Cheap VR Lime Recs

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Cheap VR Lime Recs

• Scheufler Farms, Inc.
• Lee Scheufler

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Problem (01 Funded Grant)

• Application of lime to adjust soil pH is a major
  farm expense.
• The need to apply at variable rates is already
  documented. (John Schmidt)
• Intensive grid sampling for variable lime
  recommendations is expensive.

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Purpose (01 study)

• We demonstrated that intensive sampling with
  handheld device is cost effective and accurate

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Project Objectives (03 Grant)

• Develop an algorithm (possibly field specific) to
  derive variable rate lime recommendation maps

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Methodology (01 Grant)

• 1. Collected pH measurements in-field with a
  handheld pH meter on 1 acre systematic unaligned
  grids in 2001.
• 2. Compared to lab results and demonstrated
  effectiveness of handheld device and intense
  sampling

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Methodology (01 Grant)

• Since we were unable to develop a variable
  recommendation from our work in 2001, we
  arbitrarily decided to uniformly apply 1 Ton of
  65 ECC Lime in 2001

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Methodology (03 Grant)

• 3. Resample at same locations in 2003.
• 4. Analyze data. Develop field specific lime
  recommendation.

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Methodology (05 Grant)

• 5. Apply VR lime using recommendation developed.
• 6. Retest in 2005 to monitor success/failure of
  methodology.

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Established grid in 2001
We used Red Hen Systems' FarmGPS software to
derive the grid pattern and select the target
points. We also used it to navigate to the
points when we pulled our soil samples.
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2001 Systematic, Unaligned Grid
These are the systematic, unaligned target points
shown on a 1/4 acre grid with the field boundary
displayed.
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Handheld pH meter used
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(No Transcript)
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Show relationship - pH of field tested points
with lab tested samples.
250 vs. 17
01 pH w/250 points
01 pH w/17 points
Relate 76
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Variogram 01 data 250 points
Good Variogram
Gotcha!!
Variogram 01 data 17 points
We can make a pretty Map, but is it garbage?
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Resampled 250 points in 2003
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We simply recorded our results on a sheet of
paper when we did the testing with the portable
pH meter. These were later added to the MapInfo
file containing the sample point locations.
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Our previous MapInfo file was updated to include
the 2003 sample results.
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Brought data into Excel response to lime, mean
changes from 5.5 to 6.3
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2001 2003 comparisons in Excel response to
lime
Scatter plot 03 pH over 01 pH
H Scatter plot ???
pH 03
pH 01
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Variogram shows that data is spatially related,
and therefore can be mapped.
Variogram 01 pH data
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Variogram shows that data is spatially related,
and therefore can be mapped.
Variogram 03 pH data
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The maps in 3D, same color scheme
01 pH data
03 pH data
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2001 2003 pH maps showing improvement from lime
mean 5.4 to 6.3
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Histogram of pH data
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2001 2003 pH maps showing improvement from mean
5.4 to 6.3 difference map
Change in pH
01 pH data
03 pH data
(03 minus 01)
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2003 pH minus 2001 pH and change negative
responses to zero response
We need to do this so we wont be dividing by a
negative number or zero
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To calculate the amount of lime, we will use the
response to the previous application to guide us
in making the next application.
Since the application in 2001 was a uniform 1 ton
per acre of 65 ECC, then we can use the
following formula
Response to lime
0.65 tons ECC / Change in pH
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Response to lime
0.65 tons ECC / Change in pH
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Response to lime
0.65 tons ECC / Change in pH
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Response to lime
chopped off extremely high numbers
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Response to lime
Same data, different perspective
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Scatter graph of 03 pH with response to lime
(adjusted) NOTE It looks like this would be a
great place to use boundary analysis!!!
Tons ECC per unit change in pH
pH in 2003
Regression equation y 7.9 1.1x (R2 33)
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6.5 (pH desired) minus pH observed in 2003
Amount of change in pH to bring all points to pH
6.5
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Adjusted change needed map
(renumber negatives as zero)
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Response rate map (Tons ECC/change in pH)
Times
Change in pH needed to get to pH 6.5
equals
Application rate
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We will let the computer figure lime requirement
for each 50 foot grid by multiplying
response_adjusted by pH change (no negative
numbers)
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Application map to give to Applicator (in Tons
ECC per Acre)
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Comparing our data to Veris
pH map derived from sampling
pH from Veris data
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Comparing our data to Veris
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Cheap VR Lime Recs

• Scheufler Farms, Inc.
• Lee Scheufler

42
Thank you