
Irrigated Corn/Beans Normalized Yield
1996 Beans/Corn 1997 Corn
Beans Corn
Average of Two Years
Interpreting Patterns
Straight lines are manmade Parallel with travel At an angle with travel patterns
Irregular patterns are generally naturally occurring Lines Areas/patches
Sand Pivot (1996-97 Crops)
Yield Variability
Many causes of yield variability Yield monitors and maps don’t
determine the cause Yield maps display the location and
magnitude (area and degree) This information should lead to better
decisions
Yield Variability
That which can be changed Fertility
That which must be managed Soil physical properties
3. On-Farm Research
Has the potential to expand knowledge about individual farms
Comparison of varieties, tillage practices, fertility rates, etc.
Not as easy as it may seem What do you want to know? Why do you want to know it?
YieldYield
TopsoilTopsoil
PopulationPopulation
Layering Maps
1998 Corn - Osage County
135
140
145
150
155
160
165
0 2 4 6 8 10
Topsoil, inches
Yie
ld,
bp
a
22500
25500
28500
4. Prescribing Spatial Inputs
Some input recommendation models require the use of a crop yield goal
Development of a nutrient recommendation map may require the use of a yield goal map
How can you generate variable yield goals?
Yield Stability Analysis Data were
obtained with various yield monitors
Converted to point yield and unrealistic values were removed
Data were block averaged to 180 foot cells
‘Whisker Plots’ of YM Data
-1.0
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0 20 40 60 80 100 120 140 160 180
Rank
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an
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lati
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nc
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-1.0
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Rank
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nc
e
Points are the mean relative difference for each cell
Bars are the standard deviation of yield through time.
Classification Maps
Mean Relative Difference Standard statistical analysis offers minimal
insight into spatial data Low yielding cells tend to be more variable There is a better opportunity to classify
consistently low yielding areas Because like classed cells were spatially
contiguous, this method showed more promise than typical methods
Conclusions
Yield monitor data can be used for anything that yield data are used for1. Diagnosing Crop Production2. Estimating Nutrient Removal3. On-Farm Research4. Establishing Yield Potential (Goals)